Radiocarbon is a carbon isotope (¹⁴C) created when cosmic radiation strikes our atmosphere. Because radiocarbon is radioactive mostly all of the ¹⁴C that was ever produced has already decayed, and we are left with only ¹⁴C produced in the last few thousand to tens of thousand of years. Basically since the last ice age. Radiocarbon has been used to date Egyptian mummies because the older an organic material is the less ¹⁴C it retains.

We use radiocarbon differently, back-calculating how much ¹⁴C there was when our samples from marine sediment layers or tree-rings were originally formed. Comparing the reconstructed distribution and deglacial redistribution of ¹⁴C in the natural environment gives us the unique opportunity to measure the speed of ocean circulation and marine carbon cycling.