Asked by Jack
Glaciers are shrinking world-wide, and the rate of recession is generally increasing. It is difficult to relate the behaviour of individual glaciers to climate change, but the general trend of accelerating recession is indicative of a world-wide response to global warming. Glaciers are a ‘natural thermometer’, as their changes are the result of an integrated response to climate.
This figure shows the global distribution of glaciers. The diameter of the circle shows the area covered. The area covered by tidewater glaciers is shown in blue. The number refers to the RGI region. From the IPCC AR5 Working Group.
We see glaciers shrinking particularly rapidly around the Antarctic Peninsula and I’ve written about Antarctic glacier recession here. Worldwide, the glaciers in Alaska, the Canadian Arctic, around the periphery of the Greenland Ice Sheet, the Southern Andes and the Asian mountains are shrinking fastest. We can observe and map glaciers and their recession by using satellite remote sensing. Observations of length changes generally show strong glacier recession.
Selection of long-term cumulative glacier length changes as compiled from in situ measurements. From the IPCC AR5 Chapter 4.
The IPCC Assessment Report 5 has a good summary:
Since AR4, almost all glaciers worldwide have continued to shrink as revealed by the time series of measured changes in glacier length, area, volume and mass (very high confidence).Measurements of glacier change have increased substantially in number since AR4. Most of the new data sets, along with a globally complete glacier inventory, have been derived from satellite remote sensing.
Between 2003 and 2009, most of the ice lost was from glaciers in Alaska, the Canadian Arctic, the periphery of the Greenland ice sheet, the Southern Andes and the Asian Mountains (very high confidence). Together these regions account for more than 80% of the total ice loss.
Total mass loss from all glaciers in the world, excluding those on the periphery of the ice sheets, was very likely 226 ± 135 Gt yr–1 (sea level equivalent, 0.62 ± 0.37 mm yr–1) in the period 1971–2009, 275 ± 135 Gt yr–1 (0.76 ±0.37 mm yr–1) in the period 1993–2009, and 301 ± 135 Gt yr–1 (0.83 ± 0.37 mm yr–1) between 2005 and 2009.
Current glacier extents are out of balance with current climatic conditions, indicating that glaciers will continue to shrink in the future even without further temperature increase (high confidence).