So it's going to get a little hotter, why worry?

by carl zimmer

The earth’s climate has, of course, fluctuated frequently — and at times wildly — over hundreds of millions of years, long before humans began pouring heat-trapping gases into the atmosphere. So why the concern over the current surge of warming, brought about largely by human activity? Anthony Barnosky, a University of California, Berkeley, scientist who has studied previous eras of climate change, succinctly sums up the problem: Too much warming, too fast.

In his new book, Heatstroke: Nature in an Age of Global Warming, Barnosky lays out his concerns that the planet’s fauna and flora — hemmed in by 6.5 billion people and facing steadily rising temperatures — will simply not be able to keep up with the pace of change, leading to large-scale extinctions. In previous periods of warming, when the earth moved from glacial to interglacial periods, temperatures have risen by 5 degrees C (9 degrees F) in the course of several thousand years. But, Barnosky explains, it is entirely possible that unless something is done to rein in greenhouse gas emissions, the planet could experience that magnitude of warming in a century or two.

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