Permafrost melt sets Arctic up feed global warming: study

Permafrost holds huge quantities of carbon that could speed up global warming if it enters the atmosphere. (PHOTO COURTESY OF THE U.S. GEOLOGICAL SURVEY)

By 2100 melting permafrost will transform the Arctic into a source of global warming, as it releases more than 60 billion tonnes of carbon into the atmosphere, a new computer modeling study predicts.

This release of climate-warming carbon equals about 7.5 years of man-made greenhouse gas emissions and will further speed up global warming.

Permafrost soils contain “enormous amounts” of organic carbon, says the study, Permafrost carbon-climate feedbacks accelerate global warming, published last month in the Proceedings of the National Academy of Sciences.

When that carbon is released into the atmosphere by melting permafrost, it’s released as carbon dioxide, a potent greenhouse gas.

The findings by an international team of scientists, which suggest lands North of 60 could become a source of carbon dioxide, counter results from the Intergovernmental Panel on Climate Change’s 2007 fourth assessment report.

That report said climate change would spark a growth in high-latitude vegetation, which would pull in more carbon from the atmosphere than thawing Arctic permafrost would release.

But the most recent study used a different set of figures for its starting point.

“Previous models tended to dramatically underestimate the amount of soil carbon at high latitudes because they lacked the processes of how carbon builds up in soil. Our model starts off with more carbon in the soil, so there is much more to lose with global warming,” said lead researcher Charles Koven of the U.S. Department of Energy’s Lawrence Berkeley National Laboratory in a news release on the permafrost study.