The importance of making measurements

So far, I hope it has become apparent that glaciers are changing and that this is a direct consequence of our warming climate. We have also seen that as a consequence of shrinking glaciers, there are some very profound and important consequences – namely in terms of the role that melting glaciers have on sea levels, and on melt rates and water availability in areas reliant on glacier-fed river systems. These are of great concern for the entire planet.

In order for us to better assess and understand glacier change in the past, and crucially, to make predictions of likely changes into the future, we need to be able to accurately measure and monitor the rates and magnitudes of such changes. In other words, we need to work out how quickly glaciers respond to our changing climate, and how big that response is.

So, for example, if we are concerned about the changes taking place to the mass balance of the Greenland ice sheet and what the implications are for future sea levels, then we need to be able to assess how much is lost, and how quickly that takes place over a given time. As a result, it is of vital importance that we are able to make measurements of a changing glacier(s) or ice sheet.

The image below is a satellite image showing multiple retreating glaciers in the Bhutanese Himalayas. As a consequence of this retreat, proglacial lakes form in front of these glaciers.

The challenge of measuring glacial change

In essence, if we are trying to measure glacier change, it is harder to determine than you might think! There are lots of glaciers in the world (about 198,000). So, for example, if we want to investigate the rate of retreat of glaciers in the Himalayas, how many glaciers do we need to look at? Is one enough or do we need more? If we decide on more, then how many more? All of them? There are estimated to be approximately 56,000 glaciers in the Himalayas – how on earth do we measure the changes on all of them!?

There is an added complication in that glaciers tend to be associated with quite remote, inhospitable places. As discussed previously, we find them at either high altitude or high latitude, but both these locations are dangerous, inaccessible and inhospitable, making it hard to access and then hard and dangerous to work on. Even if we did manage to get to one of these remote glaciers, we can debate how useful that one field study is to understanding Himalayan glaciers as a whole.

What we really need is an approach that enables us to explore lots of glaciers at the same time (so as to get a representative assessment of glacier change in an area). There is a fantastic tool at our disposal that has become exceptionally important in our efforts to measure and monitor changing glaciers, and this is discussed next.