  Recent astrophysical observations suggest that the value of fine structure
constant $\alpha=e^2/\hbar c$ may be slowly increasing with time. This may be
due to an increase of $e$ or a decrease of $c$, or both. In this article, we
argue from model independent considerations that this variation should be
considered adiabatic. Then, we examine in detail the consequences of such an
adiabatic variation in the context of a specific model of quantized charged
black holes. We find that the second law of black hole thermodynamics is
obeyed, regardless of the origin of the variation, and that interesting
constraints arise on the charge and mass of black holes. Finally, we estimate
the work done on a black hole of mass $M$ due to the proposed $\alpha$
variation.
