By Anthony DePalma
    The New York Times

    Thursday 12 July 2007

    By the end of this century, 100-year floods could hit New York City every 10 years, Long Island lobsters could disappear and New York apples could be hard to come by if nothing is done to reduce greenhouse gas emissions, according to a report released yesterday by a group of scientists and economists.

    "The Northeast can anticipate substantial - and often unwelcome or dangerous - changes during the rest of this century," concluded the report by the Union of Concerned Scientists, which examined the impact of global warming on the region. "The very character of the Northeast is at stake."

    The report, which covers nine states, is the product of a two-year collaboration between the Union of Concerned Scientists, an advocacy group, and a team of several dozen independent scientists and economists.

    Speaking at a news conference at the New York Botanical Garden, one of the authors of the report, James L. McCarthy, professor of biological oceanography at Harvard University and president-elect of the American Association for the Advancement of Science, said there could be droughts every summer in the Catskill Mountains, which supply drinking water for 9 million New Yorkers. At the same time, there could be heavy downpours that could turn the city's water more turbid and cause flooding.

    With higher temperatures, smog would increase and air quality in the region would decline, significantly worsening conditions for people with asthma, and the amount of pollen produced would soar, making life miserable for people with allergies.

    In a similar report released last year, the Union of Concerned Scientists laid out the regional climate changes that global warming could bring. Average temperatures could rise by more than 10 degrees Fahrenheit in both winter and summer by the end of the century, and New York City might have to swelter through 25 days a year with temperatures over 100 degrees.

    In the report released yesterday, the group focused on the possible impact of those changes.

    Earlier springs, longer summers and less snowy winters are already being felt in part because of heat-trapping gases that were released over the last 50 years. The region will have to adapt to those changes, the scientists said. But things could become far worse, and much more costly, they said, unless steps are taken now to mitigate the impact.

    Two alternative futures are laid out in the study, which was reviewed by other scientists before being released. One projects what the future would look like if steps were taken to lower emissions; the other looks at what would happen if emissions continued to grow.

    Without reductions in emissions, sea levels could rise, inundating coastal areas on southern Long Island and pushing water into parts of Lower Manhattan, flooding the financial district and swamping the subways, making them inoperable. Atlantic City could be flooded every other year by late century.

    The impact on New York State's $3.5 billion-a-year agricultural industry could be devastating, said David W. Wolfe, a professor of plant ecology in the Department of Horticulture at Cornell University and one of the scientists who contributed to the report.

    While higher temperatures might at first be welcomed because they would extend the growing season, they would bring new plant and insect pests like the corn earworm that could ravage crops.

    Unless emissions are reduced, the scientists warned, Long Island lobsters would disappear or move to cooler waters up north. Without a hard frost to set buds, New York apple trees would not produce as much fruit as before. Under stress from invasive species, maple, beech and birch trees could disappear from certain regions of the state, including the Adirondacks.

    And since it would often be hotter than dairy cows like, milk production could decline by 15 percent or more in late summer months.

    Professor McCarthy said those future effects could be eased substantially by efforts just now being put into place to curb emissions.

    Those efforts include the Regional Greenhouse Gas Initiative, in which all the northeastern states agreed to reduce power plant emissions and establish a carbon trading program. And New Jersey's global warming law, which Gov. Jon S. Corzine signed last Friday, commits the state to reducing all greenhouse gas emissions in the state by 80 percent by mid-century.

    A separate news conference was held in Trenton yesterday, focusing on global warming's potential impact on New Jersey.

    Mr. Corzine said that state and local efforts to reduce greenhouse gases are important, but controlling global warming requires a commitment on the national level, something the current administration has been reluctant to pursue.

    "In absence of leadership on the federal level, the fight to reduce greenhouse gases has now fallen upon the states," Mr. Corzine said. The governor also called on individuals to do their share with simple acts like driving less and using mass transit.

    The report did not include an analysis of the potential cost to business and consumers of the efforts of reducing greenhouse gas emissions. But Rohit T. Aggarwala, New York City's director of long-term planning and stability, said at the New York news conference that cutting carbon emissions would not necessarily have a negative cost.

    Mr. Aggarwala said that steps New York had already taken would improve the quality of life in the city and make New York more competitive. He said those efforts ranged from the relatively simple, like promoting the use of compact fluorescent light bulbs, to long-range strategic initiatives like congestion pricing.