Some of scientists’ gravest concerns about future climate change are rooted in the past. Records studied by paleoclimatologists reveal that the more extreme possibilities for this century and beyond — temperatures soaring, ice sheets vanishing, fertile lands withering into deserts — were realized previously on Earth when atmospheric greenhouse gas levels surged. At this summer’s AGU Chapman Conference on Abrupt Climate Change, researchers described this turbulent history through all manner of proxies – ice, tree rings, corals, marine and lake sediments, among others. But few talks went without a slide showing the wiggly line of a deep ice core.

Each proxy has its own merits, but ice cores offer records of climatic history whose detail and completeness are unmatched. Their data stretch back 800,000 years and are conveniently located in some of the world’s most climatically sensitive regions. Two new features on Nature Reports Climate Change pay homage to the work of scientists who, over the last few decades, have been tireless in their efforts to extract clues about the Earth’s past climate from air bubbles, isotopes and dust particles trapped in ice.

First, a timeline of deep polar cores documents in fine detail the discoveries of scientific pioneers, from the first efforts to read ice records through to today’s hunt for ice a million years old or more. Complementing this chronology of scientific discovery is an interactive map layer for Google Earth. This virtual tour takes you to the sites where polar researchers have holed up year after year, drilling thousands of metres of Greenland or Antarctic ice before hitting bedrock. In the window below, spin the globe to the pole of your choice, zoom in and click on the map points to see the drilling stations. For a full-size view and more navigation controls – plus a built-in web browser window where you can check out the timeline – download the map layer here and run it in Google Earth, which you can download here.

As I highlighted earlier on the blog, this month’s issue of NRCC also features an exclusive interview with world-renowned glaciologist Lonnie Thompson. On his quest to understand how ice is changing atop the world’s mountains, Thompson has spent more spent more time above 20,000 feet than any other human being; he’s currently with a team at the Quelccaya glacier in Peru, racing to bring back ice that is rapidly being lost to climate change. The American Museum of Natural History has put together a great video on his work.

Such endeavours come with scientific challenges as well as personal ones. As understanding abrupt climate change becomes increasingly crucial, ambitious plans for studying these icy environs will be ever more important.

Anna Barnett

At the AGU Chapman Conference last month I met up with Lonnie Thompson, the alpine glaciologist who has spent more time above 20,000 feet than any other human. Despite being interrupted by last-minute demands from Peruvian customs officials – he was squeezing me in before taking off for a new expedition in the Andes – an unphased Thompson carefully laid out the past and present-day climate change that his work has uncovered. Here’s an extract:

What information can you garner from glaciers?

Glaciers are like sentinels, and they’re telling us that the system is changing. The first thing we look for in the ice is radioactivity from thermonuclear bomb tests in 1962–1963 and 1951–1952. Back in 2006, we drilled three cores in the southwestern Himalayas. At 6,050 metres, where those glaciers reach their highest elevation, we found that neither of these radioactive layers was preserved. The glaciers are being decapitated. Not only are they retreating up the mountain slopes, but they are thinning from the top down.

This same scenario is playing out on Mount Kilimanjaro in Africa. When we drilled there in 2000 we found the 1951 test preserved, but not the 1962 test. We’ve since continued to monitor those glaciers and we know that we’ve lost three metres of ice since 2000. If we had waited until this year to drill, we would not have found the 1951 bomb horizon, because that has now been lost.

What does that mean for climate science?

Once a glacier melts, the history it contained is gone forever, so there’s an urgency in trying to collect the records before they are lost.

The loss of tropical glaciers is very telling because they’re in such sensitive places. Half of the surface of the planet lies between 30° N and 30° S. That’s where the heat that drives the climate system is received. It’s also where 70 per cent of the 6.7 billion people on the planet live.

What’s the effect on people as these glaciers disappear?

After this meeting, we’re headed to Peru to drill new ice cores at two sites. That country contains 75 per cent of the world’s glaciers. Eighty per cent of its population is in the desert on the west coast, and 76 per cent of the electricity comes from hydropower, from streams that are fed by glaciers in the Andes, all of which are retreating. Those changes are impacting the ability to produce hydropower, to irrigate crops in the desert and to provide municipal water supplies.

Read the full interview here.

Anna Barnett

Image: © Thomas Nash 2000. All rights reserved.