350 CLIMATE TRIGGER POINT

The economic stimulus package - that includes capping U.S. carbon emissions - might even get through the Senate in time for the Copenhagen climate summit in December.

And, along with stricter emission standards in Europe and a big push for clean energy and efficiency standards in China, there is some reason for hope that the world will commit to binding emissions reductions.

While the world slowly moves towards a climate treaty the nature of climate science is moving faster.

Much of the policy discussion so far has been aimed at keeping the atmospheric concentration of CO2 below 450 parts per million (ppm) - the figure once believed to be low enough to prevent dangerous levels of warming.

However, James Hansen, NASA's top climate scientist asserts that paleoclimatic evidence shows 450 ppm is the threshold for transition to an ice-free earth.

This would imply a catastrophic rise in sea levels, eventually flooding all coastal cities and regions.

To avoid reaching such a crisis stage, Hansen and a growing number of others now call for stabilizing CO2 concentrations at 350 ppm.

The world is now at 390 ppm and rising. And since CO2 persists in the atmosphere for a long time, it is difficult to reduce concentrations quickly.

The Hansen solution for climate change action requires a phase out of coal use, massive reforestation, and widespread use of carbon capture and storage could allow the world to achieve negative net carbon emissions by mid-century and reach 350 ppm by 2100.

Can the world afford to reduce atmospheric concentrations of CO2 to 350ppm by the end of this century?

According to Economists for Equity and Environment - a group dedicated to applying and developing economic principles to protect human health and the environment - estimates range from modest costs to small net economic gains.

Projections of economic ruin have not been presented by any major academic or non-profit research group.

Many economic models found that the modest steps called would have very small costs and virtually undetectable effects on total employment.

There are four major climate economics modeling groups - all at European universities - that have analyzed the costs of reaching 350 ppm.

One group starts from the assumption of high unemployment, and finds that long-run employment and economic growth would be increased by a program of public investment in green technology and emissions reduction that leads to 350 ppm.

The other three groups adopt the common assumption that short-run unemployment can be ignored in long-run models. They generally find that the needed emissions reductions will cost an average of 1 to 3 per cent of world economic output, for some years to come.

McKinsey & Company, an international consulting firm, has carried out detailed studies of the costs of hundreds of emission- reducing technologies. They found hat some emissions can be eliminated for no cost or even an economic savings.

In fact, more than half of worldwide business-as-usual emissions in 2030 could be eliminated at very small total cost.

The net costs of reducing carbon emissions are reduced significantly when the price of oil goes up, and vice versa.

McKinsey's entire package of reductions, eliminating more than half of world emissions, would have zero total cost if the price of oil were $90 per barrel.

Studies from major environ- mental groups, including Greenpeace and the Union of Concerned Scientists (UCS), have reached even more optimistic conclusions than McKinsey.

Both Greenpeace and UCS project substantial economic savings from emission reduction, with fuel savings much larger than the costs of investment. Both assume high oil prices of up to $140 per barrel along with rapid change in emissions- reduction technologies.