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Linked To Climate Change, Extreme Precipitation And Sea Surface Temperatures Rise In New England

Jonathan Winter.jpg
Jonathan Winter is on the Geography and Earth Sciences faculty at Dartmouth and coauthored a study about increases in sea surface tempratures and extreme precipitation in the Northeast.

A new study, co-authored by Dartmouth scholar Jonathan Winter, shows there's been an increase in extreme precipitation and sea surface temperatures in the Northeast. The changes are due, in part, to climate change caused by humans.

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All Things Considered host Peter Biello talked with Winter about his discoveries, what it means for the future in New Hampshire and what we can do about it. Below is a transcript of their conversation.

Peter Biello: This is All Things Considered on NHPR. I'm Peter Biello. Precipitation has been on the rise in the Northeast in recent decades and that's projected to continue because of climate change. That's according to a new study co-written by a Dartmouth scholar. The paper lays out how human action has warmed the surface of the Atlantic Ocean and driven these extreme weather patterns. Jonathan Winter is on the Geography and Earth Sciences faculty at Dartmouth, and he's a co-author of the study. Jonathan, thank you very much for speaking with me.

Jonathan Winter: Hi, Peter. Thank you for having me.

Peter Biello: So, climate change has been named in numerous studies before this one as a driver of extreme precipitation throughout the world. What evidence do you now have that climate change is the cause of extreme precipitation in our region in particular?

Jonathan Winter: To start out with a little bit of context: The Northeast has experienced a 50% increase in extreme precipitation since 1996. So if you look at 1996, the present versus 1901 to 1995, we now have 50% more extreme precipitation. What we did in our study was try to figure out whether we were responsible for that enhanced extreme precipitation. The answer is essentially we're responsible for part of it. There are really two human fingerprints that we found on that increase in extreme precipitation. The first one is greenhouse gases. Greenhouse gases warm the Atlantic Ocean, so Atlantic sea, surface temperatures, and what that can do is lead to stronger tropical cyclones. It can also increase the amount of water vapor the atmosphere can hold. Then the second thing we found, the second human fingerprint, was reduced aerosols. This is actually a result of something good that we did, the Clean Air Act, which reduced aerosols or you can think of them as particulates that come from smokestacks and automobiles. And this is great for our lungs. But those aerosols also reflected sunlight, essentially cooling the Earth. So, when we took them out, we ended up with, again, a warmer Atlantic, which increases the rainfall from tropical cyclones.

Peter Biello: So, you said that some of this extreme precipitation is the result of human behavior. Were you able to tell how much of the increase in precipitation was a result of human behavior and how much was something that was not human-related and perhaps beyond our control?

Jonathan Winter: It's really difficult to put exact numbers on how much we were responsible for versus how much was climate variability. What we did find is a substantial contribution from these anthropogenic forces.

Peter Biello: Anyone listening to the news in the past week may have heard quite a bit about the U.N. climate report released. This one unequivocally stated that climate change will worsen without immediate action. In your view, does your study reflect that same conclusion for the Northeast?

Jonathan Winter: They've concluded that the frequency and intensity of heavy precipitation events has increased since the 1950s across most land areas that we have enough data for and that we're likely the cause. So our findings are very consistent with the Sixth Assessment Report.

Peter Biello: We've seen heavy rainfall here in New Hampshire this summer. July was particularly wet. What do you think the future of rainfall looks like here in New England?

Jonathan Winter: If you look at the projections and, I'm taking this now from that Sixth Assessment Report, we see weather with more heavy precipitation. So, what we probably have to do now is think about our greenhouse gas emissions scenarios. So when we think about the future, we have to figure out, well, what are people going to do? So for our lowest greenhouse gas emissions scenario, and that's really unprecedented action, then the projections show that it's just a 5% increase in the amount of precipitation we get in these one-day and kind of the heaviest five-day events compared to pre-industrial [times]. But if we go with the higher greenhouse gas emissions scenarios, we can end up with more than 15% on our heaviest five-day stretch of rainfall.

Peter Biello: In addition to the extreme precipitation that you describe here in the study and that you're describing now, it's also going to get warmer here in New Hampshire. To what extent are those two things related?

Jonathan Winter: The primary impact of climate change is a warmer earth, so we often measure it in globally average temperatures. So, again, for that lowest greenhouse gas emissions scenario, when we look at eastern North America, of which New Hampshire is a part, we can see that for basically our hottest day per month for the low greenhouse gas emissions scenario, we're going to get about three degrees warmer. But if we switch to the highest greenhouse gas emissions scenario, which is closer to what we're on track for right now, it's going to increase by almost 10 degrees Fahrenheit. So if we think through the kinds of adaptation that we'll need, we're going to need to make sure that we take care of our vulnerable populations. Those are who are elderly or with underlying medical conditions and have cooling stations to make sure these heat waves don't become a medical condition.

Peter Biello: So, what can be done? What can we do here in New England to mitigate the impacts of all this?

Jonathan Winter: In my classes, I tell my students probably the most important thing you can do is go vote because really it's federal action on climate change that's needed to set a price on or regulate greenhouse gases. And it's also the federal leadership that's going to make sure that everybody who comes along with us, because even if the entire U.S. reduces their greenhouse gas emissions, we also need China and India and all other countries to come along with us and reduce their greenhouse gas emissions.

Some of the things that we can do locally here is we can increase the resiliency of our infrastructures, resizing of culverts and making sure we have building codes that keep things out of the flood plains and keep things out of storm surge on the Seacoast. And New Hampshire can also, as a state just like California does, it could set green energy standards. Anything that would reduce greenhouse gas emissions is helpful in kind of avoiding the worst impacts of climate change.

Peter Biello: Jonathan Winter is on the Geography and Earth Sciences faculty at Dartmouth, and he's coauthor of a new study looking at climate change in New England. Thank you very much for speaking with me.

Jonathan Winter: Thank you, Peter.

Peter Biello is the host of All Things Considered and Writers on a New England Stage at New Hampshire Public Radio. He has served as a producer/announcer/host of Weekend Edition Saturday at Vermont Public Radio and as a reporter/host of Morning Edition at WHQR in Wilmington, North Carolina.
Julia Furukawa joined the NHPR team in 2021 as a fellow producing All Things Considered after working as a reporter and editor for The Paris News in Texas and a freelancer for KNKX Public Radio in Seattle.

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