A new study says melting permafrost is likely to eventually release greenhouse gases equal to half the emissions of the entire industrial age.
The report is the first to try and estimate how much carbon will be released as the warming Arctic's frozen soil melts.
The Colorado-based National Snow and Ice Data Center says the Canadian Arctic is likely to lose about one-third of its permafrost by the end of the century.
That means over the next 20 years, the Arctic is likely to shift from being a carbon sink to a carbon source.
As well, the study's author points out that none of the carbon from melting permafrost was taken into account in UN climate change reports.
That means that in addition to the carbon they already know about, world leaders will have to deal with a massive new source of emissions in confronting global warming.
