GLACIERS AND GLOBAL WARMING

Ice core and mass balance studies from glaciers, ice caps and ice shee ts constitute an ideal medium for monitoring and studying present and past environmental change and, as such, make a valuable contribution t o the present debate over anthropogenic forcing of climate. Data deriv ed from 32 years of measurements in the Canadian Arctic show no signif icant trends in glacier mass balance, ice melt, or snow accumulation, although the mass balance continues to be slightly negative. Models su ggest that industrial aerosol loading of the atmosphere should add to the warming effect of greenhouse gases. However, we have found a sharp increase in the concentration of industrial pollutants in snow deposi ted since the early 1950's which makes the trendless nature of our var ious time series surprising. Spatial differences in the nature of clim atic change may account for the lack of trend in the Queen Elizabeth I slands but encourages similar investigations to this study elsewhere i n the circumpolar region. A global warming trend over the past 150 yea rs has been demonstrated from instrumental data and is evident in our ice cores. However, the ice core data and glacier geometry changes in the Canadian Arctic suggest the Arctic warming is more pronounced in s ummer than winter. The same warming trend is not unique when viewed in the context of changes over the past 10,000 or 100,000 years. This su ggests the 150-year trend is part of the natural climate variability.