PARIS - A leaden cloak of responsibility lies on the shoulders of UN scientists as they put the final touches to the first volume of a massive report that will give the world the most detailed picture yet of climate change.
Due to be unveiled in Stockholm on September 27, the document will be scrutinised word by word by green groups, fossil-fuel lobbies and governments to see if it will yank climate change out of prolonged political limbo.
The report will kick off the fifth assessment by the Intergovernmental Panel on Climate Change (IPCC), an expert body set up in 1988 to provide neutral advice on global warming and its impacts.
Six years ago, the IPCC's fourth assessment report unleashed a megawatt jolt of awareness. It declared that the planet was warming, that this was already starting to affect Earth's climate system and biosphere, and that there was overwhelming evidence that humans, especially by burning coal, gas and oil, were the cause.
It earned the IPCC a share in the Nobel Peace Prize with former US vice president Al Gore and stoked momentum that led to the 2009 climate conference in Copenhagen, the biggest summit in UN history.
Yet that was the high point. The near-fiasco of Copenhagen combined with a financial crisis that struck Western economies... and climate change vanished off politicians' radars. Then came damage to the IPCC's own reputation, when several errors were found in the landmark report, prompting a fightback by gleeful climate sceptics and a painful investigation of the panel itself.
A draft of the leviathan new work, seen by AFP, will amplify the 2007 warning in several ways.