GLACIERS AND CLIMATE CHANGE
Professor Mike Hambrey
A large audience assembled at Braithwaite Institute on November 9th to hear Professor Hambrey (who now lives at Threlkeld) give a comprehensive review of his own glaciological research and the implications for climate change. He outlined some of his field trips to polar regions and displayed photographic and statistical evidence of the depletion of ice from mountain glaciers in different parts of the world and from the great ice caps and ice sheets. Mountain glaciers, especially in the Himalayan chain, contribute greatly through meltwaters to the water supply of large areas of Asia. Significant loss of ice from continental areas leads to rise in sea level, a problem already affecting some low-lying Pacific islands. A special concern in the North Atlantic is the way in which major loss of ice from Greenland cools the ocean and may lead to the disruption of the important Gulf Stream which in turn could adversely affect the climate of NW Europe.
The rate of temperature increase in polar regions is higher than at lower latitudes and his Antarctic field research has revealed how the potential collapse of ice shelves along the Antarctic Peninsula would allow the release of interior ice into the ocean and its subsequent melting.
The deep drilling into the polar ice caps and in particular the extraction of 3000m of ice core from the Vostok site has enabled sampling of trapped air bubbles from the atmosphere going back millions of years. The CO2 levels measured match closely the known temperatures (from other evidence) and indicate how warm periods coincide with high CO2. Such data has shown while the CO2 concentration has not exceeded 300 ppm for most of the last million years, it reached 320 ppm in 1960 and has rapidly risen to 400ppm at present.
Professor Hambrey concluded by warning that rising CO2 together with other greenhouse gases will result in further increase of global temperatures. Present trends, unless checked by radical measures, will lead to a 40C further rise by the end of this century. At this level polar ice caps could not be sustained.