Article Open access Christina Karamperidou Communications Earth & Environment 5 , Article number: 535 (2024) Cite this article Metrics Abstract Projected changes in atmospheric blocking and associated extreme weather are marked by considerable uncertainties. While paleoclimate records could help reduce these uncertainties, their low temporal resolution makes extracting synoptic-scale signals challenging. Here, a deep learning model is developed to infer summertime blocking frequency from tree-ring-based gridded reconstructions of Northern Hemisphere surface temperature over the Last Millennium. The model, despite not directly incorporating paleoclimate proxies or their locations, is implicitly constrained by them. The reconstructions highlight the tropical Pacific’s strong influence on blocking variability at interannual-to-centennial time scales. A weakened tropical Pacific zonal temperature gradient during the Little Ice Age correlates with a hemispherically reduced -yet more variable interannually- blocking frequency and altered regional patterns. This deep learning approach offers a pathway for extracting paleoweather signals from paleoclimate records that enables improved understanding of blocking response to external forcing and constraining of model projections of blocking under climate change scenarios. Introduction Atmospheric blocking events are persistent, high-impact weather patterns in the middle and high latitudes, that divert the jet stream and storm tracks for days to weeks, and can be associated with heat waves 1 , 2 , 3 , 4 , cold spells, droughts, and flooding 5 . The response of blocking to external climate forcing remains an open question due to a limited understanding of the mechanisms of block onset, maintenance, and decay, as well as strong natural interannual and decadal variability and climate model biases in representing the phenomenon 6 , 7 , 8 , 9 , 10 . Some studies have suggested an increase in blocking frequency in the Northern Hemisphere in response to arctic warming 11 , 12 , 13 ; however, these results have […]