noaa-recon-23890 Hemispheric 1,000 Year Pseudoproxy Data and Temperature Reconstructions Neukom, R.; Schurer, A.P.; Steiger, N.J.; Hegerl, G.C. Hemispheric 1,000 Year Pseudoproxy Data and Temperature Reconstructions 2018-05-15 NCDC-Paleoclimatology ONLINE Files Pending https://www.ncdc.noaa.gov/paleo/study/23890 Investigator R. Neukom Investigator A.P. Schurer Investigator N.J. Steiger Investigator G.C. Hegerl earth science paleoclimate reconstructions air temperature geoscientificInformation Air Temperature Reconstruction 1000 AD 2000 AD 950 cal yr BP -50 cal yr BP Complete -90 90 -180 180 Geographic Region Southern Hemisphere Southern Hemisphere>LATITUDE >LONGITUDE Geographic Region Northern Hemisphere Northern Hemisphere>LATITUDE >LONGITUDE None Please cite original publication, online resource, dataset and publication DOIs (where available), and date accessed when using downloaded data. If there is no publication information, please cite investigator, title, online resource, and date accessed. The appearance of external links associated with a dataset does not constitute endorsement by the Department of Commerce/National Oceanic and Atmospheric Administration of external Web sites or the information, products or services contained therein. For other than authorized activities, the Department of Commerce/NOAA does not exercise any editorial control over the information you may find at these locations. These links are provided consistent with the stated purpose of this Department of Commerce/NOAA Web site. English DOC/NOAA/NESDIS/NCEI National Centers for Environmental Information, NESDIS, NOAA, U.S. Department of Commerce https://www.ncdc.noaa.gov/data-access/paleoclimatology-data DATA Center Contact Bruce Bauer bruce.a.bauer@noaa.gov paleo@noaa.gov 303-497-6280 303-497-6513

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Boulder CO 80305-3328 USA online ASCII Raphael Neukom, Andrew P. Schurer, Nathan. J. Steiger, Gabriele C. Hegerl 2018 Scientific Reports 7572 8 10.1038/s41598-018-25862-2 https://www.nature.com/articles/s41598-018-25862-2

Model simulations and proxy-based reconstructions are the main tools for quantifying pre-instrumental climate variations. For some metrics such as Northern Hemisphere mean temperatures, there is remarkable agreement between models and reconstructions. For other diagnostics, such as the regional response to volcanic eruptions, or hemispheric temperature differences, substantial disagreements between data and models have been reported. Here, we assess the potential sources of these discrepancies by comparing 1000-year hemispheric temperature reconstructions based on real-world paleoclimate proxies with climate-model-based pseudoproxies. These pseudoproxy experiments (PPE) indicate that noise inherent in proxy records and the unequal spatial distribution of proxy data are the key factors in explaining the data-model differences. For example, lower inter-hemispheric correlations in reconstructions can be fully accounted for by these factors in the PPE. Noise and data sampling also partly explain the reduced amplitude of the response to external forcing in reconstructions compared to models. For other metrics, such as inter-hemispheric differences, some, although reduced, discrepancy remains. Our results suggest that improving proxy data quality and spatial coverage is the key factor to increase the quality of future climate reconstructions, while the total number of proxy records and reconstruction methodology play a smaller role. STUDY NOTES: Pseudoproxy data and reconstruction outputs for Neukom et al. (2018)

GET DATA https://www1.ncdc.noaa.gov/pub/data/paleo/reconstructions/neukom2018/ Data Folder; Hemispheric Pseudoproxy Data and Temperature Reconstructions USA/NOAA DIF Version 9.8.4 2018-12-11 2018-12-11