Possible causes of data model discrepancy in the temperature history of the last Millennium

Neukom, Raphael; Schurer, Andrew P.; Steiger, Nathan. J.; Hegerl, Gabriele C. (2018). Possible causes of data model discrepancy in the temperature history of the last Millennium. Scientific Reports, 8(1), p. 7572. Nature Publishing Group 10.1038/s41598-018-25862-2

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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.

Item Type:

Journal Article (Original Article)

Division/Institute:

08 Faculty of Science > Institute of Geography > Physical Geography > Unit Paleolimnology
10 Strategic Research Centers > Oeschger Centre for Climate Change Research (OCCR)
08 Faculty of Science > Institute of Geography
08 Faculty of Science > Institute of Geography > Physical Geography

UniBE Contributor:

Neukom, Raphael

Subjects:

500 Science > 550 Earth sciences & geology
900 History > 910 Geography & travel

ISSN:

2045-2322

Publisher:

Nature Publishing Group

Language:

English

Submitter:

Raphael Neukom

Date Deposited:

24 May 2018 10:44

Last Modified:

24 May 2018 11:10

Publisher DOI:

10.1038/s41598-018-25862-2

BORIS DOI:

10.7892/boris.116550

URI:

https://boris.unibe.ch/id/eprint/116550

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