What are the plots showing?

RMSE:
Shadings indicate each model's RMSE relative to the typical model error (defined as the median of all CMIP5 RMSEs), with blue shading being better and red shading worse than the typical model error. The typical model error is fixed, i.e. new simulations are always evaluated against the same reference error. The CMIP5 RMSEs are calculated from the 1980-2005 climatological seasonal cycle (historical simulations), and are shown in CMIP5_RMSE_ref.png

BIAS:
Shadings indicate model biases, normalized by the mean bias of the CMIP5 models shown in CMIP5_BIAS_ref.png. The CMIP5 biases are calculated from the 1980-2005 climatological seasonal cycle (historical simulations).