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 …