The most complete database on how the climate has changed from 1 BCE to the present has been updated.

The second version of the PAGES2k database combines data from tree rings, corals, glacier ice, and for the first time, marine and lake sediments, to create a more complete view of past climates.

It is expected to become vital for climate reconstructions and climate modelling.

The data shows a long-term cooling trend until the 19th Century, followed by a sharp warming trend.

The authors have made the data open access so anyone can download and use the information, along with the supporting code.

This database is important because it provides much-needed information on regional temperature patterns and trends, says one of the experts involved in its creation, Associate Professor Nancy Bertler.

“It enables us to critically assess and improve earth system models used to provide future projections. The Intergovernmental Panel on Climate Change’s analysis of future change will include investigating the past 2,000 years, before looking into the future,” she said.

“How well they capture those past trends provides a tool to assess how realistic a model is, and helps to identify where improvements are necessary. This is the only tool to independently test and verify climate models beyond the past forty years.”

The database gathers close to 700 records from 648 locations, compiled by 98 regional experts from 22 countries.

It was coordinated by the Past Global Changes (PAGES) network of international paleoclimate scientists.

More information is available here.