Using global climate models and local information, the New York City Panel on Climate Change projects that by the end of the century, New York City's mean annual temperatures will increase by 4 to 7.5 degrees Fahrenheit. Annual precipitation is also projected to increase by 5 to 10 per cent, and sea levels to rise by 12 to 23 inches.

Recent evidence, however, including accelerated ice melt in Greenland and Antarctica, suggests that sea levels could rise at a faster rate than projected by the existing models - potentially by 41 to 55 inches by the end of the century.

The report also projects that extreme events - such as heat waves, short periods of intense rain, droughts, and coastal flooding - are likely to become more frequent and more intense. In contrast, cold day events, where the temperature drops below freezing, will decrease in frequency.

By the end of the century, New York could experience approximately 2.5 to 4.5 times more days per year of over 90 degrees than experienced on average from 1971-2000; approximately 2.5 to 4 times more heat waves a year than experienced on average from 1971-2000; more intense rainstorms and a current 1-in-100 year coastal flood about once every 15 to 35 years.

But releasing the grim report, Mayor Michael Bloomberg said the city is already taking steps to ensure the smooth transition from the current weather conditions to the severe conditions that it is likely to face in future.

The steps being taken include upgrading infrastructure, including electrical supply system, which is expected to come under great strain as the days experiencing extreme heat increase and floods could disable the system unless the level of the equipment is raised.

The panel was convened by the Mayor and funded by Rockefeller Foundation.The report was released at the Department of Environmental Protection's Rockaway Wastewater Treatment Plant, which is preparing for the effects of climate change by raising electrical equipment, such as pump motors, circuit breakers, and controls, to higher elevations.

"The climate change projections developed by our expert panel put numbers to what we already know - climate change is real and could have serious consequences for New York if we don't take action," said Mayor Bloomberg.

The projections will be used by the Adaptation Task Force to create a plan to protect the City's critical infrastructure and will impact other City efforts to adapt to climate change.