Mountain glaciers freeze and gain mass when the climate cools, and melt and lose mass when the climate warms. The extent to which the fluctuations in mountain glaciers are reflective of local, regional and even hemispheric climate variations, however, is less clear, which has made it more difficult for scientists to use glacial data to interpret past climate dynamics and make predictions for the future.

A team of researchers from the University of Maine conducted a National Science Foundation-funded study evaluating how atmospheric conditions are reflected in the mass fluctuations of mid-latitude glaciers on opposite sides of the Earth, comparing global temperature and wind changes with glacier snowline elevations (also called “equilibrium-line altitudes”) in the Southern Alps of New Zealand and in the European Alps observed over the course of nearly four decades. Glacier extent is dependent on the height of the snowline in the atmosphere, below which ice melts, which in turn is determined by the temperature of the atmosphere.

The data showed that the fluctuations in glacial snowlines reflected temperature changes over large regions of the atmosphere for the two mountain systems studied — even on hemispheric scales. Moreover, the latitudes of westerly wind belts were found to be important for regulating the proportion of cold versus warm air masses that influence glacier melting and freezing.

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