A graph without the scientific theory that leads to an explanation is just an opinion at best
Erm, the graphs just shows facts, no? Whether there's an explanation already or not doesn't change anything about the observation. You are basically saying 'ok so an apple always falls down from a tree, but I cannot explain it, so it's just an opinion that it falls down instead of up'
As for a): the data likely comes from http://nsidc.org