Climate change is a major topic of concern today and will be so for the
foreseeable future, as predicted changes in global temperatures,
rainfall, and sea level continue to take place. But as Jan Zalasiewicz
and Mark Williams reveal in The Goldilocks Planet, the climatic
changes we are experiencing today hardly compare to the changes the
Earth has seen over the last 4.5 billion years.
Indeed, the vast history that the authors relate here is dramatic and
often abrupt--with massive changes in global and regional climate, from
bitterly cold to sweltering hot, from arid to humid. They introduce us
to the Cryogenian period, the days of Snowball Earth 700 million years
ago, when ice spread to cover the world, then melted abruptly amid such
dramatic climatic turbulence that hurricanes raged across the Earth. We
hear about the Carboniferous, with tropical jungles at the equator
(where Pennsylvania is now) and the Cretaceous Period, when the polar
regions saw not ice but dense conifer forests of cypress and redwood,
with ginkgos and ferns. The authors also show how this history can be
read from clues preserved in the Earth's strata. The evidence is
abundant, though always incomplete--and often baffling, puzzling,
infuriating, tantalizing, seemingly contradictory. Geologists, though,
are becoming ever more ingenious at deciphering this evidence, and the
story of the Earth's climate is now being reconstructed in ever-greater
detail--maybe even providing us with clues to the future of contemporary
climate change.
And through all of this, the authors conclude, the Earth has remained
perfectly habitable--in stark contrast to its planetary neighbors. Not
too hot, not too cold; not too dry, not too wet--the "Goldilocks
planet."
