A major part of the climate change that scientists have
documented over the past few decades comes from human emissions
of heat-trapping greenhouse gases. Not all of it, however.
Natural climate cycles haven’t magically disappeared — the El
Niño/Southern Oscillation, or ENSO, for example, is entering a
phase that will likely boost global temperatures temporarily —
and scientists are still discovering new ones. The latest comes
in a new report published in Geophysical Research Letters. It’s
well known that the Sun varies slightly in brightness every 11
years, and while those changes pale beside the effect of human-
generated greenhouse gases, according to the report, they’re
enough to trigger unusually cold winters in Central Europe. The
smoking gun is the freezing of the Rhine river, something that
doesn’t happen often because it’s difficult to freeze such a
large, free-flowing volume of water. Those unusually cold
winters might come along at random, but by looking back at
records dating to all the way back to