U.S. Republican vice-presidential candidate Sarah Palin is making few friends among U.N. climate experts with her view that natural swings, along with human activities, may explain global warming.

Rajendra Pachauri, chairman of the U.N. Climate Panel, says that evidence is mounting that human activities are the main cause of warming. The panel reported last year that it was at least 90 percent certain that human activities, led by burning fossil fuels, were heating the planet.

He predicted in a telephone interview that Palin’s influence would be limited on climate change if Republican John McCain won the presidency.

“In the ultimate analysis I don’t think the vice president of the United States really matters in these subjects. I wouldn’t really worry too much about her,” he said.

 (…even so, former U.S. Vice President Al Gore won the 2007 Nobel Peace Prize, with Pachauri’s panel. Or did Gore only become a guru for greens after he left office?)

Achim Steiner, head of the U.N. Environment Programme, also said when asked about Palin’s views that: “We have the science. The debate over the science is over.”

Many delegates at an International Union for Conservation of Nature congress I am attending in Barcelona also say they worry that Palin’s views make it sound as if the science of global warming is far less certain than it is.

So, at least from interviews I have been doing for a Reuters News environment summit, Palin is out in the cold.

Who’s right?

Will the world be a slightly less messy place by Monday?

Organisers of an annual “Clean up the World” campaign say that up to 35 million volunteers in more than 110 countries will be cleaning up trash, planting trees, working out better ways of recycling and taking part in other ways to stop pollution.

 Of course it will take a lot more than just the Sept. 19-21 blitz but beaches from Vanuatu to Brazil, or cities from Buenos Aires to Sydney may benefit a bit.

And it illustrates a wider problem about the environment – nothing much happens unless a lot of people get involved in sorting out problems such as piles of stinking rubbish or global warming.

“We are faced with a unique challenge…about how we get practical about climate change,” said Achim Steiner, head of the U.N. Environment Programme which backs the clean-up campaign. “Climate change is not just something that others have to address.”

The clean up campaign was founded in 1993 by Australian Ian Kiernan, a yachtsman shocked by the amount of trash even in remote areas such as the Sargasso Sea in the Caribbean.

So get out your mops, your bins, your rags, your scrubbing brushes, your brooms…