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How Teachers Can Empower the Climate Generation

Thu, 09/19/2019 - 11:50

“We recognize that youth will inherit the unparalleled impacts of climate change and are among our most powerful advocates.”

This is the motivation—one of the “core beliefs”—behind Climate Generation, founded by National Geographic Society explorer and educator Will Steger. The nonprofit organization brought dozens of K–12 teachers to Washington, D.C., in August to immerse themselves in climate change education to give them a foundation to help better integrate it into their curriculua.

The Summer Institute for Climate Change Education, a partnership with the Lowell School and the National Oceanic and Atmospheric Administration’s Climate Office, was a multiday professional development experience to generate ideas and build new relationships that will help teachers to empower their students, whom they call the “climate generation.” AGU invited the group to spend its final day of the program at its Washington, D.C., headquarters to tour the first net-zero energy renovated commercial building in the city, one of many examples of climate action they explored during the trip.

Melissa Deas, a climate program analyst from the city’s Department of Energy and Environment, led the group in a discussion around Washington, D.C.’s Climate Action Plan, followed by a conversation with Janice Lachance, AGU’s executive vice president of strategic leadership and global outreach, who shared the history, challenges, and successes of embarking on a net-zero energy renovation project. Cristine Gibney, net-zero building operation specialist, led the teachers on a tour, pointing out examples of innovations communities can put into action to reduce energy use and emissions.

Climate science “is not isolated from the social, political, or cultural aspects of climate change.”This was the fourteenth annual summer institute, which focused this year on integrating climate change into humanities classrooms. Kristin Poppleton, the program’s director, said, “We want to make sure it’s clear that the goal of the program is climate change education,” rather than strictly climate science. “The science is not isolated from the social, political, or cultural aspects of climate change.” She explained that for a long time, climate change education remained mostly in the science classroom. This year, the teachers learned how to teach climate education through literature and the arts and found strategies to make sure that empathy and culture are part of the conversation.

Those strategies were reflected in the conversation at AGU headquarters. Taking refuge from the summer heat beneath the ceiling tile exchange system, or radiant cooling system, educators reflected on their experience throughout the program, considering the layers of social justice with regard to the science-based solutions observed. “Successful programs that support vulnerable communities are not developed solely through infrastructure but through human connection,” said Megan Van Loh, the education coordinator at Climate Generation.

Craig Johnson, a Minnesota-based environmental and climate educator, has been working with the Climate Generation program almost since its inception. In 2007, he and Steger led high school students on an expedition to Baffin Island in the Canadian Arctic, where they initiated an education exchange with an indigenous community experiencing the impacts of climate change. Since then, Johnson has been a champion of programs spearheaded through Climate Generation and recognizes the power of the #TeachClimate Network.

For others, the experiences gleaned from the program provide new additions to a growing tool kit used to prepare a younger generation for the future. Concetta Young, a third-grade teacher from a rural school district in western New York, explained that she had been seeking out resources to bring climate science into her classroom and came across the institute. She now has examples of real-world, community-based solutions that she can bring back to her students. “It is important to treat [third graders] as responsible and capable citizens of the globe,” she said. “Treat them as stakeholders.”

The summer institute for educators is just one of many programs Climate Generation carries out to equip the next leaders, scientists, and members of the workforce with the tools, knowledge, and skills necessary to tackle the rising consequences of climate change around the globe.

—Kelly McCarthy (@kmccarthy317), Centennial Communications Manager, AGU

This story is part of Covering Climate Now, a global collaboration of more than 250 news outlets to strengthen coverage of the climate story.

Climate Science Needs Professional Statisticians

Thu, 09/19/2019 - 11:50

“Climate is what you expect; weather is what you get!”

This old cliché rings true, for climate is the distribution of weather. Weather’s distribution depends on season, location, internal variability, and external influences, both natural and human. As it is weather, not climate, that is observable and measurable, any study of climate is inherently statistical in nature.

Climate change is one of the most important social issues of our time. The climate science community faces the immediate, important task of informing difficult decisions that must be made regarding our economic, environmental, and public health systems. Confidence in the effectiveness of these decisions derives from confidence in the underlying climate science. Appropriate statistical analyses can increase such confidence.

Hence, for climate science research to be most successful, statisticians and climate scientists must better integrate their research teams. Indeed, we believe that climate research requires multidisciplinary teams that include what we call climostatisticians. Such integration of these two scientific communities would likely require collaboration between divisions of research funding agencies, and might require reshaping of current reward systems in academic departments and government labs.

Taking a Cue from the Life Sciences

Depending on the climate science question, statisticians may take on the role of consultants or, alternatively, may need to do research themselves to develop novel statistical methods. Some climate questions, such as how to describe large-scale global aspects of the climate system, require existing, well-developed statistical approaches, and the statistician’s role is then to help choose and implement the appropriate methodology. It is important to have such consultants involved from the beginning of the research process so that research questions are properly paired with appropriate statistical approaches and so that appropriate data or model output are gathered. Statisticians take on a methodological research role—developing novel techniques—when they tackle more advanced questions, for example, quantifying the uncertainty of future climate projections.

The field of human biosciences can serve as a model for integrated research between domain-area scientists and statisticians.The field of human biosciences can serve as a model for integrated research between domain-area scientists and statisticians. Biostatisticians are such a fundamental part of medical and public health research today that it is hard to imagine this research being done in their absence. Indeed, biostatisticians’ work has contributed to the high level of public trust in modern medicine.

Biostatisticians work in both consulting and research roles. A biostatistician doing clinical trial work is likely to be involved in designing an experiment and subsequently analyzing the experiment’s data using techniques agreed upon by the community or required by regulatory agencies. Other projects, meanwhile, demand original statistical research. For example, a biostatistician doing public health work may need to develop a novel model to link contributing factors (e.g., air pollution data recorded at multiple locations) to medical outcome data (e.g., hospitalizations with anonymous patient information).

Integration of statisticians into climate science does not have the long history that biostatistics has. However, there are many important and successful examples of joint work between statisticians and climate scientists, and some of this work has influenced policy at the federal government level. In one such example, statisticians played a role in producing and reviewing the 2006 National Research Council report on paleoclimate reconstructions [North et al., 2006], which aimed to reconcile the “hockey stick” controversy arising from the congressional inquiry into the work of Mann et al. [1998].

Another example of collaboration between climate scientists and statisticians that should influence climate science practice is that of Paciorek et al. [2018]. This research shows that in the context of event attribution—that is, attributing the occurrence or severity of specific weather events to climate change—naïvely implemented (but commonly used) statistical bootstrap techniques quantify uncertainty poorly, particularly when estimating the small probabilities associated with attributing causes to individual events.

Hard Times for a Statistical Climatology Hub

Over the past couple of decades, statisticians dedicated to advancing climate science have emerged. These statisticians have developed advanced statistical techniques and demonstrated their use for understanding the nuances of past and future climates.

Many of the researchers in this fledgling field of statistical climatology received their graduate or postdoctoral training from a group at the National Center for Atmospheric Research (NCAR) that began in 1994 as the Geophysical Statistics Project (GSP) before evolving into the Statistics and Data Science (SDS) group.

GSP and its successor SDS developed statistical methods or models for spatial inference in the massive data sets now common to climate science, for numerical output produced by climate and other geosystem models, for studying paleoclimate, and for characterizing extreme events, among other applications. The group also hosted valuable workshops that brought together statisticians and climate scientists, and its visiting researcher program built even deeper collaborations between the two communities.

Indeed, the NCAR group served as the U.S. hub for statistical climatology, and much of the infrastructure in this emerging field has been directly tied to this successful program. Unfortunately, the field of statistical climatology suffered a major setback when SDS was eliminated in late 2017 as part of staffing cuts made at NCAR. The U.S. statistical climatology community is currently scrambling to reconstruct this infrastructure so as not to lose our capabilities in this area.

Perpetuating Success

Implementation of these new methods has not been as widespread, and the impact on contemporary climate science has not yet been as pervasive, as it should be.By many measures, the story of statistical climatology over the past 2 decades is one of success. In large part because of GSP and SDS, numerous researchers have been trained and are now leaders in statistics or climate disciplines, and statistical research has developed innovative methods useful for answering detailed climate science questions. However, implementation of these new methods has not been as widespread, and the impact on contemporary climate science has not yet been as pervasive, as it should be.

Part of the reason for statistics’ limited impact is money. The resources put into statistical climatology pale in comparison with funding for other areas, such as biostatistics. Another part of the reason has to do with the culture within both the statistics and climate science communities. Most statistical climatologists have academic homes in university statistics departments that tend to reward development of statistical methods over their application. And climate scientists have not adopted the practice, standard in biomedical research, of including statisticians when forming their teams or applying for grants. Thus, unlike for biostatistics, there is not a legion of consulting statisticians who are well trained in the techniques common to climate science.

The study of climate is every bit as important, interesting, and challenging as the study of medicine is. Although we are not calling for equivalent resources, we are calling for fundamental changes in statistical climatology so that it more closely resembles the field of biostatistics. Like biostatistics, climate studies require major research investments to develop appropriate methods for new, large, and unfamiliar data sources. Not only that, climate studies also require multidisciplinary teams, including climostatisticians, to integrate advanced statistical methods into climate science. Developing this capability will require significant resource investments from the major U.S. funding agencies as well as fundamental changes in practice from statisticians and climate scientists.

Most Southern California Mainshocks Follow Foreshocks

Thu, 09/19/2019 - 11:30

Foreshocks are the best-known precursor for earthquakes but, until now, observations of natural earthquake sequences have shown less than half of large earthquakes are preceded by foreshock activity. Trugman and Ross [2019] use a cutting-edge earthquake catalog (recently published in Science by a team including these authors) to analyze the question of how pervasive foreshock activity is before moderate-to-large earthquakes in Southern California.

They find a much higher rate of mainshocks with foreshocks than previous studies—over 72% of M4+ earthquakes—and show that our ability to identify earthquake foreshocks is tied to the magnitude of completeness of earthquake catalogs and thus the detection capabilities of earthquake networks. In other words, with improved seismic networks and advances in techniques to detect and locate earthquakes, we may find foreshocks are a more ubiquitous feature of earthquake sequences than previously thought.

While more work is needed to understand these observations, these findings likely have significant implications for earthquake hazard mitigation and our ability to forecast large earthquakes.

Citation: Trugman, D. T., & Ross, Z. E. [2019]. Pervasive foreshock activity across southern California. Geophysical Research Letters, 46, 8772– 8781. https://doi.org/10.1029/2019GL083725

—Gavin P. Hayes, Editor, Geophysical Research Letters

Methane-Releasing Tundra Soils Freezing Later Each Year

Wed, 09/18/2019 - 19:39

Arctic tundra ecosystems are hot spots for production and storage of methane, a potent greenhouse gas. As air temperatures rise, tundra soils may release more and more methane into the atmosphere. These soils freeze for several months each year, but new research by Arndt et al. suggests that the Alaskan tundra is freezing later each year, resulting in higher methane emissions in the fall.

Prior research has shown that Arctic tundra soils release a significant amount of methane well into the fall season during a period known as the “zero curtain.” In this window, the timing of which varies depending on location and from year to year, air temperatures are below 0°C, but underlying soils remain unfrozen—sometimes through January—because of slow latent heat release. However, because of limited data, zero-curtain methane emissions have been poorly understood.

The new investigation examined soil temperature and methane emissions data from four monitoring sites across the tundra in Alaska’s North Slope. One station is located at a National Oceanic and Atmospheric Administration (NOAA) observatory just outside Utqiaġvik, the northernmost city in the United States. There, atmospheric methane concentrations in late fall and early winter have been rising above background levels for 2 decades.

The researchers found that from 2001 to 2017, soils froze later, with the zero curtain extending further into winter by about 2.6 days per year. NOAA observatory data suggested that this later freezing was linked to higher above-background methane concentrations in the fall. The team’s data also showed that from 2013 to 2017, methane emissions dropped each year after the zero curtain closed.

The findings suggest that later soil freezing may increase methane release from Arctic tundra ecosystems. Because soils remained unfrozen after air temperatures dropped well below 0°C, the researchers concluded that air temperature is a poor predictor of methane emissions. Instead, long-term records of soil temperature could be essential for predicting the effects of climate change on methane release in the tundra. (Journal of Geophysical Research: Biogeosciences, https://doi.org/10.1029/2019JG005242, 2019)

—Sarah Stanley, Freelance Writer

This story is part of Covering Climate Now, a global collaboration of more than 250 news outlets to strengthen coverage of the climate story.

Katharine Hayhoe Named United Nations’ Champion of the Earth

Wed, 09/18/2019 - 19:00

On 16 September 2019, Katharine Hayhoe, a dedicated AGU member and winner of AGU’s 2014 Climate Communication Prize, was named a Champion of the Earth by the United Nations Environment Programme (UNEP). Hayhoe received this award, the highest environmental distinction bestowed by the U.N., for “her stalwart commitment to quantifying the effects of climate change and her tireless efforts to transform public attitudes.”

Hayhoe joined AGU in 2011 and has gone on to serve many of its programs. She served as deputy chair of the Technical Committee on Hydrologic Uncertainty from 2014 to 2015 and currently serves on AGU’s Climate Communication Prize Selection Committee. She has been active in AGU’s Sharing Science program and has supported members of the Voices for Science initiative.

A professor in Texas Tech University’s Department of Political Science, Hayhoe also directs the university’s Climate Science Center and teaches in the public health program of the Graduate School of Biomedical Sciences. According to Hayhoe’s biography, her primary work “focuses on establishing a scientific basis for assessing the regional to local-scale impacts of climate change on human systems and the natural environment.” She was also the lead author for the U.S. Global Change Research Program’s Second, Third, and Fourth National Climate Assessments.

“For years, Katharine has been on the leading edge of the causes and mechanisms contributing to global climate change.”The Champion of the Earth award recognizes those whose actions have had a transformational impact on the environment. Hayhoe was honored in the science and innovation category and is among five winners this year. Other categories include policy leadership, inspiration and action, and entrepreneurial vision.

Hayhoe also works to bridge the gap between the faith and scientific communities. She coauthored the book A Climate for Change: Global Warming Facts for Faith-Based Decisions, which seeks to dispel science myths about climate change, explore how faith can play a role in shaping opinions, and encourage positive actions around this global issue.

“For years, Katharine has been on the leading edge of the causes and mechanisms contributing to global climate change,” said Chris McEntee, AGU’s executive director and CEO. “At the same time, she has also been an unwavering voice helping communicate this science—and the subsequent consequences of inaction—to audiences from a diversity of backgrounds. On behalf of AGU’s community of 60,000-plus members, we congratulate her for receiving this highest of accolades.”

Hayhoe will be honored at a gala ceremony in New York City on 26 September 2019 during the 74th U.N. General Assembly.

This story is part of Covering Climate Now, a global collaboration of more than 250 news outlets to strengthen coverage of the climate story.

As Climate Changes, So Does the Apple as Rising Temperatures Push Growers Higher Into Himalayas

Wed, 09/18/2019 - 16:07

Climate change is to apples, what apples are to doctors. And, for India – where the northern Himalayan states of Jammu and Kashmir and Himachal Pradesh account for three-fourths of the fruit’s total cultivation – the stakes couldn’t be higher.

Consider this: India is the fourth-highest producer of apples globally. In 2016-17, 21,085 metric tonnes of the fruit worth Rs 57.76 crore were exported as per the National Horticultural Board (NHB). But things aren’t all well.

Take for instance, the case of Himachal Pradesh. Apple production in the state increased from 12,000 tonnes in 1960-61 to 394,000 tonnes in 1998-99.

But since then, there has been a steady decline in productivity, from an average yield of 10.84 tonnes per hectare in 1981-82, to just 0.88 tonnes per hectare by 1999-2000, as per the National Horticulture Board (NHB).

A renewed emphasis from the government with different measures like orchard rejuvenation saw an increase of productivity to 6.9 tonnes per hectare by 2013-14, but by 2016-17 this again fell to 4.4 tonnes per hectare.

“There are different factors for the lack of productivity in the state, ranging from bad management of orchards to changes in cultivation practice. But abnormal climatic conditions have definitely taken their toll,” an official said.

But farmers are increasingly realising that the ‘abnormal’ is fast becoming the new normal in the Himalayas.

In 2018, the authoritative study, The Hindu Kush Himalayas Assessment: Mountains, Climate Change, Sustainability and People came with a dire warning: act or be prepared for the consequences.

It said “even the most ambitious Paris Agreement goal of limiting global warming to 1.5 degree Celsius, would lead to a 2.1 degree Celsius spike in temperatures here and the melting of one-third of the region’s glaciers by the end of this century.”

For the crores of people who depend on the Himalayas for food, water and energy (in India, 70 percent of the water needs of the Himalayan region is met by melting of glaciers during summer), this would be devastating.

Uncertain Times

A 2016 study, titled, ‘Impact of Climate Change on Apple Production in India: A Review’, by scientists from Dr YS Parmar University of Horticulture and Forestry, Nauni, at Solan looked at the fruit production and meteorological data for the preceding four years and found that it indicated a “significant role of the abnormal climatic factors during flowering and fruit development in lowering apple productivity.”

Apart from factors that the farmers could control to a certain extent, such as moisture or soil structure, it pointed out that amongst “all the climatic components, temperature seems to be the most crucial factor in apple crop productivity”. It added that the role of “spring frosts, hails, summer droughts and unseasonal spring rain in lowering the productivity and fruit quality cannot be overlooked.”

Apples require approximately 700 to 1000 chilling hours to flower. Some require 1000-1500 hours. But melting snow caps have reduced the span of winters, Niranjan Singh, lead author of the study, told News18.

He added that melting ice also means rising sea levels, which in turn leads to erratic and unseasonal rain and hail.

Climatic factors have thus wreaked havoc on apple productions and quality by disrupting its natural flowering seasons and even pollination systems. The shape and size of Himalayan apples, Niranjan stresses, has changed.

Over the decades, farmers started shifting to varieties that did not require as many chilling hours. “The drop in quality has led to farmers in apple belts of regions like Kullu and Solan to shift completely from apples to other fruits such as peaches, apricots, pomegranates and kiwi.”

In the past decade, the incidence of premature and freak snowfall in Himachal Pradesh has seen a clear increase, while there has been a decrease in overall snowfall. In 2018, Lahaul and Spiti received heavy snowfall in the month of September. This year, Lahaul, an area that gets very little to no rainfall, received snowfall as early as August 17 – the earliest it has snowed in the area in the past decade, as per IMD director Manmohan Singh.

In 2019, Himachal also received freak spells of heavy rain and at least 24 lives were lost in August due to rain-related incidents and flooding. In one day, Himachal received 102 mm rainfall in a 24-hour spell, the highest in 70 years. Mirroring the larger pattern of unpredictable and sporadic intense rainfall, followed by lower levels of precipitation across the Himalayas, the state saw 12 percent less rainfall this monsoon than the annual average.

The 2001-2010 decade witnessed a rise in intensity and occurrence of extreme weather events such as heavy rain, severe storm, heat waves, severe droughts and splash flooding. In the past 50 years, incidents of extreme events of intense rain have doubled.

Singh though remained cautious and warned, “To correlate all instances of unusual weather phenomenon as a direct result of climate change would be rash,” he said.

But the losses are concrete. Just two days of snowfall last year, from September 22 to September 24 had reportedly led to a loss of Rs 94 crore, with multiple crops, including apples being impacted in Lahaul and Spiti. And yet, Shimla-based apple grower Ram Lal Chauhan felt that more than unseasonal snow, it was that lack of irrigation and rising temperatures that posed a bigger threat.

Warmer winters and tepid summers affect apple quality and the farmer rues that global warming has been consistently affecting the quality of fruit.

Rising Temperatures, New Heights

Temperatures of 7 degree Celsius or less are required to meet the chilling requirements of apples. But farmers said that poor snowfall and rising temperatures have resulted in bud break being erratic and delayed flowering. Apart from this, less snowfall during the winters also results in drier soil while spring frosts in the past decade have led to damaged crop, said the 2016 study.

“This year, the season was set back by 15 days but thankfully, we had good production,” Chauhan said.

Suraj Tayal, a Shimla-based farmer whose 50-year-old orchard in Rohru in Himachal Pradesh is amongst the oldest in the area said that “global warming and climate change” has made “everything very uncertain”.

“Things have completely changed. The quality and the health of the apple that we have today, compared to what we had even 10-years-ago is totally different. The best quality apples require about 300 chilling hours. That is when the skin of the apple is tight, but for that you need at least 2-3 feet of snow. Otherwise, the apple is overripe and is prone to infections from diseases,” he said.

Tayal pointed out that newer varieties of fast-growing apples imported from different countries like Italy were also prone to unfamiliar diseases. “You have to then import the medicine and the sprays to cure the plants. That is an additional cost,” he added.

Officials added that the European red mite in apple had almost become an epidemic in the apple growing regions of the state, while damage by other pests like shot hole borers and wooly apple aphid had become more prominent.

“Earlier, in 1970s…farmers routinely used four sprays for pest control. By 2016, this was up to 12 per year. This will only increase,” said an official of the state government. The 2016 study added, “Increasing incidence of pest and disease due to climate change comprises a shift in disease ecology and played a vital role in apple production…Some minor pests may become major pests in the future. Added to these, vector population may increase and new pathogens may emerge due to ecological and climatic change.”

While the 2016 study also pointed out that the extinct plantations of apple from Rajgarh in Sirmaur and lower areas of Kullu were “live examples of impact of climate change”, Chauhan pointed out another change.

A decade and a half earlier, he said, there were no apples grown in high altitude districts like Spiti and Lahul. But climate change and increasingly erratic climatic variables have compelled farmers to move up.

The hypothesis is one that has recently been gaining consensus among agrarian experts such as Dehradun-based farmer rights activist and ‎founder of Himalayan Action Research Centre (HARC), Mahendra Singh Kunwar. He noted similar migratory patterns among apple growers of Uttarakhand.

Kunwar points out that the current climatic conditions were not just compelling farmers to change locations but also shift to other crops. As per Singh, the entire apple belts of Kullu and Solan have shifted to growing apricots, peaches and fruits other than apple.

The Situation Now

Climbing to newer heights of the Himalayas might be a temporary solution to meeting chilling requirements but Niranjan Singh warns that the shift up could cause a permanent change in transpiration patterns that would encourage erratic weather anomalies such as unseasonable rain and snow. “The problem will start to manifest itself in about 10-15 years when the region gets more plantation,” Singh said.

But in spite of a “great yield” this year, farmers across Himachal Pradesh told News18 that they were suffering. “There is just no one willing to buy. The best quality apple that earlier sold for Rs 65 per kg is now selling at Rs 55 per kg, and the cheaper variety that went for Rs 50 per kg last year, is being sold at Rs 40 per year. A 28 kg box that is being sold Rs 1,100 this year was sold at Rs 1,500 last year,” said Tayal, adding that the economic downturn across the country was a key factor.

Floods in key states where a bulk of Himachal’s apples are usually sold — Maharashtra, Gujarat and prominent trading hubs of Tamil Nadu, Andhra Pradesh and Karnataka — drove down demand, added experts.

Apart from unseasonal and unexpected climatic conditions, a tapestry of other factors has also been impacting crops – from deforestation and mining resulting in land degradation and making the area more vulnerable to drought, to conflict with wildlife.

In Uttarakhand, for instance, conflict with monkeys has driven many farmers to grow medicinal plants like tulsi (holy basil) and selling tulsi-infused tea in markets.

But even if the farmer was to protect his crops from pests and have favourable climatic conditions, his job doesn’t end there. They must also physically transport the produce to mandis (wholesale markets). “They must also find their own market and set up the sale of their produce. That should not be the producer’s headache,” said Kunwar. In Uttarakhand, where occurrences of cloudburst and hailstorms have increasingly been affecting apple production due to shorter winters, farmers must find ways to store produce for long term and transport it to markets. Even if a farmer manages to protect his crop from snow or hail, he will never reach the market if roads are buried in snow or flooded with rainwater, says farmer and activist Aswal Ratan.

“We can’t control the weather, but it is the state government’s responsibility to ensure mobility for us,” an indignant Ratan tells News18, adding that inadequate cold storage facilities in the upper Himalayas were a key challenge faced by farmers.

This story originally appeared in News18. It is republished here as part of Eos’s partnership with Covering Climate Now, a global collaboration of more than 250 news outlets to strengthen coverage of the climate story.

Diverting the Mississippi River May Not Save Louisiana’s Coast

Wed, 09/18/2019 - 12:00

Louisiana has big plans to save its disappearing coastlines by harnessing the flow of the Mississippi River.

The state wants to build two massive river diversions—cuts into the river’s levees—that will redirect the water and sediment it carries to eroding wetlands. The man-made diversions are meant to mimic a natural process; before the levees were built, the Mississippi periodically flooded its banks, spilling sediment into new areas and building land.

But a new study suggests that river diversions don’t always lead to land gains, and the researchers are calling for better models of the planned diversions before the state sinks billions into this restoration effort.

The new study, published last month in Restoration Ecology, looked at two previous man-made diversions in Louisiana: the Davis Pond diversion, which began in 1991, and 2002’s Caernarvon diversion. The team used two satellite-based data sets to evaluate whether or not the diversions led to a net gain or loss of land. The first data set was collected between 1985 and 2014 to measure wetland greenness, and the second was a data set developed by researchers with the U.S. Geological Service (USGS) to quantify decades of land area change in Louisiana.

The analysis showed that although both diversions created land where the river was opened up, overall, they led to net land losses farther downstream.The analysis showed that although both diversions created land where the river was opened up, overall, they led to net land losses farther downstream. According to the researchers, that’s because most of the sediment dropped out of the water near where the diversions began, and the influx of fresh, nutrient-heavy water in the wetlands downstream increased the rate of soil decomposition and weakened plant roots.

“For thousands of years, the plants scavenged nutrients out of the soil and put a lot of biomass into it to accomplish that aim,” said Eugene Turner, an oceanography and coastal sciences professor at Louisiana State University and lead author of the new study. “But now they have lots of nutrients, so they don’t have to allocate the energy to build biomass as much below ground, so they put it above ground.”

The end result, Turner and his colleagues argue, is that the coastal wetlands are even more susceptible to erosion when tides or storms roll in. Indeed, the authors say that the diversion likely exacerbated wetland losses wrought by Hurricanes Katrina and Rita in 2005.

The main implication, Turner said, is that the state needs to have better models of river diversions that account not only for hydrological factors, such as sediment load and water height, but also the effect of nutrients and fresh water on coastal ecosystems. “As it turns out, engineering has to compensate for biology too,” he said.

A Different Kind of Diversion

However, officials and other experts said that the two diversions Turner and his colleagues evaluated aren’t the best proxies for the planned sediment diversions because they weren’t designed explicitly to build land. Rather, Davis Pond and Caernarvon were both freshwater diversions, built at a time when the consensus among managers was that salt water was the primary factor driving wetland loss.

“The idea in the 80s was that salt water was just wiping out the entire coast and that we had to prevent salinity intrusion,” said Christopher Swarzenski, a research hydrologist with the USGS. “Later, it became clear that saltwater intrusion was not such a big deal at all, but it takes so long to plan these diversions that, in the meantime, the two diversions were built and implemented.”

Turner and his colleagues also looked at another, much larger and natural diversion, called the Fort St. Philip crevasse, which opened up in 1973. In that case as well, the diversion resulted in net land losses.

It’s not clear that the benefits of any land built would outweigh the costs of other potentially deleterious effects of diversions.The two currently planned diversions, the Mid-Barataria and Mid-Breton Sediment Diversion Projects, with a price tag of $2 billion to $4 billion, are “more than an order of magnitude larger” than either Davis Pond or Caernarvon, according to Swarzenski. “That’s at the point where they can actually carry a little bit of mud out of the river into the wetlands,” he said.

However, Swarzenski notes that there is less sediment flowing down the Mississippi than there was when other historic diversions occurred. “The sediment load in the Mississippi River has decreased by half since 1980,” he said.

It’s also not clear that the benefits of any land built would outweigh the costs of other potentially deleterious effects of diversions. For example, Swarzenski points to the fact that in the wake of this year’s historic flooding in the Midwest and the prolonged opening of the Bonnet Carre Spillway, Mississippi declared that the freshwater flooding led to irreparable harm to its marine life. A river diversion at a scale large enough to build land would also divert enough fresh water to have similar effects along Louisiana’s coast, he said.

“The main take home from the Turner article,” Swarzenski said, “is that much better empirical evidence needs to be collected to understand how diversions work before committing to expensive diversions [that are] irreversible once built.”

—Kate Wheeling (@katewheeling), Freelance Writer

Invasive Species Drive Erosion in Aquatic Environments

Wed, 09/18/2019 - 12:00

Animals and plants are “geomorphic agents”, shaping the landscape around them through their daily activities of feeding, building homes, reproducing, and seeking safety. A recent article in Reviews of Geophysics focuses on the burrowing activities of various invasive species found in aquatic environments, examining how they modify the landscape and increase the risk of erosion. Here, one of the authors gives an overview of how the presence of different species can change geomorphic and hydrological processes, and suggests where additional research is needed to better understand their impact.

How do plants and animals influence the landscape?

Wherever plants and animals exist on Earth, they influence natural processes and modify the environment around them.Wherever plants and animals exist on Earth, they influence natural processes and modify the environment around them. This happens on a variety of scales from the movement of individual grains of sediment – for example, as fish forage for food on a riverbed – to the transformation of landscapes – for example, as beavers fell trees to build dams and create ponds to live in.

The actions of different species in different types of environment can be ‘positive’ – in that they create or protect landforms, encourage the restoration of degraded environments, or increase biodiversity – or ‘negative’ – in that they disturb the landscape, break down landforms, destroy habitats, and reduce biodiversity.

Why are invasive species a particular concern?

Non-native species can be quite disruptive to the natural landscape.The geomorphic activities of plants and animals in their native environments tend to be part of a well-balanced natural system. However, the introduction of non-native species can be quite disruptive to the natural landscape, and sometimes also causes damage to the economy and to human health.

Our review focuses on invasive species that make burrows in aquatic environments. Non-native species are introduced to new locations mainly through human activities; in the case of aquatic environments through commercial shipping, the aquarium and exotic pet trade, the fur trade, and aquaculture.

Burrowing can cause erosion, increase the risk of flood, and lead to habitat loss.Many creatures excavate burrows to create space for reproduction or refuge. In aquatic environments – such as rivers, lakes, estuaries and saltmarshes, as well as artificial drainage channels and flood defense structures – burrowing activities can cause erosion, increase the risk of flood, and lead to habitat loss.

Which invasive species are of particular concern in different parts of the world?

Aquatic burrowing invaders include crustaceans, fishes, reptiles, and mammals. Our review looked at the distribution of 10 different species and found that over 120 countries, states and territories in the world have at least one of these invasive non-native populations.

The red swamp crayfish (Procambarus clarkii) or Louisiana crawfish, native to northeastern Mexico and the southern USA, is now found around the world, where its extensive burrowing activities have dramatically altered freshwater environments. Credit: Rachid H (CC BY-NC 2.0)

As part our review, we searched multiple online invasive species databases.

The most globally widespread are the coypu (Myocastor coypus) and red swamp crayfish (Procambarus clarkii), which have established invasive populations in Africa, Asia, Europe and North America.

Other species, such as the isopod (Spharoma quoianum) are currently more geographically constrained in the United States of America but have the potential to spread.

Smaller animals excavate smaller burrows, but often occur in larger numbers and may also dig more burrows. This means that the impacts from smaller and less conspicuous animals such as aquatic invertebrates may rival those of larger mammals.

How does burrowing modify geomorphic and hydrological processes in aquatic environments?

The impacts of burrowing occur at different time and spatial scales. Consider, for example, a burrow in a muddy riverbank.

Burrows made by signal crayfish (Pacifastacus leniusculus) on the River Enborne, UK. Credit: Gemma Harvey

The excavation of an individual burrow will generate a relatively small input of sediment to the water body over a short time period. But multiple burrows across a larger area have the potential to generate more substantial changes to landforms and erosion rates over longer periods of time.

The creation, daily use, expansion, or even abandonment of burrows will alter the internal structure of the bank, likely weakening it, change the way water moves through the bank, and modify the flow of water around burrow entrances.

Additionally, the presence of a burrow and its occupant can modify the chemistry of the surrounding water and sediment which, in turn, can influence susceptibility to erosion.

Do we know how much damage burrowing species cause?

Despite increasing reports of damage to aquatic environments, there is a lack of research directly quantifying the impacts on instability and erosion.There are increasing reports of damage to aquatic environments, artificial drainage networks, flood defense infrastructure, and historic waterside landmarks, but there is a lack of research directly quantifying the impacts on instability and erosion. In part, this is due to the challenges of conducting such research. Erosion processes are highly variable over short distances and are episodic in nature so they are notoriously difficult to accurately quantify through field research.

What are some of the unresolved questions where additional research, data or modeling is needed?

It would be helpful if there were a model that could conceptualize the various geophysical effects of burrowing in an integrated way.It would be helpful if there were a model that could conceptualize the various geophysical effects of burrowing in an integrated way.

Our work brings together established models from soil science and fluid mechanics to hypothesize the range of effects that may be expected based on existing understanding of erosion processes in different environments. This provides a framework for future research.

Answering these questions will require a combination of computational modelling, laboratory experimentation and field research.Further research is needed to test the hypotheses set out in our conceptual model. In particular, we need a better understanding of how the size, shape and density of burrows created by different species influences the geotechnical, hydrological, and hydraulic processes that drive erosion. We need to understand how the impacts might vary for different sediment types and different types of aquatic environment.

Answering these questions will require a combination of computational modelling, laboratory experimentation and field research.

—Gemma L. Harvey (g.l.harvey@qmul.ac.uk;  0000-0003-1067-0553), Queen Mary University of London, UK

Union Leader Talks Coal and Climate

Wed, 09/18/2019 - 11:58

Cecil Roberts doesn’t have a beef about climate science and the need to do something about climate change. However, Roberts, president of the United Mine Workers of America (UMWA), does have a big beef about proposals to curb climate change that he says would cut well-paying American jobs in the coal mining industry. He also insists that no matter what the United States does to reduce or eliminate coal production and mining jobs in this country, it won’t make a dent in the amount of coal use in China and other parts of the world.

The United Mine Workers union “has never challenged the science regarding greenhouse gas emissions and man-made climate change. It is happening, and the world must address it.”“The UMWA has never challenged the science regarding greenhouse gas emissions and man-made climate change. It is happening, and the world must address it,” Roberts said in a recent speech in Washington, D.C. “We have long supported an economy-wide program to reduce CO2 [carbon dioxide] emissions, covering all major sectors of emissions—transportation, utilities, and industrial. We support global efforts to reduce greenhouse gas emissions, and believe it is short-sighted for the United States to isolate itself from international climate negotiations.”

Following his speech, Roberts told Eos that he disagrees with President Donald Trump, who has referred to climate change as a Chinese hoax. “I don’t agree that climate change is a hoax,” Roberts said. “Most people in the country, most people in the world believe there’s such a thing as climate change. We see that every day with what’s been going on in the Bahamas [with Hurricane Dorian] and other places around the world. Something is happening and the scientists tell us it’s climate change.”

“What we need to do is, OK, it’s happening, now how do we deal with it?” he continued. “The debate that we are having here, the disagreement that we have is how do you deal with it? We think we’re smart enough to deal with this without putting everybody in the country out of a job.”

Looking for a Middle Ground

“We strongly believe that there must be a way to find a middle ground in the climate discussions.”“We strongly believe that there must be a way to find a middle ground in the climate discussions,” Roberts added in his speech at the National Press Club earlier this month. “The proponents of climate action who have taken extreme positions such as the elimination of all fossil fuel use within a decade, or even two decades, either ignore or do not understand the severe level of dislocation in the economy that would result.”

For Roberts, a middle ground includes supporting carbon capture and storage (CCS) technology that removes carbon from coal plant smokestacks. He called CCS “the only real solution to seriously addressing global climate change.” Roberts said that his union supported the American Clean Energy and Security Act of 2009, the so-called Waxman-Markey climate change bill that if it had become law, would have invested heavily in “clean coal” technology and removing carbon.

Roberts told Eos that in addition to supporting CCS, the United States “ought to be investing heavily in all kinds of research and developing any kind of technology that will allow us to burn this fuel [coal] that we have an abundance of.”

In his speech, however, Roberts expressed concern about carbon tax legislation. “The impact of a carbon tax is sudden death for coal,” he said. “It means immediate job losses as utilities switch from coal to gas and renewables.”

Addressing Climate Change Globally

Although coal is on the decline in the United States, with the 289 coal-fired power plants shut down since 2019 representing 40% of the nation’s coal power capacity, the world still heavily relies on coal, he noted.

According to Roberts, currently, there are 2,000 existing coal-fired plants around the world with another 1,600 under construction. Last year, he said, the world consumed about 7.5 billion tons of coal, with about 691 million tons of that used in the United States to generate electricity. China, he added, has nearly 5 million coal miners compared with 52,000 in the United States.

“Eliminating coal jobs in America does not eliminate the global coal use.”“It’s time we talk about how to address climate change in a way that will actually have a global effect and not just serve to put American coal miners out of work while doing nothing to actually reduce greenhouse gas emissions worldwide,” Roberts said. “Eliminating coal jobs in America does not eliminate the global coal use. All we are really doing is transferring more production overseas, which will be done by poorly paid workers with little or no safety protections.”

Roberts said his union stands ready to assist in the development of climate legislation “that advances technology, protects workers and their communities, and moves the nation forward on an aggressive course of carbon mitigation while ensuring electric reliability.”

However, he said the union “will not sit quietly and watch our members, their families, and their communities be destroyed in the process. There is a way forward here that can accomplish the twin goals of maintaining good jobs for our members and their families and getting the reductions in greenhouse gas emissions the world needs.”

—Randy Showstack (@RandyShowstack), Staff Writer

This story is part of Covering Climate Now, a global collaboration of more than 250 news outlets to strengthen coverage of the climate story.

Drilling into the Past to Predict the Future

Tue, 09/17/2019 - 14:38

If your patient is seriously ill then making radiological scans, and analysing the resulting grainy images, can suggest the source of the problem. But there’s no substitute for surgeons actually opening them up and having a look.

The same applies to Antarctica’s Ross Ice Shelf, the world’s largest floating body of ice.

For several summers, scientists have been assessing what lies in front of the stalled Kamb Ice Stream, about 850 kilometres from Scott Base, near the “grounding line”, where the ice leaves land and starts floating. Radio waves have been fired into the ice and small explosives set off, creating “echoes” in black-and-white images much like those produced in hospitals.

The surveys near Kamb reveal a 600-metre-thick chunk of ice – as deep as Wellington’s Mt Victoria tunnel is long. Washing underneath is a relatively shallow 30 metres of water, part of the world’s least-explored ocean. And, at the bottom, there’s at least 200 metres of sea-floor sediment.

A multi-disciplinary group of scientists, led by New Zealand, will set up camp and drill through the ice shelf to reveal the sub-surface secrets.This season, while it’s daylight every hour of the day, a multi-disciplinary group of scientists, led by New Zealand, will set up camp and drill through the ice shelf to reveal the sub-surface secrets. Collaborators include the United States’ space agency NASA, and China’s Jilin University.

There’s something for everyone – engineers working the kilometre-long hot water drilling hose, as well as glaciologists, oceanographers, and paleoclimatologists. It’s a data treasure trove because the area is little explored. The ice shelf is about the size of France and the ocean cavity comparable to the North Sea.

There’s scant understanding of how the ocean water circulates because very few holes have been drilled through the shelf, says University of Otago associate professor Andrew Gorman, a marine seismologist who specialises in sea floor imaging. “It’s not a very good sampling.”

Craig Stevens is a physical oceanographer with Crown research institute National Institute of Water and Atmospheric Research, NIWA. The Wellington-based Australian, who became a New Zealander just this month, says it’s a “pretty weird piece of ocean”. “It’s very different to basically anywhere else in the planet.”

The sea-floor sediments are basically records of past change.

This untold narrative of what’s beneath the Ross Ice Shelf is crucial for the wider story of our warming world.

Floating ice is holding back the land-locked ice sheet, part of an Antarctic system that holds almost 90 percent of the Earth’s ice mass. Should warm ocean water trigger the shelf’s instability, sea level could eventually rise by metres, threatening coastal cities around the world. (For more on sea level rise, read this Eloise Gibson story.)

Has some instability already been triggered, which will lead to deglaciation of the interior of West Antarctica?Nearby Pine Island and Thwaites Glaciers, which flow into the Amundsen Sea, are already thinning, accelerating and receding. Has some instability already been triggered, which will lead to deglaciation of the interior of West Antarctica?

“We don’t know if that’s the case or not,” says University of Otago Professor Christina Hulbe, a glaciologist who leads the Ross Ice Shelf drilling project. “It hasn’t started over here [on the Ross Ice Shelf] yet. But it might.”

The not knowing keeps scientists up at night, she says. “And wanting to fill in the details to improve the projection.”

West Antarctica might be seriously sick, so it’s time to open up the patient and take a look.

Antarctica is divided by the 3200km-long Transantarctic Mountains, with an ice sheet on either side. The larger, thicker, and more stable East Antarctica ice sheet, on which the South Pole sits, has some of the coldest and driest conditions on earth. Because of its shape and elevation, West Antarctica’s ice sheet is more vulnerable to climate change.

Hulbe says satellite maps show that the bed on which ice is grounded in West Antarctica is far below sea level “and that makes this region particularly vulnerable to rapid change”. Evidence from the continental shelf suggests that the response to past climate change hasn’t been uniform. “It’s happened in fits and starts,” she says.

The West Antarctic Ice Sheet is dominated by ice streams, fast-flowing rivers of ice surrounded by more ice. The streams penetrate far into the interior and move the ice relatively quickly (compared to the East) to the coast.

It’s predicted that by the end of the century there could be anything between slight melting of the Ross Ice Shelf and its complete loss.As the ice moves from land to floating on water, going from a “sheet” to a “shelf”, it tends to speed up, stretch out and get thinner, eventually calving off at the ice shelf’s imposing front face. The ice sheet rests in a bowl-shaped depression, with its base far below sea level – a shape that inherently causes instability. Hulbe says once the fast retreat begins, the ice will always tend to go afloat as there’s no higher ground to stabilise on.

Victoria University of Wellington’s Nick Golledge, a climate modeller focused on ice sheets and sea level rise, says depending on the simulations, it’s predicted that by the end of the century there could be anything between slight melting of the Ross Ice Shelf and its complete loss. “So, quite a lot of uncertainty.”

Huw Horgan, Golledge’s colleague at Victoria’s Antarctic Research Centre, says 90 percent of the ice that leaves Antarctica does so via ice streams. “So that really tells you if we want to know how ice leaves the continent we need to understand ice streams.”

The big concern, Otago University’s Hulbe says, is a “non-linear” response – what’s called marine ice sheet instability – started by warming and melting at the coast. In a linear response, a little bit of warming gets a little bit of response. With non-linear instability, what starts as a small change is amplified into a runaway response. (The same ice flow physics is at work in both cases, Hulbe says – the difference is the rate of change.)

As Hulbe puts it, the rate of retreat depends on the rate of retreat. “So it just goes faster and you can’t stop it, until the climate changes such that the ice sheet starts to re-grow.”

That puts greater weight on this season’s health check near Kamb Ice Stream.

The drill site is “where the rubber hits the road in terms of the whole melting story.”NIWA’s Stevens says the drill site is “where the rubber hits the road in terms of the whole melting story” – where the under-shelf ocean narrows. This season’s work will be the furthest south Stevens has been, after conducting much of his previous Antarctic research along the northern edge of ice shelves, studying the outflow impacts on sea ice and ocean flows.

“This is the first point at which the warm ocean and the warming ocean contacts the ice and starts melting and starts setting off a train of processes that we’re trying to measure and model and predict how they’ll influence the future ocean.”

Through the drilling, scientists want to know how much melting is happening on the underside of the ice shelf, what ocean temperatures are like, the melt-water outflow from the grounded ice, and, through the sea-bed sediment cores, how that area has responded to past changes.

Gavin Dunbar, also of Victoria’s Antarctic Research Centre, is one of New Zealand’s most experienced geologists at examining Antarctic sediment cores. He first went to the ice as a post-doctoral fellow in 2003, to conduct a site survey for the multi-country, $US30 million ANDRILL project. (What’s being attempted this summer is smaller, less ambitious and, importantly, more affordable.)

“The accumulation of sedimentary rocks, is basically nature’s tape recorder,” Dunbar says. “The sediments accumulate over time and the type of sediment – the micro-fossils within them, the size of the particles, all of those things – indicate what the environment was like at the time this material was deposited.”

ANDRILL records, for example, show that three or four million years ago the earth was about three or four degrees warmer than today. That rock record, collected near Scott Base, shows that where there’s now ice, back then there was open water. “We can use that information to build up a picture of how Antarctica responds to climate change on a large-scale, long timeframe.”

Drillers near the Kamb Ice Stream will use equipment last used in 2017, at a site dubbed Hot Water Drilling Site Two, or HWD2 (even though it was the first drilled), about 350 kilometres from Scott Base, nearer the middle of the Ross Ice Shelf. This season’s drill site is known as HWD1.

Then the fun starts, with winches sending down scientific equipment.A kilometre-long hose uses hot-water jets from a nozzle to “drill” through the ice. That pilot hole is then reamed wider to about 30cm. (“As soon as you make it it starts to freeze closed again,” Otago’s Hulbe says. “It’s a battle against temperature and salinity, as soon as you make the borehole.”)

Then the fun starts, with winches sending down scientific equipment.

As a one-off this season, the team will collaborate with China’s Jilin University, which has designed a specialist sediment coring tube. NASA, meanwhile, in association with US university Georgia Tech, has developed a 3.5m-long, 130kg underwater robot called Icefin which one day might be sent to explore the oceans of Europa, Jupiter’s innermost icy moon.

“Their submarine obviously it comes with lots of NASA tech that we certainly couldn’t afford ourselves,” Dunbar says. “It’ll be a great thing if it works.” (Icefin was meant to be used at HWD2 in 2017 but 12 days of fog meant the plane couldn’t fly there.)

Cores collected from HWD2 were 65cm long, covering about 20,000 years of sedimentary history. The longest corer this season is 3m – which is expected to produce a record over tens of thousands of years rather than millions, but still useful.

“So if we get a good record there we’re confident that we’ll be able to get a much better understanding of what the most vulnerable, large bit of Antarctica was behaving like in the past, which was something that ANDRILL couldn’t do directly,” Dunbar says.

Scientists think the Ross Ice Shelf is fairly close to a state of balance right now, Golledge says. That’s an average – so while some parts, like Thwaites Glacier, are melting relatively quickly, other areas of ice are thought to be thickening. But that potentially good news is based on limited observations.

There are plenty of other important, unanswered questions.There are plenty of other important, unanswered questions.

More than 90 percent of the extra heat coming from increased greenhouse gas emissions is being stored in the ocean. Climate modeller Golledge says: “The chances are we’re going to put a lot of extra heat into the ocean, we just don’t really know how much.”

What does that mean for the ocean under the Ross Ice Shelf? That depends on how much heat from the open ocean is flowing into the cavity, and how much extra melting that causes on the ice’s underside.

NIWA’s Stevens believes there is more mixing within the interior of the ocean cavity than perhaps we originally thought. “This may actually be a mechanism for slowing down the melt process. It might be a slightly good news story – but that’s active research.”

On the flipside, there’s the potential effect of ocean mixing on the global thermo-haline circulation – in which cold, salty water sinks near the poles, flows along the ocean bed and slowly mixes back to the surface in the mid-tropics.

“To have that initial kick of salty, cold and oxygenated water, things need to be cold enough and structural enough to be actually growing lots of sea ice,” Stevens says. “If things warm up so much that that process closes down then we’ll change how that heat and salt and oxygen is injected into the planet’s oceans.”

Another Ross Ice Shelf conundrum is why the calving line, the shelf’s dramatic front face in the Ross Sea, has remained fairly static for the last 6000 to 6500 years, despite big temperature swings.

Part of the answer is thought to be pinning points, quirks of geography that can stall ice movement. One such point is Minna Bluff, a rocky promontory south of Ross Island, in the corner of the ice shelf. “It’s kind of like holding the cork in the bottle,” Golledge says

Worryingly, it’s an area known to have high melting. If the ice shelf retreats from that area that could cause huge problems, Golledge says. “Because it’s such a key part then once we lose that pinning point the ice shelf can then retreat a whole lot more quickly from that point on.”

Gorman, the marine seismologist, is adamant humans still have time to take action.It’s not all doom and gloom.

University of Otago’s Gorman, the marine seismologist, is adamant humans still have time to take action. “Quite often people are thinking it’s too late, I can’t do anything so let’s not even bother trying. But I think it really is worth trying to bring things back to some sort of level that will make things not quite as bad for future generations.”

Gorman’s colleague, Hulbe, says it matters when humans stop pushing the climate. “Even if you’ve committed to getting rid of a lot of the West Antarctica ice sheet, how fast it goes depends on how hard you were pushing when you stopped. In a weird way it’s an optimistic thing, right? It’s always going to matter that we do something.”

Climate modeller Golledge has just returned from France, where he’s helping write the ice sheet, sea level, and ocean chapter of the next big Intergovernmental Panel on Climate Change assessment report, due out in 2021. If his comments can be taken as some sort of medical report, then the planet’s health is heading south.

“Basically if we continue on the temperature emissions trajectory that we’re on, we’re pretty much going to lose those big ice shelves – the Ross and the Filchner-Ronne – probably within the next couple of centuries. That’s pretty bad news for the ice sheet, of course, and then the ice flows into the sea.”

Some studies suggest parts of West Antarctica, particularly in the Amundsen Sea embayment where Thwaites Glacier is, are essentially already undergoing retreat, and even if temperatures are stabilised at present-day values, that retreat won’t stop.

Action by governments is absolutely urgent. Gorman says the sooner temperatures are under control the more chance there is of slowing the warming process.“Unfortunately, I guess it looks as if we’re not going to be in a position to completely prevent some loss of West Antarctica,” Gorman says.

That makes action by governments absolutely urgent. Gorman says the sooner temperatures are under control the more chance there is of slowing the warming process.

“It’s about buying us time. People talk about irreversible retreat and thresholds for collapse and stuff, but these things play out at different rates – and that’s what we have control over.

“It’s not a case of, ‘It’s already happening so there’s nothing we can do’. It’s very much, ‘It’s already happening so we have to do absolutely everything possible to make sure it happens slow enough that the effects can be managed and dealt with’.”

This story originally appeared in Newsroom. It is republished here as part of Eos’s partnership with Covering Climate Now, a global collaboration of more than 250 news outlets to strengthen coverage of the climate story.

Ancient Precipitation Reveals Clues About Mountains and Climate

Tue, 09/17/2019 - 12:10

The supercontinent Pangea was formed from titanic collisions of landmasses that folded and lifted Earth’s crust. Now, researchers have pieced together evidence about the mountains created by these collisions, though they have long since eroded away.

Using chemical measurements of 300-million-year-old precipitation from modern-day France, scientists have shown that the peaks situated roughly in the middle of Pangea were about as tall as the European Alps. Because mountainous geography affects atmospheric circulation, these results also shed light on the paleoclimate during the Carboniferous period, the researchers suggest.

“The roots of the mountains are outcropping at the surface.”In 2016 and 2017, Camille Dusséaux, a geologist at the University of Plymouth in the United Kingdom, and her colleagues collected granite in northwestern and southern France. The sites they sampled contained the eroded remnants of the Variscan mountain belt, a span of mountain ranges created when the continents of Laurussia and Gondwana converged hundreds of millions of years ago. The granite the researchers collected was once 3–12 kilometers underground. “The roots of the mountains are outcropping at the surface,” said Dusséaux.

Dusséaux and her collaborators preferentially selected rocks in detachment zones, fractures in Earth’s crust. Detachment zones function like conduits that allow precipitation like rainwater and snowmelt (“meteoric water”) to percolate down, said Dusséaux.

Back in the laboratory, Dusséaux and her colleagues crushed the rocks and looked for muscovite, a mineral in the mica family. Because muscovite interacts with water, it records the chemistry of falling precipitation.

“The meteoric water goes down in the crust and exchanges with the muscovite,” said Dusséaux. “That will change its hydrogen and oxygen isotope composition.”

Isolating Isotopes

That’s important because in a twist of physics, the chemical composition of precipitation reflects a landscape’s topography.

Water molecules—each containing two hydrogen atoms and one oxygen atom—come in slightly different forms. Some water molecules contain deuterium, an isotope of hydrogen with one proton and one neutron in its nucleus (“heavy hydrogen,” 2H), rather than 1H, which contains only a proton in its nucleus. Water can also contain 18O, an isotope of oxygen with 8 protons and 10 neutrons in its nucleus, rather than 16O, which contains 8 protons and 8 neutrons.

In clouds, heavier water molecules—those containing deuterium or 18O—tend to condense before their lighter brethren and fall as precipitation. Therefore, a mass of air at higher elevation, which has condensed multiple times, tends to have fewer water molecules containing deuterium or 18O.

“Every time precipitation forms, the air mass will become more depleted in heavy isotopes,” said Dusséaux.

Dusséaux and her colleagues found that the muscovite in their samples was relatively depleted in deuterium, consistent with the original meteoric water falling from a higher elevation (i.e., over taller mountains). Using known relations linking the prevalence of deuterium-containing water molecules and elevation, Dusséaux and her collaborators estimated that the elevation of the Variscan mountain belt was once comparable to that of the European Alps.

“No one had ever measured the hydrogen before,” said Dusséaux. “This is the oldest hydrogen isotope composition of rainwater ever recovered.”

Contributions to Climate Modeling

These paleoaltimetry estimates reveal more than just topography. They’re also important for climate modeling because mountain ranges affect atmospheric circulation. For example, the contours of Himalayan peaks and valleys have been shown to affect monsoon precipitation.

“There are all of these mountain belts where I think this is the best approach.”In agreement with previous research, Dusséaux and her colleagues suggest that modern-day France was previously located near the equator in a warm climate. These results, some of which were published in Terra Nova earlier this year, were presented at the 2019 Goldschmidt geochemistry conference last month in Barcelona, Spain.

“This was a really well done study,” said Page Chamberlain, a geochemist at Stanford University not involved in the research. A lot of research has focused on younger mountains, but no one had previously used this technique in the Carboniferous period, he said.

Dusséaux and her team’s methodology should be applied to other regions as well, said Chamberlain. “There are all of these mountain belts where I think this is the best approach.”

—Katherine Kornei (@katherinekornei), Freelance Science Journalist

Climate Change Is Coming for Our Fish Dinners

Tue, 09/17/2019 - 12:09

Omega-3 fatty acids could be one reason that human brains evolved to be so powerful, but changing water conditions associated with climate change may reduce the amount of omega-3 available for human consumption. A new global tally of the omega-3 fatty acid docosahexaenoic acid (DHA) found it will drop in availability by 10%–58% depending on how aggressively humans curb greenhouse gas emissions over the next century.

Humans get their dietary dose of DHA from eating fish and shellfish. The Food and Agriculture Organization of the United Nations recommends infants consume 100 milligrams per day, and studies advise that adults consume between 50 and 500 milligrams per day (adult dosage is an active area of research). DHA helps with signal transduction in the brain; past research suggests it aids learning in toddlers, and it may be linked with lower rates of Alzheimer’s.

Fish will have lower amounts of DHA because of climate change, said Stefanie Colombo, an assistant professor in aquaculture nutrition at Dalhousie University in Halifax, Canada, and an author on the new study published in Ambio.

Fish get DHA from algae, tiny aquatic organisms that grow in fresh and salt water. Algae use DHA to moderate the fluidity of their body; when the water around them is cold, they avoid freezing by amping up their DHA. Because climate change is warming waters around the world, algae are producing less DHA. In a 2016 study, Colombo and colleagues found a “significant and powerful correlation” between increasing water temperature and the amount of DHA in algae.

The scientists took the research one step further in the latest study, modeling the total DHA in fish around the world over the next century under four different greenhouse gas emissions scenarios.

Under the scenario with increasing greenhouse gas emissions, which most closely aligns with today’s emissions behaviors, “we found that up to 50% of our DHA could decrease in the next 80 years,” Colombo said. “To me, that was the biggest number.”

“An Underappreciated Risk of Global Warming”

High-latitude countries like Norway, Greenland, and Chile are projected to sustain enough fish yields to remain above the daily recommended dose of DHA in 2100. But the new model predicts that countries such as China, Japan, and Indonesia that currently produce enough DHA for their populations will have insufficient stores by the end of the century.

Countries in Africa that rely on inland fisheries will be hit the hardest. Lake and river waters are warming faster than the ocean, and countries that aren’t affluent may not have access to trade or new technologies. Many African countries will produce less than 25 milligrams per person each day by 2100, far below the recommended intake for both infants and adults.

Technologies to combat a reduced amount of DHA are still in their early stages. Early trials on genetically modifying the oilseed in canola oil to include DHA are awaiting approval by U.S. regulatory bodies. Growing algae in controlled environments is often prohibitively expensive, Colombo said.

The new study “describes one of the most important threats for humans during ongoing climate change,” said Martin Kainz, a scientist at WasserCluster Lunz who was not involved with the research.

Humans can’t create their own omega-3 fatty acids but need it in the cell membranes in our neural tissues to facilitate signal transfer among cells. The projected decline in DHA availability “will thus have detrimental effects for human well-being and perhaps even for human evolution,” said Kainz.

Irina Guschina, a research fellow in the School of Biosciences at Cardiff University in Wales who did not participate in the new study, said that the research raises awareness of an “underappreciated risk of global warming.” She cautioned that the recommended dose of DHA for adults is still being debated, however, and that other fatty acids like omega-6 are also important for human health.

Colombo said that how fish react to lower DHA still needs to be tested in the lab, including their metabolic response to warming temperatures. She plans to feed fish in tanks with different levels of DHA and increase their water temperature. “That’s kind of a follow-up study that I probably wouldn’t have done unless we did this model,” she added.

—Jenessa Duncombe (@jrdscience), News Writing and Production Fellow

This story is part of Covering Climate Now, a global collaboration of more than 250 news outlets to strengthen coverage of the climate story.

Local Climate Projections: A Little Money Goes a Long Way

Tue, 09/17/2019 - 12:07

Long-term planning and decision-making for fundamental societal infrastructure must take a changing climate into account. This infrastructure includes elements such as transportation, energy supply, and water and drainage systems. Typically, the relevant climate projections include substantial inherent uncertainty, and appropriately accounting for this uncertainty is critical to good decision-making.

To this end, decision-makers, engineers, and scientists from all fields urgently need new generic eScience tools. These data-intensive, information technology–intensive, and collaborative capabilities enable users to apply the extensive existing repositories of observations and climate model data as well as recent methods for uncertainty quantification in climate science.

In the Nordic Council–funded project eScience: Statistical Analysis of Climate Projections (eSACP), climate scientists and mathematical scientists from seven partner organizations (including the national meteorological institutes) in Denmark, Finland, and Norway joined forces to develop a suite of open access tools for climate assessment. The tools provide the following:

functionality to handle automatic downloads from the dynamically growing data repositories methodology to effectively quantify and visualize uncertainty in climate projections a multiplatform approach to decision-making under uncertainty that can flexibly be tailored toward a variety of situations

Our focus has been on Nordic data and local or regional questions regarding temperature, precipitation, wind, and sea level. Here we describe several of the tools we developed under the eSACP project.

Making Data Manageable

One important objective of eSACP was to distill relevant information from large data volumes and from multiple sources. One prototype app developed by the Norwegian Meteorological Institute (NMI) presents empirical-statistical downscaling results for large multimodel ensembles of global climate models (Coupled Model Intercomparison Project 5 (CMIP5)) based on R Shiny, an interactive Web app builder for the R computer language [Benestad et al., 2017a]. The results presented in the app are based on a data compression technique called singular vector decomposition that reduces the data volume while retaining the most important information from climate model ensembles [Benestad et al., 2017b].

One analysis highlights the presence of nonstationarity in sea level, not just in terms of rising mean seas but also in the height of storm-driven surges.The three meteorological institutes collaborated on a method to analyze extreme values of storm-driven sea level surges by analyzing Danish sea level tide gauge records (P. Thejll et al., Non-stationarity in Esbjerg sea-level return levels: Applications in climate change adaptation, submitted to Extremes, 2019). For this analysis, they used storm tracks found by analyzing reanalysis data over the north European area, derived by the Finnish Meteorological Institute and visualized by its Norwegian counterpart, NMI. The extreme surges display nonstationarity (a change in what is considered normal) and depend on mean sea level for their location and the North Atlantic Oscillation index for their scale parameter, with the latter being related to the spread of storm tracks near Denmark.

In another effort, we used a statistical downscaling approach for sea levels [Bolin et al., 2015] to produce sea level projections for all Permanent Service for Mean Sea Level stations with known glacial isostatic adjustment in Denmark (6 sites), Finland (12), Norway (8), and Sweden (5). Figure 1 shows the projections under the Representative Concentration Pathway (RCP) for Oslo, Norway, using RCP 8.5, a relatively high estimate of greenhouse gas emissions. (Norwegian authorities require communal planning to be based on the 95th percentile of RCP 8.5.)

Fig. 1. Observed (blue) and projected (red) sea level rise (in centimeters) for Oslo under the highest emissions scenario (RCP 8.5) using the CMIP5 climate projections. The dashed purple lines are pointwise 90% confidence bands (coverage probability for each year separately), whereas the thick black lines are simultaneous 90% bands (all years simultaneously). In Oslo, the magnitude of land rise due to postglacial rebound dominates the effect of sea level rise, so even under the RCP 8.5 scenario, it is possible that hardly any sea level rise relative to 2000 will be observed by 2100.

Thorarinsdottir et al. [2017] and Guttorp and Thorarinsdottir [2018] describe how to combine sea level rise projections and decision-making into adaptation plans. This work is continued in a further collaboration between colleagues from the Norwegian Computing Center, Danish Meteorological Institute (DMI), and Technical University of Denmark (DTU). The new study assesses sea level in three Danish coastal cities. The analysis highlights the presence of nonstationarity in sea level, not just in terms of rising mean seas but also in the height of storm-driven surges. These results will be used in a future study of the costs to the communities of such changes, given projected future climate change.

Getting the Word Out and Moving Ahead

Our project also organized a workshop bringing together practitioners and researchers to discuss “practical and methodological challenges of climate change adaptation” [Thorarinsdottir and de Bruin, 2016]. Climate scientists, environmental economists, statisticians, climate service providers, and practitioners in various decision contexts, mainly at the city and state levels, attended the workshop, which was structured around three themes: adaptation, uncertainty, and visualization. Discussions during the workshop provided the project with valuable feedback from practitioners regarding both the content and the presentation of climate information needed in practice.

The amount of money in our project grant was quite modest, but the work has had substantial consequences.The amount of money in our project grant was quite modest, but the work has had substantial consequences. Although R Shiny apps might not be the optimal design for eScience products with a large number of users, this approach is very efficient for the necessary experimentation and prototyping before a full-fledged product can be designed and built. For example, NMI is currently applying this same approach to develop prototypes of further applications for visualizing and exploring climate model data in the Copernicus Climate Change Service project Data Evaluation for Climate Models. This work directly builds upon work that started with eSACP.

Several of eSACP’s original aims are met by the forthcoming Danish Climate Atlas (DCA) to be hosted at DMI. The objective of DCA is to deliver a common Danish data set for use in, for example, climate adaptation based on national and international data repositories, including tools for decision support and for visualization and analysis of the expected impacts of climate change on society. The DCA will use several of the methodologies developed in eSACP, including the above-mentioned statistical downscaling approach for sea levels. Guttorp et al. [2014] further developed this approach, and it is currently used in a joint Ph.D. study between DMI and DTU that will feed into the DCA.

The atlas, which received funding in 2017, is scheduled to reach the first milestone in September 2019: delivery of an eScience information portal. This portal will allow citizens and end users in municipalities as well as from engineering consultancy businesses to evaluate the expected climate-driven impacts and to download quantitative data.

Acknowledgments

This research was partially funded by the Nordic Council. Data and code are available at the project website. The partners of eSACP are the Norwegian Computing Center (lead), Norwegian Meteorological Institute, Uni Research Norway, Finnish Meteorological Institute, University of Helsinki, Danish Meteorological Institute, and the Technical University of Denmark.

Looking Away from the Sun: Improved Tracking of Solar Storms

Tue, 09/17/2019 - 11:30

Coronal mass ejections (CMEs) drive many of the most disruptive space weather impacts; these clouds of plasma can enhance the flow of energy carried by the solar wind and those CMEs that hit the Earth can drive strong geomagnetic activity leading to impacts on many vital technologies including power grids and satellites.

Wharton et al. [2019] provide a proof of concept on how heliospheric imaging can be used to refine forecasts of the arrival of CMEs at Earth, a key element in forecasting a wide range of space weather impacts. Current forecasts are based on conditions at the time of CME launches and can use ensemble methods to forecast a range of potential outcomes. These forecasts are typically based on coronagraph observations of CMEs close to Sun. Those observations can now be complemented by data from heliospheric imagers, very sensitive cameras that can observe CMEs at greater distances from the Sun.

The authors present an improved CME analysis tool (CAT-HI) that can include observations from heliospheric imagers. They show that these additional images may be used to prune ensemble forecasts and thereby provide updated forecasts during the CME transit to Earth.

Such updates have the potential to help operations teams preparing to deal with adverse impacts that may follow CME arrival at Earth. Hence this proof of concept adds real practical value to space weather forecasts, especially if, as planned, the next generation of space weather monitoring missions from Europe and the United States provides greater access to heliospheric imager data.

Citation: Wharton, S. J., Millward, G. H., Bingham, S., Henley, E. M., Gonzi, S., & Jackson, D. R. [2019], Incorporation of Heliospheric Imagery into the CME Analysis Tool for improvement of CME forecasting. Space Weather, 17. https://doi.org/10.1029/2019SW002166

—Michael A. Hapgood, Editor, Space Weather

Ceres: Evolution of the Asteroid Belt’s Icy Giant

Mon, 09/16/2019 - 13:01

Ceres, the largest object in the asteroid belt, is composed of rock and ice. NASA’s Dawn spacecraft, which orbited Ceres between 2015 and 2018 gave scientists lots of new insights into its shape and internal structure, surface morphology, and composition. A special collection in Journal of Geophysical Research: Planets focuses on evidence of ice in Ceres’ subsurface and its dynamical behavior. I asked Hanna Sizemore, guest editor of the special collection, some questions about the mission and what has been discovered.

Ceres was one of two bodies in the asteroid belt visited by NASA’s Dawn mission. Why was Ceres a focal point of this exploration mission?

Ceres and Vesta are generally viewed as two extreme cases of the possible evolution of large asteroids. Before the Dawn mission, both objects were thought to have formed in the same neighborhood but at different times. Because Vesta formed early, it accreted Aluminium-26 (26Al), which produced abundant internal heat and rapid loss of water and other volatiles. Ceres formed later, experienced less heating, and was able to retain much more of its water [McCord and Sotin, 2005].

An important goal of the Dawn mission was linking large asteroid interiors to early conditions in the protoplanetary disk, with Ceres representing one extreme scenario. There has been a long debate about how much of Earth’s water was delivered from the main belt, and whether it came in the form of hydrated minerals or ice. The amount of water in the main belt is only beginning to be inventoried.

Having a spacecraft in orbit around an ice-rich main belt object is extremely valuable.There are big challenges in linking surface composition information derived from telescope data to information about asteroid interiors [Rivkin et al., 2019]. These challenges make having a spacecraft in orbit around an ice-rich main belt object extremely valuable. As both the largest and the most ice-rich object in the main belt, Ceres was a prime target for a mission.

The special collection has a focus on water ice. How has ice been an important factor in shaping the evolution of the surface of Ceres?

Ceres owes its internal structure and its spherical shape to ice.At the most basic level, Ceres owes its internal structure and its spherical shape to ice. It was able to partially differentiate (to form a rocky interior surrounded by an icy outer shell) because ice melts at lower temperatures than rock. It was able to retain enough mass to be spherical because it was cool enough to hang on to most of its H2O and other volatiles, unlike Vesta.

Ice also plays a key role in modern landscape development on Ceres.Of course, ice also plays a key role in modern landscape development on Ceres. There are eight broad classes of surface features that have been specifically linked to subsurface ice and are observed over most of the dwarf planet’s surface [Sizemore et al., 2019b].

Large domical mountains, such as Ahuna Mons [Reusch et al., 2019], were some of the first to be recognized in the earliest images to be returned by Dawn. Some of these mountains may be cryovolcanoes, or they may be formed by massive ice diapirs [Sori et al., 2018; Sizemore et al., 2019b].

Dramatic intermingling of landslide and ejecta material at the intersection of two craters. Credit: NASA/JPL-Caltech/ UCLA/ MPS/ DLR/ IDA (public domain)

Lobate landslides and ejecta were also recognized as ice-controlled features early in the Dawn mission [Schmidt et al, 2017].

Landslides are nearly everywhere on Ceres, but they are morphologically diverse [Chilton et al., 2019; Duarte et al., 2019].

Some show similarities to rock glaciers on Earth and Mars, some have characteristics in common with landslides on Iapetus.

Ice in Ceres’ subsurface contributes to the formation of fluidized, lobate, and layered ejecta around craters.

In some cases, Cerean ejecta is similar to layered ejecta formed in icy terrains on Mars and Ganymede [Hughson et al., 2019].

Intermingling of ice-rich ejecta and landslides creates unique Cerean terrains [Duarte et al., 2019]. Some smooth ejecta on Ceres is also pitted, probably due to water vapor and other gasses escaping soon after the impact [Sizemore et al., 2017].

The Juling Crater, which is about 20 kilometers in diameter, hosts several features linked to ice in the subsurface, including lobate landslides, fluidized and lobate ejecta, and fractures circumferential to the crater rim. Surface ice is also exposed on the crater walls and may undergo seasonal cycles. Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA (public domain) A high-resolution topography map of Haulani crater showing extensive pitting on the crater floor. Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA (public domain)

 

Large-scale fractures in crater interiors have been linked to upwelling of ice and brines in the subsurface [Buczkowski et al., 2019]. Ice also causes craters themselves to relax on Ceres, sometimes leading to fracturing around crater rims that retain distinct topography [Otto et al., 2019] and, more rarely, flattening the topography of large craters [Bland et al., 2018].

Enhanced color image of large fractures on the floor of Dantu crater. These fractures may be caused by upwelling of ice, brine, or mud beneath the crater floor. Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA (public domain)

Isn’t there also evidence that Ceres is active – including losing material to space? Why is this happening and why is it important?

There are two main lines of evidence that Ceres outgasses water to space, at least periodically.

The first line of evidence comes from astronomical observations of Ceres from Earth. In the early 1990s, the International Ultraviolet Explorer (IUE) detected OH near Ceres’ limb [A’Hearn & Feldman, 1992]. In 2014, immediately prior to Dawn’s arrival at Ceres, water vapor was detected by the Herschel Space Observatory [Küppers et al., 2014]. Both of these detections spurred speculation about cometary style outgassing and/or possible cryovolcanism on Ceres.

The second line of evidence for episodic outgassing comes from Ceres’ geomorphology and minerology, as observed by Dawn. In Occator Crater, we see bright carbonate deposits (faculae) that likely formed via extrusion or even fountaining of brines on to the surface in the last several million years [Scully et al., 2019]. Problematically, Dawn did not observe any direct evidence for outgassing during its mission at Ceres or active brine extrusion. Any outgassing from faculae formation would have stopped millions of years ago, so it cannot explain the IUE and Herschel detections.

Explaining the Herschel data in particular has been challenging. Ice in Ceres’ subsurface is slowly receding to greater depths, which produces a steady background rate of water vapor loss much lower than the Herschel rate [Landis et al., 2017]. Any time ice is exposed on the surface, it will quickly sublimate. So stochastic events, landslides and small impacts that expose ice, can cause short bursts of outgassing. A cluster of these events might have produced the water vapor detected by Herschel [Landis et al., 2018].

Additionally, seasonal changes in shadowing on crater walls may lead to periodic accumulation and sublimation of surface ice [Formisano et al., 2019a; 2019b].

Color topographic view of Ahuna Mons, the youngest and most prominent mountain on Ceres. It has been proposed to be a cryovolcanic dome. Older more subdued mountains on Ceres may also be cryovolcanoes. Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA (public domain)

These passive, near-surface processes most likely drove the outgassing events observed in 1992 and 2014, although we can’t be certain.

Near-surface processes fall under the umbrella of cometary style outgassing. Understanding these processes is important, because they likely operate on numerous small, volatile rich bodies throughout the solar system, and dominate water vapor production at Ceres today.

Regular outgassing from stochastic, passive processes does not preclude more dramatic outbursts of water from deeper in the interior in the recent geologic past.

There is ongoing work to understand the formation of the bright spots in Occator, and the development of the large cryovolcano Ahuna Mons.

With NASA’s Dawn mission having come to an end what are the next steps in the exploration of Ceres now that we know how important water ice has been for the body?

In the near term, there is work to do to understand the Dawn data better.In the near term, there is work to do on Earth to understand the Dawn data better. In particular, laboratory experiments to determine the material properties of the unique mixtures of ice, salts, and clays that occur on Ceres. Knowing more about the properties of these mixtures will allow us to build better models of Ceres’ structure and evolution [Sizemore et al. 2019a].

Longer term, of course, we hope there will be new spacecraft missions.Longer term, of course, we hope there will be new spacecraft missions. These might include orbiters with instrumentation designed specifically to interrogate the ice and brine content of Ceres’ interior at depths we couldn’t probe effectively with Dawn’s instrument payload.

For example, an orbiter carrying a sounding radar could help us quantify the ice content of lobate landslides and ejecta, helping us understand stratigraphy at the 100 meter to 1 kilometer scale. An orbital magnetometer could constrain whether or not there is a deep brine layer. And of course, a future lander might be able to directly sample the structure and chemistry of the ice – much like the Phoenix lander did on Mars.

—Steven A. Hauck, II (hauck@case.edu; 0000-0001-8245-146X), Department of Earth, Environmental, and Planetary Sciences, Case Western Reserve University, Ohio; and Hanna Sizemore ( 0000-0002-6641-2388), Planetary Science Institute, Arizona

Vintage Radar Film Tracks What’s Beneath Antarctic Ice

Mon, 09/16/2019 - 12:07

Antarctic ice melts from the top down and the bottom up. Researchers and art historians recently digitized an archive of 1970s radar film that peers through the ice surface into the shapes below. The vintage measurements will let glaciologists and climate scientists track changes to the ice across double the time frame offered by modern radar data alone and will aid glacial melt projections.

“A lot of the changes in Antarctica are happening at the bottom,” said Dustin Schroeder, a radar glaciologist at Stanford University in California who led the digitization project. “In the past, we were limited to 1 or 2 decades of modern digital data. But now we have this older record that can extend that back to 40 or 50 years,” he told Eos. “And that time will just grow.”

Peering Through the Ice

“You look through the ice down to the bed…like a slice of layer cake.”Radar sounding is “the geophysical method we use to map what the topography of the continent looks like under the ice sheet,” Schroeder explained. “You send a radar pulse straight down from an airplane, and you look through the ice down to the bed…like a slice of layer cake.”

The technique was groundbreaking for Antarctic research in the 1970s because “we didn’t know what the continent looked like at all,” Schroeder said. From 1971 to 1979, an international survey team flew a 400,000-kilometer zig-zagging path across Antarctica, mapping beneath the ice and storing the radar profiles on 35-millimeter optical film. Much of that film had never been analyzed in detail.

Schroeder’s team worked with art historians and Hollywood vintage film experts to digitize those film reels and archive them online for easy access. The team then combined those older radar profiles with modern radar and altimetry data to measure how the bottom of the Antarctic ice sheet has changed in the past 40–50 years.

With the longer radar timescale, the researchers found that the eastern ice shelf of Thwaites Glacier in West Antarctica has thinned faster than suggested by only 1 decade of data. The ice shelf lost 10%–33% of its thickness between 1978 and 2009 at a rate of about 40 meters per decade, higher than the 25-meter-per-decade rate suggested from modern data alone.

Another subglacial feature, a basal channel beneath the Filchner-Ronne Ice Shelf, remained relatively stable over about 40 years. That at least one feature remained unchanged after including the vintage radar demonstrated that the changes his team saw near Thwaites are real, Schroeder explained. These results were published on 3 September in Proceedings of the National Academy of Sciences of the United States of America.

Learn from the Past to Model the Future

“I think in terms of luck, or prescience, we have film in some of the places we’d most want it.”“Digitizing these old radar lines was a real service to the community,” Leigh Stearns told Eos. Stearns is a glaciologist at the University of Kansas in Lawrence and was not involved with this study. “Being able to extend our record of observations, particularly of key variables such as ice thickness and basal condition, provides context for current ice sheet dynamics and helps parameterize ice sheet models,” she said.

The digitization project is a “Herculean effort,” according to Joseph MacGregor, a project scientist for NASA’s Operation IceBridge. “Operation IceBridge’s plans for its final Antarctic campaign this fall include potential repeats of these pioneering missions across the coastline of East Antarctica,” he told Eos. “Repeating these flights gives us a chance to measure any ice thickness change over 4 decades.”

Importantly, the vintage radar film covers some of the most dynamic places in Antarctica, Schroeder said. “The Ross Ice Shelf is one of the densest areas covered by this old survey,” he said. “I think in terms of luck, or prescience, we have film in some of the places we’d most want it.”

You can learn more about the radar digitization project in the video below.



—Kimberly M. S. Cartier (@AstroKimCartier), Staff Writer

This story is part of Covering Climate Now, a global collaboration of more than 250 news outlets to strengthen coverage of the climate story.

A New Proxy for Past Precipitation

Mon, 09/16/2019 - 12:01

To understand our rapidly changing climate, researchers often look back at how Earth’s climate has behaved in the past. Marine sediment cores, like tree rings, can provide a log of former environmental conditions, allowing scientists to infer everything from the temperature and salinity of the oceans to precipitation rates on land.

Precipitation rates affect river flows and thus sediment erosion rates, which means researchers can look at ratios of marine to terrestrial materials in marine sediment cores to reconstruct past precipitation rates. But this and other existing proxies for precipitation, including examining hydrogen isotopes in plant wax compounds in cores, have limitations as they can be affected by other factors and processes.

Here Mendes et al. describe a new proxy for determining past precipitation from marine sediment cores using luminescence signals from feldspar and quartz grains. Together with other reconstructive methods, the new technique can provide a more complete picture of precipitation and continental erosion, the team notes. Researchers have previously used such luminescence signals to study processes on Earth’s surface, such as mountain uplift rates, and in surface exposure dating. But here the team applied the method to sediment cores collected 180 kilometers off the northeastern coast of Brazil, where the Parnaíba River spills into the Atlantic.

The Parnaíba is the main source of land-based sediments where the core was extracted, so the authors reasoned that changes in luminescence sensitivity in the core likely stemmed from changes in the amount of suspended sediments in the river over time.

The cores contained a record of the past 30,000 years. Over that time, the region has gone through three millennium-scale shifts in the Intertropical Convergence Zone, the major driver of precipitation in northeastern Brazil. These shifts triggered periods of increased rainfall over much of tropical South America, making the cores ideal for testing new methods of precipitation reconstruction.

The team compared the optically stimulated luminescence and thermoluminescence signals in the marine core sediments to luminescence measurements from sediment samples collected on land where the core sediments may have originated. Quartz and feldspar luminescence can change on the basis of where these materials come from and their exposure to surface processes, which means scientists can use the signal to trace sediments back to their parent rocks on land.

The team showed that the results from the new proxy generally agree with those from other proxies of precipitation in marine cores, as well as model simulations. The authors also confirmed the occurrence of other, shorter periods of increased precipitation that were suggested in a 2009 analysis of stalagmites in Brazil.

The new study provides an elegant and inexpensive way to bolster reconstructions of Earth’s paleoclimate—critical information for researchers and policy makers planning for the future. (Paleoceanography and Paleoclimatology, https://doi.org/10.1029/2019PA003691, 2019)

—Kate Wheeling, Freelance Writer

This story is part of Covering Climate Now, a global collaboration of more than 250 news outlets to strengthen coverage of the climate story.

AGU Position Statements Now Open for Member Comment

Fri, 09/13/2019 - 16:58

Starting today, 13 September 2019, AGU members will have 30 days to comment on revisions to two position statements: one on data and one on climate change. This open comment period is both an important opportunity for and responsibility of our members to contribute to AGU’s mission of promoting Earth and space science for the benefit of humanity.

These position statements—created, revised, and approved by members—are what enable AGU to take adaptive stances on important societal topics, including the role of government in the sciences, the importance of early geoscience education, the availability and accessibility of data, and the implications for the world of understanding ocean and climate science, among others. They are cited not only by AGU members and leadership but also by other organizations, policy makers, and the media.

These statements are written to be forward looking and with relevance to the near future but not to last forever. Every 4 years, AGU’s Position Statement Committee considers all the statements and decides whether each one should be reaffirmed, retired, or revised. In 2019, the committee agreed that the topics of data and climate change had evolved so significantly that our position statements required major revisions.

The committee appointed two distinguished panels of scientists to make those revisions. The text of both revised statements is what is now available for comment, as noted below. After the 30-day deadline, the panels will consider all member comments and address as many as they can.  Ultimately, the updated statements will go to the AGU Council and Board for their approval. Our goal is to announce both the data and climate statements during our Centennial celebrations at AGU’s Fall Meeting 2019.

Position Statement on Data

Data are paramount to the scientific research that drives our economy, health, and security—from monitoring our atmosphere and oceans to tracking short-term extreme weather events to understanding long-term climate change. At the same time, changes in technology, such as improved computing and artificial intelligence, are creating even more vast and complicated data.

AGU’s data position statement makes it clear that for data to serve society, it must be robust, verifiable, transparent, and open. Moreover, the scientists and creators of data and all the governing bodies that deal with the storage or dissemination of data must hold themselves to the highest standards of scientific integrity. Policy makers need to support investment in data infrastructure, and scientists need to build data management into the research process from the very beginning to ensure its proper collection.

Position Statement on Climate Change

Human-caused climate change is one of the most serious issues of our time, affecting not only the state of the natural world but our ability to live in the world safely. Climate change will cause increasing health, economic, security, and ecological risks, from heat-related deaths and illnesses, hazards such as flooding, water scarcity, wildfire, and extreme weather and impacts to coastal infrastructure, agriculture, fisheries, and global migration.

AGU’s climate change statement makes it clear that reducing these harms will take substantial emissions reductions, which in turn will require significant changes to our energy sources and uses, as well as our food production and the active removal of carbon dioxide from the atmosphere. Society must also be prepared to adapt to unavoidable climate change, but if these transitions are done strategically, efficiently, and equitably, the adaptations could lead to increased prosperity and well-being for society. The statement calls on communities, businesses, and governments to get involved and for the scientific community—both individuals and institutions—to engage with the public on solutions.

Read the full data and climate position statements and leave your comments before 13 October at 12:00 a.m.

Hiding Deep Hydrous Melts at the Core-Mantle Boundary

Fri, 09/13/2019 - 11:30

H2O is notorious for having a solid phase (ice) that is less dense than the melt (water), making ice float in water. But what happens when H2O is added to silicate melts in the Earth’s interior at pressures near the core-mantle boundary? Would such melts sink, or float?

Du et al. [2019] used sophisticated molecular dynamics simulations to determine the atomic-scale structures and density of iron-rich, hydrous silicate melts at pressure-temperature conditions mimicking those near the base of the Earth’s mantle. They found that partial melts of mantle rock containing several weight percent of water can be denser than the bulk solid left behind in the lowermost mantle and therefore should sink, instead of float.

The results can potentially explain seismologically observed slow and dense structures on the core-mantle boundary with further implications for the cycling of water and other volatiles in the Earth’s deep interior throughout its evolution.

Citation: Du, Z., Deng, J., Miyazaki, Y., Mao, H.‐k., Karki, B. B., & Lee, K. K. M. [2019]. Fate of hydrous Fe‐rich silicate melt in Earth’s deep mantle. Geophysical Research Letters, 46. https://doi.org/10.1029/2019GL083633

—Steven D. Jacobsen, Editor, Geophysical Research Letters

So You Want to Write an Abstract

Fri, 09/13/2019 - 11:25

Let’s be honest: You don’t want to write an abstract. Like everyone else (including this author), you’ve put it off until the submission deadline for the conference was almost upon you or until you knew you had to submit your paper or your coauthors might threaten you with violence.

However, since you need to write an abstract, you want to do it well. Here are some tips.

Start with the Guidelines

What are the requirements for this abstract in terms of its length, formatting, and inclusion of figures? Do you need to be a member of a society, pay dues or submission fees, or have created a log-in to a specific platform before you can submit?

For example, if you’re planning to attend an AGU meeting, you can start by looking up the information on all aspects of submission and registration, such as those for Fall Meeting and the joint Ocean Sciences Meeting. If you’re preparing a paper, you can check out submission procedures for the AGU journals.Take a look at archives of past abstracts for the conference or journal to which you’re submitting to get a better sense of how others have framed their work.

Learn from Your Peers

Take a look at archives of past abstracts for the conference or journal to which you’re submitting to get a better sense of how others have framed their work (e.g., try browsing the Ocean Sciences Meeting 2018 abstracts). This is also a great way to identify the best keywords to include with your abstract to ensure meeting attendees or researchers can easily find your work.

Begin with the Basics (Try Simple Sentences)

Sometimes we find writing difficult because of the pressure to be polished right from the start. In the stressful days when I was “working on” my dissertation (my apartment was never so thoroughly cleaned), my adviser suggested that I start with simple sentences: don’t write formally, yet—just explain the very basics of the background on the issue, the question you’re asking, what you found, and why it matters. Which leads me to…

Try a Plain Language Summary First

Submitting plain language summaries is an excellent opportunity to get your paper noticed by scientists outside your field, journalists, and even members of the science-interested public.Plain language summaries, or plain language abstracts, are becoming a more common option to submit in addition to your scientific abstract. (All AGU conferences and journals encourage, and some require, plain language accompaniments.) These jargon-light, accessible synopses are an excellent opportunity to get your paper noticed by scientists outside your field, journalists, and even members of the science-interested public. And writing your plain language summary first is a good way to make sure it flows; trying to work backward and translate a jargon-heavy, field-specific abstract into something a nonscientist can follow is usually much harder. Take a look at our recommendations for how to write a plain language summary, and give it a try.

Remember all the important elements: Have you made sure to provide sufficient context and background by explaining why your science questions arise naturally from what we already know about the field? Have you briefly described how you conducted your experiment and what you found? (For conferences, the findings may not be quite as specific—that’s understood.) Have you explained why your study matters and what societal implications it might have?

Scientific Abstract: I’ve Tricked You into Thinking There Was an Involved Second Step

Once you’ve written a plain language summary, you’re almost done. For your scientific abstract, you can put the jargon back in and add any details about methods or results that were too technical or field specific to include before.

Before you know it, you’re finished, until the next abstract you need to put off writing.

—Olivia V. Ambrogio (@squidfan), Sharing Science Program Manager, AGU

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