Teleconnections between Andean and New Zealand glaciers

Abstract

Retreat and advance of glaciers in the Southern Alps of New Zealand have occurred over two distinct 20-yr climate periods (1954–1974) and (1974–1994). Changes in tropical and southern Andean glaciers are compared over these same periods. Behaviour of glaciers in the tropical Andes are out of phase with the Southern Alps glaciers, but some glaciers in Patagonia appear to be in phase. Southern Hemisphere atmospheric circulation using 700 hPa geopotential height anomalies and sea surface temperature patterns are examined for these periods. Glacier response on inter-decadal timescales is linked with distinctive shifts in atmospheric circulation patterns around the Southern Hemisphere. Retreat (advance) of glaciers in the Southern Alps and southern Andean glacier and advance (retreat) of glaciers in the tropical Andes are all associated with weaker (stronger) westerlies, blocking events in the South-east Pacific, negative (positive) geopotential height anomalies over Southern Africa and higher latitudes of the Southern Hemisphere. These glacier changes are also linked with the negative (positive) phase of the Inter-decadal Pacific Oscillation, a higher frequency of La Niña (El Niño) events, and warm (cool) sea surface temperatures in the New Zealand region and cool (warm) sea surface temperatures in the equatorial eastern region of the Pacific Ocean off the coast of Peru.