Extended Data Fig. 3: Epoch timings in proxy data.

The figure shows peak warming/cooling for each epoch in the proxy records. a–e, All proxies that have full coverage of the respective epoch are shown. f–i, As for panels a–e, but also showing proxies with only partial coverage of the respective epoch. In contrast to Fig. 3, here colours are coded by century, using a differential colour scheme for better visibility. The relative fraction of proxy records with peak warming/cooling in each century is indicated with barplots under the maps. We note that for this figure we use the full, unscreened PAGES2 k v2.0.0 proxy database (the screened network yields a consistent picture). This analysis shows that the heterogeneity in the timing of maxima and minima is an inherent property of the input proxy data themselves, which show a similar lack of global coherence in the timing of each putative preindustrial climate epoch. However, the proxy maps are not directly comparable to the reconstruction maps because the reconstructions are an objectively weighted, statistically optimal fit between all available proxy values using covariance information from a spatial temperature field.