  A two-dimensional Yukawa liquid is studied using two different nonequilibrium
molecular dynamics simulation methods. Shear viscosity values in the limit of
small shear rates are reported for a wide range of Coulomb coupling parameter
and screening length. At high shear rates it is demonstrated that this liquid
exhibits shear thinning, i.e., the viscosity $\eta$ diminishes with increasing
shear rate. It is expected that two-dimensional dusty plasmas will exhibit this
effect.
