1,700 billion metric tonnes of carbon dioxide. That's twice the current record amount of atmospheric CO2. 1,700 billion metric tonnes is the estimated amount of CO2 held in the northern hemisphere's permafrost that is now at risk of being released.
A report of the U.N. Environment Programme released at the Doha climate summit warns that data from existing monitoring networks, "indicates that large-scale thawing of permafrost may have already started."
With Arctic temperatures warming twice as fast as the global average,
scientists estimate thawing permafrost could release large amounts of
carbon into the atmosphere through the end of the century with
significant climate impacts.
Thawing permafrost could emit 43 billion to 135 billion metric tons of
carbon dioxide equivalent by 2100, and 246 billion to 415 billion metric
tons of CO2 by 2200, the U.N. report says.
"Uncertainties are large, but emissions from thawing permafrost could
start within the next few decades and continue for several centuries,
influencing both short-term climate (before 2100) and long-term climate
(after 2100)," it continues.
Despite that risk, current climate models do not include the risk of
emissions from thawing permafrost, the UNEP analysis warned.
As a consequence, the projections of future climate change made in the
IPCC's next major report, due next year, "are likely to be biased on the
low side," the new report says.