Mayor's endorsement could turn climate change into a serious election issue – and it might even embolden Republicans
Bill Clinton and Al Gore among those calling for fresh focus on issue that neither candidate mentioned in televised debates
President insists his 'all of the above' policy will ensure energy independence and denies accusations he is trying to crush coal
New poll shows over two-thirds of US voters now accept global warming is happening
Company confirms it has slashed North American workforce by a fifth as a result of ongoing confusion over extension of wind farm tax breaks
Vice President Joe Biden defends loan guarantee programme and pressures candidate Paul Ryan into admission during last night's debate
Republican candidate accused of using presidential debate to push falsehoods about Obama administration's support for green economy
Congressional Research Service says emissions levy would benefit households and businesses, but admits opposition is overwhelming
Poll reveals crucial swing voters are much closer to Obama’s stance on climate and energy policy than that of Romney
President expected to use Convention speech to put clear water between Democrats and Republicans on energy and environment issues