Antarctica according to Climate Scientist George Denton

George Denton meeting Sir Edmund Hillary. Source: Antarctic Heritage Trust. 

Inspired by Shackleton and the great explorers, climate scientist George Denton has researched ice ages and glaciers all over the world including in the Antarctic and the Southern Alps of New Zealand.  

Denton made his first visit to Antarctica in 1958, while studying at Tufts University in Massachusetts, and fell in love with the vast polar environment. He gained his Masters and PhD from Yale, and in 1990 was awarded the prestigious Vega Medal by the Swedish Society for Anthropology and Geography. 

Since ’58, Denton has returned to Antarctica 30 times and both the Denton Glacier and the Denton Hills were named in his honour. These Antarctic landmarks are a way of recognising his decades of work at the bottom of the world.  

Now a Professor at the University of Maine, in the School of Earth and Climate Sciences and in the Climate Change Institute, Denton’s research continues to inspire generations of students.  

Denton splits his time now, between America and Aotearoa, and even on the 7th continent, the American and Kiwi bases are side by side. Denton’s acclaimed research in glacial geology is crucial in charting the future of the earth’s climate with his research focused on identifying the rise and eventual demise of ice ages.  

“One of the biggest unknowns is what causes ice ages, and scientists been working on that for more than two centuries,” Denton said. Ice ages reach a peak approximately every 100,000 years and the last glacial peak was 20,000 years ago when the sea surface temperature dropped by 5 or 6 degrees, which Denton said is huge. He also said a profound warming 18,000 years ago ended the ice age, “the real big global warming,” he said. 

The ages of the Earth are cyclical, ice ages grow and vanish in rhythmic turn. But the current climate has been influenced irrevocably by modern human behaviour, and global warming has flourished on an unprecedented scale.  

“It was interesting, and then it became important. Climate change is affecting human beings now”, Denton said, his work in Antarctica and Aotearoa escalating from fascinating to important research.  

Denton now spends half the year in Maine, and half the year in New Zealand, bringing American geology students down with him, to study the role of ice ages in Southern Alps glaciers in Aotearoa. Denton believes in the Southern Hemisphere “somehow holding the key” to both modern and historic climate change, and his colleagues are able to analyse air bubbles in Antarctic ice sheets, and examine the isotopes of oxygen in ancient ice. “The bubble is ancient atmosphere”, Denton said, and by sampling the atmosphere from hundreds of thousands of years ago, climate scientists can determine that CO2 fell and then rose in the atmosphere “at the peak and at the demise,” of recent ice ages. 

Crucially, the Southern Hemisphere is home to the strongest wind system in the world; the austral westerlies. And Denton believes that this unique wind system may be a key to global climate change. The austral westerlies migrate with the seasons, and they are far stronger than their counterparts in the Northern Hemisphere, because friction imposed on the westerlies by the northern continents is less important in the very watery south. Denton explained significant shifts in the strength, position, and duration of austral westerly winds leads to the upwelling of warm marine water deep in the Southern Hemisphere, affecting vulnerable, peripheral areas of Antarctica. As warm currents melt the ice beneath the ice sheet, increased accumulation of ice on the surface creates what the Antarctic Heritage Trust calls “a ‘battle’ in the Southern Ocean,”  which could have significant implications for future sea level rise, and will determine the future of the ice sheet. 

Denton, who is immensely proud of his students and his colleagues alike, cites friend and Nobel prize physicist Syukuro (Suki) Manabe. He told Canta: “using the Suki model, when we change the latitude of the westerly winds, we change the behaviour of the western Pacific whirlpool, which controls the global climate”, this key to global climate change can be found in the Southern Alps of New Zealand and deep in the Pacific Ocean. 

The mystery of ice ages, and their rapid and profound ends, remains unsolved. But there are many theories. Denton suggests there may be a large scale capacitor deep in the Southern Pacific Ocean, which stores heat and CO2 during the long course of an ice age, and then releases it almost overnight, resulting in the quick end to ice ages and their slow formations. 

Modern humans spread around the world in the last ice age, and that ancient polar climate created an entirely different world. “Humans had nothing to do with it, except we were here when it happened”, Denton said. The frozen climate was home to spectacular animals which roamed the Northern Hemisphere, “and we know they existed, because humans painted them onto cave walls”.  

Necessity is truly the mother of all invention, and ice age humans “produced some of the greatest art humans have ever made”. Now, necessity calls for a new kind of climate action. We have thrived in ice ages before, but never have humans experienced the kind of global climate warming we are causing now. 

Denton's work in climate research is more important now than ever, and he is mentoring a new generation of students who will continue his legacy. “I participate with the Antarctic Heritage Trust because they support young people”, and Denton is passionate about his young students, and the continuation of climate science through organisations like the AHT.