A new global warming report issued Friday by the United Nations paints a near-apocalyptic vision 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, the report was quickly criticized by some scientists who said its findings were watered down at the last minute by governments seeking to deflect calls for action.
"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.
Even in its softened form, the report outlined devastating effects that will strike all regions of the world and all levels of society. Those without resources to adapt to the changes will suffer the most, according to the study from the U.N.'s Intergovernmental Panel on Climate Change.
"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," said Rajendra Pachauri, chairman of the IPCC, which released the report in Brussels.
The report is the second of four scheduled to be issued this year by the U.N., which marshaled more than 2,500 scientists to give their best predictions of the consequences of a few degrees increase in temperature. The first report, released in February, said global warming was irreversible but could be moderated by large-scale societal changes.
That report said with 90% confidence that the warming was caused by humans, and its conclusions were widely accepted because of the years of accumulated scientific data supporting them.
In contrast, the latest report was more controversial because it tackled the more uncertain issues of the precise effects of warming and the ability of humans to adapt to them.
"When you put people into the equation, people who can adapt and respond and change their behavior, it adds another layer of complication," said Gary Yohe, an economist at Wesleyan University who helped write the report.
But 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.
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.
