Shrinking tropical glaciers

Ohio State University’s Professor Lonnie Thompson is a glaciologist and also a senior research scientist at Byrd Polar and Climate Research Center. He studies glaciers in tropical and subtropical ice fields. For the past 30 years, Professor Thompson has mapped changes to glacier ice levels.

Jargon alert

Cosmogenic nuclides are rare isotopes that form in surface rocks due to high-energy cosmic (solar) rays.

Transcript

Professor Lonnie Thompson

My name is Lonnie Thompson. I am a University Distinguished Professor at Ohio State University, Columbus, Ohio. I am also a senior research scientist for the Byrd Polar Research Center. I have spent my life looking at glaciers and looking at the history that is recorded in the ice as well as looking at what’s happening to ice through time as a result of increasing temperatures on our planet.

A glacier is a wonderful archive of our past, and I believe it is the best archive we have on Earth because it records not only climate – things like temperature through the stable isotopes of oxygen and hydrogen – precipitation – the net balance. In the tropics where we have a very distinct wet and dry season, every dry season, there is a dust layer. Measure the distance between the dust layers, you have a precipitation history, and very few archives will provide that to us. But on top of that, they also record the forcings of climate. They do record the tephra from major volcanic eruptions, the sulphates coming from those eruptions. We can look at the greenhouse gases in the bubbles in the ice. We can look at cosmogenic nuclides and find out how the Sun has varied through time, and we need to understand both the natural and the human-driven forces in order to understand what lies ahead of the 21st century.

And ice is probably our best recorder. If you go to the low latitudes, of course, in order to find ice, you have to go to higher and higher elevations, and the higher you go the colder it is. The colder it is, the better the archive, and so we have made it our mission to go to the tops of the highest mountains on Earth to recover that frozen archive. In starting to look at these glaciers and then returning to many of these year after year, we could actually see how rapidly they were retreating in today’s world, and as we documented that and we started to map these glaciers, then we started becoming concerned about the rate that not only were they retreating, but they were accelerating in the rate of ice loss, and not only was that happening in the Andes of South America, it was happening on Kilimanjaro in Africa, throughout the Himalayas, the Rocky Mountains. So you get a global picture of this change taking place.

And in the tropics, in the low latitudes, probably the take-home message is that 100% of the glaciers are retreating, and where we have this time-lapse data, they are accelerating, and that gives us possible concern for our future and what will happen to these glaciers and the resource that they represent for the people who live in these areas.

Acknowledgements

This video is an extract from Thin Ice – The Inside Story of Climate Science, a David Sington/Simon Lamb film.

The full documentary film is available by emailing thiniceclimate@vuw.ac.nz. The link for streaming is available free of charge. The DVD is also available to New Zealand schools for $20 to cover costs.