At Perrotti Park in Newport, the top picture shows a high tide last July; the bottom photo, digitally altered, illustrates a 3-foot rise in sea level combined with an average spring tide, a stronger tide that occurs during full and new moons.

Rhode Island Sea Grant / Angela J. Wilson

By the time today’s babies become elderly, scientists predict that climate change will cause local ocean waters to be at least 3 to 5 feet higher than they are now.

If that happens, South County’s popular barrier beaches will be rolled up against the northern shores of the salt ponds. The sidewalks in Providence’s Waterplace Park will be under water. And coastal salt marshes will be inundated.

This fall, the state agency that regulates coastal development in Rhode Island plans to become one of the first local regulatory agencies in the country to officially recognize the likelihood of sea-level rise and write policies and regulations to prepare for higher water.

The rising waters will require that new buildings in flood zones be constructed at higher elevations, says Grover Fugate, executive director of the Coastal Resources Management Council. He says there should also be changes in the state building code for coastal development and different rules for septic systems. Sewer outfalls and bridges may be affected.

“Climate change will have tremendous implications for us [in Rhode Island],” says Fugate. “Water temperature changes already are affecting the ecosystem. Last year, the shoreline erosion rate doubled to four feet in certain places.”

A CRMC subcommittee recently authorized Fugate to seek public comment on a new draft policy that recognizes the problems posed by sea-level rise and creates the framework for CRMC to prepare regulatory responses.

CRMC chairman Michael Tikoian said the local agency is striving to “create the country’s first regulations to address sea-level rise.”

The National Oceanic and Atmospheric Administration, the federal agency that provides funds and guidance to CRMC, confirms that Rhode Island is out front on the sea-level rise issue. Oregon, Alaska and California are addressing global warming issues, according to NOAA spokesman Ben Sherman. “But Rhode Island is probably the first to have a sea-level policy not rolled in with other flooding issues.”

Fugate said sea-level rise became an issue during the last year as CRMC began revising its management plan for what it calls the Metrobay region that includes Providence, East Providence and Pawtucket, where intense waterfront development is expected to take place in the next few years.

CRMC, working with the Sea Grant program and the Coastal Resources Center at the University of Rhode Island’s Bay Campus, began taking a longer look, he said. It also recruited a panel of scientists for advice.

Last week, one of those scientists, John King, an oceanographer at URI’s Graduate School of Oceanography, gave a primer on sea-level rise to the full council. Some of his conclusions were surprising.

“We’re going to have a significant warming, no matter what we do,” King said. “Models for the Northeast range from an increase of 6 degrees Fahrenheit to 12 degrees Fahrenheit by 2100.”

Water temperatures in the region are also expected to go up by 5 to 10 degrees Fahrenheit, King said. The rising temperatures are caused by increases of carbon dioxide in the atmosphere, which traps the sun’s energy. Much of the carbon dioxide comes from combustion for transportation and energy generation.

King said there are several reasons why climate change will cause sea levels to rise in this region: Seawater expands as it warms. Melting glaciers and ice caps, already well under way, add more water to the oceans. And as it gets warmer, ice sheets flow faster into the oceans.

Sea levels are already rising, he said. And they are rising faster than the most pessimistic computer models predicted.

King said the report last February from the Intergovernmental Panel on Climate Change, an assemblage of thousands of scientists and government officials from around the world, gave a worst-case scenario of about a half-meter of sea level rise by 2100.

“Unfortunately, those numbers don’t stand up to scientific scrutiny,” King said. “No scientist I know accepts those numbers. The IPCC was a political/scientific exercise. These are rosy estimates.”

King said some recent predictions by independent scientists put the possible range of sea level rise at 3 to 5 feet. And that could be just the beginning. The last time the world had as much carbon dioxide in the atmosphere as it does now was 130,000 years ago, and the seas were 20 feet higher, King said.

King cited data from Jonathan T. Overpeck and Jeremy Weiss at the University of Arizona. They plotted the consequences of sea-level rise on all of the country’s coastlines. (The researchers’ findings can be found at www.geo.arizona.edu/dgesl/index.html)

Regulators should be planning for the 20-foot sea-level rise, rather than 3 to 5 feet, King said.

A 20-foot sea-level rise would leave the South County coastline looking like the south shores of Block Island, with waves crashing at the foot of high bluffs. The bluffs would be along Route One.

A sea-level rise of 3 feet would force the barrier beaches to retreat back to the north shores of the ponds.

One problem with plotting the effects of sea-level rise is that scientists now work with data generated by the U.S. Geological Survey, which has a margin of error of 5 feet, plus or minus. King and Fugate say Rhode Island needs funding to use Light Detection and Ranging technology that fires lasers from aircraft to record topographical data with a precision of up to 6 inches.

CRMC has been meeting with the state’s congressional delegation to try to raise the roughly $1 million it would take to do the mapping.

W. Michael Sullivan, director of the state Department of Environmental Management and a council member, observed last week that King seemed to have a pessimistic view of the future.

“We have 20 to 30 years to ratchet down greenhouse gases. That would lead to the low-end scenario,” King said. “The worst-case scenario is getting into a race with China to see who can burn the most coal. The Chinese have a lot of coal and they seem eager to burn it. We don’t seem too determined to do much about greenhouse gas emissions in this country either.”

During the next few months, CRMC will issue a public notice of the new policy, host a public hearing, and place the rules before the full council for consideration.

To see Professor King’s presentation, go to www.crmc.ri.gov/, click on CRMC Coastal Education Series and Policy Agenda, and then Coastal Education Series Presentations. The proposed, new CRMC policy is also available on the Web site. Rhode Island Sea Grant is hosting a two-day symposium on urban waterfront development Friday and Saturday at URI’s Bay Campus, that will focus in part on sea-level rise. For more information, go to seagrant.gso.uri.edu/ccd/07symposium/index.html.

plord@projo.com