Hypothetically, if man were able master the climate...

I don't think it matters what we do. Ice ages have come and they have gone. Same with lasting hot eras. I'm not an expert, but from what I understand is that these extremes are pendulum like phenomena which have been triggered by volcanoes, meteor strikes, the changing of lands from continental drift, the varying tilts of the earth over millenniums, and now carbon emissions from a more advanced evolutionary species. We wouldn't do very well in the extreme climes, nor would most of today's life. But I do believe these extremes create a cleansing and renewal of life. There's no motive or purpose for this, it just is what it is. The dinos dying off after they ruled for hundreds of millions of years wasn't a shame, it just was and it made clear for our turn. We have the luxury of being self aware of sharing a similar fate. We have the luxury of expediting our demise. And we have the luxury fixing out our follies. But to think that we have the power to permanently destroy the earth forever, is hogwash. We might temporarily ruin it for ourselves and the life who currently share it with us, but there will be amazing development of life long after we are gone.