“The good news from this study is that the Greenland ice sheet is not as sensitive to temperature increases and to ice melting and running out to sea in warm climate periods like the Eemian, as we thought.”
Scientists analysing ancient ice samples say that the Greenland ice sheet withstood temperatures much higher than today’s for many thousands of years during a period of global warming more than 120,000 years ago, losing just a quarter of its mass. It had been widely suggested – by the UN Intergovernmental Panel on Climate Change for instance – that any such warming would melt the entire sheet, leading to massive sea-level rises.
The new research was carried out by analysing a 2.5km long ice core drilled from the Greenland ice last year by a major scientific expedition involving top boffins from around the world. The core data showed that 115 to 130 thousand years ago, temperatures above the Greenland ice were much higher than they are today: 8±4°C, in fact.
Until now it had been generally assumed that any such temperature rise – or indeed a much lesser rise of more than 3°C – would mean that all the Greenland ice would inevitably melt, causing the oceans of Earth to rise by as much as 7 metres. Based on the current IPCC status report, the climate-hardlinerhippies at Greenpeace have this to say (pdf):
There is a major risk that the warming expected during the next five decades would trigger meltdown of the Greenland ice sheet …
Ice sheet models project that a local warming of larger than 3°C … would lead to virtually a complete melting of the Greenland ice sheet …
But we now know that the Greenland ice was exposed to much greater heat for many thousands of years and lost only a quarter of its mass, so the models are evidently wrong and another IPCC doom warning has been consigned to the dustbin of history (previously the organisation has attracted widespread ridicule for suggesting that the glaciers of the Himalayas would all be gone by 2035 and that the Amazon rainforest might suddenly catch fire, burn up and vanish).
“The good news from this study is that the Greenland ice sheet is not as sensitive to temperature increases and to ice melting and running out to sea in warm climate periods like the Eemian, as we thought,” explains Dorthe Dahl-Jensen of Copenhagen uni, one of the lead boffins working on the ice core research.