Sea ice thickness averaged over 1979–1998 for CNRM-CM3 (left) and for CNRM-CM5.1 (middle). PIOMAS data are plotted to the right for the Arctic. The first and second rows respectively represent Arctic March and September ice thickness. The third and fourth rows respectively represent Antarctic March and September ice thickness. The mean 1979–1998 ice edge (thick black line) is defined as the 15% sea ice fraction contour computed from the HadISST data (Rayner et al.