Global environmental challenges
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).