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Q&A: Climate Change, Drought and the Future

By Amanda Lechenet

Benjamin Cook
Benjamin Cook

From a small office in Manhattan’s Upper West Side, you can peer out the window and watch sparrows in the trees as people rush by, trying to get out of the sweltering heat. The heat wave just happens to coincide with the conversation I am about to have with Benjamin I. Cook, 34, a leading climatologist and drought researcher.

In order to get a better picture of climate change within a region, Cook, a research physical scientist for the NASA Goddard Institute for Space Studies, is working to determine the effects of climate change on drought and what that means for the American West. Cook is also an adjunct associate research scientist at the Lamont-Doherty Earth Observatory.

The following are edited excerpts from an interview conducted on July 17.

Q: On June 25, President Obama presented his plan on climate change policy. What are your thoughts on his policy?

A: I think it’s a good start to begin addressing the issue. It’s certainly the most political will that anyone has shown towards addressing these issues. As a private citizen, the best potential it has is to start motivating other political entities and countries to start engaging with the problem following the U.S.’s lead and getting a critical threshold of political will to address these issues. … By itself, it’s not going to do a whole lot. You basically have India and China building a ton of coal power plants, and until they stop it’s not going to make much of a difference.

Q: What did you think of the plan to install a natural gas infrastructure in the U.S. and other countries to battle climate change?

A: If we decide as a country that the most important thing is to mitigate climate change, we should be abandoning coal and going to natural gas. However, hydro-fracking has a lot of other concerns. If you are in a region that has water concerns, it might not be the best idea. Coal has it’s own issues – like mountaintop removal. This is where the value judgments come in at the higher level interests versus the local-level interests. You might be gung-ho about climate change, but you are going to think twice if someone wants to build a fracking well in your backyard. I, personally, have not quite made my mind up about it.

Lake Powell, NASA Earth Observatory
Lake Powell, a prime water resource for much of the American Southwest, in 1999 and 2013. Photo: NASA Earth Observatory

Q: One of the major focuses of your research is the West. What do you think is going to happen with water in the West with climate change?

A: One of the ways that climate change is going to manifest is through warmer temperatures. Water resources are not just rainfall – it’s also evaporation. You can have the same amount of rain falling, but if you warm up the atmosphere, it will increase evapotranspiration. This dries out the soil. What we are seeing, in line with our projections, is that even if you assume constant precipitation, the temperature effects are so large that it is going to dry things out.

This is going to have really big impacts on soil moisture, reservoirs and stream flow for irrigation and drinking water. The availability of water is going to decline into the future, and the challenge is adjusting for that, and what that means for agriculture and development.

Q: Is your current research still focused on droughts, or has it transitioned to climate modeling?

A: Most of my research is still focused on droughts in Western North America, and also globally trying to understand precipitation and temperature patterns and what that is going to mean for droughts.

I’m also doing some climate modeling as a part of that to understand drought risk. We can use these big models that give us all the physics we need to understand the atmosphere response. We can run them for a situation in the past and see what drought variability looks like, and we can run them for the future with an increased greenhouse gas forcing to see what drought risk looks like the in the future.

Q: As climate change continues to happen, what does the picture of water in the American West look like in the near-term and the longer-term?

A: By the end of the 21st Century, the climate models generally converge and point to a significantly dryer future. That’s because by the end of the 21st Century, the signal from greenhouse gases is going to be large enough that the projections are pretty unequivocal – the physics makes sense. The challenge is more the near-term, the coming decades.

At the same time we have climate change pushing us in one direction, we have a lot of variability. Look at Iowa – last year they had one of the driest years on record, and this year they are back to normal and having floods. That’s part of this intrinsic variability that is superimposed over this long-term trend. So one of the challenges is to figure out at what point that long-term trend moves so far beyond the natural variability that we can say yes, this is climate change.

Q: Speaking of flooding, do you think that as temperatures warm the incidences of flooding will be more or less severe?

A: The flooding question is interesting and a challenge from a couple of perspectives. Even if your annual total precipitation declines a little bit, we expect that with global warming we will get fewer low intensity rainstorms, and more high intensity rainstorms. Basically, it will rain less often, but when it does, it will rain a lot. For flooding concerns, those big events overwhelm the ability of the soil to absorb water.

The challenge, though, is how people actually handle floods. There are a lot of things that you can do to decrease your flood risk independent of what the climate is doing. One thing that can be done is to increase levee zones, and not allow people to live there. In cities you can build green roofs, which are soil and sod and grass on top of your roof. Instead of the water hitting your roof and running off, it gets absorbed and mitigates flooding.

Q: How do you think droughts and flooding are going to impact the energy infrastructure in the US? Specifically, how will this impact power plants that require water for cooling?

A: With climate change, if the water starts getting a lot warmer, it potentially decreases the cooling capacity of the water, which can be worrisome for the plants that rely on cold water. And with flooding, we have to think about the placement of generators.

Benjamin Cook
Benjamin Cook gets closer to his subject.

Q: Why is your research important?

A: My role is to provide the best information that we have on how climate, particularly drought, is going to change into the future. I feel that it’s important, however you decide policy-wise, that any decisions need to be based on our best understanding of the system, As a scientific community, that is our role – providing the best information for management and policy stakeholders.

One of the reasons I got into climate is because it matters to people. It matters if you are a farmer, if you’re trying to manage land for a certain species, or you want to go hiking or hunting. It matters for everything. That’s why I get excited about it, and I think it’s important.

Q: Finally, we recently passed the 400 parts per million threshold of carbon dioxide in the atmosphere. According to a Lamont-Doherty Earth Observatory study, the last time this level was reached was about 3 million years ago. Have we reached a climate tipping point?

A: Everyone loves to talk about tipping points. They are dramatic, but they are a challenge to define. One of the problems with carbon dioxide in the atmosphere is that it is going to stay up there for hundreds and thousands of years. At a certain point, we’ve already passed a tipping point of committing to a certain degree of warming due to the inertia in the system.

Other tipping points, like the disintegration of the Greenland Ice Sheet, we don’t have a handle on. At a certain point, if you compromise the structure of the ice sheet, it’s going to disintegrate. But we have no idea where that is or what amounts of CO2 and temperature we need to get there. So as far as tipping points of these big, dramatic, rapid events, there’s no evidence that we’ve reached that point of return, but there’s also no evidence that we haven’t reached that point.

Q: The Intergovernmental Panel on Climate Change is getting ready to release its Fifth Assessment Report. Are the climate models used in the Fifth Assessment showing significantly different results than Fourth Assessment?

A: Generally they are showing similar patterns – the basic temperature and precipitation responses seem to be robust between the two reports. Where things are starting to get complicated is the uncertainties with aerosols and atmosphere chemistry. These could be especially important for regional changes. For global scale, we have things pretty well down, but it’s these other factors that could have big impacts regionally.

Amanda Lechenet is a graduate student at Columbia University pursuing her Master of Science in Sustainability Management. She currently is working as an intern at Feel Good Foods, a gluten-free appetizer company in Brooklyn.

Science for the Planet: In these short video explainers, discover how scientists and scholars across the Columbia Climate School are working to understand the effects of climate change and help solve the crisis.
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