Another kind of answer might focus on the following: Ed Mazria, founder of Architecture 2030, distills research studies from NASA that go something like this, if memory serves me correctly. If global mean temperatures rise more than 2 or 3 degrees centigrade, which is the business as usual trajectory, then we could lose 25% of all plant and animal species by 2050. (How's that for a parting present for our grandkids?) Backing into the way that buildings need to be built to help mitigate these risks -- for example, buildings producing 50-60% less carbon now than average buildings per the Architecture 2030 goals -- we might get a little depressed if we were to calculate the number of buildings that are built or undergo major renovations this year to meet that goal.
So, similar to my last blog, you be the judge: Pessimist or optimist. I am not sure which to pick most days.