Where will we go when the water rises?

Computer models may hold answers, research says

Brown University

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A new modeling approach can help researchers, policymakers and the public better understand how policy decisions will influence human migration as sea levels rise across the globe, suggests a paper published on Tuesday, Nov. 26, in Nature Climate Change. 

The study indicates that global policy decisions about greenhouse gas emissions, and a range of policy decisions that determine where people live and work in coastal areas, will determine whether people need to migrate as a result of sea level rise and where they may go — and the best way to weigh the potential effects of these policies is to build new climate change models, computer-generated predictions of how and when global temperatures and landscapes will change.

“This paper homes in on policy as the key to managing climate change impacts,” said Elizabeth Fussell, a contributor to the paper and an associate professor of population studies (research) at Brown University’s Population Studies and Training Center. “Analyzing the effects of current and potential policies on sea-level rise can bring real data, real investigations and real analyses to the table in political discussions that will shape our future.”

The report comes from Fussell and 19 other members of an international research network assembled by the National Socio-Environmental Synthesis Center at the University of Maryland. The network comprises global experts on sea level rise and environment-related migration from the U.S., the United Kingdom and Europe.

Lead author David Wrathall, an assistant professor at Oregon State University’s College of Earth, Ocean and Atmospheric Sciences, said that global policy decisions will play a major role in determining not only how many people will migrate away from the coast due to climate change but also where those migrants will go.

“We’ve been looking at this problem the wrong way,” Wrathall said. “We’ve been asking how many people will be vulnerable to sea level rise and assuming the same number of people will migrate. In reality, policies being made today and moving forward will exert a strong influence in shaping migration. People will move in very specific ways because of these policies.”

Wrathall, Fussell and the research team suggest that policymakers who are seeking to understand how their decisions affect migration cannot afford to experiment on vulnerable populations in the real world with expensive and potentially dangerous policies. 

Instead, decision-makers can anticipate the effects of realistic policy alternatives using simulations thanks to advances in computation and modeling, taking into account a wide range of economic policies, planning decisions, infrastructure investments and adaptation measures. 

For example, Wrathall said, some current tax codes incentivize businesses to locate near ports, which could potentially put whole industries at risk in the face of sea level rise. 

High interest rates could prevent some homeowners from borrowing money to protect their coastal homes, which may cause them to leave. And global decisions about the management of greenhouse gas emissions could impact how quickly the planet warms and sea levels rise. 

“Modeling allows us to look at all kinds of scenarios to identify the specific policies that might work to help people migrate and anticipate the policies that cause problems,” Wrathall said. 

The researchers’ report is the result of a three-year project that sought to unite the expertise of social scientists, environmental scientists and computer modelers to determine the best way to predict the future effects of sea level rise. The research was funded by the University of Maryland and the National Science Foundation.

“With this paper, we have advanced an interdisciplinary conversation on how to meaningfully predict the effects of sea level rise on people,” Fussell said. “Whatever losses and damage are caused by sea level rise, they are human losses — so understanding how humans react to changes, and how policy drives those changes, is crucial.”