Humans to blame for polar melting
30 October 2008
A new study shows human activities are to blame for melting the coldest regions of Earth. Antenna breaks the news to climate experts and finds out what they think...
This research was published in the journal Nature Geoscience on 31 October 2008.
Image: Amanda Graham
There's no doubt the North and South Poles have been warming over recent decades. In the north, the Arctic has suffered dramatic declines in summer sea ice, and at both poles ice shelves have melted and collapsed.
Until now, there's been no evidence that the melting in Antarctica is due to us churning out too much climate-changing greenhouse gas. For the first time, British climate experts have shown that we cannot escape the blame.
Image: Sandy Briggs
The scientists took 100 years of existing temperature records from the Arctic and 50 years of records from Antarctica. They compared the patterns they found to the most reliable computer simulations. Some modelled temperature affected only by natural changes in climate while others included human-driven climate change.
And the results? Nathan Gillett, lead researcher, says they give conclusive evidence that human activity is the cause. The actual records only matched the simulation for human-driven climate change.
The Scott-Amundsen research station at the South Pole - one of the places where temperatures are recorded.
Image: Chris Danals, National Science Foundation
Nathan Gillett, climate-change expert, University of East Anglia.
Image: UEA
'Both poles have warmed over past decades and our research shows that this cannot be explained by natural influences, but is caused by human activity - mainly pumping out greenhouse gases.' |
So do other experts agree?
Ron Lindsay - an Arctic climate expert - thinks the results make sense: 'I'm not surprised by their finding. The changes in ice cover are truly unprecedented and the only thing that's also been changing substantially is human activity, and that's been immense by any measure.'
Ron Lindsay, climate expert, University of Washington.
Image: University of Washington
Temperature records are limited, so spotting trends in the Arctic and Antarctic can be more difficult than elsewhere in the world. Ignatius Rigor, an expert on polar science, explains: 'We can see that there is a warming trend, but we still need to be cautious given the small amount of data.'
Ignatius Rigor, polar science expert, University of Washington.
Image: University of Washington
Nathan says that human influence can be seen despite the limited data: 'We took into account the small amount of data we have and still found that natural changes in climate cannot explain the warming in either polar region.' The computer models have been thoroughly tested and used in lots of other studies.
Meanwhile, the melting continues. 'The long-term outlook is clear - perhaps as early as 2030, the Arctic Ocean will become ice-free in summer,' warns Mark Serreze, an expert on Arctic climate from the University of Colorado.
Ron Lindsay agrees: 'The trend is that ice is getting thinner, but it's likely to vary greatly from year to year depending on wind patterns and air temperatures. I expect next year to have very low levels of ice at the end of summer.'
The polar bear was listed as a threatened species in May 2008, because of the loss of its icy habitat.
Image: U.S. Fish and Wildlife Service
Lack of data from Antarctica meant that scientists on the International Panel for Climate Change(IPCC) agreed in 2007 that it was the only continent where human influence on climate had not been detected. Will this new study change their minds? The experts seem convinced.
The Antarctic.
Image: NASA