Reacting quickly to the latest UN climate change report, Prime Minister Gordon Brown is pledging that Britain will lead the world in reducing carbon emissions. For VOA, Tom Rivers reports from London.

In what is being described as a landmark report, the Intergovernmental Panel on Climate Change (IPCC) describes the impact of global warming in stark terms, saying it will affect both rich and poor in the coming decades.

The IPCC says that human activity is largely responsible for warming.  Its report says that as early as 2020, between 75 million and 250 million people in Africa will suffer from water shortages, main Asian urban centers will be at risk for flooding, and many species will disappear from Europe.

In London, British Prime Minister Gordon Brown said the message is simple. The time to act is now.

"This is a wake up call for the whole world. Britain has led the way, the first climate change bill in history, now the rest of the world must follow," he said.  "And at Bali in the next few weeks we need a climate change agreement that is global, that is comprehensive, that is radical and meets our ambitions that we have a 50 percent cut in carbon emissions around the world and we will do even better than that."

The latest report will form the basis for policy makers when they meet next month in Bali, Indonesia.  The conference will aim to hammer out an agreement that succeeds the Kyoto Protocol, due to expire in five years.

The U.N. says a new global plan must be in place by 2009 to ensure a smooth transition after Kyoto.

Addressing the tough domestic policy measures ahead, Prime Minister Brown said Britain is willing to take up the challenge.

"What we want is low carbon homes, low carbon businesses, low carbon buildings and we are already on the way to doing that," he added.  "But it is also a huge opportunity for Britain, because we can lead the world in environmentally-friendly industries and creating thousands of jobs for British people."

The IPCC report says while the planet will continue to warm in the near term, worst case scenarios can be avoided if political leaders act quickly, decisively and in concert now.