NEW YORK - New York Mayor Michael Bloomberg laid out an ambitious environmental plan for the city on Sunday, including a congestion charge for driving in Manhattan and proposals to plant one million new trees.

In a speech to mark Earth Day, Bloomberg unveiled 127 broad policy initiatives to cut greenhouse gas emissions by 30 percent, increase access to parks, reclaim unused industrial land and reduce water pollution.

"We need to start meeting the challenges we'll face as we grow by nearly one million people" in the coming two decades, he said.

The pilot congestion pricing plan would involve charging those entering Manhattan from the north eight dollars during weekdays between 6am and 6pm if they pass south of 86th street in uptown Manhattan.

Those entering by bridges and tunnels already face similar charges.

Special rules would apply for residents, Bloomberg said, without elaborating, while taxis would be exempt from the fee. The changes would affect only five percent of the New Yorkers who work in Manhattan, he said.

"I understand the hesitation about charging a fee. I was a sceptic myself. But I looked at the facts, and that's what I'm asking New Yorkers to do," Bloomberg said.

"The fact is, in cities like London and Singapore, fees succeeded in reducing congestion and improving air quality."

He said the fee had to be high enough to encourage people to use public transport but no so expensive as to prove onerous for those who needed to drive.

"We believe that an eight dollar charge would achieve these goals."

"As a test run, we will seek state authority for a three-year pilot project, and we are very optimistic that, in working with state officials, we will secure hundreds of millions of dollars in federal funding for it," he said.

Other headline announcements included a plan to plant one million new trees in the city over the next decade -- a quarter of them along roadsides -- and to reforest some 900 hectares (2,000 acres) of parkland.

The "street-greening" initiative would also involve cleaning up around 3,000 hectares of brownfield -- or former industrial -- sites in the city.

Bloomberg has already committed the city to cutting greenhouse gases and said energy conservation and a shift to cleaner and more efficient power plants would meanwhile saving seven million tons of carbon dioxide every year.

"Climate change is a national challenge, and meeting it requires strong and united national leadership," Bloomberg said. "That means we can't -- and we won't -- wait for Washington. The time to act is now."

"The science is there. It's time to stop debating it and to start dealing with it," he said, adding that global warming could not be separated from issues such as transportation policy, air quality and energy use.

New York City has led much of the United States in some public health and environmental policies since Bloomberg became mayor in 2002.

In 2003, the city brought in a tough anti-smoking law that was considered by many at the time to be draconian, but which has been copied by cities around the world.

Last year, the city banned restaurants from using artificial cooking oils known as trans fats, in an attempt to improve residents' health and help tackle heart disease and obesity. - AFP/ir