Well, Cap'n! Where to begin. Your post suggests that you think you know something about the climate change matter . It actually displays overwhelming ignorance.
Stern is a most respected economist. One affirded the highest honours by the British government and no "Left" Winger. His report was of studies done for the British government but about climate change in general not just the effects on Britain. It was a report on the economic implications.
And they were hopeful if the issue was addressed immediately but scarier by the decade if not. We are now at about the 2% cost thanks to Bush and Harper primarily. The only political leaders who deliberately prevented action.
Harper is now alone in the world in that.
As for Mann (not Stern) and the Hockey Stick, you must be about the only one left who still takes comfort from that fraud MccIntyre's slanders.