General Trends

Over the last week I have read a few articles of interest regarding research related to glaciers. The question I have been pondering is whether glaciers can be used to predict future climate change? They have of course been around for a long time and are affected by the climate so it would make sense that if we can look at how past climate has affected them then perhaps we can infer what will happen in the future.

Indications of their usefulness

-       The Intergovernmental Panel on Climate Change (IPCC) has recognized the significance of glacial melt as a temperature sign. They have used fluctuations in there extent in all of their reports since 1990 (Barry, 2006). The use of the data implies that they are a reliable sign of climate fluctuations.

-       A change in glacier length is an obvious illustration of the impact that climate change is having, but this doesn't foresee future climate change. There are 800 glaciers that are monitored every 5-10 years but of these only 100 have long term records (Haeberli, 1998).

-       The issue with just using glacier length as an indicator of climate change is the time lag between temperature change and the change in the glacier length.

-       Oerlemans (1994) used glacial length data to predict global warming. The graph underneath shows Oerlemans prediction in relation to other predictions made using different proxies. It is very similar to the predictions that are made using other proxies, indicating that glaciers can be used to infer temperature. 

Figure 1: Source Real Climate Blog (WWW)

-       The response times of glaciers have been split in to three different groups, listed below; so progress has been made for inferring climate change.

-       Type 1 – steep slopes, extensive crevassing, high velocities near the terminus – 30-20 years response time

-       Type 2 – intermediate characteristics – 40-60 years response time

-       Type 3 – low slopes, moderate crevassing and low terminal velocities – 60-100 years response time.

Barry, 2006

As discussed in previous posts a survey of glacial trends worldwide is not yet possible due to an uneven distribution of measurements. Despite the lack of available data for individual areas the general trends are well known and are illustrated in the below graph which shows the retreat of numerous glaciers over time.

Figure 2: Top graph shows the glacial retreat and advance, bottom graph shows the location of the glaciers.
Source: Real Climate Blog (WWW)

My View


It is true that glaciers can be used as a proxy to infer past temperature. Anybody doing a study on such a thing must take in to account the time lag between the temperature change and the change in the glacier. However, temperature is not the only thing that impacts glaciers, there are a number of factors to take in to account including the amount of precipitation and perhaps human influences. This presents a problem for inferring past temperatures from glaciers, a solution may be to look at multiple proxies and infer temperatures from them, glaciers just being one of the proxies used.

In terms of future climate change, this post does not answer the question and the question must therefore roll over on to future posts.

Bibliography

Haeberli, W. (1998) Historical evolutionand operational aspects of worldwide glacier monitoring, in Haeberli, W., Hoelze, M. and Suter, S. (Eds.), Into the second century of worldwide glacier monitoring – prospects and strategy. Paris: UNESCO, Paris, 35-51.