RESEARCH - Beachfront Property in Peril? Sea-Levels to Rise by 2100 Print

Melting glaciers in Greenland and Antarctica, combined with other effects of global climate change, are likely to raise sea levels in parts of Western Washington by the end of this century, though geological forces will offset the rising water in some areas.

A Jan. 17 report suggests a moderate scenario is for sea levels on the Washington coast and in the Puget Sound basin to rise an average of 6 inches by 2050 and 14 inches by 2100.

The analysis, conducted by the Pacific Northwest Climate Impacts Group at the UW and the Washington State Department of Ecology, suggests that a worst-case scenario could raise sea levels in some places by as much as 22 inches by 2050 and 50 inches—more than 4 feet—by 2100.

“We can’t rule out higher rates of sea-level rise, but given what we know now they seem improbable,” says Philip Mote, a UW research scientist and lead author of the analysis. The scenarios are based on projections for worldwide sea-level increases contained in the latest report of the Intergovernmental Panel on Climate Change, a United Nations body that shared the 2007 Nobel Peace Prize. Mote was a lead author for one chapter of the panel’s report.

The new report indicates that some of the sea-level rise in Washington state would be mitigated by rising shorelines, the result of uplift from plate tectonics. That would be especially true along the northwest coast on the Olympic Peninsula.

The authors noted that even a small increase in sea level, when combined with higher tides or large storm surges, could bring more frequent floods that inundate the coastline.

The authors say that the report is not a prediction of what will occur but rather aims to examine probabilities that can guide planning. “If you have a high-value project and low risk tolerance, then you want to plan for the worst-case scenario,” Mote says.

“We have had inquiries from coastal engineers who are considering major projects, but we also have heard from at least one retiree who said he was thinking of buying some waterfront property and wondered whether it would be under water.”

The risk of rising sea levels might be acceptable for someone such as the retiree, who might only plan to use the land for 10 or 20 years, but that risk might be unacceptable for a city or a corporation planning to build a major plant to last 50 or 100 years, Mote says.