Barack Obama on Tuesday renewed his promise to make a decisive break with George W. Bush on the environment, using a summit convened by Arnold Schwarzenegger to promise a "new chapter in America's leadership on climate change".

The video appearance by Obama confirmed the Californian governor's role as a global leader on climate change, a position shored up only hours earlier when Schwarzenegger set a bold new target for his state to get a third of its electricity from renewable sources by 2020.

In his address, the president-elect accused Bush of failing to show leadership on the issue of climate change. "That will change when I take office," said Obama.