Weather is complicated than first thought III: mass extinctions

A research paper in Today's issue of Nature (Editor's summary is here. Full text requires subscription) claims that Mother Nature systematically and repeatedly causes mass extinctions ("species turnover"). They studied the past 22 million years and found that cyclical changes in the Earth's orbit cause climate change and extinctions:

Because obliquity nodes and eccentricity minima are associated with ice sheet expansion and cooling and affect regional precipitation, we infer that long-period astronomical climate forcing is a major determinant of species turnover in small mammals and probably other groups as well.

The subset of environmentalists who believe that Mother Nature is perfect now have to consider climate change and mass extinctions as part of that perfection.

More on this here and here.