But, I’m not sure why you think the effects of climate change are limited to the last decade, and I’m pretty sure we are talking about a disaster. Hurricane Sandy was not a pleasant summer storm, and that was just one item.

A couple of points: he wasn’t the coiner of the term “hockey stick”, that was the climatologist Jerry Mahlman discussing a graph from the 1999 paper of which Mann was lead author, and it refers more to the long low handle of proxy averages than to the known uptick of thermometer measurements which was shown in context by that handle.
The context that carbon dioxide was causing global warming had already been established to the extent that the Kyoto Protocol had been agreed. The ‘hockey stick’ gave a simple graphical demonstration that this recent measured warming was exceptional, showing a correlation rather than cause. What tends to be forgotten is that Mann was investigating long term climate cycles, and has made a significant contribution to that field.

It also seems rather premature to say that carbon in the atmosphere is “causing one of the greatest disasters this planet has seen in tens of thousands of years”, given that we’ve only had about a decade so far of effects emerging from natural variability and in theory the trend could be halted.
In practice, that looks unlikely, due in no small part to the denial of science exemplified by the attacks on Mann’s work.
Mann’s fightback against the deniers is well covered in his book “The Hockey Stick and the Climate Wars” which is an excellent read.