Reproducible climate reconstructions of the Common Era (1 CE to present) are key to placing industrial-era warming into the context of natural climatic variability. Here we present a community-sourced database of temperature-sensitive proxy records from the PAGES2k initiative. The database gathers 692 records from 648 locations, including all continental regions and major ocean basins. The records are from trees, ice, sediment, corals, speleothems, documentary evidence, and other archives. They range in length from 50 to 2000 years, with a median of 547 years, while temporal resolution ranges from biweekly to centennial. Nearly half of the proxy time series are significantly correlated with HadCRUT4.2 surface temperature over the period 1850–2014. Global temperature composites show a remarkable degree of coherence between high- and low-resolution archives, with broadly similar patterns across archive types, terrestrial versus marine locations, and screening criteria. The database is suited to investigations of global and regional temperature variability over the Common Era, and is shared in the Linked Paleo Data (LiPD) format, including serializations in Matlab, R and Python.

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The concept of megadroughts came to prominence with research into Common Era (CE; Year 1-present) palaeo climate droughts over western North America 1-5 . This research documented multi decadal periods of extreme aridity (or various hydrological deficits 1-5 ) before 1600 CE, as well as widespread ecological disturbances [6][7][8] and societal disruptions [9][10][11][12] . Although recurrent and persistent droughts are an intrinsic feature of North American hydroclimate variability, these megadroughts were primarily distinguished by their much greater per sistence (for example, multiple decades) than even the most extreme decadal length instrumental era droughts during the 1930s and 1950s 13,14 .Since then, extreme droughts across the globe have been increasingly referred to as megadroughts, despite often large differences in their severity, duration, or spatial extent. These include multi decadal periods of enhanced aridity in Australia 15,16 , South America 17 , Europe 18 , Central Asia 19,20 , and Mesoamerica 21 ; a multi season drought in 1540 CE over Europe 22 ; spatially extensive multi year droughts in India 23 ; the late Ming Dynasty drought in China 24,25 ; and an early twenty first century decadal drought in Chile and Argentina [26][27][28] . As anthropogenic warming is expected to increase drought severity and risk in many regions of the world 29,30 , the term has also been increasingly applied to droughts amplified by climate change, both in observations 26,31 and in model projections 32,33 .The use of the megadrought label has therefore been inconsistent, owing partly to an absence of applicable objective criteria that define when a drought becomes a megadrought, or when a period of moisture deficit