The Earth's climate system at fine spatial and temporal scales is chaotic, with evolving weather patterns often notoriously difficult to predict very far in advance. At regional scales, surface conditions are modulated by seasonal to decadal oscillations in surface temperature, precipitation, sea-ice extent, and ocean upwelling. However, ‘climate’, which in essence is the statistics of weather on time-scales of a few decades or more, is relatively well behaved and predictable. Indeed, over the past few thousands years and up until the time of the Industrial Revolution (ca.