TACKLING GLOBAL WARMING BY EXPLORING THE EBB AND FLOW OF THE ICE AGES

TACKLING GLOBAL WARMING BY EXPLORING THE EBB AND FLOW OF THE ICE AGES

By Lakshmi Chandrasekaran/Video by Kelly Calagna –

“Don’t get old if you can help it,” climatologist George Denton joked at the Comer Abrupt Climate Change Conference in Wisconsin this fall. But he must have been proud. As one of the earliest and premiere veterans of climate change research, the University of Maine professor had three generations of students in the room.

Denton has devoted a better part of his life to studying and quantifying ice sheets across the globe. He does this by gleaning the geological history going back across more than 2.5 million years of ice ages. He studies smaller mountain glaciers to understand what causes abrupt ocean and atmospheric changes that lead to the warming spells, changes that our contemporary world may be triggering at an ever faster pace.

“We as humans have reached 7 billion and we are living in a world where the climate is changing rapidly. Understanding how ice age climate works will help us understand what is going on now,” said Denton.

One of the biggest questions for climate change now is to understand what caused the Ice Ages – and what caused rapid shifts out of them, he said. Equally important is that “during the Ice Age, humans spread around the planet as a result of climate shift,” said Denton. About 60,000 years ago, humans spread out from Africa to Europe and then to Australia and even Siberia, he noted. With hundreds of feet of water gripped in the glaciers, a land bridge opened between Siberia and Alaska and humans followed the great mammals such as the mammoths into the Americas at least 15,000 years ago.

With human activities altering climate along with natural forces, “It’s to our benefit to understand the whole system that we are fooling with. So I think the studies of Ice Age that happened in the past will provide us with a foundation as to how the climate system is working now,” remarked Denton

George Denton explores the important clues about abrupt climate changes revealed by the end of the ice ages. (Abigail Foerstner/MEDILL)
George Denton explores the important clues about abrupt climate changes revealed by the end of the ice ages. (Abigail Foerstner/MEDILL)

“The biggest question in modern geology is what causes ice ages. George Denton’s research in New Zealand focuses on mountain glacier fluctuations during the last ice age cycle” that ended some 18,000 years ago, said Alice Doughty, a former student of Denton’s who is currently a post-doctoral fellow at the Department of Earth Sciences of Dartmouth College. “Calculating the timing of glacier change is KEY to solving the question of cause and that this would help us predict future change,” she said.

“George Denton is well-known for several decades of research concerning the role of the Southern Hemisphere in climate change. This work, has led to fundamental insights into the cause of ice-age terminations and of abrupt climate change,” said Brenda Hall, another former student and now a research collaborator and associate professor at the Climate Change Institute of the University of Maine where Denton teaches.

Denton’s results from several expeditions to Southern Chile show a rather unusual observation that past climate change events occurred in both the hemispheres at the same time. Denton and his colleagues tested and supported the idea that atmospheric influences link both the hemispheres in controlling climate during the last ice age meltdown and “this has gotten the community closer to understanding how the climate system works,” said Peter Strand, a graduate student at the Climate Change Institute. In other words, they showed that climate change is global.

But Denton is involved in trying to resolve the many yet unsolved mysteries of the sprawling ice ages. “Ice ages are enormous events. They caused sea levels to go up and down 300-400 feet, caused huge ice masses to break off the northern tier of Canada and United States. They changed temperature around the world by six degree Celsius which is a lot and then the Ice Age went away for reasons we don’t understand,” said Denton, during an interview.

Denton has dozens of publications to his credit. He has been elected to the prestigious National Academy of Sciences and the Royal Swedish Academy of Sciences – among his plethora of awards and honors.

The Advisory Committee on Antarctic Names commemorated his contributions to research on glaciers in Antarctica by naming Denton Hills after him. His colleague, Robert Nichols named a small hanging glacier in Victoria Land in Antarctica the Denton Glacier in his honor as well.

Much of climate change research, as we know it today, began gaining momentum in the 1950s. Talking about his initial foray into climate research, Denton reminisced fondly about his days as a graduate student at Yale in the 1960s – a time when there were few grants and even fewer role models for research in the field. But Denton’s Ph.D. thesis advisor just set him out in the world to find his own thesis problem.

Denton began reconstructing ice sheets in the glaciers of the Saint Elias Mountains of the Southwestern Yukon territory and set his field of research rolling with this expedition.

Soon, his research led to several successful odysseys to glaciers in South America, New Zealand and elsewhere across the globe. When philanthropist Gary Comer became concerned about climate change, he began to work with Denton and brought him together with other pioneers in the climate change field such as Richard Alley of Pennsylvania State University and Wally Broecker of Columbia University.

Comer, the founder of Lands’ End, sailed the Northwest Passage in his yacht “Turmoil” in 2001 and noticed that the notorious shipwreck alley of icebergs seemed ominously ice free. The “successful” completion of his expedition, stoked Comer’s interest in what was different about ocean water conditions and why they had changed drastically. He approached Broecker – one of the earliest scientists to coin the term “global warming.” And Broecker brought in Alley and Denton to investigate the causes of “abrupt” climate change. With Comer’s substantial funding for climate research and fellowships, the triumvirate brought together top climate scientists from across the country as mentors for a new generation of researchers who studied with them.

As a prominent scientist at the Climate Change Institute, Denton has successfully collaborated with many other researchers worldwide throughout his career. Denton emphasized the importance of interdisciplinary research in the field of climate change research. “Staff members in the institute, spread through a number of departments such as earth sciences, soil sciences, agriculture, biology, anthropology work on climate research,” said Denton, adding that climate change was important to all these fields and in particular to agriculture in Maine.

The Gulf of Maine is the fastest warming body of water on Earth and the fishing industry on this coast provides livelihoods to a lot of people. “So the University of Maine has decided, since climate change is very important to the state, they better try and understand it. They set up the Climate Change Institute, which is interdisciplinary,” Denton said.

Denton has passed on his scientific legacy to numerous climate change researchers of today. Many of his former students are professors who mentor their own research team of students and postdocs. And that brought the generations of students from the Denton era to this conference in Wisconsin.

“These students at the Comer Conference, are largely from the Earth Sciences School and Climate Change Institute at the University of Maine. Under the auspices of the Comer Foundation, they travel all over the world. They go to Mongolia, China, Western US, Europe, South America, New Zealand, and to the southernmost landmass on Earth. They are trying to piece together climate change all over the world,” said Denton.

Denton’s contribution to climate change is outstanding, his colleagues agree. “We are all embarked together on a great adventure. And that is to unravel the mystery of ice ages. That is one of the greatest mysteries of Earth sciences and we are lucky to be involved in that pursuit,” said Denton concluding his talk and not his work.

Photo at top: Glaciers shrouded the entire Great Lakes region during the last great ice age some 20,000 years ago. Thick walls of ice covered the areas shown in white (USGS image).


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