  We perform an analysis of jet quenching in heavy ion collisions at RHIC and
LHC energies with the temperature dependent running QCD coupling. Our results
show that the $T$-dependent QCD coupling largely eliminates the difference
between the optimal values of $\alpha_s$ for the RHIC and LHC energies. It may
be viewed as direct evidence of the increase of the thermal suppression of
$\alpha_s$ with rising temperature.
