Thaw of polar permafrost has major implications for climate change

The thawing of polar permafrost about 55 million years ago led to a massive CO2 release, exacerbating a series of major ancient global warming events, according to new research.

A study led by the University of Massachusetts Amherst, with support from scientists at Yale and other universities, suggests that today’s thawing polar permafrost could play a similar role in the future.

“Whether it’s 55 million years ago or 55 years from today, climate models predict a series of feedbacks that lead to permafrost melting and carbon emissions once high-latitude threshold temperatures are crossed,” said Yale geochemist Mark Pagani, an author of the paper. “Failing to consider the capacity of this particular chunk of CO2 to move climate is a grave oversight.”

The paper was published April 4 in the journal Nature.

Permafrost — perennially frozen ground — contains huge amounts of organic carbon. Thawing permafrost releases carbon as CO2. That gas subsequently traps heat in the Earth’s atmosphere.

The research team developed a model to explain the origin of the carbon that was released from the permafrost during the Paleocene-Eocene Thermal Maximum, or PETM. One especially notable element it accounts for is the role of the Earth’s orbit, which affects the amount of solar radiation received in the highest latitudes.

According to the research team, the Earth’s specific orbit during the PETM, combined with other factors, hastened the release of CO2 from Arctic and Antarctic permafrost.

The paper is “Past extreme warming events linked to massive carbon release from thawing permafrost.”