The authors find glaciers showed little change in length during the latter part of the Little Ice Age 1800-1850, but following the end of the Little Ice Age in ~1850 most began a relatively rapid retreat that began to decelerate after ~1950. The data shows that calving glaciers [red lines in fig 10a below] reversed to a net advancing trend after ~2001, and that the number of calving glaciers [fig 10b below] has sharply decreased from ~99% to 50% since the year 2000.
The Cryosphere, 8, 659-672, 2014
1Institute for Marine and Atmospheric research Utrecht, Utrecht University, Princetonplein 5, Utrecht, the Netherlands
2Department of Geology, Portland State University, Portland, OR 97207, USA
3Institute of Geography Russian Academy of Sciences, Moscow, Russia
4Department of Geography, Swansea University, Swansea, SA2 8PP, UK
5Department of Geography, University of Zürich, Zurich, Switzerland
*now at: Department of Geosciences, University of Oslo, P.O. Box 1047, Blindern, 0316 Oslo, Norway
Abstract. Glacier fluctuations contribute to variations in sea level and historical glacier length fluctuations are natural indicators of past climate change. To study these subjects, long-term information of glacier change is needed. In this paper we present a data set of global long-term glacier length fluctuations. The data set is a compilation of available information on changes in glacier length worldwide, including both measured and reconstructed glacier length fluctuations. All 471 length series start before 1950 and cover at least four decades. The longest record starts in 1535, but the majority of time series start after 1850. The number of available records decreases again after 1962. The data set has global coverage including records from all continents. However, the Canadian Arctic is not represented in the data set. The available glacier length series show relatively small fluctuations until the mid-19th century, followed by a global retreat. The retreat was strongest in the first half of the 20th century, although large variability in the length change of the different glaciers is observed. During the 20th century, calving glaciers retreated more than land-terminating glaciers, but their relative length change was approximately equal. Besides calving, the glacier slope is the most important glacier property determining length change: steep glaciers have retreated less than glaciers with a gentle slope.