A vast majority in many countries now believes human activity is causing global warming and that major steps are needed quickly to halt its devastating advance, a BBC World Service poll has found.

The survey of more than 22,000 people in 21 countries, conducted a day after 150 countries met at the United Nations to discuss warming, found agreement among 79% of respondents that “human activity, including industry and transportation, is a significant cause of climate change”.

Nine out of 10 said action was necessary, with two-thirds saying “it is necessary to take major steps starting very soon.” In no countries did a majority say no action was needed.

The survey also found support among 73% of respondents for an international agreement to limit greenhouse-gas emissions in developing countries. Currently, China and India, the world’s first and second most-populous nations, are exempt from the Kyoto Protocol. China recently topped the U.S. as the biggest spewer of greenhouse gases.

Still, a majority in some of the key developing countries even favor limiting emissions, including China (68%), Brazil (63%) and Indonesia (54%).

A day earlier, UN Secretary General Ban Ki-moon told the highest-level UN gathering on climate change that “the time for doubt has passed,” Ban is hoping to inject a sense of urgency to the political negotiations on global warming that are due to be held in Indonesia in December.

“If we do not act now, the impact of climate change will be devastating,” he said.

Some world leaders, however, are slow to get the message. U.S. president Bush didn’t even attend the UN meeting, the largest-ever forum on global warming, preferring instead to huddle with 16 “major emitter” countries on Thursday and Friday.

Prime Minister Stephen Harper told delegates Canada favors an approach that balances global-warming mitigation with economic growth.

Lets hope they read the survey.