In New Zealand, mountain glaciers have been in general retreat since 1890, with an acceleration since 1920. Most have measurably thinned and reduced in size, and the snow accumulation zones have risen in elevation as the 20th century progressed. Between 1971 and 1975 Ivory Glacier receded from the glacial terminus, and about 26% of its surface area was lost. Since 1980 numerous small glacial lakes formed behind the new terminal moraines of several of these glaciers. Glaciers such as Classen, Godley and Douglas now all have new glacial lakes below their terminal locations due to the glacial retreat over the past 20 years. Satellite imagery indicates that these lakes are continuing to expand. There has been significant and ongoing ice volume losses on the largest New Zealand glaciers, including the Tasman, Ivory, Classen, Mueller, Maud, Hooker, Grey, Godley, Ramsay, Murchison, Therma, Volta and Douglas Glaciers. The retreat of these glaciers has been marked by expanding proglacial lakes and terminus region thinning. The loss in Southern Alps total ice volume from 1976 to 2014 is 34 percent of the total.