Kerry Emanuel focuses the study of cyclones away from policy and back on expanding fundamental scientific understanding.
Having contributed much to the broader conversation about a warming climate and its global implications for changing weather patterns and extreme storms, Cecil and Ida Green Professor of Atmospheric Science Kerry Emanuel would much rather talk about specifics, like whether tropical cyclones offer important feedback and controls on climate itself.
In recent years, Emanuel made headlines defending the science of climate change and urging depoliticization—from penning op-ed articles for the Wall Street Journal, Boston Globe, Foreign Policy, and CNN, to authoring the book What We Know About Climate Change and appearing on panels in the media, like NPR’s Science Friday, all the way to testifying before Congress. “I spend a lot of time doing that. But I do that because I feel obligated. It’s not the thing that excites me,” said Emanuel.
Emanuel notes that while there’s a strong applied component to earth sciences, including weather forecasting, climate projections, and risk assessment, “climate is much, much broader than global warming,” he said. “There’s a lot of basic science that’s very exciting. We want to know how things work. If I were in cosmology, you wouldn’t ask me what’s in it for mankind; you’d be exploring the intellectual content of it, and that’s what climate science needs more of.”
His argument is a fundamental one, easily forgotten as the world eyes melting glaciers, rising waters, stranded polar bears, and impending deadlines on greenhouse gas emission levels, with the media and public demanding solutions. Emanuel makes the compelling case that, when looking at the history of science, the really big leaps forward have come out of nowhere from people doing curiosity-driven research, “who didn’t set out to improve the world but stumbled on something that made a much bigger difference than people beavering away on incremental applied problems.” To help catalyze bold research about basic scientific questions, in 2011 Emanuel and his colleague, EAPS Professor Dan Rothman, co-founded EAPS Lorenz Center, a privately funded interdisciplinary think tank devoted to expanding our knowledge about how climate works on a fundamental level—performing the type of research which may lead to discoveries that inform our future
understanding of climate change.
“Generally if you read popular accounts [of work on hurricanes]—and there are many—the question is entirely about, ‘Well, if there’s global warming, what will happen to hurricanes?’ And I do work on that. But the real question is much broader,” said Emanuel.
As a leader in the field of tropical cyclone research beginning some 30 years ago, Emanuel is excited to be exploring how much these storms stir cold, nutrient-rich water to the ocean’s surface, potentially inciting long-term ocean heat circulation responses and making for giant plankton blooms which, among other things, take carbon out of the atmosphere. And that’s not all. Cyclones and other forms of deep thunderstorm convection with their intense rains, “wring water out of the atmosphere, and water vapor is the most important greenhouse gas in the atmosphere,” he said, “they’re opening up the planet to more infrared radiation going off to space. Indirectly, they may cool the planet.”
Despite that apparent service as a negative feedback mechanism, providing cooling in a time of general warming, Emanuel would prefer that his work on the basic physics of storms and their connection with climate not be plugged automatically into a narrative about combating climate change and global warming—there are too many as yet unanswered questions about the complex mechanisms that drive our climate to make predictions in absolutes. A case in point: this potential cooling phenomenon really only works in the tropics, not at the poles, and when looking at geological time scales the tropics have been very stable—cooling perhaps just 2 degrees centigrade during the last ice age.
“This is what I’m excited about because it’s very, very new and involves a rather sophisticated interplay of radiative transfer and convection and water in the atmosphere,” Emanuel said.
Some of the specific questions Emanuel has investigated in order to gain that necessary broader understanding of climate’s synergistic components include a 2012 study published in the Proceedings of the National Academy of Sciences. Wondering about the effect of rising greenhouse gases on cyclones, he embedded a high-resolution local hurricane model into six coarser, global models run in support of the Intergovernmental Panel on Climate Change (IPCC), along with IPCC data projecting future carbon dioxide emissions. With this technique he predicted that the next century could see the frequency of tropical cyclones increase by 10 to 40 percent, and that these storms could be 45 percent more powerful than those we see today. He expanded his use of these models to produce his latest paper, appearing in the journal Nature Climate Change just this past September, which reported that coastal regions in Florida, Australia, and even the Persian Gulf (an area that historically has never experienced a tropical storm) could see unprecedented storm surges generated by extreme future cyclones like those anticipated by his earlier work.
As if to further underscore his emphasis on the need for more fundamental climate science, as a co-investigator on a 2014 study in the journal Nature, the research not only revealed that, over the last 30 years, the region of peak cyclone intensity is expanding out from the tropics at the rate of over 30 miles per decade toward each of the poles, but also raised questions about the exact mechanisms causing this phenomenon. Is it due to changes in the Hadley circulation pattern of global winds? Is it due to increasing ocean temperatures? Emanuel says there is more work to be done.
And still, he’s not quite done in the role as the earth sciences’ ambassador to the court of public and political opinion—in December he’s planning travel to Paris with three fellow climate scientists to “rather forcibly” argue for putting nuclear power back on the table—and yet he has hope for a future filled increasingly with pure science.
“Maybe just the sheer facts of climate change are changing a lot of minds. I think we’ve reached the bottom of climate denial and are slowly pulling up,” he said. “So, yes, I will have more time to go back to my research.”
Read more about Kerry Emanuel’s latest research on extreme cyclones: http://bit.ly/emanuel-cyclone
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