Island County is getting a leg up in planning for the likelihood of rising sea levels.

Washington Sea Grant, an outreach arm of the University of Washington’s College of the Environment, put together a study estimating the rise over the next century as it applies to the waters around Whidbey and Camano islands.

Though it’s notoriously difficult to make predictions involving changes to the climate, Sea Grant researcher Ian Miller has taken a stab at it by combining historical data and previously published research into a new way of looking at the problem.

The result is a number that Island County planners can use — 5.9 feet.

That’s the amount the sea level is likely to rise around Whidbey and Camano islands by 2150, the data suggests.

There is a lot of uncertainty in that number still, and it’s based in part on the effects of a once-a-year major storm.

“The audience for the document really is planners — it’s a really small audience — and people who are designing and planning restoration projects,” said Miller, a coastal hazard specialist.

That’s because it is the planners who have to figure out what concrete measures to take in order to adapt to changes that are largely outside their control.

There’s still a long way to go before they’ll have something approaching certainty, and the numbers that form the basis of those projections are likely to change as the science becomes more refined.

Coastal resilience

Local governments are already working on projects focusing on coastal resilience, the term used to describe how well communities can resist and rebound from extreme weather events and longer-term changes to climate patterns.

Dawn Pucci, a manager in Island County’s salmon recovery program, said the Sea Grant study was used to prioritize ecosystem restoration projects.

“We could look at where we wanted to do restoration work, so we could make efficient, wise use of money that comes to us through the salmon recovery program,” Pucci said.

Salmon restoration projects have long been at the forefront of building up coastal resilience because the wild environments the fish prefer also serve as buffers during floods and extreme weather. In 2015 the Tulalip Tribes restored the 400-acre Qwuloolt Estuary in Marysville to tidal influence, recreating salmon habitat and a natural flood plain on Ebey Slough.

Earlier this summer the tribes also hosted a symposium on sea level rise that directly addressed ways to get scientists from many different agencies to join forces.

Pucci’s team steered the focus of the Sea Grant study to five specific locations in Island County: Crescent Harbor, Crockett Lake, Moran Beach and Useless Bay, all on Whidbey, and around Livingston Bay on Camano.

Those areas were selected because there was some restoration potential and are close to important infrastructure such as dikes, wastewater treatment plants or waste storage facilities.

Those locations also were selected because the topography was flat enough to get more accurate and readable maps, Pucci said.

“There’s a lot of nuance in the map,”she said.

The maps are likely to change over time, and aren’t refined enough for parcel-by-parcel planning. But they are starting points.

Science of extremes

Miller and his co-authors mined a trove of existing data and repackaged it for an audience beyond the scientific community.

“It’s really about communication,” he said. “We’re not coming up with any new science out there. We’re taking data readily available and presenting it in new ways.

Miller said he realized that climate change effects would be intensely localized, and what people really need iss a way to figure out how their specific communities would be affected, and a way to communicate that to non-scientists.

The IPCC report outlined several different scenarios for carbon emissions, with the worst-case assuming no effort to reduce them.

While the most extreme scenario might not come to be, there is a lot of uncertainty in the IPCC report, in part because scientists’ ability to project effects of global carbon emissions over the course of a century is still imperfect.

The rate at which glaciers in Antarctica and Greenland melt is incredibly difficult to estimate. “It is the biggest source of uncertainty of sea level rise predictions of any sort,” Miller said.

The other big unknown is the rate at which carbon continues to be emitted into the atmosphere.

The IPCC report doesn’t specify which (if any) of the various carbon emissions scenarios is most likely.

Miller used the worst-case scenario as the basis for the Island County report and flood maps. He also provided data for less-drastic scenarios.

“The community has to decide what they’re going to plan for,” he said.

The report says it’s 99.9 percent certain that sea level will rise by a measurable amount in the region by 2050, but there is a 5 percent chance that the rise will be by more than a foot.

Historical data was used going back as far as possible to determine averages over time.

Risk factors

The spectrum of possibilities range from the near-certainty of some sea level rise to the most extreme disaster-movie scenario of more than 20 feet. That has only a one-tenth of a percent chance of occurring by 2150.

Those probabilities also will likely change over time. There would likely be a succession of high sea/storm surge events leading up to a Hollywood-scale catastrophe.

The most extreme scenario, if it happens, would not come as a surprise, Miller said.

There is another factor that doesn’t enter into the pilot study — waves, reinforced by a March 10 storm which knocked out power, caused flooding and resulted in damage across Whidbey and Camano.

That storm is considered a 100-year-storm in some locations, said Eric Grossman, a research geologist with the U.S. Geological Survey’s Western Fisheries Research Center.

In Skagit Bay, the water rose more than 16 feet above low tide at the height of the March 10 storm, he said, and was measured nearly 13 feet above low tide at Snee-Oosh Point, across from the northern tip of Whidbey Island.

“It’s pretty impressive,” Grossman said.

The good news

While the initial report offers some guidance for county planners, Miller’s study was only the first stage of a much larger project.

Washington Sea Grant is the recipient of funding from the National Oceanic and Atmospheric Administration’s Office for Coastal Management to use a similar methodology to do a comprehensive study of the entire Washington coast, including all of Puget Sound.

The grant is for about $880,000 and covers three years of research.

Sea Grant and numerous partner agencies, including Island County, plan to prepare models for 3,067 miles of Washington coast, including 45 cities.

Like the pilot study on Island County, all coastal communities would receive a localized set of projections.

“You have different communities with different situations,” said Penny Dalton, the director of Washington Sea Grant.

“The idea is to learn from each other and figure out what works.”

Miller said he plans to try and incorporate wave effects into the longer-term study.

”That’s good news for Island County, which now has a head start on the problem and can look forward to a more refined projection in the near future.

It’s a concern county leaders are already thinking about.

“They want to make sure there’s good science, there’s good data, and they want Island County residents to be safe,” Pucci said.