Wow, can't believe some of the denial on here.  Makes me wish my university wasn't doing massive amounts of research on climate change in the late 90's, early 2000's, and that the projections we ran hadn't already come true.  Broke my heart for a decade that every time I tried to talk about what I learned in my lab work I was shutdown by deniers who argued opinion over data.  The data is all there, it goes back millennia and much farther, and comes from different environments and locales around the entire planet.  Ice cores, pollen, dust, tree rings (dendrochronology), insects, glaciers, etc. have given scientists an accurate view of what is occurring with climate change.  Heck, give scientists some credit, they figured out CFC's were depleting the ozone layer and fixed it by getting them banned.  Now there is ozone over the ice caps again!