Lonnie Thompson, a glaciologist at The Ohio State University (O.S.U.) in Columbus, does not believe in the impossible. More than three decades ago he led an expedition that retrieved ice cores from the Quelccaya Ice Cap in Peru at 5,670 meters above sea level, which most glaciologists at the time considered too high for humans to conduct this kind of work. The exquisitely preserved layers of dust and air bubbles in the cores provided an unprecedented climate history of the tropics, and Thompson’s work has come to focus on the increasingly important climate change lessons to be learned from Earth’s so-called “third pole”—the ancient and massive buildup of glacial ice straddling the subtropics in Tibet.

Thompson has since led more than 60 expeditions around the world, painstakingly retrieving ice cores from low and middle latitudes in 16 countries, including the world’s highest ice-core site on the Dasuopu Glacier in Tibet at 7,200 meters. In September 2015—three and half years after having a heart transplant—the 67-year-old glaciologist reached 6,700 meters on Tibet’s Guliya Ice Cap. It was the highest altitude a heart transplant recipient has ever reached, according to Rodrigo Guzman, an expert on high-altitude medicine who accompanied Thompson on the expedition.

Lonnie Thompson inspecting a glacier terminus of the Guliya ice cap in western Tibet. Credit: Jane Qiu

Thompson and his colleagues have just opened a new center at O.S.U. for the Third Pole Environment (TPE)—an international research program focusing on the Tibetan Plateau and surrounding mountain ranges. He explains to Scientific American why low- and mid-latitude glaciers are good climate indicators, what they have told us about Earth’s climate history and why the new TPE center is important.

[An edited transcript of the interview follows.]

The Arctic and Antarctic have been the focus of climate research. Why have you been studying glaciers from the tropics and subtropics?

Climate records from low and middle latitudes are crucial additions to those from polar regions. What happens there is extremely important for understanding our changing climate, especially phenomena such as monsoons and the El Niño–Southern Oscillation [the irregular variation in winds and sea-surface temperatures over the equatorial Pacific Ocean that affects much of the tropics and subtropics].

This is where we have the highest sea-surface temperatures and where large quantities of water vapor are produced by evaporation from the oceans. They are the engine of the climate system. On top of that, low and middle latitudes cover over half of the Earth’s surface and are home to 70 percent of the global population. Climate perturbations in those regions don’t show up strongly in ice cores from the poles. We have to look to places like Peru, Tibet, Tanzania and Papua New Guinea.

Your latest expedition was in western Tibet, where you retrieved ice cores from the Guliya Ice Cap at 6,700 meters above sea level. What was it like to work at such high elevations—especially after a heart transplant?

It’s one of the hardest expeditions I’d ever undertaken. We had only a small window of time to drill the ice cap—when it’s cold enough to retrieve good ice cores but not too cold to prohibit the operation. At the beginning it seemed the entire world was up against us: We got held up by visa problems; it took much longer than planned to haul seven tons of equipment onto the ice cap; and it was extremely windy for days on end.

I had a very strict regime to slowly adjust to increasing altitudes—from the sea level in Beijing to the top of the Guliya Ice Cap. An expedition doctor also closely monitored my pulse, blood pressure and blood oxygen levels several times a day. My new heart worked wonders. I think it will go on much longer than the rest of my body.

Lonnie Thompson (right) logging an ice core on top of the Guliya ice cap in western Tibet at 6,700 metres above sea level. Credit: Jane Qiu

What have you learned from Tibetan ice cores?

They have given us a glimpse of Tibet’s climate history going back to more than half a million years. We learned that the extent of glaciation is related to how far monsoonal rains penetrate the Tibetan Plateau. This is in step with the slow wobbling of Earth’s rotational axis, which drives tropical rainfall in 21,000-year cycles. We also identified periods when average temperatures in Tibet went up and down by several degrees Celsius in roughly 200-year cycles. It’s still a mystery why that was the case, but we suspect this may be related to the 205-year cycle of solar activity.

In more recent times an interesting discovery is that the higher the elevation, the greater warming we have. This is in line with the observation that the vast majority of glaciers in Tibet and the Himalayas are retreating. In some extreme cases, as ice cores from the Naimona’nyi Glacier in southern Tibet show, all the snow and ice that accumulated since 1950 has melted or sublimated away at altitudes as high as 6,000 meters above sea level.

Is this ice loss unique to Tibet and the Himalayas?

It’s not unique to Tibetan and Himalayan glaciers. The picture is the same for nearly all mountain glaciers around the world. The summit ice cover of Tanzania’s Mount Kilimanjaro, for instance, has shrunk by 85 percent in the past century. If the current climate conditions persist, it won’t be long before Africa’s highest mountain is ice-free. At the Quelccaya Ice Cap in the Peruvian Andes, glaciers that accumulated over 1,600 years have melted in just 25 years.

Such analyses provide some of the strongest evidence to date that our climate is going through a period of unprecedented warming on a large scale. One of the biggest challenges we face in the 21st century is how to get along with each other, and another is how to get along with our planet. The world should act together to curb emissions of greenhouse gases and other pollutants.

Last month saw the launch of a new TPE centre at O.S.U. What’s the program about?

The third pole refers to the Tibetan Plateau and surrounding mountain ranges. Encompassing five million square kilometers of land—[the equivalent of] about half of the U.S. landmass—with an average elevation of over 4,000 meters above sea level, it boasts the largest stock of ice outside the Arctic and the Antarctic and affects over 1.4 billion people by supplying precious water resources, affecting monsoons and providing ecosystem services.

An ice core retrieved from the top of the Guliya ice cap in western Tibet at 6,700 metres above sea level. Credit: Jane Qiu

Launched in 2009, TPE sprang from the realization that we could not fully understand this vast geographic region with individual research groups focusing on their own pieces of the puzzle. One important aim of the program is to promote international collaboration, especially between the 12 third pole countries. Another is to study all aspects of environmental changes—from geology, atmospheric science, glaciology, hydrology, ecosystems to human activities—and how they relate to one another.

O.S.U. is far away from the third pole. Why would you want to set up a TPE center here?

Ohio is indeed far away from the third pole but we are not immune from its influence. The extent of ice and snow cover in Tibet, for instance, could affect climate in North America by affecting large-scale atmospheric circulation patterns.

TPE is headquartered in Beijing and also has a center in Kathmandu, [Nepal]. A new center here at O.S.U. aims to serve as a neutral ground for strengthening regional cooperation, especially between rival countries such as China, India and Pakistan. It will also serve as a hub to train young scientists and raise the capacity of science in third pole countries. The beauty of science is that it can transcend politics. Scientists can come together with common humanity trumping any division of race and ideology. But only by working together can trust be built.

What are the program’s plans in the near future?

Indian, Chinese and U.S. glaciologists are discussing the possibility of retrieving ice cores from glaciers in the Indian Himalaya—for the first time. Together with ice cores from the Tibetan Plateau, north of the Himalayas, this will provide an excellent opportunity to compare climate records from both sides of the mountain range.

Meanwhile TPE is getting increasingly global. It’s in the process of establishing a European center in Germany or Sweden. There are also plans to expand the program’s geographical coverage farther to the west and to the south—to include more central and south Asian countries. The new program, called Pan-TPE, is a natural extension of the holistic philosophy because many aspects of science such as geology, climatology, hydrology and pollution studies go beyond the current third pole boundary.