SOURCE: Harvard Gazette

DATE: June 6, 2019

SNIP: About a quarter of the Northern Hemisphere is covered in permafrost. Now, it turns out these permanently frozen beds of soil, rock, and sediment are actually not so permanent: They’re thawing at an increasing rate.

Human-induced climate change is warming these lands, melting the ice and loosening the soil, and that can cause severe damage. Forests are falling; roads are collapsing; and, in an ironic twist, the warmer soil is releasing even more greenhouse gases, which could further exacerbate the effects of climate change.

Shortly after scientists first noticed signs of thaw in the early 1970s, they rushed to monitor emissions of the two most influential greenhouse gases — carbon dioxide and methane. But until recently, the threat of the third-most-prevalent gas, nitrous oxide (N2O) — known in dentistry as laughing gas — has largely been ignored.

In a 2010 paper, the Environmental Protection Agency (EPA) rated permafrost nitrous oxide emissions as “negligible,” and few studies counter this claim.

But a paper published this month in the journal Atmospheric Chemistry and Physics shows that nitrous oxide emissions from thawing Alaskan permafrost are about 12 times higher than previously assumed. Since N2O traps heat nearly 300 times more efficiently than carbon dioxide does, this revelation could mean that the Arctic — and the global climate — are in more danger than we thought. “Much smaller increases in nitrous oxide would entail the same kind of climate change that a large plume of CO2would cause,” said Wilkerson, the paper’s first author and a Ph.D. student at the Graduate School of Arts and Sciences based in the lab of James G. Anderson, the Philip S. Weld Professor of Atmospheric Chemistry at Harvard.

Greenhouse gases rise into the atmosphere, where they trap heat and warm the planet. And nitrous oxide poses an even greater threat: In the stratosphere, sunlight and oxygen team up to convert the gas into reactive nitrogen oxides that eat away at the ozone layer, which absorbs most of the sun’s harmful ultraviolet radiation. According to the EPA, atmospheric levels of the gas are rising overall, and the molecules can stay in the atmosphere for up to 114 years.