BALI, Indonesia - Just a few days into the two-week U.N. Climate Change Conference here, developing nations yesterday demanded rapid transfers of technology to help them combat global warming, and more than 200 leading climate scientists, losing their patience, urged government leaders to take radical action because "there is no time to lose."

Meanwhile, a new report warned that some of Asia's biggest cities could be threatened by rising sea levels several decades from now. Calcutta and Mumbai lead the Top 10 list of endangered cities, nine of which are in developing Asian nations.

Miami is listed as No. 9.

And in Washington yesterday, a Senate committee advanced the first bill calling for mandatory U.S. limits on so-called greenhouse gases that has been taken up in Congress since global warming emerged as an issue more than two decades ago.

The scientists' petition, signed by at least 215 climate experts, calls for the world to cut in half greenhouse-gas emissions by 2050. The appeal follows a petition last week from more than 150 global business leaders with the same goal.

Fifty percent is scientists' calculated estimate for what would hold future global warming to a little more than a 3-degree Fahrenheit increase and is in line with what the European Union has adopted.

In the past, many of these scientists have avoided calls for action, leaving that to advocacy groups. The dispassionate stance was taken during the release this year of four reports by the U.N.'s Intergovernmental Panel on Climate Change. No more.

"It's a grave crisis, and we need to do something real fast," said petition-signer Jeff Severinghaus, a geosciences professor at the Scripps Institution of Oceanography in La Jolla, Calif. "I think the stakes are way, way too high to be playing around."

The petition includes scientists from more than 25 countries and shows that "the climate-science community is essentially fed up," said signer Andrew Weaver of the University of Victoria in Canada. It includes many coauthors of the panel's reports, among them Michael Oppenheimer, a professor of geosciences and international affairs at Princeton University.

The petition is online at

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Negotiators in Bali are working on the initial groundwork for a treaty that would take effect after 2012, the expiration date of the Kyoto Protocol, which the United States did not sign. But no one expects concrete results at the closed sessions.

While the scientists called for action, leaders of poor and emerging countries say they need more technological know-how to reduce pollution and improve energy efficiency. They criticize wealthy nations for their focus on getting booming countries such as China to set goals for cutting emissions, delegates and activists said.

"How on earth can you talk about targets if you don't want to engage on the scope, the depth and need of technology?" said Meena Raman, chairman of Friends of the Earth International. "In the last two days, the sincerity and urgency that is needed and goodwill . . . is not happening."

Failure to reach a new international consensus on curbing emissions, experts warn, will raise the threat of catastrophic droughts and floods, increased heat waves and disease, and sea level rises caused by melting ice.

Plants and animals are already feeling the change, and it is occurring too quickly for them to evolve.

Butterflies that lived at high altitudes in North America and southern France have vanished, and polar bears and penguins are watching their habitat melt away. The spread of a deadly fungus that thrives in warmer conditions has decimated frog populations in South America, Africa and Europe.

Globally, 30 percent of the Earth's species could disappear if temperatures rise 4.5 degrees, scientists reported last month.

In Washington, meanwhile, the Senate Environment and Public Works Committee yesterday approved legislation that represents the first move forward by Congress on mandatory greenhouse gas reductions.

The legislation, approved on an 11-8 vote, would:

Require carbon dioxide and other so-called greenhouse gas emissions to be reduced by 20 percent from 2005 levels by 2020, and 70 percent by 2050.

Cover electric power, manufacturing and transportation, accounting for 80 percent of U.S. economy-related greenhouse gas emissions.

Allow trading of emission allowances, a "cap-and-trade" system. Companies unable to meet their cap could buy allowances from companies that have exceeded their required cuts.