Ah, the subtle joys of global warming. As you may have read, the largest ice shelf in the northern hemisphere broke in half last week, scaring the living bejesus out of climatologists. They knew things were getting warmer, but they didn’t think that was going to happen for a while now. And, of course, greenhouse-gas naysayers immediately jumped all over it, claiming it had nothing to do with human activities warming the planet.

Now comes some much more unusual — and weird — evidence that human activity really does have an effect on the temperature. Two scientists at the National Oceanic and Atmospheric Administration analyzed data collected over 40 years by 10,000 surface stations. They looked at the “diurnal temperature” (DTR) — the difference between the hottest temperature recorded during the day, and the coldest one recorded at night.

The result? Weekends had distinctly different DTRs. And the week is, of course, a completely human construct — it’s a totally artificial timescale. As Scientific American reported:

Because weekly cycles are rarely if ever found in nature, the observed fluctuations must therefore be anthropogenic in origin, the researchers write. In particular, they propose that cloud changes associated with aerosol particles in the atmosphere could be causing the weekend effect, though other pollution processes cannot be ruled out at this time. The authors conclude that “the data strongly support the view that human emissions play an important role in climate change and represent a key test for climate change theory.”

Of course, this will all seem kind of beside the point twenty years from now, when Manhattan — which lies right at sea level — is three feet deep in water. I’m sort of intrigued as to how Manhattan will deal with massive global warming, actually. My theory is the local government will build 20-foot dikes to surround the city, and it’ll become a lovely sort of walkway: A place for a pretty afternoon stroll, brought to you by apocalyptic climate change.

(Thanks to Slashdot for this one!)