The Iceman Cometh
When it comes to analyzing tropical glaciers, Lonnie Thompson is at the very top of his game. As part of his research into global climate change, the Ohio State University–based paleo-climatologist has led a whopping 57 ice-drilling expeditions in 16 countries. Jaime Bedrin caught up with Thompson (featured in our Winter 2011 cover story) when he was back on dry land.
What were you investigating on your recent trip to Peru?
We're looking at the history of climate and how it's recorded through time in high‑elevation ice fields. We're also monitoring what's happening to the ice today. Peru is home to 70 percent of the Earth’s tropical glaciers, including the Quelccaya Ice Cap, the largest tropical ice cap on the planet. Quelccaya has a visible annual history going back to 315 AD. And because it’s annual, you can look at abrupt changes in the past: You can look at the Little Ice Age in that part of the world, and you can see how climate has changed in this particular tropical location.
What, specifically, do you look for in the ice?
There are a lot of things you can see while drilling. In the Peruvian Andes, you can actually see annual layers in the dust when you bring the ice cores up. So you can put a timescale on the cores while you’re drilling them.
If there was an unusually warm period, for example, you'll find a clear layer of ice in the core. That indicates that melting has taken place and gas bubbles have been released. In the tropics, you can also see organic material that you wouldn’t find in ice caps anywhere else in the world. That's because you're often drilling above a rain forest, and the thunderstorms bring up insects that get captured by the updrafts and then come out with the snow. They’re perfectly preserved in the glacier. If we’re fortunate enough to drill a core that captures these, you can identify the insects and use them to carbon‑14 date the ice, which is an added advantage of working in the tropics.
How is technology changing the way you conduct your research?
At no other time in human history could we have accomplished what we’ve been able to do today. In order to drill an ice core from one of these mountain ranges, you have to move six tons of equipment up to 20,000 feet, drill the cores, and then bring them back, keeping them frozen while getting them out of the tropics. Only in today's world -- where we have photovoltaic cells (to power the drills), lightweight Kevlar cable (to supply the power down the borehole to the drill), and airplanes (to move frozen core from distant regions to the freezers here in Ohio) -- could we do this.
Growing up in West Virginia, you liked to predict the weather. Did this lead to your interest in climate science?
I'm sure it did. I used to predict the weather for lunch money when I was in high school. Back then, you could get daily weather maps from NOAA, which you could use to predict what was going to happen the next day or the next couple of days.
Sometimes I think that if there had been a meteorology department in West Virginia or in Ohio, I may well have become a meteorologist. But the interest in understanding the weather and how it changes still plays a role in what we do.
We have satellite-linked weather stations on some of the ice caps -- they’re linked with our colleagues at the University of Massachusetts -- with which we are monitoring hourly wind speed, radiation, and snowfall, and using that data to calibrate the histories that we’ve recovered from the ice cores. So it's very much linked.
You’re asthmatic, right? How do you negotiate the high altitudes with asthma?
It's a real challenge, because the symptoms of asthma mimic the symptoms you have at high elevations -- shortness of breath, etcetera. My doctors have tried many things to reduce the symptoms of asthma. But I must say that I generally have larger problems here in Columbus, Ohio, than I have on top of a mountain in the Andes, because the air there is so clean.
What’s next for your team?
We’re looking at an ice field in far western Tibet. And we also have a program on the Otztal Icecap, in the Italian Alps. It’s very close to where Otzi, the iceman, came out of the ice back in 1991. Otzi is 5,200 years old, from a glacier in the Northern Hemisphere. He is the same age as plants that we’ve recovered down in Peru. We’re hopeful that we’ll recover a record that would capture the climate during the period of time when he actually died and was subsequently buried by the glaciers.
