If greenhouse gas concentrations increase , it will become hotter than ever in 90 years . The temperature rise during man - made global warming has not happened before . Global warming has propelled Earth 's climate from one of its coldest decades since the last ice age to one of its hottest -- in just one century . 1900 - 1909 was one of the coldest decades in 100 years . 2000 - 2009 was one of the hottest decades in 11,300 years .
If greenhouse gas concentrations increase , it will become hotter than ever in 90 years . The temperature rise during man - made global warming has not happened before . 1900 - 1909 was one of the coldest decades in 100 years . 2000 - 2009 was one of the hottest decades in 11,300 years .