BAR HARBOR — As more information comes out regarding recent, unprecedented rises in coastal sea levels, state and local officials are considering the risks involved with such events.
According to a study published in February in the scientific journal “Nature Communications,” sea levels along the Northeastern coast of the United States rose over 5 inches from 2009-2010. This rise was even more pronounced along the Maine coast, where water levels grew by an average of six inches that year, said Peter Slovinsky of the Maine Geological Survey.
“These were the highest water levels that we’d ever recorded, going back to 1912,” Slovinsky said.
The impacts of the rise were felt significantly in mid-coast and southern Maine, where many low-lying beaches suffered from serious erosion, Slovinsky said. But, closer to home, the geography of Mount Desert Island largely protected the area from such problems.
“The geology of the MDI area itself is much less susceptible to coastal events and even flooding,” Slovinsky said. “In terms of coastal development, the island areas are a lot steeper sloped and tend to have a lot of bedrock on the coastline. It’s much less susceptible in our lifetimes to erosion than, say, a sand beach or coastal beach.”
While the rate of rising seas has returned to the average of two millimeters a year since 2010, those who study the issue say that ocean levels are going to continue to go up. Peaks such as the one in 2010 are likely to grow. When mixed with high tides or other astronomical or weather events, the chances of destructive floods and coastal erosion also increase.
“We’ve got these anomalies that are occurring, but the overall long-term trend is a rising of sea levels up and down the Maine coastlines,” Slovinsky said.
Hancock County planners have turned much attention to the island of Stonington. The town already feels significant impact during high tides and storms, with the problems only expected to get worse, said Tom Martin, executive director of the Hancock County Planning Commission.
The Stonington waterfront is one of the busiest in the state, and as such, a very important part of the local economy, Martin said, lending great importance to planning for the future there.
“Stonington has the highest number of landings of any fishing port in the State of Maine. The town found that, as of today, its waterfront facilities are threatened by current storms,” Martin said. “The fishing community was very concerned about what was happening, and there was concern about preparing for future storms.”
The Stonington Waterfront Adaptation Project was launched in the fall of last year. The initial presentation detailed the current risk from storm surges and higher-than-usual tides, while also presenting possible future scenarios that could include much worse damage. The goal of the project is to develop response plans and infrastructure goals to allow the town to continue to thrive as a working waterfront.
MDI does not face the same issues in the short term, but Slovinsky said that at some point, just about every coastal community is going to have to start doing the kind of thinking that Stonington is doing.
“Nobody thinks that sea levels are going to stop rising for the next 100 years. That background increase of sea level that we’re seeing … creates a much bigger impact from storms,” Slovinsky said.
The best climate models available suggest a rise of anywhere from a conservative one foot to a moderate two to four feet over the next century, Slovinsky said, with other predictions as high as six feet.
“Depending on which scenario you pick, the impacts could be much greater. If we’re looking at three feet potentially, it would have a significant impact on Bar Harbor.”
Coastal flooding has long been on the radar of the Hancock County Emergency Management Agency, director Andrew Sankey said. Two areas that are already suffering consistent problems during high water events are Seawall, in Southwest Harbor, and the Deer Isle/Stonington Causeway, Sankey said.
While the bridge and causeway connecting MDI with the mainland sits fairly close to the water, the protected nature of the bridge’s location has so far kept it from any flooding trouble, Sankey said, but his agency still considers planning around such an event important.
“Just because it hasn’t happened yet doesn’t mean it isn’t susceptible to flooding,” Sankey said. “Is it a potential problem? Without question. Is it something we plan for? Without question.”
In 2010, heavier, longer-lasting North Atlantic winds combined with slower-than-usual gulf stream currents to create a surplus of water along the coast of the Northeastern United States. Many geologists were aware of the extreme sea level rise that year, but not until the “Nature Communications” article had the regional cause been outlined so clearly. According to the authors of the article, climate models predict an increase in both the magnitude and frequency of events similar to those in 2010.
“Over the longer term, it’s going to happen a lot,” Slovinsky said about coastal flooding. “With 3 feet of sea level rise, we’ll be getting flooding on an almost daily basis.”