Disappearing Arctic sea ice predicted under CO2 doubling

Sea-ice thickness plays a central role in climate processes. Ice extent and thickness have important stabilising effects on world climate, insulating large areas of the oceans from solar radiation in the summer and preventing heat loss to the atmosphere in the winter.

The effects of a warming climate are expected to be felt more strongly at the poles, and particularly in the Arctic. However, current global ocean-ice-atmosphere models are not yet able to accurately reproduce observed sea-ice coverage. Arbitrary flux corrections in these models, which essentially hold the sea surface temperature at freezing in regions where there is sea ice, make the calculation of the effect of 'perturbations' such as CO₂ –induced warming questionable (Gates et al, 1996).

The physics of sea ice in global climate models is, at the moment, oversimplified. With the recognition that variations in thermohaline circulation may have important consequences for poleward-bound heat transport – the next years will see more complete sea-ice physics within global ocean-atmosphere models. These developments demand more information on sea-ice extent and volume changes – which will be provided by the CryoSat-2 mission.