Data released by the U.S. National Oceanic and Atmospheric Administration this week showed a significant jump in the amount of methane in the atmosphere despite a global economic slowdown caused by the COVID-19 pandemic.
Preliminary analysis of samples from 2020 showed an annual increase in atmospheric methane of 14.7 parts per billion, which is the largest annual increase in atmospheric methane since systematic measurements began.
NOAA’s Global Monitoring Laboratory (GML) releases a preliminary estimate of the global annual atmospheric increase for key greenhouse gases in early April each year. These estimates are based on weekly air samples collected at 40 sites around the world.
These estimates are usually a little higher than the final calculation released later in the year, which incorporate additional measurements, but according to NOAA the 2020 increase is likely to remain one of the largest in the entire record.
Human caused methane emissions comes from three main sectors: fossil fuels, agriculture, and waste. Natural sources include the decay of organic matter in wetlands and from climate impacts like thawing permafrost. According to NOAA, determining the specific sources responsible for the increase in methane is difficult. Preliminary analysis of the NOAA air samples from 2020 show that the primary driver of last year’s increase comes from biological sources such as livestock and wetlands, rather than thermogenic sources like oil and gas production.
Reducing methane emissions from the fossil fuel sector, however, remains one of the most cost-effective ways to reduce the amount of methane in the atmosphere.
"Although increased fossil emissions may not be fully responsible for the recent growth in methane levels, reducing fossil methane emissions are an important step toward mitigating climate change," GML research chemist Ed Dlugokencky said.
Reducing methane emissions is critical to rapidly reducing the rate of warming in the near term. Methane exists in the atmosphere for 10 to 12 years before breaking down, but while it’s up there it has a warming potential 84 times that of carbon dioxide (CO2) over a 20-year period.
Human caused methane emissions must be reduced by 40 to 45 per cent by 2030 if countries are to achieve the Paris Agreement goal to keep warming to 1.5˚Celsius. According to an upcoming assessment by the Climate and Clean Air Coalition there are readily available targeted measures that can reduce methane emissions that reduce human-caused methane by 30 per cent, and additional measures that can add another 15 per cent in reductions by 2030.
Doing so would have additional significant benefits for health, crops, and ecosystems. Because methane is a key ingredient in the formation of tropospheric (ground-level) ozone in the atmosphere, reducing it could prevent hundreds of thousands of premature deaths each year and 26 million tonnes of crop losses from ozone air pollution each year.
The NOAA observations also showed a significant rise in CO2 in 2020 despite the pandemic lockdown. While it didn’t break previous records, the global rate of increase in CO2 was the fifth highest in NOAA’s 63-year record. The average global surface average for CO2 was 412.5 parts per million in 2020, rising by 2.6 parts per million during the year.
Without the economic slowdown caused by the COVID-19 pandemic, which reduced carbon emissions by about seven per cent, the 2020 increase would have been the highest on record.
The atmospheric burden of CO2 is now comparable to where it was during the Mid-Pliocene Warm Period around 3.6 million years ago, when concentrations of carbon dioxide ranged from about 380 to 450 parts per million. During that time sea level was about 78 feet higher than today and large forests occupied areas of the Arctic that are now tundra.
The Climate and Clean Air Coalition focuses on reducing methane emissions from all three key human sources – oil and gas, agriculture, and waste. The Coalition believes that reductions in short-lived climate pollutants like methane, black carbon, tropospheric ozone, and hydrofluorocarbons (HFCs), must complement necessary global efforts to reduce CO2 and move to a zero carbon world.
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