U.S. Methane Emissions 50 Percent Higher Than EPA Estimates
Emissions of methane from fossil fuel extraction and refining activities in the South Central U.S. are nearly five times higher than previous estimates, according to researchers at Harvard University and seven other institutions. Their study, published this week in Proceedings of the National Academy of Sciences (PNAS), also suggests that the contribution from livestock operations may be twice as high as previously thought.
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Methane, a potent greenhouse gas, is produced through natural gas production and distribution, cattle farming, landfills, coal mining, manure management and many other anthropogenic and natural sources, though human activities are thought to contribute approximately 60 percent of the total.
Overall, according to the new study, total methane emissions in the U.S. appear to be 1.5 times and 1.7 times higher than the amounts previously estimated by the U.S. Environmental Protection Agency (EPA) and the international Emissions Database for Global Atmospheric Research (EDGAR), respectively.
The difference lies in the methodology. The EPA and EDGAR use a bottom-up approach, calculating total emissions based on “emissions factors”—the amount of methane typically released per cow or per unit of coal or natural gas sold, for example. The new study takes a top-down approach, measuring what is actually present in the atmosphere and then using meteorological data and statistical analysis to trace it back to regional sources.
Generated by a large, multi-institutional team of researchers, the latest findings offer a robust and comprehensive baseline for assessing policies designed to reduce greenhouse gases. They also point to a few areas where the assumptions built into recent emissions factors and estimated totals may be flawed.
“The bottom-up and top-down approaches give us very different answers about the level of methane gas emissions,” notes lead author Scot M. Miller, a doctoral student in Earth and Planetary Sciences through the Harvard Graduate School of Arts and Sciences. “Most strikingly, our results are higher by a factor of 2.7 over the South Central U.S., which we know is a key region for fossil-fuel extraction and refining. It will be important to resolve that discrepancy in order to fully understand the impact of these industries on methane emissions.”
Miller is a 2007 graduate of Harvard College and earned a master’s degree in engineering sciences at the Harvard School of Engineering and Applied Sciences (SEAS) in 2013. He studies in the lab of Steven C. Wofsy, Abbott Lawrence Rotch Professor of Atmospheric and Environmental Science at SEAS.
“When we measure methane gas at the atmospheric level, we’re seeing the cumulative effect of emissions that are happening at the surface across a very large region,” says Wofsy, a coauthor of the PNAS study. “That includes the sources that were part of the bottom-up inventories, but maybe also things they didn’t think to measure.”
Miller and Wofsy, along with colleagues at the Carnegie Institution for Science, the National Oceanic and Atmospheric Administration (NOAA), and five other institutions, used a combination of observation and modeling to conduct their analysis.
NOAA and the U.S. Department of Energy collect observations of methane and other gases from the tops of telecommunications towers, typically about as tall as the Empire State Building, and during research flights. The team combined this data with meteorological models of the temperatures, winds and movement of air masses from the same time period, and then used a statistical method known as geostatistical inverse modeling to essentially run the model backward and determine the methane’s origin.
The team also compared these results with regional economic and demographic data, as well as other information that provided clues to the sources—for example, data on human populations, livestock populations, electricity production from power plants, oil and natural gas production, production from oil refineries, rice production and coal production. In addition, they drew correlations between methane levels and other gases that were observed at the time. For example, a high correlation between levels of methane and propane in the South Central region suggests a significant role for fossil fuels there.
“This paper provides the most solid and the most detailed estimate to date of total U.S. methane emissions,” says coauthor Anna M. Michalak, a faculty member in the Department of Global Ecology at the Carnegie Institution for Science. Michalak is also an associate professor of environmental Earth system science at Stanford University. “This was really, from beginning to end, just a very clean analysis.”
Along with carbon dioxide, methane is one of the most important greenhouse gases in terms of its potential to raise global temperatures. It also encourages the formation of surface ozone in cities and affects other aspects of atmospheric chemistry.
Seeking to establish a baseline against which to measure future change in methane emissions, the researchers compared observational data collected in 2007–2008 against EDGAR and EPA data for the same year (using the revised EPA data for 2007–2008 that was published in April 2013). Future studies will apply the same analysis to present-day data.
“The beauty of the approach we’re using is that, because we’re taking measurements in the atmosphere, which carry with them a signature of everything that happened upwind, we get a very strong number on what that total should be,” says Michalak. “Now that we know the total does not equal the sum of the parts, that means that either some of those parts are not what we thought they were, or there are some parts that are simply missing from the inventories. It really offers an opportunity for governments to reexamine the inventories in light of what we now know.”
In addition to Miller, Wofsy and Michalak, coauthors included Eric A. Kort, S.M., Ph.D., the University of Michigan, Ann Arbor; Arlyn E. Andrews, Ph.D., Edward J. Dlugokencky and Stephen A. Montzka at NOAA’s Earth System Research Laboratory; Sebastien C. Biraud and Marc L. Fischer at Lawrence Berkeley National Laboratory; Janusz Eluszkiewicz and Thomas Nehrkorn at Atmospheric and Environmental Research in Lexington, MA; Greet Janssens-Maenhout at the European Commission Joint Research Centre in Italy; and Ben R. Miller, John B. Miller and Colm Sweeney at the University of Colorado Boulder.
Typhoon Molave is expected to make landfall in Vietnam on Wednesday with 90 mph winds and heavy rainfall that could lead to flooding and landslides, according to the U.S. Embassy and U.S. Consulate in Ho Chi Minh City. To prepare for the powerful storm that already tore through the Philippines, Vietnam is making plans to evacuate nearly 1.3 million people along the central coast, as Reuters reported.
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A stretch of coastline in the Philippine capital, Manila has received backlash from environmentalists. The heavily polluted Manila Bay area, which had been slated for cleanup, has become the site of a controversial 500-meter (1,600-foot) stretch of white sand beach.
Sand Makeup Crucial for Ecosystems<p>While UNEP/GRID-Geneva generally supports finding <a href="https://www.dw.com/en/not-enough-sand-for-construction-industry-despite-abundance/a-49342942" target="_blank" rel="noopener noreferrer">alternative sources of sand</a> so as not to disrupt ecosystems in rivers and oceans when extracting them, Vander Velpen stressed it was vital to use sand which closely matches the makeup of the native sand to protect beach fauna.</p><p>"If you change the core characteristics of the native sand, the original sand, you need to do an environmental impact assessment (EIA) to find out how it's going to impact the ecosystem and nearby ecosystems," he told DW.</p><p>But according to Torres, such an assessment was not done in Manila.</p>
Beautification Stunt Instead of Proper Cleanup?<p>Manila Bay's waters are heavily polluted by oil and trash from nearby residential areas and ports. A huge "No swimming" sign warns visitors to stay away from the ocean.</p><p>Philippines' <a href="https://denr.gov.ph/index.php/priority-programs/manila-bay-clean-up/25-priority-programs/1825-frequently-ask-questions-faqs-on-the-dolomite-and-the-beach-nourishment-project" target="_blank">Department of Environment and Natural Resources (DENR)</a> has denied dolomite sand poses any risk to human health and the ecosystem.</p><p>However, scientists of the University of the Philippines have come forward disputing the DENR's claims. A <a href="https://biology.science.upd.edu.ph/index.php/ib-statement-regarding-dolomite-in-manila-bay/" target="_blank" rel="noopener noreferrer">statement by the Institute of Biology</a> said that using crushed dolomite did not address any of the rehabilitation phases and instead was "even more detrimental to the existing biodiversity as well as the communities in the area," pointing to the case of water birds. "The dumping of dolomite in Manila Bay has effectively covered part of the intertidal area used by the birds thereby reducing their habitat."</p><p>At peak migration season, Manila Bay is home to 90 aquatic bird species, including species of international conservation concern that are facing a very high extinction risk in the wild. </p><p>Authorities should focus on protecting and conserving biodiversity, the Institute of Biology added. "Rehabilitating mangroves is an example of a nature-based solution that is cheaper and more cost-effective than the dolomite dumping project," the scientists said.</p><p>Moreover, <a href="http://www.msi.upd.edu.ph/" target="_blank" rel="noopener noreferrer">the Marine Science Institute</a> has warned that prolonged inhalation of finer dust particles of dolomite could "cause chronic health effects," leading to discomfort in the chest, shortness of breath and coughing.</p><p>They also warned dolomite sand grains would erode during storms and be carried out to sea, essentially being washed away.</p>
Rehabilitation vs. Reclamation<p>Environmentalists say covering up the beach doesn't address the real issues of the bay. Torres and others believe the best way to clean up Manila Bay is not to add anything, but rather remove trash and pollution.</p><p>"There have been studies saying much of the waste comes from already collected waste — so these are open dump sites along the coast that get washed up because of the rain," Torres said.</p><p>She criticized the authorities for continuing to push reclamation projects she says are at odds with each other. These projects will affect large areas of mangrove forests, she said, and experts warn that this, in turn, exacerbates coastal erosion.</p><p>"If you've removed the areas that helped trap the sand, like mangrove forests, then the likelihood increases that you will have to nourish a beach. Same as building right up to the waterfront," said Vander Velpen of UNEP/GRID-Geneva.</p>
Plenty of Sand in the Sea?<p>The question of Manila's contentious white beach echoes larger questions about sand mining worldwide. <a href="https://unepgrid.ch/storage/app/media/documents/Sand_and_sustainability_UNEP_2019.pdf" target="_blank">Global sand consumption has tripled</a> over the past two decades, UNEP/GRID-Geneva has found. A huge chunk of it is now taken up by construction.</p><p>"Many operate on the assumption that natural sand is endless in its supply," said Vander Velpen.</p><p>Sand scarcity is a concern shared by Stefan Schimmels of <a href="https://www.fzk.uni-hannover.de/fzk_start.html?&L=1" target="_blank">Forschungszentrum Küste</a> who's done extensive research on shore nourishment to stop coastal erosion. And as climate change and rising sea levels are threatening coasts, demand for sand will grow even more.</p><p>A large study, the <a href="http://www.stencil-project.de/wp-content/uploads/2019/10/STENCIL_SWOT_Analyse_191026.pdf" target="_blank">Strategies and Tools for Environment-Friendly Shore Nourishments as Climate Change Impact Low-Regret Measures (STENCIL project)</a>, focused on the German island of Sylt, a popular vacation spot.</p><p>About 1 million cubic meter of sand per year is used to maintain the coastal area of Sylt, STENCIL project head Schimmels said. That's about 100 million 10-liter buckets of sand.</p><p>When sand was extracted off the coast of Sylt, underwater craters were formed. "You can still detect these craters even decades later," Schimmels told DW.</p><p>"Also when you add a couple of meters sand onto the beach — you essentially bury all things that do creep and fly," he said. "How quickly will they recover?" Schimmels said more research was needed as there was still too little known about long-term effects on the environment. </p>
Criticism Piling Up<p>As for Manila's artificial white sand, it looks like some might have already been blown away by a recent storm. DENR claims it wasn't washed away, but said that grayish sand, stones and other material had simply piled up over the dolomite sand. People in Manila have tweeted photos showing how the storm has ravaged the beach. </p>
<div id="adc0b" class="rm-shortcode" data-rm-shortcode-id="98f9390db6bb81cb421aaf0bb9d9a6fb"><blockquote class="twitter-tweet twitter-custom-tweet" data-twitter-tweet-id="1318816633280851969" data-partner="rebelmouse"><div style="margin:1em 0">Exactly one month after giving excited netizen a glimpse of Manila Bay white sands, look what happened now after ju… https://t.co/X0Z9i0bPB0</div> — M*A*S*H (@M*A*S*H)<a href="https://twitter.com/Magtira_Matibay/statuses/1318816633280851969">1603265362.0</a></blockquote></div><p>Authorities have been called tone-deaf for spending around 389 million pesos ($8 million) on a beach nourishment project in the middle of a raging pandemic.</p><p>An image of cake iced with the words "It really hurts - that's [worth] 389 million pesos?" has since gone viral.</p>
<div class="rm-shortcode" data-rm-shortcode-id="4387aad52ea316e4db7330052318ca2f"><div class="fb-post" data-href="https://www.facebook.com/theweekendpatisserie/posts/144564207350008"></div></div><p>"It's just a waste of precious resources," Torres said. </p><p>The environmental activist now also worries that she might be labeled a terrorist for speaking out under the <a href="https://www.dw.com/en/philippine-anti-terrorism-law-triggers-fear-of-massive-rights-abuses/a-53732140" target="_blank" rel="noopener noreferrer">Philippines' controversial new anti-terrorism law</a>. She says she could be arrested for inciting fear when talking about environmental dangers.</p>
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