|Figure 1. Data used in this study.
Distribution of annual resolution proxy indicators used in this study. Dendroclimatic reconstructions are indicated by 'tree' symbols, ice core/ice melt proxies by 'star' symbols, coral records by 'C' symbols. Long historical records and instrumental 'gridpoints' series are shown by squares (temperature), or diamonds (precipitation). Groups of '+' symbols indicate principal components of dense tree ring sub-networks, with the number of such symbols indicating the number of retained principal components. Sites are shown dating back to at least 1820 (red), 1800 (blue-green), 1750 (green), 1600 (blue), and 1400 (black). Certain sites (e.g., the Quelccaya ice core) consist of multiple proxy indicators (e.g., multiple cores, and both d18 isotope and accumulation measurements).
Distribution of the (1082) nearly continuous available land air/sea surface temperature gridpoint data available from 1902 onward indicated by shading. The squares indicate the subset of 219 gridpoints with nearly continuous records extending back to 1854 that are used for verification. Northern Hemisphere (NH) and global (GLB) mean temperature are estimated as areally-weighted (ie, cosine latitude) averages over the Northern hemisphere and global domains respectively.