Bucha, who has been able to determine, using samples of baked clay from archeological sites, what the intensity of the earth's magnetic field was at the time in question.
Sometimes it slows down to a trickle so that much more water is leaking out the barrel than is coming in; sometimes it goes full blast so that a lot more water is coming into the barrel than is leaking out. Lingenfelter's paper was written in 1963, before the cycles of C-14 variation we described had been fully documented.
Thus, the mere fact that the present rate of water coming in exceeds that of the water leaking out cannot be extrapolated back to a starting time. The point is that fluctuations in the rate of C-14 production mean that at times the production rate will exceed the decay rate, while at other times the decay rate will be the larger.
Contrary to creationist Barnes' totally discredited claims, which I've covered in Topic 11, the earth's magnetic field (dipole moment) has, indeed, increased and decreased over time.
Strahler presents a graph of the earth's dipole moment going back 9000 years.
We say that the input and output of water is in equilibrium.