  We perform a meta-study of recently published Redshift Space Distortion (RSD)
measurements of the cosmological growth rate, f(z) \sigma_8(z). We analyse the
latest results from the 6dFGS, BOSS, LRG, WiggleZ and VIPERS galaxy redshift
surveys, and compare the measurements to expectations from Planck. In this
Letter we point out that the RSD measurements are consistently lower than the
values expected from Planck, and the relative scatter between the RSD
measurements is lower than expected. A full resolution of this issue may
require a more robust treatment of non-linear effects in RSD models, although
the trend for a low \sigma_8 agrees with recent constraints on \sigma_8 and
\Omega_m from Sunyaev-Zeldovich cluster counts identified in Planck.
