Assumptions baked into the VMS carbon dating

[eggyk]

I'd be interested to know if there is a list anywhere of where the comparison tree-ring samples for the carbon dating database come from (obviously there are some places where there will be no/few samples available) and whether/how quickly C-14 is distributed across the world. for instance, is it less accurate for objects from deserts or the southern hemisphere and if so how much?

The northern and southern hemispheres have different C-14 levels as the air currents don't mix all that much between the two. A different calibration curve is used for objects from the southern hemisphere (SHCal instead of IntCal). As for different areas of the northern hemisphere, I believe that the air currents are pretty well mixed, so there shouldn't be any issues. Sahara sands blow over europe frequently, as well as cold air from the poles. The hurricanes off the coast of northern america drift east towards here too. I imagine it's much the same over in the east. 

As it's almost certain that the VMS is from the northern hemisphere somewhere, IntCal was definitely the right one to use.