Climate change is man-made, and difficult to slow

Man-made pollution is driving global warming, and the scale of the warming is now more intense than at any time over the past 20,000 years, according to a draft report of the Intergovernmental Panel on Climate Change.

The draft report says:

* Arctic sea ice has shrunk by 2.7 per cent per decade since 1978 and by 7.4 per cent each decade during the summer months: “the smallest extent of summer sea ice was observed in 2005”;
* Five of the six warmest years have occurred in the past five years, with 2005 and 1998 being the two warmest years on record;
* Global average sea levels rose at a rate of about two mm a year between 1961 and 2003, and by an average of more than three mm a year between 1993 and 2003;
* Melting glaciers and polar ice sheets could cause sea levels to rise by up to 43 cm by 2100, and the increase for the next 200 years is predicted to be nearly double that figure;
* Mountain glaciers and polar land ice have, in general, melted faster than they have formed over the past 40 years;
* Permafrost temperatures have increased, and the area covered by seasonally frozen ground has decreased by about seven per cent over the past 50 years.

The draft report concludes there is now overwhelming evidence to show that the global climate is changing because of human activity.

And it says climate change will continue for decades and perhaps centuries if man-made greenhouse gas emissions can be reduced.

The draft report says concentrations of carbon dioxide, methane and other greenhouse gases are at the highest for at least 650,000 years.

It predicts that global average temperatures will rise by between 2 C and 4.5 C by 2100 as a result of the doubling of carbon dioxide levels caused by greenhouse gas emissions.

Average temperatures could increase by 6 C as a result of “positive feedbacks” in the climate resulting from the melting of sea ice, thawing permafrost and the acidification of the oceans.

The draft report is the fourth climate assessment by the IPCC since it was created in 1988. The report was to be kept under wraps until the final version is ready for publication next year.

However, a U.S. government committee made a copy of the draft report available on the Internet to anyone who made an e-mail request for a password to access the area on its web site, and the draft report has surfaced since on many media and web sites.

The IPCC’s Working Group 1, which examines scientific findings related to the physical cause of climate change, drafted the document. The analyses of working groups II and III, outlining consequences from the first group’s findings and suggested solutions, have not been released yet.