A key element of the second major report on climate change being released Friday in Belgium is a chart that maps out the effects of global warming, most of them bad, with every degree of temperature rise.
There's one bright spot: A minimal heat rise means more food production in northern regions of the world.
However, the number of species going extinct rises with the heat, as does the number of people who may starve, or face water shortages, or floods, according to the projections in the draft report obtained by The Associated Press
Some scientists are calling this degree-by-degree projection a "highway to extinction."
It's likely to be the source of sharp closed-door debate, some scientists say, along with a multitude of other issues in the 20-chapter draft report from the Intergovernmental Panel on Climate Change. While the wording in the draft is almost guaranteed to change at this week's meeting in Brussels, several scientists say the focus won't.
The final document will be the product of a United Nations network of 2,000 scientists as authors and reviewers, along with representatives of more than 120 governments as last-minute editors. It will be the second volume of a four-volume authoritative assessment of Earth's climate being released this year. The last such effort was in 2001. (Volume 1: Humans 'very likely' cause warming)
Andrew Weaver, a climate scientist with the University of Victoria in British Columbia, said the chart of results from various temperature levels is "a highway to extinction, but on this highway there are many turnoffs. This is showing you where the road is heading. The road is heading toward extinction."
Weaver is one of the lead authors of the first report, issued in February.
While humanity will survive, hundreds of millions, maybe billions of people may not, according to the chart -- if the worst scenarios happen.