Permafrost carbon content double the old estimates

The amount of frozen organic carbon locked away in the world’s permafrost regions, a major potential source of atmospheric carbon dioxide (CO₂) and methane (CH₄), is double what has been previously estimated, according to new research.

In a paper published in Bioscience, an international team of scientists says whereas some of the CO₂ produced as a result of decomposition of previously frozen vegetation would be absorbed by increased, global warming-induced plant growth, it is likely the net effect would be a significant net increase in atmospheric CO₂.

Involving collaboration between scientists from Australia, Russia, US, Britain, Canada and Europe, the three-year study concluded that accounting for carbon stored deep in the permafrost more than doubles (to more than 1500 billion tonnes) previous estimates of the world’s high-latitude carbon inventory.

”This is equivalent to twice the current amount of CO₂ in the world’s atmosphere,” said co-author, CSIRO’s Dr Pep Canadell, from The Centre for Australian Weather and Climate Research, a partnership between CSIRO and the Australian Bureau of Meteorology.

“With temperatures in the higher latitudes estimated to rise by as much as eight degrees by the end of this century, the world could experience a major melt of large tracts of permafrost in Canada, Russia, Alaska, Norway, Sweden, Finland and Greenland.

“However, accurately predicting the magnitude and effect of thawing permafrost on the world’s climate is difficult for several reasons.

“While global carbon models may include simple permafrost dynamics they do not adequately represent the broader consequences, such as the decomposition of organic matter in thawing permafrost and the transformation of landscapes.”

Canadell says that despite such limitations, scientists now know that even the release of a small fraction of this vast frozen reservoir of carbon would significantly accelerate climate change.

“At current rates of warming in the higher latitudes, the evidence indicates that this is likely to happen,” Canadell said.