The report, issued Friday, paints a bleak picture of Earth's future: hundreds of millions of people short of water, extreme food shortages in Africa, a landscape ravaged by floods and millions of species sentenced to extinction.

Despite its harsh vision outlining devastating effects that will strike all regions of the world and all levels of society, the report was quickly criticized by some scientists who said its findings were hijacked by some governments.

"The science got hijacked by the political bureaucrats at the late stage of the game," said John Walsh, a climate expert at the University of Alaska Fairbanks who helped write a chapter on the polar regions.

"It's the poorest of the poor in the world, and this includes poor people even in prosperous societies, who are going to be the worst hit (by global warming)," said Rajendra Pachauri, chairman of the UN's Intergovernmental Panel on Climate Change (IPCC).

The report is also, in a sense, a more pointed indictment of the world's biggest polluters -- the industrialized nations – and a more specific identification of those who will suffer, said the paper.

Thus, some nations lobbied for last-minute changes to the dire predictions. Negotiations led to deleting some timelines for events, as well as some forecasts on how many people would be affected on each continent as global temperatures rose, the paper noted.