  Extensive measurements of macroscopic stress in a 2D LJ glass, over a broad
range of temperatures ($T$) and strain rates ($\dot\gamma$), demonstrate a very
significant decrease of the flowing stress with $T$, even much below the glass
transition. A detailed analysis of the interplay between loading, thermal
activation, and mechanical noise leads us to propose that over a broad
($\dot\gamma,T$) region, the effect of temperature amounts to a mere lowering
of the strains at which plastic events occur, while the athermal avalanche
dynamics remains essentially unperturbed. Temperature is then shown to correct
the athermal stress by a (negative) additive contribution which presents a
universal form, thus bringing support to and extending an expression proposed
by Johnson and Samwer [1]. Our prediction is shown to match strikingly well
numerical data up to the vicinity of $T_g$.
