Greenhouse gases: saints, villains or future saviours from an Ice Age?
It’s not often that greenhouse gases spewed out by human activities get praise as potential saviours of the planet in a leading scientific journal — they’re normally viewed as villains for causing global warming.
But a study in Nature today shows that heat-trapping gases such as carbon dioxide can help avert an even worse problem in thousands of years’ time — a shift to a freeze worse than an Ice Age that could blanket much of the northern hemisphere with ice (see picture on the left and story here).
The scientists say that the Earth is close to a natural tipping point, partly based on shifts in the orbit around the sun, that could abruptly end swings between warm periods, like the present, and Ice Ages like the one that ended 10,000 years ago.
Sometime between 10,000 and 100,000 years in the future, a shift would bring an icy blanket to much of North America, Russia and Europe — permanently. (…well, the projection only goes about half a million years into the future, but it shows no let up).
But greenhouse gases can come to the rescue by keeping the planet artificially warm, the scientists say. Still, they say the findings are no excuse to ignore the fight against global warming now — at least 10,000 years is a long time to work out how to avoid the freezer.
“I’m sure some headline writers will want to say ‘CO2 good for the atmosphere’, or ‘CO2 is good for us’. That’s not the case,” said Thomas Crowley, an American scientist at Edinburgh University who was one of the two authors. (…he stressed that point several times in an interview).
Greenhouse gases are of course a reason why the planet is warm enough to support life in the first place. But the problem is that extra emissions of the gases, mainly from burning fossil fuels since the Industrial Revolution, are upsetting the climate. (A small minority disagrees — the U.S. Competitive Enterprise Institute famously produced pro-fossil fuel advertisements about CO2, saying: “They call it pollution, we call it life”)
…Maybe the Nature study adds a new twist for greenhouse gases — from saints, for creating the conditions for life, to criminals to future saviours?