NOAA National Centers for Environmental Information’s (NCEI), Paleoclimatology group recently archived the Last Millennium Reanalysis (LMR) Project, Global Climate Reconstructions Version 2 for the public, providing new ways for the scientific community to examine low frequency climate. The archival at NCEI is the result of a multiyear project funded by CPO’s Climate Observations and Monitoring Program led by PIs G.J. Hakim and E. Steig (University of Washington), J. Emile-Geay (University of Southern California), D. Noone (University of Colorado) and D. Anderson (formerly NOAA’s NCDC Paleoclimatology Branch, University of Colorado).
Over the last five years, data and methods advancements (resulting in more than a dozen publications) produced by the LMR project have started to transform the ways in which the climate community investigates low frequency climate. For example, it is difficult to understand what causes variations in temperatures, or phenomena such as drought and tropical cyclones, on 10- to 100-year timescales because the instrumental record is comparatively short. To examine past climate, researchers typically use proxy records — measurements collected from corals, tree rings, ice cores, deep sea sediments, or other features that preserve a record of the state of the climate over time, based on known biogeochemical and physical processes. However, while paleo proxy records are incredibly useful, coupling paleo proxy records with modern climate modeling has proved challenging. The development of the LMR, the first multivariate, gridded reanalysis for the past 1000 years, overcame many of these challenges, while associated data assimilation advancements opened up many new areas of research.
Just in the last year, multiple studies have utilized LMR data to study variability in temperatures on long time scales. Results have shown that specific regions (e.g. North Pacific and North Atlantic Oceans) are associated with global temperature variations on decadal timescales (Parsons and Hakim 2019) and study findings have increased confidence in future projections of climate change on multidecadal scales (Neukom et al. 2019; Zhu, Emile-Geay, and others 2019). Others have utilized the LMR to provide millennium-length perspectives on drought across the continental U.S. (Baek et al. 2019) and Atlantic Multidecadal variability (Singh et al. 2018).
While the LMR v2 has only been available for a short time, it has proved valuable to the research community, already resulting in multiple publications that advance efforts in multidecadal climate variability understanding and prediction. PIs continue to work to elevate the visibility of the LMR dataset, so that it may serve as a resource for researchers.