An interesting diary over at Talking Points Memo on this topic attempts such an analysis from reading the quotes of Harper in the media over the last week before and after talking to Obama:

Interestingly, on their conversation regarding climate change Harper said: “The new president has expressed a desire to participate fully in global efforts to fix the problems of greenhouse gases.” I stress “global” since it appears to be a subtle shift from statements made by the Canadian Foreign Minister Lawrence Cannon earlier in the week that indicated the Canadian desire to pursue a “North American” approach. My initial concern was that Harper would use some regional [...]