To be frank our understanding is so weak that for all we know us releasing greehouse gases could in fact be delaying the current iceage that we don't want to return to full glory. Every single tonne of CO2 could be posposoning a planetary reset by a few years. So on that basis, even the 'do what we can' argument falls down. We just arn't powerful enough to make or break anything on a plantary scale. It's quite big headed to think we are! The bottom line is that our planet is not back in rude health until all the ice has melted and the temperature picks up by 2.5 degrees globally. Yellowstone is also way overdue, and we want it to go pop sooner rather than later if we are to hope that the species survives in meaningful qty's. There are so many unknowns. All that we do know, is that any species who wants to safeguard themselves from planatary events, avoidable or otherwise, needs to set up camp off the planet. If we make that leap, then we are really safe - if not, we are hanging on a knife edge and always have been, no matter what we do.