Figure 4. Spatial relationship between external forcings and instrumental North Atlantic SSTs.

Cross-covariances between instrumental North Atlantic SSTs obtained from HadISST⁵⁶ and the combined solar and volcanic forcing (Fig. 1d) between 1870 and 1982 for time lags of 0 years (a), 5 years (b), 20 years (c) and 30 years (d). The colour bar showing the covariance (in °C × W m⁻²) is the same for all panels.