The map of the world would change utterly if climate change caused the Antarctic and Greenland ice sheets to melt. Ocean levels would rise by 70 metres, swamping coastal towns and cities and submerging vast inland areas.
Such a dramatic event was unlikely, however, according to glaciologist Prof Liz Morris, who is an adviser on arctic affairs to the British National Environmental Research Council. She delivered a Science Week Ireland lecture yesterday in Tralee entitled "Global warming and ice sheet stability".
The ice sheets are the vast kilometre-deep ice layers sitting on the Antarctic and Greenland land masses, she explained to her audience at the Siamsa Tire Theatre. These were very different to the ice "shelf", floating ice which projects outwards from the land for hundreds of miles into the oceans.
The floating ice would have no impact on sea level rise but the enormous sheets would have a tremendous impact, she said. "If all the ice sheets melted there would be a 70 metre rise in sea levels."
This however was "not realistic" as temperatures remained low enough to prevent this. Substantial ice loss, for example of the glaciers that cover the Alps and other mountains was adding to sea level rise, however. She described how the glaciers on Mount Kilimanjaro in Africa were melting so quickly that at the present rate all ice would be gone within 20 years.
This climate change-driven loss was expected to raise ocean levels by about 70 centimetres within the next 100 years, she said. While this rise seemed manageable, it would still have a major impact on low-lying areas, she warned.
Storms would more easily breach sea defences and barriers meant to protect cities such as London because of these higher sea levels. She described how ice cores and tree-ring studies were providing researchers with weather forecasts and atmospheric conditions from thousands of years ago.
"We have records of temperatures made for 150 years," she said, but the cores and ring studies pushed this back 400,000 years. "The tree rings tell you whether the tree had a good year or not." Growth was slower in cool cloudy years and faster in warm sunny years.
