The greatest storm to hit the city in more than 20 years, providing the plants with a needed drink, causing some challenging commutes, and threatening the Long Island coastline, is escalating the debate about a climate shift.

The gusty winds and record rainfall came a day after a series of protests across the country to draw attention to the global warming debate, and a week before Vice President Gore opens the Tribeca Film Festival with seven short films about the environment. Mayor Bloomberg plans to unveil the city’s environmental sustainability plan on April 22, Earth Day.

“There’s something ironic about the fact that we were down on the Battery yesterday, forming a line to show where the new tide line will be in New York with rising sea levels,” Bill McKibben, the founder of the group that organized the protests, Step It Up 2007, said. “Today, Bloomberg is issuing emergency flood warnings for Lower Manhattan.”

The members of the group that descended on Lower Manhattan called themselves the “Sea of People.” Participants, wearing water-themed clothing and costumes, re-created what some scientists predicted would be the new permanent tide lines with a 10-foot sea-level rise.

More rain fell in New York yesterday than on any other April day since such things were measured. About 5.5 inches of water had fallen in Central Park by late evening and more was expected throughout the night. The previous record of 1.82 inches was set on April 15, 1906.
“This is unusual to have a nor’easter this time of year,” a meteorologist at the National Weather Service, John Murray, said. “A number of locations have beat records for daily rainfall.”

An associate director of Harvard Medical School’s Center for Health and the Global Environment, Paul Epstein, said it was the storm’s intensity that made it stand out.

“It’s not unusual to have a storm happen that is a cold reversal of the warming from the winter,” he said. “This is exaggerated. The storms are staying longer, and they’re more profound because of climate instability. … It’s becoming in your face. It’s hitting everybody.”

Still, several climate experts, scientists, and policy advocates said that it was impossible to tie a single storm to a global climate phenomenon. The general population now has a greater sensitivity to the weather because of the debate about the climate, several experts said.

“It’s very difficult to connect any given instance with a global long-range phenomenon,” the director of the Institute for Civil Infrastructure Systems at New York University’s Wagner School of Public Service, Rae Zimmerman, said. “However, that said, certainly this is in keeping with some of the effects of climate change.”

Two days before the Tribeca Film Festival kicks off with seven short films about the “global climate crisis,” the Pacific Research Institute is hosting a screening, also in Tribeca, of “An Inconvenient Truth … or Convenient Fiction.” Steven Hayward, a senior fellow at the institute, created the film to refute the Oscar-winning “An Inconvenient Truth.” Much of the latter film revolves around Mr. Gore.

Mr. Hayward said yesterday that calling the nor’easter of 2007 a product of global warming was a good example of the anti-intellectual nature of one side of the debate.

“If we have hot weather, it’s climate change. If it’s cold weather, it’s climate change, too,” he said. “Climate change has become what philosophers call a nonfalsifiable hypothesis. It’s something where everything is for it and nothing can be accounted against it.”

Mr. Hayward’s film starts off with the premise that a climate change is happening, but goes on to show that understanding of the issue is inadequate, he said. Mr. Gore’s position “shuts down debate” when more is needed, he said.

“An Inconvenient Truth” highlights the ravaging of New Orleans by Hurricane Katrina as an example of the power of weather and the need for adaptation to changing weather conditions.

Last week, Mr. Bloomberg released a survey that said New York City was responsible for nearly 1% of the world’s greenhouse gas emissions.

At the unveiling, he said: “We can no longer deny the science and bury our heads in the sand. Climate change is real issue with real consequences. And as a coastal city, New York can’t just sit back and hope for the best.”

The president and CEO of the Partnership for New York City, Kathryn Wylde, who is helping organize Mr. Bloomberg’s sustainability conference, said the weather was tied to global warming.

“It’s clear from all the unusual weather occurrences, from El Nino to the 70-degree day we had in December, that global warming is responsible for all of these shifts,” she said. “It’s safe to say that any expert will make the point that all the dramatic changes in weather patterns are related to global warming.”

At one flood site on the corner of Grand Street and West Broadway, a veteran bartender, Esther Santiago-Babb, said the condition was mild compared with previous years.

“In the past, there’s been tampons and toilet paper floating in the streets, and we’ve had paper sailboat races and the bar has flooded,” she said. Ms. Santiago-Babb was sitting with other staff as taxis drove like motorboats through the flooded street. Water was approaching the window frames.

Mr. Bloomberg said at a 6 p.m. press conference that there were no weather-related fatalities in the city.

There were several areas of flooding, and areas in all five boroughs were on alert for rising water levels last night. The Office of Emergency Management opened nine storm shelters in low-altitude sections of the city, including Chinatown, Flushing, and Gowanus.
About 1,700 Queens residents lost power after trees were knocked onto power lines, a spokesman for Consolidated Edison, D. Joy Faber, said. Another 1,700 in Westchester had no power, she said.

More than 400 flights were cancelled at New York’s three airports. The Greek-American Independence Day Parade and a Mets game with the Washington Nationals were rained out.

With more rainfall overnight and high tides, coastal areas of Long Island were expected to bear the worst of the storm in the early this morning.

Mr. Bloomberg said there were many disruptions on the roadways, especially in the Bronx.

“Clearly, the roads are very bad — and nightfall will only make things worse,” he said, adding that residents should avoid driving and take the subways. Alternate side parking is suspended today.

The storm is forecast to move out over White Plains before looping back across New York City and Long Island late tonight. By Tuesday, it should return to sea. The last storm to hit the city with such force was the 1991 Halloween nor’easter, which was also dubbed by a National Weather Service meteorologist “the perfect storm.” There was $1 billion in damages and 12 people died.

“Today’s weather could be spring weather or it could be a component of a larger trend of more dramatic weather,” the director of New York University’s Center for Catastrophe Preparedness and Response, Bradley Penuel, said. “In any case, it should show people that these things happen. Prudent planning and forethought should be something on every family’s mind.”