The UN’s Intergovernmental Panel on Climate Change predicts that the Arctic ocean will be ice-free during summer from 2050. But its figures, based on computer modelling, are conservative and have been challenged by a group of Colorado researchers, who used ship and aeroplane records to build up a picture of the summer ice pack since 1953.
The results show that the area covered by ice in the summer has shrunk by 7.8% per decade. If only the post-1979 satellite data are included, the figure is 9.1% per decade - twice the maximum rate predicted by the models. On this basis the true retreat is 30 years ahead of the IPCC’s predictions, the researchers say.
Sea level rise has also outstripped the IPCC’s forecast in recent years (ENDS Report 386, p 28 ), although this could be a temporary spurt. Satellite measurements of Greenland’s ice sheets show they too are melting faster than predicted (ENDS Report 381, pp 34-36 ).