Friday, March 12, 2010


There’s some hot new actual SCIENCE that can tell us a lot about temperature over the last millenium.

I’m talking about what I can't resist calling “paleoCLAMatology," a lovely new method of detecting not just the climate, but the WEATHER over the last two thousand years. Clams live in shallow water and build their shells using the minerals and other elements that are in the water. One of the elements that goes into a clamshell is oxygen, and the ratio of oxygen isotopes dissolved in water varies linearly with the temperature of the water. Heavy oxygen (O-18) is more prevalent in colder water.

By slicing ancient clamshells with a microtome and sending those slices through a mass spectrometer, scientists can read the O-18 concentrations down to week-by-week precision. Preliminary results using clams from a bay in Iceland show clear evidence of both the “Medieval Warming Period” (MWP) and a “Roman Warm Period” (RWP).

That doesn't resolve the debate about the MWP--proponents of the man-made global warming theory don't pretend it never happened. They just believe it was a localized phenomenon that affected northern Europe but not the planet as a whole. Clams from Iceland can’t rebut that argument–but “clamatology” can be used on shells from anywhere. We finally have a methodology that gives us fine-grained information about the temperature of shallow waters anywhere we’d like to look–there are LOTS of clams out there!

Note: shallow-water temperature measurements are NOT the same as surface temperature measurements, so we’ll have to do some new modeling to see how air temperature relates to shallow seas. I think it’s promising work in its own right–a huge amount of heat is stored in the top layer of the ocean, and it’s hard to model planetary climate just by looking at proxies of inland air temperature.

So–is there ANYBODY here who isn’t happy to get a new scientific tool that gives us more information about reality? If so, speak out–I’d like to know who can be unhappy about ancient clamshells!