Which scenario would you prefer - a global economy with an annual growth rate of 4.9% that is plunging the world into catastrophic global warming? Or, a healthy world economy with an annual growth rate of 4.78% and averting a climate catastrophe?

Those are the two options that were delivered to world leaders today in Bangkok as the UN's International Panel on Climate Change (IPCC) released the results of its third report of 2007. Their first report showed that global warming is occurring and that human's are the primary cause. The second demonstrated the catastrophic impacts of unchecked global warming on the world. Now, in their third report, the IPCC's panel of scientists and economists offers the solutions to this problem.

Keeping the global rise in average temperature to about 2C, the most radical and expensive scenario addressed here, would shave about 0.12% off the average annual GDP growth rate.

For comparison, the International Monetary Fund (IMF) projects annual global growth of 4.9% this year and next. So taking a small bite out for reducing emissions would leave the expanding cake virtually untouched.

That's cheap at twice the price.