UW Today

October 20, 2015

UW study: Will Puget Sound’s population spike under climate change?

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What began as mere speculation has started to take a more serious turn. Climate change is now implicated in flooding, droughts, heat waves and other catastrophes that computer models predict will become more common. Suddenly, a region long mocked for its gloomy weather seems like it could be a welcome refuge from a hot, dry future.

Last summer, University of Washington atmospheric science professor Cliff Mass asked: “Will the Pacific Northwest be a climate refuge under global warming?” Later headlines read: “Climate refugees are coming to the Pacific Northwest” and “What do you get if you map coming climate disasters? Hello, Pacific Northwest.” When a New York Times article pondered where to go to ride out climate change, one expert said: “The answer is the Pacific Northwest, and probably especially west of the Cascades.”

Seattle panorama at night

The population of the Puget Sound region is already growing, and some wonder about the future effects of climate change.CheWei Chang/Flickr

Naturally, this got the attention of people who already live west of the Cascades. A UW graduate student recently took an in-depth look at the issue, which would have implications for the region’s long-term water supplies, transportation and other infrastructure.

“This notion of climate refugees swarming into the Pacific Northwest has come up before, often mentioned in passing, but over the last year or two the questions around this issue have become more serious,” said Lara Whitely Binder, an outreach specialist with the UW Climate Impacts Group.

She and her colleagues requested the study to help inform these discussions by better understanding the factors that influence people’s decisions to move. The resulting research paper, posted online this week by the UW Climate Impacts Group, is the first to look at what we know about climate-related migration and whether it is likely to be an issue for Puget Sound.

“It’s obviously a question that’s on a lot of people’s minds,” said author Alison Saperstein, a master’s student in the UW’s Evans School of Public Policy and Governance. “I get a lot of questions about it. Planners want to know what they can do to prepare for the full range of possibilities.”

On an early September lunch hour downtown, Saperstein presented her work to a group of about a dozen city and county utilities planners. It was one of four such presentations she made this summer.

“Some of the media coverage probably overstates the role that climate plays in where people decide to live,” Saperstein began.

While her report doesn’t provide any hard numbers, it synthesizes what is known about the subject. The literature suggests climate may play a role in the future population of the Puget Sound region, but is unlikely to create a sudden or dramatic population spike in the next few decades.

No published research exists on climate-induced migration to Puget Sound, Saperstein found. Studies for other places show that the top two factors influencing people’s decisions to migrate are economic opportunities and social ties, even when climate is a major factor.

Saperstein suggests the term climate “migrant” rather than climate “refugee,” which refers specifically to a person who is forced to move across international borders.

How money plays into climate migration is tricky, Saperstein said. People with more money have more opportunity and ability to move. But they may also have ties to their current location, and can afford to make it more tolerable (by buying an air conditioner, for example, or by getting together as a community to build a levee).

Studies elsewhere show that existing migration patterns get reinforced over time.

“Grooves get worn between different locations,” Saperstein said. “For Puget Sound, that means if we want to look at the future, we should look at past migration ties.” In other words, a possible change in Puget Sound’s existing migration flows with other parts of Washington, Oregon, California and overseas.

The UW Department of Philosophy is hosting a fall lecture series on migration, including a Nov. 18 talk on migration, ethics and climate change

Such networks also bring up the idea of “trapped populations” that have neither the resources nor social connections to move, which raises ethical questions.

Public policy can be another factor in migration – both internationally, through refugee and immigration policies, or domestically, like when the federal government offers support to rebuild or relocate after a natural disaster. Those policies are hard to predict but could have a big influence on who ends up where, Saperstein said.

“I’m thrilled at what she’s been able to accomplish,” said Whitely Binder, who advised the paper. “Alison’s work doesn’t answer the question, but it does allow for a better understanding of where people come from when they do come to our region, and of the dynamics and the different factors that influence people’s decisions to move.”

The UW Climate Impacts Group hopes to use the report as a foundation to begin conversations between regional planners and social scientists looking at whether to add a climate migration buffer to long-term population projections, and, if so, how to create some realistic low, medium and high estimates.

Saperstein will present her paper Nov. 5 in Idaho at the sixth annual Northwest Climate Science Conference, before graduating in December with her UW Master of Public Administration degree.

She earned her undergraduate degree in geology but became increasingly interested in human impacts of climate change and adaptation efforts.

“I hope that this adds some nuance to these discussions,” Saperstein said. “I think it helps shift the perspective from the physical science predictions, that changes in the climate will be a direct causal trigger, to seeing what social science has to bear on the question.”

For the paper, she consulted with Jaqueline Meijer-Irons, a UW demography researcher who has studied climate-related migration in Thailand, and was advised by Ann Bostrom, a UW professor in the Evans School who looks at how people perceive risk and use that information to make decisions.


For more information, contact Saperstein at atarbox@uw.edu or Whitely Binder at 206-616-5349 or lwb123@uw.edu.