CHATHAM – The effects of climate change could cost the town $3 billion by 2100 if nothing is done to mitigate sea level rise and a host of other potential impacts.

Those findings were extrapolated by the town's energy and climate action committee from a recent Cape Cod Commission climate change report, which put the total impact to the region at $50 billion.

The figure for Chatham was reached by applying a projected 6.3 percent loss in property taxes to other impacts of climate change, including road damage, decreases in land value, loss of tourism and damage to buildings, said committee chair Robert Wirtshafter.

The cost of doing nothing is “severe” and far exceeds that of strategies to adapt to and mitigate climate change, he said during a presentation to the select board Dec. 14.

The numbers are “pretty shocking,” Wirtshafter said. “That's why it's important we deal with this now as an immediate emergency and that we don't get into the situation as projected.”

The cost of retrofitting existing buildings that are at risk and assessments of low-lying roads and coastal resources went into the commission study. It's important to protect natural systems such as salt marshes which provide a buffer to sea level rise. Buildings can be elevated or in some cases moved. Vulnerable roads are a challenge, Wirtshafter said, because they are very expensive to raise out of danger. In some cases, roads may have to be abandoned, he said.

According to the report, some 12,000 acres of eelgrass and 14,000 acres of salt marsh are at risk Cape-wide. Some $800,000 million worth of cranberry bogs could be inundated, and other key economic drivers, such as loss of beach area, could cost the region more than $9 billion. Climate change also puts the commercial fishing industry at risk, according to the report.

Based on 2020 housing and land prices, a combination of sea level rise and storm surges across the Cape could cause $15.3 billion in building damage and $14.5 billion in land lost to inundation, according to the report, along with nearly $9 billion in tax revenue and $600 million wages lost. Protecting the Cape's shoreline from an eight-foot increase in sea level (including storm surges) would avoid $28 billion in damages, but would be very expensive. A targeted approach to shoreline protection would be more cost effective, the report recommends, along with consideration of shoreline retreat for less dense areas.

Other strategies for fighting climate change include revising flood plain regulations, adopting a revised energy-efficient building code and reducing emissions with more electric cars and heat pumps to heat homes. This would increase the region's electric load by some 89 percent, Wirtshafter said, so it's also important to establish clean renewable sources of power. The cost of solar power and other renewable sources has dropped considerably, he noted, but it will still take state and federal subsidies to encourage more. It will also be important to motivate residents to make those changes, “which is going to be a challenge,” he said, “because just changing lightbulbs is over and we really now need to make what are going to be deep retrofits to our buildings and [have] very efficient new construction.”

A projected seven-foot increase in sea level plus more frequent severe storms by 2100 would eliminate the outer beach and significant areas along the town's eastern shoreline, but will leave downtown mostly in tact, Wirtshafter said.

“We can't really look at Chatham alone because we are part of the rest of Cape Cod,” he said. “Damage to some areas of the Cape will be greater than they may be to Chatham, but it's going to be hard to get to Chatham, going to be hard to get to places that we are used to going to, if we don't do some remediation here.”

The town has done coastal resiliency studies of the Little Beach area and other sections of the coast. Town Manager Jill Goldsmith said while the commission report's findings have not been discussed with department heads and committees, coastal resiliency is at the “foundation” of much of the town's planning and budgeting.

The town has to be proactive in addressing climate change and can't kick the issue down the road, said Select Board member Shareen Davis.

“I just have this gut feeling that five years from now we're going to see Chatham looking differently,” she said. “We are very vulnerable here where we are, where we live.” The outer beach is fragile and there is a lot of stress put on the town's resources by visitors every year. “I think this is a really good start.”

“I see it now, in those northeast storms, the beach overwashes and its dramatic,” Select Board member Jeffrey Dykens said. “We're losing the ability of the outer beach to be resilient with these overwashes.” The numbers are daunting, he added, but the sooner the issues are addressed the less it will cost.

“We are hard by the sea, and we're going to have to deal with it,” he said.

The select board authorized the committee to work with Goldsmith to identify existing mitigation and adaptation strategies. The committee also plans to make a presentation similar to the one given to the select board to all town boards and committees, and to identify and assess recommendations in the Cape Cod Commission report for effectiveness and feasibility for Chatham.

“We've raised the alarm here, but we want to let you know that we are ready to commit to mobilizing to address these issues,” Wirtshafter said.