Surprisingly this gut wrenching danger of additional greenhouse gases being released into the atmosphere from thawing permafrost will not be coming from the permafrost in the north that is currently thawing, but from the top of the world, such as Alaska’s north slope and northern Siberia.
Permafrost in the coldest northern Arctic — formerly thought to be at least temporarily shielded from global warming by its extreme environment — will thaw enough to become a permanent source of carbon to the atmosphere in this century, with the peak transition occurring in 40 to 60 years, according to a new NASA-led study.
The study calculated that as thawing continues, by the year 2300, total carbon emissions from this region will be 10 times as much as all human-produced fossil fuel emissions in 2016.
The study, led by scientist Nicholas Parazoo of NASA's Jet Propulsion Laboratory in Pasadena, California, found that warmer, more southerly permafrost regions will not become a carbon source until the end of the 22nd century, even though they are thawing now. That is because other changing Arctic processes will counter the effect of thawing soil in these regions
Permafrost is soil that has been frozen for centuries under the surface soil. Global warming is causing the frozen soil to thaw. The organic material in that frozen soil decomposes and becomes either carbon dioxide or methane and is released into the atmosphere.
There is far more permafrost in the northern region than in the southern one. Over the course of the model simulations, northern permafrost lost about five times more carbon per century than southern permafrost.
The southern region transitioned more slowly in the model simulations, Parazoo said, because plant growth increased much faster than expected in the south. Plants remove carbon dioxide from the air during photosynthesis, so increased plant growth means less carbon in the atmosphere. According to the model, as the southern Arctic grows warmer, increased photosynthesis will balance increased permafrost emissions until the late 2100s.