of Earth
's atmosphere and oceans and its projected continuation. In the last 100 years, Earth's average surface temperature increased by about 0.8 C-change with about two thirds of the increase occurring over just the last three decades. Warming of the climate system is unequivocal, and scientists are more than 90% certain most of it is caused by increasing concentrations of greenhouse gases
produced by human activities such as deforestation
and burning fossil fuel
.
Global warming causing climate change may be the ultimate issue that unites us all. 
"Why try to change the future when the present is so bleak"
"There's a better scientific consensus on this than on any issue I know -- except maybe Newton's second law of dynamics," said D. James Baker, administrator of the U.S. National Oceanic and Atmospheric Administration. "Man has reached the point where his impact on the climate can be as significant as nature's."
"The answer to global warming is in the abolition of private property and production for human need. A socialist world would place an enormous priority on alternative energy sources. This is what ecologically-minded socialists have been exploring for quite some time now."
‘Since global warming Eskimos now have twenty different words for water.’
“If you asked me to name the three scariest threats facing the human race, I would give the same answer that most people would: nuclear war, global warming and Windows.”
“While human-induced global warming is not going to turn present-day Earth into present-day Mars, global warming is dire enough that our most distinguished scientists recently concluded that as many as 1 million species on the planet could be extinct by 2050 if affairs do not change.”