Michael Bender on Anthropogenic Global Warming
How should we view the prospect of anthropogenic climate change? From the perspective of paleoclimate, it might not be particularly troubling, or even seem unwelcome. The present world is good enough for human habitation. However, it would improve if Greenland and Antarctica were unglaciated and habitable, and if there was more rainfall in areas that are currently deserts. For humans, in other words, the world might be more habitable if conditions resembled the high CO2 equable climates of the Cretaceous, Paleocene, and Eocene.
The problem of anthropogenic global change, then, is not necessarily that we are heading for a less habitable planet. The problem is that both natural ecosystems and civilizations are aligned to the historic pattern of climate and water resources. Global warming will destroy this alignment is some regions. The most obvious example is sea level rise, which will render regions uninhabitable that are now occupied by tens or hundreds of millions of people. Shifting temperatures and rainfall belts will open some northern areas to agriculture while making agriculture impossible in some currently farmed regions. The disappearance of mountain glaciers will make water unavailable for agriculture in the seasons it is needed, and will supply water at other times when it may not be used efficiently.
Bender, Michael L. (2013-08-25). Paleoclimate (Princeton Primers in Climate) (Page 291). Princeton University Press. Kindle Edition.