  We address the important question of whether the newly discovered exoplanet,
Proxima Centauri b (PCb), is capable of retaining an atmosphere over long
periods of time. This is done by adapting a sophisticated multi-species MHD
model originally developed for Venus and Mars, and computing the ion escape
losses from PCb. The results suggest that the ion escape rates are about two
orders of magnitude higher than the terrestrial planets of our Solar system if
PCb is unmagnetized. In contrast, if the planet does have an intrinsic dipole
magnetic field, the rates are lowered for certain values of the stellar wind
dynamic pressure, but they are still higher than the observed values for our
Solar system's terrestrial planets. These results must be interpreted with due
caution, since most of the relevant parameters for PCb remain partly or wholly
unknown.
