PROVIDENCE — The overriding issue facing some 1,600 coastal scientists and policymakers from around the world who gathered at the Rhode Island Convention Center this week is the observance of rapid ecological changes — with many linked to climate change.

“We’re all seeing climate changes in the [ecological] systems where we study,” said Robert H. Howarth, a professor of ecology and evolutionary biology at Cornell University and incoming president of the Estuarine Research Federation, which is holding its biannual convention.

“Every single system we study is changing, and that scares of the hell out of us,” Howarth said.

He said the scientists are becoming increasingly frustrated with politicians and lay people who question the reality of climate change or quibble over the consequences.

“Climate change is here,” Howarth said. “We’re measuring it. Half the talks being given here are about how things look different now compared to 10 or 15 years ago.”

The federation is the largest scientific group that focuses research and policy studies on estuaries, highly productive areas where freshwater and salt water mix.

The federation last met in Providence in 1997. Growing concerns about the poisonous Pfiesteria microbe were a big topic then and about 1,000 scientists and policymakers attended.

Howarth said the group likes Providence because Narragansett Bay is so close and so important to Rhode Islanders, local scientists are major players in estuarine research, and the convention center so comfortably holds such a large group in once place.

Jim Latimer and Giancarlo Cicchetti, scientists at the Environmental Protection Agency laboratory in Narragansett, organized the conference. Past presidents include two University of Rhode Island oceanographers, H. Perry Jeffries and Candace Oviatt.

Scientists from 22 foreign countries attended. A total of 1,200 scientific presentations were given, either orally or with posters.

“The Impact of Climate Change on Estuarine and Coastal Environments” was the title of the keynote address Sunday night by Rosina Bierbaum, a former acting director of the White House Office of Science and Technology and current dean of the School of Natural Resources and Environment at the University of Michigan.

Bierbaum said climate change is already causing wide-ranging changes in coastal waters and the future will bring surprises.

Serious impacts are already occurring, she said. They include more major floods, droughts, heat waves and wildfires all over the world, more powerful tropical storms, more acidic oceans as they take up carbon dioxide, the drying out of tropical forests and changes in the distributions of hundreds of species, including pathogens and carriers of disease.

Hundreds of attendees jammed a session Tuesday on ecosystem-based management of estuaries, a management style that Rhode Island expects to embrace for Narragansett Bay in coming years.

Andrew Rosenberg, professor in the Institute for the Study of Earth, Oceans and Space at the University of New Hampshire and a member of the U.S. Commission on Ocean Policy, said two national oceans panels in 2004 concluded that the oceans are in trouble and existing management structures are incompatible with the complexity of ecosystems.

“You need to look at ecosystems as a whole, and how the pieces all fit together,” said Rosenberg. “There should be integrated management, rather than sector by sector.”

Michael J. Fogarty, a URI graduate who is now a scientist with the Woods Hole Oceanographic Institute and the National Ocean and Atmospheric Administration, said the United States needs a legislative mandate to impose a new ecosystem-based management system nationally, and “you need political leadership, unlike what we have in this country.”

He said Australia and Canada have leaders who are launching the new ocean management systems.

Fishermen first noticed reductions of cod in the oceans in 1859, and ocean managers still haven’t solved the problem 150 years later, Fogarty said.

Heather M. Leslie, an assistant professor of environmental studies at Brown University, said that in order to move ahead, there needs to be a common vision of what people want their local ocean systems to look like.

plord@projo.com