Top scientist Bob Watson says that we need to prepare for a rise in temperature of 39 degrees Fahrenheit. A jump that big would have catastrophic effects — it means between 7 million and 300 million more people would be affected by flooding and that the water availability in Africa would dry up by 50 percent.
In other words, 4 billion people left without water, 5 billion at risk for flooding, and half a billion left hungry. Some say there's no planning for that coming shift and that humans are staring down the barrel of extinction. Or in the possible words of Chief Seattle, "the end of living and the beginning of survival."
Want more science to hammer that home?
To see how far this process could go, look 55.5 million years to the Palaeocene-Eocene Thermal Maximum, when a global temperature increase of 6C coincided with the release of about 5,000 gigatons of carbon into the atmosphere, both as CO2 and as methane from bogs and seabed sediments. Lush subtropical forests grew in polar regions, and sea levels rose to 100m higher than today. It appears that an initial warming pulse triggered other warming processes. Many scientists warn that this historical event may be analogous to the present: the warming caused by human emissions could propel us towards a similar hothouse Earth.
Are we the new dinosaur?