Natural response or human activity? A new study indicates that agricultural and industrial sources are the main cause of the spike in atmospheric methane.
SCIENCE OF CHINESE PRESSURES
Climate change is causing rapid warming in the tropics and arctic regions, where wetlands naturally store carbon and emit methane. As the climate continues to warm, there are concerns that methane emissions in wetlands will increase and contribute even more to atmospheric greenhouse gases and climate change. Since 2007 atmospheric methane concentrations have increased at a rapid rate, 2020 having the largest observed increase in methane since systematic measurements began. The exact cause is difficult to determine because methane is released from many natural and human activities, and methane removal is from complex chemical processes. Here, using new data on stable isotope methane, combined with thousands of potential emission scenarios, a new study confirms that emissions from anthropogenic sources, including agriculture, are industry, landfill/waste and the fossil fuel industry, have clearly been the driving force for a new increase in strong greenhouse gases since 2007, while global wetlands have played only one role. small with a contribution of less than 20%.
Methane is a potent greenhouse gas with the potential to warm 80 times more than carbon dioxide over a 20-year period and has been responsible for nearly half of global warming since the industrial revolution. Methane is also a precursor to ground-level ozone pollution, and thus addressing methane emissions will have short-term climate benefits as well as improved air quality. Since 2007, the concentration of methane in the atmosphere has increased rapidly and even more since 2014, and the cause of the increase has been debated over the contribution of natural processes compared to the previous year. with human activities.
According to the Global Carbon Project’s Global Methane Budget, about a third of global methane emissions come from microorganisms in wetlands that naturally produce methane- soluble on decomposition of organic matter in the absence of oxygen. Human activities account for about 60% of global methane emissions, including agriculture, landfills and waste, and oil and gas activities, each accounting for 20–25% of methane emissions -tan global. This means that any change in natural wetlands to increased temperatures could have a significant effect on atmospheric methane concentrations.
The scientists tested a comprehensive set of emissions scenarios using data from different greenhouse gas inventories and wetland models. They found that emissions scenarios assuming large amounts of methane in wetlands increased were inconsistent with the observed atmospheric isotope profiles. In contrast, sources of methane emissions related to human activities are more consistent with the observed atmospheric isotopes. The work provides a detailed breakdown of methane growth for agricultural emissions, which increased by nearly 20% between 2000 and 2017 due to increased livestock populations, landfills and emissions. waste increased by 10 million tons, largely due to an increase of more than 40% in the world’s urban population between 2000 and 2017. Emissions from the oil and natural gas industry increased by 5 million tons with an uncertain level sure, and coal production increased by 40% globally over the same period.
“Increased human activities are clearly the main cause of the increase in atmospheric methane concentrations. No evidence of a strong natural climate response to wetland methane emissions exists to date despite its potential dominant role in the future as temperatures rise. than “. Zhen Zhang, an Earth system researcher at the University of Maryland College Park who led the study.
“This study demonstrates the value of observing methane isotope signatures as a technique to isolate and better understand methane sources. Strategic and ongoing observations of methane over wetlands are needed to detect responses to climate change, which are more likely to occur each year as the climate warms.” Benjamin Poulter, a research scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland.
recent 26NS The Conference of the Parties to the United Nations Framework Convention on Climate Change also emphasized that reducing methane is an essential component of addressing climate change. This study demonstrates that mitigation in areas dominated by human activity will have a significant impact on the development of atmospheric methane.
“The good news is that organic feedback is still not as strong. But without significant mitigation actions, we will lose the opportunity to control methane because we will have no solution with natural feedback once it is there.” Zhen Zhang said.
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See article:
Man-made emissions are the main cause of the increase in atmospheric methane (1993-2017)
https://academic.oup.com/nsr/advance-article/doi/10.1093/nsr/nwab200/6425695
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National Science Review
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