Impact of melting snow and ice dire: UN report
Last Updated: Tuesday, June 5, 2007 | 9:52 PM ET
CBC News
Billions of people face dramatic risks and changes to their livelihoods if snow cover, sea ice, glaciers and permafrost continue to melt, a UN report says.
The Global Outlook for Ice and Snow, released Monday, says as temperatures rise, drinking and agricultural water sources could disappear, and at the same time, avalanches and flooding from unstable glacial lakes will increase.
Meanwhile, declining snow cover and sea ice could accelerate the pace of global warming, because snow and ice reflect sunlight, decreasing warming that occurs when it is absorbed by darker surfaces, such as water and land.
And if permafrost thaws, greenhouse gases that were trapped in ice will be released, which could drastically increase the pace of global warming and its impact, according to the report, written by a UN panel of some 70 researchers who are experts in their field.
As permafrost melts, it is creating new bodies of water that are releasing the global-warming gas methane into the atmosphere.
In places like Siberia, the force of those emissions keeps holes open in the ice on the lakes even in deep sub-zero temperatures. The amount of gas being emitted by the lakes — called thermokarst lakes — is as much as five times greater than previously thought.
By the end of this century, almost all of the permafrost in sub-Arctic Canada, northwest Siberia and Europe's northern regions could be thawing, according to some climate models.
If the permafrost melts, volumes of greenhouse gases equivalent to the amount already present in the atmosphere would be released, according to the report. Between 750 billion and 950 billion tonnes of organic carbon are thought to be locked in permafrost. There are some 750 billion tonnes of organic carbon in the atmosphere today.
The resulting shifts in climate would cause major changes in the presence and possibly affect the survival of animal and plant species, the report states.
