GLOBAL WARMING HOW TO FIX A CLIMATE EMERGENCY

The effect was temporary,but scientists began to wonder if the volcano hadn’t revealed a possible weapon against climate change. A judicious application of sulphur dioxide to the upper atmosphere,which could be accomplished by launching the gas from rockets,spraying it from high-altitude planes or releasing it from a big chimney,would have an almost immediate impact on temperature. And it would cost a thousand times less than even the most optimistic scenarios for cutting emissions. A small group of scientists began looking into how this kind of geo-engineering could be done most efficiently and with the fewest side effects.

Over the past two decades geo-engineering began to include other ways of fixing climate,including new spins on the Pinatubo effect. Using sulphur dioxide or other materials,they aim to reflect sunlight back into outer space. One would boost a series of mirrors into orbit,shading Earth from sunlight,but at a cost that would likely bankrupt the planet. In the 1990s,the controversial inventor of the hydrogen bomb,Edward Teller,proposed floating reflective particles of metal in the atmosphere,adding a Dr Strangelove air to the geo-engineering field.

The other,more publicly acceptable form of geo-engineering would focus on removing carbon from the atmosphere and storing it underground. Known as carbon capture and storage (CCS),this idea is behind today’s experimental clean-power plants. But clean-coal plants will only reduce future emissions,which does not address the root of the problem. Among all the uncertainties that still surround climate change,one thing has become clear: the scary durability of carbon,which will hang in the air for a thousand years,continuing to warm the planet no matter how drastically future emissions are cut.

Geo-engineering laboured on the lunatic fringe of climate policy until recently. Experts shunned its ideas as mad science,and for fear that it would undermine the campaign to cut carbon emissions. Now,as more and more climate specialists come to believe that even current levels of carbon pollution are warming the globe more rapidly than previously thought,the case for developing an emergency earth-rescue plan is getting difficult to resist. Nobel laureates Paul Crutzen and Thomas Schelling have endorsed the need for a climate-engineering plan.

The most eloquent argument for geo-engineering as a Plan B is the failure of Plan A—emissions cuts. The Kyoto agreement calls for a 5.2 percent reduction of emissions below 1990s levels by 2012. Of the 40 countries that signed the agreement in 2001,21 have seen carbon emissions increase since then. The campaign to expand and tighten Kyoto now looks likely to fall short,too. No one is certain how sharp the cuts in greenhouse-gas emissions need to be,but the best guess is a reduction of 80 per cent below current levels by 2050. That’s a radical goal.

The irony is that the more respectable geo-engineering option,carbon capture,is also by far the more expensive and less likely to counteract a steep rise in temperatures. Each year roughly 30 billion metric tonnes of carbon dioxide are released by the world’s industries and autos. If converted to liquid form,it would take less than four years to fill an underground space with the volume of Lake Geneva. And that doesn’t take into account the 1.8 percent yearly rise in emissions,or the billions of tonnes of carbon dioxide that have already accumulated in the atmosphere for the past 100 years. Scientists still think there’s enough porous rock deep beneath the earth’s surface to accommodate all the liquid carbon dioxide we can pump,but getting it there would take many years and cost billions. Assuming the cost of removing carbon eventually falls to $50 a tonne (it now costs $200 per tonne),the bill for removing only the current year’s emissions would reach $150 billion.

Geo-engineering,say critics,would create many nasty side effects. One of the drawbacks to SO2 is that it destroys the ozone layer,exposing people in the Southern Hemisphere to deadly ultraviolet radiation. One way around the problem is to release SO2 a bit at a time,study how the climate responds and try a bit more.

David Keith,a physicist at the University of Calgary,is working on designing particles that are more efficient at cooling than sulphates,but without the side effects. Because sulphates tend to settle on the ground after a few months,they’d need to be replenished regularly. Keith’s engineered particle would absorb the sun’s energy unevenly,causing one side to heat more quickly than the other and to drift upward. Such a particle might be released on the ground and rise up on its own accord. It might be built in such a way that it rises higher than the ozone layer—to the mesosphere,100 km up—where it would reflect light but leave the ozone intact. For safety reasons,these particles could also have preordained lifetimes. “It’s something we’re developing,” he says. “It may not work. But it’s almost certain that if engineers put their minds to this,something could be made to work better than sulphates.”
_FRED GUTERL —with Michael Levitin & Sangwon Yoon,Newsweek