PORTLAND — Sea level is rising, emergency-level storms are becoming more frequent, and the city must start planning for an uncertain future where extreme weather is not only possible but probable, officials said during a series of events at the end of February.
The city sponsored two events last week to release the details of a pair of reports that outline the costs climate change has, and could have, on the city.
The first, presented by the New England Environmental Finance Center at a public forum at the University of Southern Maine on Feb. 24, as well as to a City Council committee on sustainability the week before, charts sea level rise over the last century and projects damages in the tens of millions of dollars in the future if the city doesn’t take protective measures.
The second, a study tracking the increase in extreme weather events in Maine and around the country, was released by Environment Maine at a City Hall press conference on Feb. 22. At both events, Mayor Michael Brennan introduced the presenters, lending his policy-shaping sway to the risks from climate change and rising sea level.
The City Council needs to make decisions about the future – 50 and 100 years from now – on a regular basis, Brennan said Friday.
“This is about things we know are happening. We see more events and they are getting more intense,” said Sam Merrill, director of the New England Environmental Finance Center, before he and Maine Geologic Survey marine geologist Peter Slovinsky explained the NEEFC findings to a group of about 100 people at USM’s Wishcamper Center on Friday.
The findings include that sea level rise, which marched at a steady pace of just under 2 mm a year for the last century, for a total of about 7.5 inches, has jumped to more than 4 mm a year since 1990, and could rise by an additional 1 to 6 feet by 2100.
“The key part is we have seen an acceleration,” Merrill said.
Pointing to maps of the city projected on a screen, Merrill said sea rise alone won’t cause dramatic changes to Portland’s coastlines or damage its existing infrastructure. But general sea rise means that incoming tides will be higher, and storm surges more destructive.
“We need to start thinking about the difference between daily events and extreme events,” he said.
Already, the land along Marginal Way and Somerset Street can become inundated with water at high tide, Merrill said, noting a 2010 event that left that area and the city’s piers under a foot of water.
With 2 feet of additional sea rise, the highest annual tide would be approximately the same as the storm surge of a 1978 storm used as the most extreme benchmark of sea water inundating the city, he said.
Both the city’s industrial and commercial waterfronts and neighborhoods around Back Cove stand to be affected by higher seas and strong storms in the future, Merrill said.
He zeroed in on Back Cove, home to well-established residential areas and a Bayside neighborhood still very much in development. Damage from storm surges there could amount to nearly $450 million in a worst-case scenario by 2050 if no measures are taken to prepare for rising sea, he said.
Merrill and his colleagues did not promote any specific solutions, but listed some possibilities, including: identifying undeveloped areas to preserve as wetland buffers, building flood gates under Tukey’s Bridge or a series of levees along the Back Cove, raising roads and the minimum height for buildings in the floodplain, and retrofitting storm drains.
Other options include moving buildings out of the growing floodplain, or doing nothing at all, officials at the event said.
But Environment Maine’s study, released a few days before the Friday forum, underscored the likelihood that devastating storms lurk in the future.
Since 2006, every county in Maine has at some time been declared a federal disaster zone, thanks in part to blizzards in 2010 and spring flooding and Tropical Storm Irene in August 2011, which damaged nearly 200 roads and a dozen bridges, the report said.
Last year, weather-related disasters set records, with 14 events costing more than $1 billion, said Anika James, an Environment Maine field associate. Research shows the trend is likely to continue, with greater rainfall and more intense hurricanes likely in the future, James said.
Established residential areas and upcoming developments along Portland’s Back Cove could be threatened in the future by rising sea levels and storm surges from increasingly powerful weather events if measures aren’t taken to protect the city’s coastal properties, city officials said at a pair of February events.
Building a storm gate below Tukey’s Bridge at the mouth of Back Cove is a possible solution to the dangers that future storm surges, coupled with rising sea levels, could present to Portland.