In the past three decades , GISS report surface temperature records show an upward trend of about 0.2 degrees Celsius ( 0.36 degrees Fahrenheit ) per decade . 2000 to 2004 was the warmest decade since records began . 2006 was warmest year of all time , 2008 coolest in decade . Global temperatures have averaged 0.8 degrees C since 1880 .
2000 to 2004 was the warmest decade since records began . 2006 was warmest year of all time , 2008 coolest in decade . Global temperatures have averaged 0.8 degrees C since 1880 .