Editorial: Measuring the costs of preparing for rising seas

By The Herald Editorial Board

The wall we ought to be building isn’t along the U.S. southern border with Mexico but along more than 50,000 miles of coastal shoreline in 22 states, according to a recent report on sea-level rise.

And its costs would dwarf anything so far proposed for President Trump’s wall, regardless of who’s paying: $400 billion in the next 20 years, an amount that would nearly rival what was spent to build the interstate highway system.

Last month, the Center for Climate Integrity, affiliated with the Canadian-based Institute for Governance and Sustainability, released its report, “The High Tide Tax,” a comprehensive analysis of the costs of addressing sea-level rise along the coastline of the contiguous United States between now and 2040.

The report says its intention is to encourage the public and elected representatives to honestly face and begin preparing for the massive costs ahead in responding and adapting to global warming and the resulting changes in climate. Even assuming the U.S. and other large producers of carbon dioxide and other greenhouse gases might eventually slow those emissions and avoid the worst temperature increases, the slow nature of the physics behind sea-level rise would mean oceans and inland seas will continue to rise regardless.

The report bases its costs estimates on predictions of sea-level rise coupled with flooding from a one-year storm event, the type of storm seen as typical each year.

In Florida, with nearly 8,500 miles of coastline, the report estimates it would cost about $75.9 billion to build enough seawall to protect near-shore property and infrastructure, a figure that rises to $109.4 billion to offer the protection necessary by 2100.

With more than 3,000 miles of coastline, Washington state’s bill would be about a third of Florida’s: $23.9 billion to protect 1,651 miles of shoreline by 2040, most of that within the Puget Sound region.

The report drills down even further, offering cost estimates by congressional district, county and even one for Possession Sound’s Hat Island. Offering estimates for per-capita costs for select communities, the report estimates that protections for Hat Island’s threatened properties would amount to $2.1 million per person, based on the island’s few dozen residents. That’s a bargain next to Junction City in Gray’s Harbor County along the Washington coast, where the per capita cost was pegged at $7.2 million, the highest per capita cost cited in the report.

For Snohomish County — with shoreline communities that include Stanwood, the Tulalip reservation, Marysville, Everett, Lynnwood and Edmonds — the projected seawall costs are $1.1 billion.

Those communities, in the county and throughout the Puget Sound region, however, aren’t going to rush to raise the bulwarks anytime within in the next 20 years. If anything, the move in recent years — in response to the obligation to improve habitat for salmon and other marine wildlife — has been to breach dikes and other barriers.

In Snohomish County, work continues near Smith Island to restore more than 1,200 acres of marine estuary — part of a 2005 salmon recovery plan for the Snohomish River basin — by breaching dikes that were built in the first half of the 20th century and earlier to create agricultural land. That work is similar to a project by the Tulalip Tribes at the Qwuloolt Estuary and the Port of Everett’s Blue Heron Slough project, which begins this year.

The ethic in Western Washington, pointed out in a story in Crosscut about the CCI report, has been to recognize the damage that seawalls, bulkheads and other barriers have done to marine habitats, seeking to limit and mitigate their impacts if not remove them.

The report’s estimate of seawall costs, CCI responded to Crosscut, was offered as a way to measure the costs of a range of responses across the nation to sea-level rise, as opposed to advising a single cure.

That comparison, however, may be of limited value.

“I don’t know if it’s a good proxy for the cost of adaptation,” Guillame Mauger, with the Washington Coastal Resilience Project, told Crosscut. “I can think of some cases where the damages due to flooding, in the absence of a seawall, could be comparable or greater than the expense of building a seawall. In the long run, on the other hand, I would expect ‘nonstructural approaches’ [like] buyouts and retreat would be less expensive.”

What is of value, however, is the recognition of the threat that sea-level rise in the next 20 years and beyond poses to property and infrastructure and what preparations must be made to answer that threat.

Add to that the even higher costs that will be incurred if those preparations aren’t made.

Washington state, according to WCRP projections, can expect an average of about 5 inches of sea-level rise by 2040 and more than a foot by 2100. The hazard increases during storm events that can push water onshore or flooding that comes down river, jeopardizing what’s near shore or in the path of a flood, including homes, businesses, roads, sewage lines and treatment plants, ports and marinas, roads, schools, hospitals, nursing homes, gas stations, parks and military bases, to name a few.

Even if we aren’t likely to build that wall, it doesn’t mean we can escape the costs of preparing for rising seas and climate change.