Scientist Kate Marvel Provides Some Answers on Climate Change and Sustainability

Bridget O'Brian
November 13, 2017

In high school, Kate Marvel “absolutely hated” math and science. When her physics teacher showed the class a ball rolling down an inclined plane, Marvel thought, “Oh God, who cares?”

But when she got to University of California, Berkeley, she took an astronomy course for non-science majors and learned about black holes and other cosmic mysteries. “It had never occurred to me that this was a thing people could study,” she said. “I decided that I wanted to know more, and I was willing to overcome my fear of math to do that.”

Today, Marvel is an associate research scientist at both the NASA Goddard Institute for Space Studies, which is is affiliated with the Columbia Earth Institute, and Columbia Engineering School, where she is a member of the Department of Applied Physics and Mathematics. She writes scientific papers with titles like “Implications for Climate Sensitivity from the Response to Individual Forcings.”

She also reaches out to an audience beyond the academic community. Her TED Talk, filmed in April, “Can Clouds Buy Us More Time to Solve Climate Change?” has been viewed over one million times. In 2015, Marvel provided the underlying data for’s best performing story of that year, a data visualization titled “What’s Really Warming the World?”

She writes with wit and humor for Nautilus, a web publication that describes itself as “a different kind of science magazine,” and for the website On Being, tackling such subjects as why calling our planet “Earth” is a misnomer. (Because 71 percent of its surface is water.)

Marvel is among a phalanx of Columbia researchers across the University who concentrate on climate change, adaptation and sustainability. They include scientists at the Columbia Earth Institute and Lamont-Doherty Earth Observatory as well as faculty from schools as disparate as Law, Business, Engineering and the Mailman School of Public Health.

Q. What are you studying right now?

A. I’m really interested in what we call “climate sensitivity,” which is basically a fancy science way of saying we don’t know exactly how hot it’s going to get. The main reason is that it’s difficult to predict human behavior. What will society look like 10, 20, 30 years from now? Will we take aggressive global action to mitigate climate change? But even if you remove that uncertainty associated with humans, we still don’t know the answer. We know that carbon dioxide is a greenhouse gas, and that would increase the Earth’s temperature, but we’re not sure how much it will rise.

Q. What are the current estimates for a rise in Earth’s temperature?

A. They range from an increase of about 1.5 to 4.5 degrees Celsius in response to a doubling of atmospheric CO2. It’s important to note that this measures something very long-term. It takes the planet hundreds of years to warm up completely. If you put carbon dioxide in the atmosphere all of a sudden, the atmosphere is going to warm up, followed by the land and then the shallow ocean. But it takes the deep ocean a really long time to react, and that’s the longest timescale factor in the system.

Q. How do you make observations on future warming?

A. Obviously, we don’t have observations of the future. So we project future warming by using sophisticated computer models, which allow us to do experiments in ways that we can’t in the real world. And while models are all based on the same physics, and they all project warming in response to CO2 emissions, they give different values for the warming. A famous British statistician, George Box, said that “all models are wrong, but some models are useful.” If you look at those we use to project the future, they give us different answers in large part because they disagree on what we call “feedbacks.” As the Earth heats up, that affects all the components of the Earth’s system—oceans, vegetation, cloud cover, all the constituents of the atmosphere. And those effects can then feed back to change the warming process. How do we narrow this uncertainty, how do we figure out what the physical processes are? They’re going to be really important in the future and are important right now.

Q. Is there current evidence of climate change that can help with these models?

A. We know we have emitted greenhouse gases and we know that the temperature has been rising. But what happens in the recent past isn’t necessarily predictive of what’s going to happen, because some changes take a very long time. What’s going to happen to the climate in the long term isn’t represented very well by what’s happening now.

Q. Could the research you do have been possible before now?

A. I would not have been able to do the work that I do, which requires sophisticated computer models, 10 years ago. Climate models are theory written in code, with information from physics, chemistry, biogeochemistry, all representing our best knowledge of how the climate system works. We incorporate massive amounts of information about the atmosphere, oceans, land, ice. More complexity requires more equations, and those equations all interact with one another. We’re gearing up for the next generation of climate models right now. And we expect this new batch of models will produce more than 20 million billion bytes of data. Climate is one of the world’s biggest data problems.

Q. How did you come to study clouds?

A. I came to it by accident, really. Climate models don’t really agree on how hot it’s going to get because they can’t agree on what clouds are going to do. Clouds have a kind of warming effect because they’re made of water vapor and they have a greenhouse effect, and at the same time they also have a cooling effect because they block the sun. Because of this dual role, they play a crucial part in determining how hot it is right now.

Q. What have you found out about clouds that can be distilled in a few sentences?

A. We now have about 30 years of satellite observations of clouds, and we’re getting better at modeling them. If you take the observations and you take the models, what they are suggesting is that clouds will not only slow down global warming, they’re also likely to make it worse. The greenhouse effect of clouds is going to intensify in the future. That’s based on fairly solid physics. In this case it’s reinforcing feedback: it makes global warming worse. We now have a very good understanding of how that’s going to happen. There are still uncertainties about whether clouds are going to block more or less sunlight in the future. Clouds are not going to save us. It’s going to have to be us, I’m afraid.

Q. What’s the best way to talk about climate change?

A. People respond and engage with stories—and not just stories about sad polar bears. There’s been this amazing work showing that in medieval Mongolia there was a period of pluvials—rainy periods that are essentially the opposite of drought—that created an exceptionally fertile climate period. At the end of that period, Genghis Khan’s army marched across Europe and Asia and took over 91 million square miles, stretching from the Sea of Japan to Eastern Europe. In 1815, Mount Tambora [in what is now Indonesia] erupted for two weeks straight in one of the the largest volcanic events ever. Its ash covered the globe and created what was called the year without a summer, where crops were killed off from New England to China. A bunch of writers got trapped inside, went stir crazy, and one of them, Mary Shelley, wrote Frankenstein. We have the climate to thank for a great work of Gothic literature. And climate also helps explain the rise of the Mongol Empire.

Q. How do you talk with climate skeptics, or deniers?

A. The number one thing to know is that it’s never about the science. You can’t change people’s minds by just giving them more facts, and you certainly won’t change their minds by calling them stupid. I think we have a responsibility as scientists to communicate our results, because most of us are funded by public money, and we are doing this to serve the country, we’re doing this to serve the world. But I don’t think we have a responsibility to personally convert or change every single person’s mind. You’re just going to drive yourself crazy if you focus on that one person you just can’t get to. I think we all just need to do the best that we can.

Q. How does being at Columbia help your research?

A. There are just so many smart people here. The guy in the office right next door is the world’s expert on drought. On campus there are experts on atmospheric circulation and ozone. And up at Lamont-Doherty Earth Observatory there are experts in paleo-climate and tree rings. It’s an incredible range of fascinating topics. I think it’s an amazing collection of people.

Q. What fascinates you most about what you study?

A. Climate science touches on everything we know about science. There’s physics and there’s chemistry and there’s biology and things like “how do plankton respond to greenhouse gases?” There are so many really interesting questions. You don’t just work on one thing. You think about important questions and that leads you in directions that you could never anticipate. I love that I’m never going to get bored doing this.