US urges scientists to block out sun

[Subhash]

THE US wants the world's scientists to develop technology to block sunlight as a last-ditch way to halt global warming.

It says research into techniques such as giant mirrors in space or reflective dust pumped into the atmosphere would be "important insurance" against rising emissions, and has lobbied for such a strategy to be recommended by a UN report on climate change.

The US response says the idea of interfering with sunlight should be included in the summary for policymakers, the prominent chapter at the front of each panel report. It says: "Modifying solar radiance may be an important strategy if mitigation of emissions fails. Doing the R&D to estimate the consequences of applying such a strategy is important insurance that should be taken out. This is a very important possibility that should be considered."

Scientists have previously estimated that reflecting less than 1 per cent of sunlight back into space could compensate for the warming generated by all greenhouse gases emitted since the industrial revolution. Possible techniques include putting a giant screen into orbit, thousands of tiny, shiny balloons, or microscopic sulfate droplets pumped into the high atmosphere to mimic the cooling effects of a volcanic eruption. The IPCC draft said such ideas were "speculative, uncosted and with potential unknown side-effects".

But Professor Stephen Schneider, a climate consultant to the US government for more than 30 years and a key figure in the panel process for more than a decade, says the world is "playing Russian roulette" with its future by responding too slowly to climate change.

The panel's draft report shows projections for average global temperature rise from 1990 to 2100 will expand slightly, with a new range of one to 6.3 degrees. The 2001 report's range was 1.4 to 5.8 degrees.

Professor Schneider said he was concerned the increase was more likely to be three degrees or higher, with a 10 per cent chance of a six-degree rise by the end of the century.

"Hell, we buy fire insurance based on a 1 per cent chance," he said. "If we're going to be risk averse … we cannot dismiss the possibility of potentially catastrophic outliers and that includes Greenland and West Antarctica [ice sheets breaking up], massive species extinctions, intensified hurricanes and all those things. "There's at least a 10 per cent chance of that. And that to me for a society is too high a risk … My value judgement when you're talking about planetary life support systems is that 10 per cent, my God, that's Russian roulette with a Luger."


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