Scientists are measuring emissions from dying mangrove forests in order to learn something about soaring global levels of the greenhouse gas.
Levels of methane in Earth’s atmosphere are soaring. In April 2022, NOAA reported that concentrations of the potent heat-trapping greenhouse gas averaged 1,895.7 parts per billion (ppb) over the past year, a new record. The 17 ppb increase in 2021 was the largest recorded since systematic measurements began in 1983. That followed a 15 ppb increase in 2020.
“The growth we’ve seen in 2020 and 2021 is totally surprising and unexpected,” said NASA atmospheric scientist Benjamin Poulter. “What really worries me is that we don’t understand what’s causing this increase, whether it’s human activities or climate-change feedbacks, or a combination of both.”
Several activities and processes—some natural, some human-caused—affect methane levels. The list includes fossil fuel production, agriculture, fire activity, precipitation, and the presence of methane-scrubbing chemicals (hydroxyl radicals) in the atmosphere. But the global network of monitoring stations only offers a measure of methane that has dispersed throughout the atmosphere; it does not show where the methane is coming from or what specific activities have pushed levels so high.
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Image via NASA Earth Observatory