There is evidence to support what you are saying: every year there is new research that brings the inhospitable-deadline closer to today - there is a high degree of uncertainty. However, assuming that humans are at the very least responsible for the acceleration of climate change by pumping out GHGs, we could start by reversing that single change that we have made.
It's not as though we should just give up.
You might be reacting to my parting, pessimistic shot - that's fine. I don't think we should give up either. I'm just not optimistic when it comes to humans and collective action problems.
[1] details may be incorrect; I haven't paid a ton of attention to the specific proposals.
I really hope that I am proven wrong about it being too late due to trapped GHGs (but we can still try).
[1]: http://ewn.co.za/2016/08/22/Victory-for-DA-as-Herman-Mashaba...
I always want to suggest to these people that they should start smoking, because clearly, the future's so bright there will be a cancer cure soon.
And, not to be too crass, but that admittedly snarky reply is about one body. The geoengineering proposals are about intentionally influencing a hugely complex system we still don't fully understand, and that is undergoing changes with implications we don't fully understand. All the talk about ecological engineering seems to assume that the worst that happens is it doesn't work. That sort of naive optimism would be cute if we weren't literally talking about the planet. And if at least some of it weren't duplicitous.
This isn't the reason I chose not to have kids, but it sure does reaffirm that choice. Perhaps the Drake pessimists are correct, and intelligent life can't get off-planet before offing itself.