Pretty simple when their jobs\funding\lives are predicated on the alleged fact of AGW.
No AGW.....no funding for studies. No funding...........no job. No job............no groceries.
Remember the earth is flat and the sun revolves around it.
Not to mention: the earth used to be warmer, remember the dinosaurs? Or why is Greenland called Greenland even though it's covered in ice? Or why the hurricanes were only going to become more frequent, more devastating and more deadly yet we have had minimal hurricanes since Katrina.
"Science is the belief in the ignorance of the experts" – Richard Feynman