An Interhemispheric Comparison of the Recession of Mountain Glaciers in the Last 150 Years
As of 2002, Degree of Master of Science (MS) Quaternary and Climate Studies published under the auspices of the Climate Change Institute.
Historical records in the Northern Hemisphere show overall glacier retreat since about AD 1860-1890. A glacial retreat of similar timing and magnitude in the Southern Hemisphere is less well established. Comparison of the timing and magnitude of glacial recession in the two polar hemispheres over the past century can elucidate mechanisms driving global climatic change. In order to determine the recession patterns of Murchison, Hooker, and Tasman Glaciers in the Southern Alps of New Zealand, geomorphic maps were constructed and recent glacial deposits were dated using lichenometry. Since the mid-to-late nineteenth century, each glacier terminus has retreated about 1.5 km. The timing and magnitude of this recession of New Zealand glaciers are similar to that of the recent glacial retreat in the European Alps and elsewhere in the Northern Hemisphere. Such near-synchronous recession is consistent with global, not merely hemispheric, warming. Mechanisms other than the Broecker ocean circulation model and the bipolar see-saw must be used to explain the synchronous retreat of glaciers in both polar hemispheres. Some of the recent warming could be linked to decreased global albedo, increased concentrations of trace gases in the atmosphere, and variations in solar activity.