  Wet active matter in the presence of an imposed temperature gradient, or
chemical potential gradient, is considered. It is shown that there is a new
type of convective instability that is caused by a (negative) activity
parameter. Physically this corresponds to active fluids with contractual
stress. In this non-equilibrium steady state the singular generic long-ranged
correlations are computed and compared with the analogous results in a passive
fluid. In addition, the singular non-equlibirum Casimir pressure or force is
determined. The fluid motion above the instability is determined by
generalizing the Lorenz equations for the Rayleigh-Benard instability in a
passive fluid to Lorenz-like equations to describe this new instability.
