Shanghai: Asia’s economic boom could be linked to increasing pollution levels in the US, scientists say. Photograph: Alamy

Ozone blowing over from Asia is raising background levels of a major ingredient of smog in the skies over western US states, according to a new study appearing in today’s edition of the journal Nature.

The amounts are small and, so far, only found in a region of the atmosphere known as the free troposphere, at an altitude of two to five miles, but the development could complicate US efforts to control air pollution.

Though the levels are small, they have been steadily rising since 1995, and probably longer, said lead author Owen R Cooper, a research scientist at the University of Colorado attached to the National Oceanic and Atmospheric Administration’s Earth System Research Laboratory in Boulder, Colorado.

Scott Brown and his wife, Gail, celebrate after he won the Massachusetts Senate seat previously held by Ted Kennedy. Photograph: Robert Spencer/Getty

An ambitious climate change bill had been sliding down President Barack Obama‘s to-do list even before the Republican upset in Massachusetts that saw Scott Brown take Ted Kennedy’s Senate seat.

Now it seems more likely than ever that Democrats in the US Senate will not touch global warming in 2010 unless they can be assured of sizeable Republican support. Brown’s election has also led to international concern that any failure to act by the US – the world’s biggest historical polluter – would undermine attempts to seal a global deal.

However, Senator John Kerry, who is leading the push on climate change in the Senate, said he remained confident of getting broad support for a bill.

The Sierra Club‘s new leader will come to the job with a record of “environmental agitation” against big industrial polluters.  The group announced on Wednesday that Michael Brune, 38, currently head of Rainforest Action Network (RAN), will replace Carl Pope as executive director as of March 15. Brunehoned RAN’s strategy of negotiating politely with corporate heavyweights such as Bank of America, Citigroup, and General Motors—and then, if they don’t clean up their acts, campaigning mercilessly against them. The two-pronged approach earned results that belie RAN’s modest size—it helped convince Home Depot to stop selling wood from endangered forests, for example.

Brune spoke to me about his plans to bring similar ferocity to the comparatively mild Sierra Club, the nation’s largest environmental group, which claims 1.3 million members. With its self-governing regional chapters, its way-outside-the-beltway headquarters in San Francisco, and a smaller D.C. policy shop than other Big Green groups, the Sierra Club has always relied more on grassroots advocacy than direct work with Congress. Brune offered thoughts about what’s ahead for the Sierra Club and the environmental movement as a whole. 

Yvo de Boer lets his frustration show on the final day of the December 2009 summit. Photograph: Olivier Morin/AFP/Getty Images

The UN has dropped the 31 January deadline by which time all countries were expected to officially state their emission reduction targets or list the actions they planned to take to counter climate change.

Yvo de Boer, UN climate change chief, today changed the original date set at last month’s fractious Copenhagen climate summit, saying that it was now a “soft” deadline, which countries could sign up to when they chose. “I do not expect everyone to meet the deadline. Countries are not being asked if they want to adhere… but to indicate if they want to be associated [with the Copenhagen accord].

“I see the accord as a living document that tracks actions that countries want to take,” he told journalists in Bonn.

“It’s a soft deadline. Countries are not being asked to sign the accord to take on legally binding targets, only to indicate their intention,” he said.