Global warming is already 1.4 degrees since 1750. Global warming WILL make us humans EXTINCT if we don't stop burning coal. Snow in Florida and rain on Olympic snow are both caused by Global Warming [GW]. GW causes the wind to shift, causing droughts and floods. The #1 kill mechanism is famine. See "The Long Summer" by Brian Fagan and "Collapse" by Jared Diamond.
7 degrees C is one more than the for-sure extinction point for Homo Sapiens as reported in a bunch of reports and books.
The book "Six Degrees" by Mark Lynas says: "If the global warming is 6 degrees centigrade, we humans go extinct." See:
Lynas lists several kill mechanisms, the most important being famine and methane fuel-air explosions. Other mechanisms include fire storms.
The following sources say H2S bubbling out of hot oceans is the final blow at 6 degrees C warming:
"Under a Green Sky" by Peter D. Ward, Ph.D., 2007.
www.astrobio.net is a NASA web zine. See:
"Climate Code Red" by David Spratt and Philip Sutton says the following:
Long term warming, counting feedbacks, is a least twice the short term warming. 560 ppm CO2 gets us 6 degrees C or 10.8 degrees F. We will hit 560 ppm before mid century.
Per "Climate Code Red", we need ZERO "Kyoto gas" emissions RIGHT NOW and we also need geo-engineering because we have already gone way beyond the safe CO2 level of 300 to 325 ppm. We are already at 455 ppm equivalent and we have tripped some very big tipping points. We aren't dead yet, but the planet needs critical intensive care if we humans are to have a chance of survival.
"The Vanishing Face of Gaia" by James Lovelock has identified a 9 degree lurch in the temperature that happens at 450 ppm equivalent.
Looks like we are not going to make it. We HUMANS could be EXTINCT by 2050 because politicians are not considering sufficiently strong action.
The ONLY economical competition for coal is nuclear.