China’s Methane Emissions Rise Despite Tougher Laws, Satellite Data Shows
By Daisy Dunne
Methane emissions from coal mining in China have risen despite stricter government regulations that aimed to curb the greenhouse gas, satellite data shows.
The data, which is published in Nature Communications, finds China's methane emissions rose by 1.1m tonnes a year between 2010 and 2015. This could account for up to a quarter of the rise in methane emissions seen globally over that period, the study finds.
China is the world's largest emitter of methane—a greenhouse gas that is 34 times more potent than CO2 over a 100-year period.
The findings show how satellites can be used to pinpoint greenhouse gas emissions "from misbehaving industries that nobody may have suspected," the lead author told Carbon Brief.
Methane is the second largest contributor to human-caused global warming after CO2.
Globally, the largest driver of human-caused methane emissions is agriculture—particularly livestock and rice production. The second main driver is fossil fuel production, which allows underground methane to "escape" into the atmosphere during the drilling, extraction and transportation process.
China is the world's largest producer and consumer of coal. When coal is mined, methane can escape from the "coal seam"—the name given to a layer of coal in the earth that is thick enough to be exploited, said study lead author Prof. Scot Miller, a researcher of greenhouse gases and air pollution from John Hopkins University in Baltimore. He told Carbon Brief:
"Coal forms underground over long geological time scales and methane is often produced in the coal seams during this process. The methane remains trapped in the coal seam, but it can be released into the atmosphere if the coal seam is mined."
However, there are ways to reduce the methane emissions from the mining process, he added:
"One option is to burn or 'flare' the methane. This process converts methane to CO2, a greenhouse gas that is much less potent per molecule. Another option is to capture this gas and use it to generate electricity or heat homes."
(Methane flaring has faced criticism for being "wasteful". In the U.S., Obama-era environmental regulations sought to minimize the practice—though the new rules were later rolled back by the Trump administration.)
China's government has laid out "ambitious plans" to pursue these options, Miller said. In its 12th five-year plan, which set out policies for 2011-15, the Chinese government aimed to recover and utilize 5.6m tonnes of methane from coal mining. By 2020, it aims to recover 13.2m tonnes of methane.
But the satellite data collected by the research team suggests that these regulations have been "unsuccessful" in curbing methane emissions from mining, Miller said:
"We found that China's methane emissions have been increasing 'business as usual'—and these increases are likely driven by increasing emissions from coal mines. In other words, China's methane regulations have not had a detectable impact on the country's methane emissions."
To study methane emissions from China and other parts of East Asia, the research team used data from the Greenhouse Gases Observing Satellite (GOSAT). The satellite was launched in 2009 by the Japan Aerospace Exploration Agency. (In 2016, Carbon Brief published an interactive showing how satellites, including GOSAT, are used to monitor climate change.)
The satellite detects levels of methane in the atmosphere using infrared sensors. This information is then analyzed by statistical models to link it to changes in methane observed at the Earth's surface, Miller said.
The results show that China's methane emissions rose at a rate of 1.1m tonnes a year between 2010 and 2015. This is indicated on the chart below, which shows the results from this study (green) alongside other previous estimates.
Above chart: Methane emissions from China, according to this study (green; anthropogenic emissions in dashed green), Bergamaschi et al. (2013) (dark blue), Thompson et al. (2015) (light blue), Peng et al. (2016) (triangles), the Emissions Database for Global Atmospheric Research (EDGAR) (black), the U.S. Environmental Protection Agency (EPA) and official statistics reported to the United Nations Framework Convention on Climate Change (UNFCCC) (stars). Note: the y-axis does not begin at zero. Source: Miller et al. (2019)
Since 2007, global methane emissions have been increasing at an annual rate of between 5m and 8m tonnes a year, the study says. This means the increase seen in China could represent between 11 percent and 24 percent of the global rise in methane emissions.
The researchers compared their results to previous studies looking at China's methane emissions from 2000-10 (shown on the chart above). This comparison shows that "China's emissions have been increasing at the same rate as during earlier years, in spite of the government's coal mining regulations", Miller says.
One estimate—from the Emissions Database for Global Atmospheric Research (EDGAR; black line on chart)—found China's methane emissions to be even higher from 2010 to 2012.
This estimate uses a "bottom-up" approach—which involves recording methane emissions from the ground, said Prof. Greet Janssens-Maenhout, a project leader of EDGAR at the European Commission's Joint Research Centre. She told Carbon Brief:
"I think this is a nice [study] and, in fact, the bottom-up estimates and top-down estimates [from this study] don't differ that much. There is much more agreement now than there was in the past."
Also notable is that the estimates for China's methane emissions in 2012 from both this "bottom-up" approach and the new study are higher than the figure reported by China to the United Nations Framework Convention on Climate Change (UNFCCC).
(China is a "non-Annex I" country and so not required to report its greenhouse gas emissions to the UNFCCC on an annual basis.)
Detecting Cow Fields
The modeling technique also allowed researchers to decide whether methane detected by the satellite had originated from a coal mine, a rice paddy, a cow field or a natural source, such as a wetland, Miller said.
The chart below shows a breakdown of methane emissions in China by sector. The sectors considered include coal (orange), rice (purple), agriculture (turquoise), waste (red), oil and gas (green) and natural sources (grey).
Methane emissions (in millions of tonnes) in China between 2011 and 2015 from coal (orange), rice (purple), agriculture (turquoise), waste (red), oil and gas (green) and natural sources (grey). Miller et al. (2019)
The results suggest that coal mining was the main driver of the rise in methane emissions in China from 2011-15, Miller said:
"We saw the largest increases in methane emissions from regions with a lot of coal production and from regions where the coal seams are known to have large amounts of trapped gas.
"Methane is also emitted by agriculture – by cows, manure management and rice paddies. But between 2010 and 2015, coal mining in China increased enormously while rice production and the number of cows did not. These two lines of evidence indicate that coal mining has probably been driving recent increases in methane emissions from China."
The findings suggest that China's "ambitious benchmarks, regulations and incentives" for slashing methane emissions from coal mining had little effect from 2010-15, the authors say.
This could be down to "insufficient infrastructure," "inadequate technology" and "inadequate or poorly-designed policies," the authors write in their research paper.
For example, "most coal mines are located in remote mountainous areas, areas that are poorly connected to cities or natural gas infrastructure"—which is needed to recover methane from coal mines, the authors say.
In addition, some policies to promote methane utilization may have "backfired", the authors noted: "Government policy requires that all mines utilize drained gas with greater than 30 percent methane content…[There is] anecdotal evidence that mine operators may be diluting drained gas to circumvent the requirement."
The new findings highlight how using satellites can give an unbiased picture of how greenhouse gas emissions are changing from country to country, Miller said:
"Countries like the US and China estimate their emissions by tallying the number of coal mines, the number of cows, or the number of natural gas wells. However, these inventories can overlook sources or underestimate emissions from misbehaving actors.
"By contrast, greenhouse gas measurements in the atmosphere can detect emissions across an entire landscape, including emissions that government inventories overlook and emissions from misbehaving industries that nobody may have suspected."
The evidence presented in the study is "alarming" said Dr. Michelle Cain, a science and policy research associate at the Oxford Martin School at the University of Oxford, who was not involved in the research. She told Carbon Brief:
"This is useful [for] piecing together the full story of what is driving global atmospheric methane upwards. Increasing levels of methane in the atmosphere mean additional warming, so this is an important question to answer if we want to work out whether we are on track to limit warming to 1.5 or 2C."
Reposted with permission from our media associate Carbon Brief.
By Frank La Sorte and Kyle Horton
Millions of birds travel between their breeding and wintering grounds during spring and autumn migration, creating one of the greatest spectacles of the natural world. These journeys often span incredible distances. For example, the Blackpoll warbler, which weighs less than half an ounce, may travel up to 1,500 miles between its nesting grounds in Canada and its wintering grounds in the Caribbean and South America.
Blackpoll warbler. PJTurgeon / Wikipedia<p>We used this information to determine how the number of migratory bird species varies based on each city's level of <a href="https://www.britannica.com/science/light-pollution" target="_blank" rel="noopener noreferrer">light pollution</a> – brightening of the night sky caused by artificial light sources, such as buildings and streetlights. We also explored how species numbers vary based on the quantity of tree canopy cover and impervious surface, such as concrete and asphalt, within each city. Our findings show that cities can help migrating birds by planting more trees and reducing light pollution, especially during spring and autumn migration.</p>
Declining Bird Populations<p>Urban areas contain numerous dangers for migratory birds. The biggest threat is the risk of <a href="https://doi.org/10.1650/CONDOR-13-090.1" target="_blank">colliding with buildings or communication towers</a>. Many migratory bird populations have <a href="http://dx.doi.org/10.1126/science.aaw1313" target="_blank">declined over the past 50 years</a>, and it is possible that light pollution from cities is contributing to these losses.</p><p>Scientists widely agree that light pollution can <a href="https://doi.org/10.1073/pnas.1708574114" target="_blank">severely disorient migratory birds</a> and make it hard for them to navigate. Studies have shown that birds will cluster around brightly lit structures, much like insects flying around a porch light at night. Cities are the <a href="https://doi.org/10.1002/fee.2029" target="_blank" rel="noopener noreferrer">primary source of light pollution for migratory birds</a>, and these species tend to be more abundant within cities <a href="https://onlinelibrary.wiley.com/doi/abs/10.1111/gcb.13792" target="_blank" rel="noopener noreferrer">during migration</a>, especially in <a href="https://doi.org/10.1016/j.landurbplan.2020.103892" target="_blank" rel="noopener noreferrer">city parks</a>.</p>
Composite image of the continental U.S. at night from satellite photos. NASA Earth Observatory images by Joshua Stevens, using Suomi NPP VIIRS data from Miguel Román, NASA's Goddard Space Flight Center
The Power of Citizen Science<p>It's not easy to observe and document bird migration, especially for species that migrate at night. The main challenge is that many of these species are very small, which limits scientists' ability to use electronic tracking devices.</p><p>With the growth of the internet and other information technologies, new data resources are becoming available that are making it possible to overcome some of these challenges. <a href="https://doi.org/10.1038/d41586-018-07106-5" target="_blank">Citizen science initiatives</a> in which volunteers use online portals to enter their observations of the natural world have become an important resource for researchers.</p><p>One such initiative, <a href="https://ebird.org/home" target="_blank" rel="noopener noreferrer">eBird</a>, allows bird-watchers around the globe to share their observations from any location and time. This has produced one of the <a href="https://doi.org/10.1111/ecog.04632" target="_blank" rel="noopener noreferrer">largest ecological citizen-science databases in the world</a>. To date, eBird contains over 922 million bird observations compiled by over 617,000 participants.</p>
Light Pollution Both Attracts and Repels Migratory Birds<p>Migratory bird species have evolved to use certain migration routes and types of habitat, such as forests, grasslands or marshes. While humans may enjoy seeing migratory birds appear in urban areas, it's generally not good for bird populations. In addition to the many hazards that exist in urban areas, cities typically lack the food resources and cover that birds need during migration or when raising their young. As scientists, we're concerned when we see evidence that migratory birds are being drawn away from their traditional migration routes and natural habitats.</p><p>Through our analysis of eBird data, we found that cities contained the greatest numbers of migratory bird species during spring and autumn migration. Higher levels of light pollution were associated with more species during migration – evidence that light pollution attracts migratory birds to cities across the U.S. This is cause for concern, as it shows that the influence of light pollution on migratory behavior is strong enough to increase the number of species that would normally be found in urban areas.</p><p>In contrast, we found that higher levels of light pollution were associated with fewer migratory bird species during the summer and winter. This is likely due to the scarcity of suitable habitat in cities, such as large forest patches, in combination with the adverse affects of light pollution on bird behavior and health. In addition, during these seasons, migratory birds are active only during the day and their populations are largely stationary, creating few opportunities for light pollution to attract them to urban areas.</p>
Trees and Pavement<p>We found that tree canopy cover was associated with more migratory bird species during spring migration and the summer. Trees provide important habitat for migratory birds during migration and the breeding season, so the presence of trees can have a strong effect on the number of migratory bird species that occur in cities.</p><p>Finally, we found that higher levels of impervious surface were associated with more migratory bird species during the winter. This result is somewhat surprising. It could be a product of the <a href="https://www.epa.gov/heatislands" target="_blank">urban heat island effect</a> – the fact that structures and paved surfaces in cities absorb and reemit more of the sun's heat than natural surfaces. Replacing vegetation with buildings, roads and parking lots can therefore make cities significantly warmer than surrounding lands. This effect could reduce cold stress on birds and increase food resources, such as insect populations, during the winter.</p><p>Our research adds to our understanding of how conditions in cities can both help and hurt migratory bird populations. We hope that our findings will inform urban planning initiatives and strategies to reduce the harmful effects of cities on migratory birds through such measures as <a href="https://www.arborday.org/programs/treecityusa/index.cfm" target="_blank" rel="noopener noreferrer">planting more trees</a> and initiating <a href="https://aeroecolab.com/uslights" target="_blank" rel="noopener noreferrer">lights-out programs</a>. Efforts to make it easier for migratory birds to complete their incredible journeys will help maintain their populations into the future.</p><p><em><span style="background-color: initial;"><a href="https://theconversation.com/profiles/frank-la-sorte-1191494" target="_blank">Frank La Sorte</a> is a r</span>esearch associate at the </em><em>Cornell Lab of Ornithology, Cornell University. <a href="https://theconversation.com/profiles/kyle-horton-1191498" target="_blank">Kyle Horton</a> is an assistant professor of Fish, Wildlife, and Conservation Biology at the Colorado State University.</em></p><p><em></em><em>Disclosure statement: Frank La Sorte receives funding from The Wolf Creek Charitable Foundation and the National Science Foundation (DBI-1939187). K</em><em>yle Horton does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</em></p><p><em>Reposted with permission from <a href="https://theconversation.com/cities-can-help-migrating-birds-on-their-way-by-planting-more-trees-and-turning-lights-off-at-night-152573" target="_blank">The Conversation</a>. </em></p>
EcoWatch Daily Newsletter
By Lynne Peeples
Editor's note: This story is part of a nine-month investigation of drinking water contamination across the U.S. The series is supported by funding from the Park Foundation and Water Foundation. Read the launch story, "Thirsting for Solutions," here.
In late September 2020, officials in Wrangell, Alaska, warned residents who were elderly, pregnant or had health problems to avoid drinking the city's tap water — unless they could filter it on their own.
Unintended Consequences<p>Chemists first discovered disinfection by-products in treated drinking water in the 1970s. The trihalomethanes they found, they determined, had resulted from the reaction of chlorine with natural organic matter. Since then, scientists have identified more than 700 additional disinfection by-products. "And those only represent a portion. We still don't know half of them," says Richardson, whose lab has identified hundreds of disinfection by-products. </p>
What’s Regulated and What’s Not?<p>The U.S. Environmental Protection Agency (EPA) currently regulates 11 disinfection by-products — including a handful of trihalomethanes (THM) and haloacetic acids (HAA). While these represent only a small fraction of all disinfection by-products, EPA aims to use their presence to indicate the presence of other disinfection by-products. "The general idea is if you control THMs and HAAs, you implicitly or by default control everything else as well," says Korshin.</p><p>EPA also requires drinking water facilities to use techniques to reduce the concentration of organic materials before applying disinfectants, and regulates the quantity of disinfectants that systems use. These rules ultimately can help control levels of disinfection by-products in drinking water.</p>
Click the image for an interactive version of this chart on the Environmental Working Group website.<p>Still, some scientists and advocates argue that current regulations do not go far enough to protect the public. Many question whether the government is regulating the right disinfection by-products, and if water systems are doing enough to reduce disinfection by-products. EPA is now seeking public input as it considers potential revisions to regulations, including the possibility of regulating additional by-products. The agency held a <a href="https://www.epa.gov/dwsixyearreview/potential-revisions-microbial-and-disinfection-byproducts-rules" target="_blank">two-day public meeting</a> in October 2020 and plans to hold additional public meetings throughout 2021.</p><p>When EPA set regulations on disinfection by-products between the 1970s and early 2000s, the agency, as well as the scientific community, was primarily focused on by-products of reactions between organics and chlorine — historically the most common drinking water disinfectant. But the science has become increasingly clear that these chlorinated chemicals represent a fraction of the by-product problem.</p><p>For example, bromide or iodide can get caught up in the reaction, too. This is common where seawater penetrates a drinking water source. By itself, bromide is innocuous, says Korshin. "But it is extremely [reactive] with organics," he says. "As bromide levels increase with normal treatment, then concentrations of brominated disinfection by-products will increase quite rapidly."</p><p><a href="https://pubmed.ncbi.nlm.nih.gov/15487777/" target="_blank">Emerging</a> <a href="https://pubs.acs.org/doi/10.1021/acs.est.7b05440" target="_blank" rel="noopener noreferrer">data</a> indicate that brominated and iodinated by-products are potentially more harmful than the regulated by-products.</p><p>Almost half of the U.S. population lives within 50 miles of either the Atlantic or Pacific coasts, where saltwater intrusion can be a problem for drinking water supplies. "In the U.S., the rule of thumb is the closer to the sea, the more bromide you have," says Korshin, noting there are also places where bromide naturally leaches out from the soil. Still, some coastal areas tend to be spared. For example, the city of Seattle's water comes from the mountains, never making contact with seawater and tending to pick up minimal organic matter.</p><p>Hazardous disinfection by-products can also be an issue with desalination for drinking water. "As <a href="https://ensia.com/features/can-saltwater-quench-our-growing-thirst/" target="_blank" rel="noopener noreferrer">desalination</a> practices become more economical, then the issue of controlling bromide becomes quite important," adds Korshin.</p>
Other Hot Spots<p>Coastal areas represent just one type of hot spot for disinfection by-products. Agricultural regions tend to send organic matter — such as fertilizer and animal waste — into waterways. Areas with warmer climates generally have higher levels of natural organic matter. And nearly any urban area can be prone to stormwater runoff or combined sewer overflows, which can contain rainwater as well as untreated human waste, industrial wastewater, hazardous materials and organic debris. These events are especially common along the East Coast, notes Sydney Evans, a science analyst with the nonprofit Environmental Working Group (EWG, a collaborator on <a href="https://ensia.com/ensia-collections/troubled-waters/" target="_blank">this reporting project</a>).</p><p>The only drinking water sources that might be altogether free of disinfection by-products, suggests Richardson, are private wells that are not treated with disinfectants. She used to drink water from her own well. "It was always cold, coming from great depth through clay and granite," she says. "It was fabulous."</p><p>Today, Richardson gets her water from a city system that uses chloramine.</p>
Toxic Treadmill<p>Most community water systems in the U.S. use chlorine for disinfection in their treatment plant. Because disinfectants are needed to prevent bacteria growth as the water travels to the homes at the ends of the distribution lines, sometimes a second round of disinfection is also added in the pipes.</p><p>Here, systems usually opt for either chlorine or chloramine. "Chloramination is more long-lasting and does not form as many disinfection by-products through the system," says Steve Via, director of federal relations at the American Water Works Association. "Some studies show that chloramination may be more protective against organisms that inhabit biofilms such as Legionella."</p>
Alternative Approaches<p>When he moved to the U.S. from Germany, Prasse says he immediately noticed the bad taste of the water. "You can taste the chlorine here. That's not the case in Germany," he says.</p><p>In his home country, water systems use chlorine — if at all — at lower concentrations and at the very end of treatment. In the Netherlands, <a href="https://dwes.copernicus.org/articles/2/1/2009/dwes-2-1-2009.pdf" target="_blank">chlorine isn't used at all</a> as the risks are considered to outweigh the benefits, says Prasse. He notes the challenge in making a convincing connection between exposure to low concentrations of disinfection by-products and health effects, such as cancer, that can occur decades later. In contrast, exposure to a pathogen can make someone sick very quickly.</p><p>But many countries in Europe have not waited for proof and have taken a precautionary approach to reduce potential risk. The emphasis there is on alternative approaches for primary disinfection such as ozone or <a href="https://www.pbs.org/wgbh/nova/article/eco-friendly-way-disinfect-water-using-light/" target="_blank" rel="noopener noreferrer">ultraviolet light</a>. Reverse osmosis is among the "high-end" options, used to remove organic and inorganics from the water. While expensive, says Prasse, the method of forcing water through a semipermeable membrane is growing in popularity for systems that want to reuse wastewater for drinking water purposes.</p><p>Remucal notes that some treatment technologies may be good at removing a particular type of contaminant while being ineffective at removing another. "We need to think about the whole soup when we think about treatment," she says. What's more, Remucal explains, the mixture of contaminants may impact the body differently than any one chemical on its own. </p><p>Richardson's preferred treatment method is filtering the water with granulated activated carbon, followed by a low dose of chlorine.</p><p>Granulated activated carbon is essentially the same stuff that's in a household filter. (EWG recommends that consumers use a <a href="https://www.ewg.org/tapwater/reviewed-disinfection-byproducts.php#:~:text=EWG%20recommends%20using%20a%20home,as%20trihalomethanes%20and%20haloacetic%20acids." target="_blank" rel="noopener noreferrer">countertop carbon filter</a> to reduce levels of disinfection by-products.) While such a filter "would remove disinfection by-products after they're formed, in the plant they remove precursors before they form by-products," explains Richardson. She coauthored a <a href="https://pubs.acs.org/doi/10.1021/acs.est.9b00023" target="_blank" rel="noopener noreferrer">2019 paper</a> that concluded the treatment method is effective in reducing a wide range of regulated and unregulated disinfection by-products.</p><br>
Greater Cincinnati Water Works installed a granulated activated carbon system in 1992, and is still one of relatively few full-scale plants that uses the technology. Courtesy of Greater Cincinnati Water Works.<p>Despite the technology and its benefits being known for decades, relatively few full-scale plants use granulated active carbon. They often cite its high cost, Richardson says. "They say that, but the city of Cincinnati [Ohio] has not gone bankrupt using it," she says. "So, I'm not buying that argument anymore."</p><p>Greater Cincinnati Water Works installed a granulated activated carbon system in 1992. On a video call in December, Jeff Swertfeger, the superintendent of Greater Cincinnati Water Works, poured grains of what looks like black sand out of a glass tube and into his hand. It was actually crushed coal that has been baked in a furnace. Under a microscope, each grain looks like a sponge, said Swertfeger. When water passes over the carbon grains, he explained, open tunnels and pores provide extensive surface area to absorb contaminants.</p><p>While the granulated activated carbon initially was installed to address chemical spills and other industrial contamination concerns in the Ohio River, Cincinnati's main drinking water source, Swertfeger notes that the substance has turned out to "remove a lot of other stuff, too," including <a href="https://ensia.com/features/drinking-water-contamination-pfas-health/" target="_blank" rel="noopener noreferrer">PFAS</a> and disinfection by-product precursors.</p><p>"We use about one-third the amount of chlorine as we did before. It smells and tastes a lot better," he says. "The use of granulated activated carbon has resulted in lower disinfection by-products across the board."</p><p>Richardson is optimistic about being able to reduce risks from disinfection by-products in the future. "If we're smart, we can still kill those pathogens and lower our chemical disinfection by-product exposure at the same time," she says.</p><p><em>Reposted with permission from </em><em><a href="https://ensia.com/features/drinking-water-disinfection-byproducts-pathogens/" target="_blank">Ensia</a>. </em><a href="https://www.ecowatch.com/r/entryeditor/2649953730#/" target="_self"></a></p>
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