US: Environmental experts yesterday hailed a hint of a softening in US scepticism about global warming but saw scant chance that President George W. Bush might ever rejoin international efforts to cap greenhouse gases.
Some said the US administration report this week, saying warmer temperatures in North America since 1950 were probably caused in part by human activity, might simply be a bid to reach out to green voters before the November presidential election.
"I don't think there is any policy shift at all," said Mr Steve Sawyer, climate policy director of Greenpeace. "It's election season and Bush may be trying to reach out to the elusive centre."
Mr Bush dismayed many allies in 2001 by pulling the US out of the UN's Kyoto protocol, the main international pact meant to cap emissions of greenhouse gases. Despite White House denials of a shift in policy, the report seemed to contradict Mr Bush's long-held view that there is no scientific proof that human use of fossil fuels like oil and coal is an underlying cause of global warming.
And some experts said evidence for global warming was likely to strengthen and could eventually put pressure on Mr Bush to do more, if he beats Democratic challenger Mr John Kerry.
"This report could be very significant," said Mr Hans Joachim Schellnhuber, a director of the Tyndall Centre for Climate Change Research in England.
"If Bush wins, he may have to soften his opposition to the idea of global warming and this could be an advance sign." But none saw Mr Bush as a convert to concerted international action. "Any new Bush administration will not change its climate policy radically," said Mr Pal Prestrud, head of the Centre for International Climate and Environmental Research in Oslo.
The administration report, sent to Congress this week, said: "North American temperature changes from 1950 to 1999 were unlikely to be due only to natural climate variations."
It said temperature trends were consistent with human interference including emissions of greenhouse gases, mainly carbon dioxide from cars, power plants and factories, that scientists say are blanketing the planet.
But in an interview with the New York Times Mr Bush was asked why his administration had changed its position. "Ah, did we?" Mr Bush replied. "I don't think so." Scientists say that global warming may bring drastic costly changes like more floods, tornadoes and a melting of polar icecaps that could push up sea levels. Mr Bush has said the Kyoto emissions pact, which has still not entered into force because of doubts by Russia, would be too costly and unfairly exempted developing nations.
Many foreign nations said Mr Bush was seeking to protect US lifestyles, underpinned by high energy use.
"This belated recognition of the scientific consensus on human-caused global warming is in itself not a big deal," said Ms Katherine Silverthorne, head of the WWF environmental group's US climate change programme.
"It is only significant if it leads to solutions." Mr Kerry, an advocate of stronger action to protect the environment, has said that the US should take a lead in confronting global warming but says it is too late to sign up for Kyoto, which runs until 2012.