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that over half of the northern hemisphere's permafrost could thaw by 2050.
The melting of millions of square kilometres of permafrost will unleash billions of tonnes of methane, the US National Center for Atmospheric Research (NCAR) reported in the Dec. 17 issue of Geophysical Research Letters.
Methane is a greenhouse gas that is 20 times more potent than carbon dioxide, and will dramatically accelerate global warming. A major permafrost meltdown will have a major impact on climate, NCAR scientists said.
The first direct measures of Greenland's massive ice sheets released in December found that they lost 162 cubic kilometres of ice a year between 2002 and 2005. This is higher than all previous estimates and is contributing to rising sea levels, scientists from the US National Aeronautics and Space Administration reported.
Greenland alone has enough ice to raise global sea levels three metres.
Earlier in the year, European scientists reported that analysis of ice cores from Antarctica shows that today's level of carbon dioxide in the atmosphere is 27 percent higher than any previous peak - looking back 650,000 years.
In bizarre twist, air pollution has so far cushioned the full impact of all that additional carbon dioxide, a team of international scientists reported in the Dec. 22 issue of the journal Nature.
Tiny lung-clogging particles from burning coal, diesel and other fossil fuels scatter sunlight in the upper atmosphere and have been preventing the full heat of the sun from reaching the Earth's surface. The full effect of these particles or aerosols had never been calculated before now. It turns out that the "cooling effect" offsets about 30 percent of the warming from greenhouse gas emissions.
In other words, without a haze of polluted air circulating the Earth, global temperatures ought to be 30 percent warmer right now. However this "pollution umbrella" is weakening. Because of the major health affects of air pollution on children and the elderly, ever-stricter emission controls means cleaner air. Good for lungs, bad for global climate.
The only way to avoid the worst impacts of climate change is to cut emissions, experts agree.
"Kyoto won't be enough. Emissions will need to fall by 80 or 90 percent, rather than 5 or 10 percent, to have an effect on the models. In terms of a response, Kyoto is only a start," Guy Brasseur, head of the Hamburg-based Max Planck Institute for Meteorology, told the European Parliament in late November.
"Political leadership is all that's missing to achieve emissions cuts of 30 to 40 percent," said Marshall.
While the public is more concerned about the issue than politicians, most people tend to believe that if climate change is a truly serious problem, their governments would take action, he said.
"We need to deepen people's understanding of impacts and that they have to be directly involved in doing something about it," Marshall said.
The Suzuki Foundation and other environmental groups commissioned a detailed study of how Canada could achieve greenhouse gas emissions levels 25 percent below 1990 by 2020, and 80 percent below 1990 levels by 2050.
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