Bubbling Up: Methane from Reservoirs Presents Climate Change Challenge

By Rose Keane

EPA researcher Jake Beaulieu spends a lot of his time on the water, especially at Harsha Lake, a reservoir just southeast of Cincinnati, OH. He’s not a sailor, nor does he work with marine life. Instead, Beaulieu studies how methane (CH4)—a less discussed but more powerful greenhouse gas than carbon dioxide—is emitted from reservoirs. He and other EPA researchers are developing new models and tools to improve methane emission estimates in reservoirs and our understanding of their contributions to greenhouse gas levels globally.

Beaulieu’s team using a new surveying technique to measure methane emissions from reservoirs.

Beaulieu’s team is applying surveying techniques in novel ways to estimate methane emissions.

Methane gas contributes to rising temperatures and one way it is produced is by tiny organisms in sediments at the bottom of lakes. One important source of food for these organisms is decaying algae, which is converted to methane when eaten by these tiny organisms.

According to Beaulieu, the way that methane emission rates from reservoirs are currently estimated doesn’t take into account a number of factors that can affect how much is emitted into the atmosphere such as the location, water depth, overall size of the reservoir and other conditions.

One of the main ways that large amounts of methane are released from reservoirs is through something called ebullition—or more simply, the bubbles that come up from the mud. The bubbles are filled with methane, and Beaulieu’s research has shown that in areas where the water is deeper and less disturbed, there’s less of these methane bubbles coming to the surface. In areas where the water is more shallow or more frequently disturbed, there’s not enough weight (from the atmosphere or from the water itself) to hold the bubbles in, so emissions increase.

In April this year, 177 countries and states across the world signed the Paris Agreement on Climate Change—a landmark agreement that outlines ways for countries to limit their greenhouse gas emissions, encourage more sustainable infrastructure and economic development, and better plan for responding to the impacts of changing climatic conditions. Beaulieu says that improved estimates of methane emissions from reservoirs will result in better information that can aid in the global effort to reduce greenhouse gas emissions.

His paper, Estimates of reservoir methane emissions based on a spatially balanced probabilistic survey, was recently published in Limnology and Oceanography.

About the Author: Rose Keane is an Oak Ridge Associated Universities contractor with the science communications team in EPA’s Office of Research and Development.

Editor's Note: The views expressed here are intended to explain EPA policy. They do not change anyone's rights or obligations. You may share this post. However, please do not change the title or the content, or remove EPA’s identity as the author. If you do make substantive changes, please do not attribute the edited title or content to EPA or the author.

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Climate Change…By the Seashore

By Andy Miller, Ph.D.

As the summer winds down, many of us return to school or work with fond memories of trips to the seashore. For me and for many others, where the ocean meets the land are places that are deeply relaxing, reminders of our connections with the natural world.

Cordgrass growing across Great Marsh, Jamestown, RI.

Cordgrass growing across Great Marsh, Jamestown, RI.

For several EPA researchers, the shores and estuaries that we value for their beauty and wonder are the sites for investigating the rich and complex ecosystems that support a multitude of species and provide us with benefits well beyond a calming walk along the shore.

Researchers have recently published results of work examining how different impacts of climate change are affecting coastal ecosystems. They demonstrate how vulnerable these natural resources are to drought, sea level rise, and other impacts of a changing climate.

Several studies looked at how the effects of climate change affected cordgrass, dominant salt marsh plants that are key to the vitality of salt marsh ecosystems in southern New England coastal wetlands. One study looked at how saltmeadow cordgrass, Spartina patens, responded to drought and sea level rise in a greenhouse set up for research. This study found that sea level rise was a threat to the long-term survival of the species. The loss of saltmeadow cordgrass would reduce the wetlands’ habitat quality, plant diversity, carbon sequestration, erosion resistance and coastal protection.

A second study examined smooth cordgrass, Spartina alterniflora, under similar stresses, and also added an additional stressor, increased levels of nitrogen in the water, an environmental pollutant resulting from agricultural runoff, urban stormwater runoff, wastewater from sewers and septic systems and other sources. EPA researchers Alana Hanson and her colleagues simulated all these plant stressors in the same research greenhouse and concluded that the effects of climate change and nitrogen runoff were likely to reduce the sustainability of salt marshes because the conditions made it more difficult for cordgrass to flourish. Without cordgrass, Atlantic coastal ecosystems would be as vulnerable as a sea turtle without its shell.

On the other side of the country, researchers on the Pacific coast have been developing an approach to evaluate how climate change is affecting coastal biodiversity. Working with experts from several federal, state, and local agencies, EPA researcher Henry Lee and his colleagues developed an approach to use environmental tolerances and other scientific information to estimate how groups of species can be expected to respond to changes in ocean temperature and acidity. Their tool, the Coastal Biodiversity Risk Assessment Tool, or CBRAT, provides an open-source platform that allows researchers and resource managers to examine the potential vulnerability of coastal Pacific fish and invertebrate species as they are impacted by climate change.

These research efforts help us understand more than just the impacts of climate change on coastal ecosystems—they also help us understand how we can respond to those changes in ways that will help protect them. Francis Bacon is credited with the saying, “The best part of beauty is that which no picture can express.” Although we see the natural beauty of our coasts and shores, the best part of that beauty may well be the unseen ways in which they nurture and support nature as a whole.

About the Author: Andy Miller is the Associate Director for Climate in EPA’s Air, Climate, and Energy Research Program that conducts research to assess the impacts of a changing climate and develop the scientific information and tools to act on climate change.

References

Hanson, A., R. Johnson, C. Wigand, A. Oczkowski, E. Davey and E. Markham (2016). “Responses of Spartina alterniflora to Multiple Stressors: Changing Precipitation Patterns, Accelerated Sea Level Rise, and Nutrient Enrichment.” Estuaries and Coasts: 39: 1376–1385.

Watson, E. B., K. Szura, C. Wigand, K. B. Raposa, K. Blount and M. Cencer (2016). “Sea level rise, drought and the decline of Spartina patens in New England marshes.” Biological Conservation 196: 173-181.

Lee II, H., Marko, K., Hanshumaker, M., Folger, C., and Graham, R. 2015. User’s Guide & Metadata to Coastal Biodiversity Risk Analysis Tool (CBRAT): Framework for the Systemization of Life History and Biogeographic Information. EPA Report. EPA/601/B-15/001. 123 pages.

Editor's Note: The views expressed here are intended to explain EPA policy. They do not change anyone's rights or obligations. You may share this post. However, please do not change the title or the content, or remove EPA’s identity as the author. If you do make substantive changes, please do not attribute the edited title or content to EPA or the author.

EPA's official web site is www.epa.gov. Some links on this page may redirect users from the EPA website to specific content on a non-EPA, third-party site. In doing so, EPA is directing you only to the specific content referenced at the time of publication, not to any other content that may appear on the same webpage or elsewhere on the third-party site, or be added at a later date.

EPA is providing this link for informational purposes only. EPA cannot attest to the accuracy of non-EPA information provided by any third-party sites or any other linked site. EPA does not endorse any non-government websites, companies, internet applications or any policies or information expressed therein.