  According to Babichev et al., the accretion of a phantom test fluid onto a
Schwarzschild black hole will induce the mass of the black hole to decrease,
however the backreaction was ignored in their calculation. Using new exact
solutions describing black holes in a background Friedmann-Robertson-Walker
universe, we find that the physical black hole mass may instead increase due to
the accretion of phantom energy. If this is the case, and the future universe
is dominated by phantom dark energy, the black hole apparent horizon and the
cosmic apparent horizon will eventually coincide and, after that, the black
hole singularity will become naked in finite comoving time before the Big Rip
occurs, violating the Cosmic Censorship Conjecture.
