All this suggests that the climate sceptics are right in one sense. They say the future is much less certain than the climate models predict. They have a point. We know less than we think. But the sceptics are wrong in concluding the models have been exaggerating the threat. Far from it. Evidence emerging in the past five years or so suggests the presence of many previously unknown tipping points that could trigger dangerous climate change.
The article, about how we have not thought through how fast Greenland can melt, is timely in this recent period of hightened awareness of global warming. It is coalescing from tectonic shifts in the public discussion caused by Al Gore's "An Inconvenient Truth" world tour, the release of the Stern Report, the admission from John Howard about AGW, and not least, uncle Rupert Murdoch's conversion. Proof plenty of this are the estimated 10,000 to 12,000 people who 'Walked against Warming' in Sydney's CBD today, despite the wet and rain. Thank goodness, because now we badly need to talk about tipping points:
That is what is so worrying about the British Met Office's warning that the Amazon rainforest could die by mid-century, releasing its stored carbon from trees and soils into the air. And why we should take serious note when Peter Cox, professor of climate systems at Exeter University, warns that the world's soils - soaking up carbon for centuries - may be close to a tipping beyond which they will release it all again.
Other threats lurk on the horizon. We know that there are trillions of tonnes of methane, a virulent greenhouse gas, trapped in permafrost and in sediments beneath the ocean bed. There are fears this methane may start leaking out as temperatures rise. It seems this happened 55 million years ago, when gradual warming of the atmosphere penetrated to the ocean depths and unlocked the methane, which caused a much greater warming that resulted in the extinction of millions of species.
The only good tipping point is the one going on right now in the public conversation. Gore is right, the the impetus for a global warming policy that deals with the problem, rather than pander to Big Fossil or Radiological Fuel, is only going to come from voters.
Other blogs on: global warming climate change tipping points