An article on BBC News from the beginning of April discusses a new study by Glasser et al. (2011) which identified both new ice loss figures and the resulting sea level contribution of melting mountain glaciers in Patagonia. This covered changes for 270 of the largest glaciers in Argentina and Chile, and showed new estimates for the amount of melting that has occurred since the end of the Little Ice Age. The new method, which utilises the spread of glacier debris and vegetation extents to calculate ice loss, has also revealed new findings.
Figure 1. Clear trimline of vegetation used to delimit vertical extent of ice
The study showed that the glaciers, which covered a huge area at the end of the Little Ice Age , have lost approximately 606 km3 since then. As the lead author, Prof. Neil Glasser stated:
"Previous estimates of sea-level contribution from mountain glaciers are based on very short timescales... They cover only the last 30 years or so when satellite images can be used to calculate rates of glacier volume change. We took a different approach by using a new method that allows us to look at longer timescales.”
The paper made an interesting discovery that the rate of melting at the start of the 20th century was actually lower than previously suggested. However, a much starker discovery showed that in the last 30 years, the rate of glacial melting has become over 100 times that of the previous 320 year average!
Not only does this paper reveal new insights into past melting rates and contributions to global sea level rise, but it also shows how present melting rates are the highest in over 350 years. This has been the first estimate of glacier melt contribution to sea level rise during industrial times and evidently has important points to consider for the future. With local impacts of glacier retreat to consider (such as water supply), it has been shown that the melting of mountain glaciers can also have a global effect both now and certainly in the future.
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