More than 20,000 protesters rallied in London on Saturday ahead of international talks on climate change in Kenya, demanding that world leaders act to curb global warming, Reuters reported. The event included a march from the United States embassy in protest against U.S. President George W. Bush's refusal to ratify the Kyoto Protocol on cutting climate-warming gases from fossil fuels. Police said the crowd reached 22,500 people, packing out Trafalgar Square in the capital's centre. "We are reaching audiences today in a way that was impossible a year ago," Ashok Sinha, director of organisers Stop Climate Chaos (SCC) said. "We are getting people to look at the total carbon emisson of their lives and to start making adjustments, because every single bit helps. "We are talking about personal actions but it is also bulding up pressure on governments to take action to stop the destruction of the planet." United Nations climate talks involving 189 nations start next week in the Kenyan capital Nairobi to negotiate a successor to the U.N.'s Kyoto Protocol beyond 2012. Reaching a deal is expected to take up to three or more years.