Mayor Bloomberg could be laying the groundwork for a campaign to institute mandatory rules or tax incentives to reduce carbon emissions in the city.

Mr. Bloomberg, who will play host to dozens of mayors from cities around the world at a climate summit next month, released an “inventory” of citywide greenhouse gases yesterday.

The first-of-its-kind survey comes 12 days before the mayor is scheduled to unveil a plan with proposals to prepare the city’s infrastructure for 2030.

The survey looked at carbon dioxide emissions from a laundry list of sources, including the city’s commercial and residential buildings, its streetlights, its subways, its water and sewage facilities, and its garbage. It found that while New Yorkers have, on average, less impact on the environment per capita than their American counterparts, the city as a whole produces nearly 1% of all of the country’s greenhouse gas emissions. That, the report said, is about what countries such as Portugal and Ireland produce.

“We can no longer deny the science and bury our heads in the sand,” Mr. Bloomberg said, during a news conference at 7 World Trade Center. “Climate change is a real issue with real consequences. And as a coastal city, New York can’t just sit back and hope for the best.”

While the mayor did not say whether he plans to push for mandatory energy restrictions on cars, buildings, power plants, or trash, he has set a goal of reducing the city’s emissions by 30% by 2030. His presentation yesterday, coupled with the sustainability advisory panel he has created, suggests he plans to do more than just urge New Yorkers to make sure to turn off the lights when they leave the kitchen.

The deputy mayor for economic development and rebuilding, Daniel Doctoroff, who is leading the 2030 team, hinted that some of the proposals would target buildings. The report found that 79% of all of the city’s greenhouse gas emissions in 2005 came from the city’s skyscrapers and other buildings.

“We’ve learned a lot about what’s producing what and that will all be fed into the plan that you’ll see in the next couple of weeks,” Mr. Doctoroff said.

It is unclear exactly what the city has the authority to do on its own, given that many energy issues are overseen by the state. Mr. Bloomberg, who has not been shy about enforcing mandates that ban smoking and the use of trans fats, could also have a partner in Governor Spitzer, who has vowed to address climate change.

The president and CEO of the Partnership for New York City, Kathryn Wylde, a member of mayor’s sustainability advisory board, said the mayor’s plan, which will be presented on Earth Day, would likely rely more on voluntary measures.

“The focus would have to be on voluntary cooperation or incentives because virtually anything involving mandates would require state or federal action,” Ms. Wylde said.

The mayor — who was joined by the speaker of the City Council, Christine Quinn, and several other city officials — will have another stage for his environmental vision next month when he plays host at an international “climate summit.” Mayors from London, Tokyo, Moscow, Bangkok, and dozens of other cities will attend. Mr. Bloomberg and President Clinton will deliver keynote speeches.
Mr. Bloomberg said New York should be a policy leader, not a follower.

He did not say whether congestion pricing would be part of his plan. In the past, he has said it should be considered, but that it is not politically viable in Albany.

The 65-page emissions inventory, which will be used as a reference point as the city works towards its emission reduction goals, comes less than a week after United Nations panel of scientists said if no action is taken changes in climate will cause droughts, floods, and hazardous conditions across the globe.

Mr. Bloomberg brushed off global warming skeptics, who say there is simply not enough evidence to take action that could damage local economies.

“It’s easy to say environment problems are a figment of your imagination,” the mayor said.

Just because the last couple of months have been unseasonably cold doesn’t mean that there is no environmental problem, he said: “It has nothing to do with each other. It’s very cute to say on a talking head radio or television show.”

The report found that city emissions have increased more than 8% between 1995 and 2005 and are expected to jump another 25% by the year 2030.

Mr. Bloomberg was quick to point out that emissions from city government entities have remained stable since 2001, largely because the city has phased in greener taxis, streetlights, and employed other energy reduction measures. Still, the report found that 53% of city employees commute to work in cars.