Clim. Dynam. http://doi.org/bnrf (2016)

Credit: DANIEL A. LEIFHEIT / MOMENT / GETTY

Around the world, glaciers are being affected by climate change. Glacier mass balance — the difference between accumulation and loss of mass — allows us to track changes, but it is difficult to draw global conclusions as individual glaciers show significant variability related to the local climate.

To address this, William Medwedeff and Gerard Roe from the University of Washington, USA, statistically evaluated datasets of glacier mass balance from around the world. Data of sufficient time periods was available for 158 glaciers, which have a Northern Hemisphere bias, with most coverage in Europe and North America. The authors investigated the trend in individual datasets and associated variability.

Comparison of seasonal variability revealed that around 70% of the datasets had greater variance in the summer than winter, although this was not true for maritime climates. Negative mass balance trends were typically seen in the summer, with 25% of the individual annual records having statistically significant negative trends. Considering all data available, the trend is negative and significant. These results highlight the overall decline in glaciers globally, and suggest caution at considering individual records as being representative of broader regions.