By 2100, sea levels at Montauk Point could be 6 feet higher than today. In Manhattan, levels at Battery Park could be 6 feet, 3 inches higher by that year.

Those figures and other climate changes were discussed at a meeting of the state Department of Environmental Conservation yesterday, about its plans to set sea-level rise projection regulations by 2016.

"Overly aggressive projections could lead to maladaptation and unnecessary economic cost," said Mark Lowery, DEC's climate policy analyst. "On the other hand, decisions made now could put infrastructure, natural resources and communities at risk if they are based on excessively low projections of future sea-level rise."

The sea-level projections are required by the 2014 Community Risk and Resiliency Act. As part of that act, DEC will establish the range of how high sea levels could be in the 2020s, 2050s, 2080s and 2100. Projections must be updated every five years.

"It is likely that sea-level rise will continue for a millennia regardless of what we do," Lowery said. "Again the question is largely when, not if, sea-level rise will reach 6 feet."

The sea-level rise projections will be used to determine regulatory changes for permitting, facility siting regulations and funding of major projects under 19 state programs, ranging from wetland and water protections to sewage service and location of liquefied natural and petroleum gas facilities, DEC associate attorney Jonathan Binder said at the meeting.

The act also requires applicants to factor in sea-level rise, storm surge and flooding when working with the state on projects.

Those regulations are due in 2017.

The agency is relying heavily on two documents to develop the projections: One is ClimAID by the New York State Energy Research and Development Authority. It was published in 2011 and updated in 2014.

The other document is the Climate Risk Report for Suffolk and Nassau done by the New York State Resiliency Institute for Storm and Emergencies published in 2014.

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For Montauk Point, the ClimAID report projected sea levels could rise between 2 and 10 inches by the 2020s, and 13 to 58 inches by the 2080s.

"Sea-level rise is not limited to urban areas but threatens rural and natural areas as well," Lowery said.

At the meeting, held at Wertheim National Wildlife Refuge in Shirley, Defend H2O president Kevin McAllister said municipalities are at times working in isolation and he hoped the regulations would change that.

"We need some real, substantive policy," said the environmental advocacy group founder. "We need the state of New York to come in and say, 'These are the rules.' "

The sea-level rise meetings will also be held today in Manhattan and Queens. Tomorrow, a meeting in Albany will be live-streamed online and available as a telephone conference call.

Details on other meetings and how to join the call are at dec.ny.gov.