Scientists consider ways to manage global warming

Many scientists don't like the idea of interfering so aggressively with nature.
TORONTO GLOBE AND MAIL
It may be hard to imagine the world getting so hot that scientists and engineers would design a fleet of 55,000 mirrors, each bigger than Manhattan, and send them into space to deflect sunlight away from Earth.
Or that they would mimic a major volcanic eruption in order to cool the melting Arctic, shooting dust and other particles into the upper atmosphere where they would scatter the sun's light away from Earth.
Using geoengineering, the large-scale manipulation of the environment, to combat global warming has been proposed by scientists like Lowell Wood at Lawrence Livermore National Laboratory in California.
He argues that simulating a volcanic winter -- the cooling that follows major volcanic eruptions like Mount Pinatubo in 1991 -- is the most practical approach to managing global warming.
"It appears, of all the things I have heard discussed, to be the most economical and readily implemented," Wood says.
Critics
The idea of interfering with nature in such an aggressive and intentional way is seen as irresponsible by many other scientists and environmentalists. They worry that focusing on high-tech fixes will distract politicians and ordinary citizens from the measures that could be taken today to reduce the world's dependence on fossil fuels, which produce carbon dioxide when they are burned. Carbon dioxide and other greenhouse gases act like a solar blanket, trapping heat in the atmosphere.
"If we really knew we could do this, there is no question it would lessen efforts to push politicians to reduce carbon dioxide levels," says David Keith, an expert on geoengineering who holds the Canada Research Chair in Energy and the Environment at the University of Calgary.
But what if global warming is more severe or happens more quickly than scientists predict? The worst-case scenarios are bad enough, and would see cities like Vancouver, New York and Shanghai swamped by rising sea levels caused by melting Greenland and Antarctic ice. Other parts of the world could be periodically devastated by more severe droughts, hurricanes and other weather.
"You would like to have a backup system to try -- to have an alternative," Mike MacCracken, with the Climate Institute in Washington, said.