NASA climatologist James Hansen has continued, in recent years, to offer the most useful projections of climate change, and the most outspoken interpretation of their meaning. Last December, in a paper delivered at the American Geophysical Union, he said that carbon concentrations in the atmosphere (currently 387 parts per million) were already above the safe line for preventing the possibility of the rapid rise of sea levels, shifts in monsoons, and other civilization-shaking disasters. We needed, he said, to take emergency action to push that number back below 350 parts per million. The only way to achieve that result, he added, was to close all coal-fired power plants in the next few decades, a truly monumental challenge. This summer's rapid melt of Arctic ice has served only to underline the magnitude of Hansen's challenge, and indeed new data released in late September showed that carbon emissions have grown even faster than the most dire predictions of the IPCC. (The new numbers, ironically, came during the worst week so far of the Wall Street crisis, and the financial meltdown served to blot out any discussion of the meltdown meltdown.)
If the Chinese continue building coal-fired power plants for another decade while we wait for America to construct a shiny green city on the hill, the carbon load from those Chinese plants will force us toward many of the dangerous tipping points that Hansen and other scientists have identified in recent years. In that world, the rising seas will be lapping at the bottom of the hill, and the city up on top will be spending most of its dwindling capital dealing with the damage.
The world's governments are now nearing a real deadline: December 2009, when a negotiation session in Copenhagen is supposed to produce a new climate treaty, the successor to the Kyoto protocols And there's no good reason to think that the planet needs America alone to be in the lead position-the Europeans and the Japanese have already done far more, with technology and with policy, to limit global warming, and if you visit China you know that the hotels are already full of foreign consultants and advisers on global warming.
There is, therefore, no escaping the need for politics, for a robust international agreement that, among other things, commits America to sharing the burden for helping China and India develop without burning their piles of coal; building wind farms in Mongolia is even more crucial than in Minnesota. The controlling metaphor here is not the Manhattan Project or the Apollo moonshot; it is a Marshall Plan for carbons by which the global north makes up some of the difference between cheap coal and more expensive renewable energy for the global south-another possibility that has probably grown less likely as our financial strains have increased. But if the conventional wisdom doesn't line up behind such a plan soon, before the Copenhagen talks, then the chance will pass. Consider the words of a scientist, Rajendra Pachauri, who last year accepted the Nobel Prize on behalf of the IPCC, which he heads: "If there's no action before 2012, that's too late. What we do in the next two to three years will determine our future. This is the defining moment."
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