  In the range of temperatures reached in future heavy ion collision
experiments, hadronic pair annihilations and creations of charm quarks may take
place within the lifetime of the plasma. As a result, charm quarks may increase
the bulk viscosity affecting the early stages of hydrodynamic expansion.
Assuming thermalization, we estimate the charm contribution to bulk viscosity
within the same effective kinetic theory framework in which the light parton
contribution has been computed previously. The time scale at which this physics
becomes relevant is related to the width of the transport peak associated with
the trace anomaly correlator, and is found to be < 20 fm/c for T > 600 MeV.
