Proxy-based reconstructions of hemispheric and global surface temperature variations over the past two millennia

2008/09/02 by Michael Mann, Zhihua Zhang, Malcolm K. Hughes +4 · 11 citations
Earth and Planetary Sciences · Environmental Science · Mathematics · #Tree-ring climate responses #Geology and Paleoclimatology Research #Plant Water Relations and Carbon Dynamics #Proxy (statistics) #Centennial #Northern Hemisphere #Climatology #Context (archaeology) #Climate change #Dendrochronology #Global change #Research council #Southern Hemisphere #Geography #Geology #Environmental science #Archaeology #Oceanography #Mathematics #Statistics

paper · doi:10.1073/pnas.0805721105

openalex publication_date 2008/09/02 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05

Abstract

Following the suggestions of a recent National Research Council report [NRC (National Research Council) (2006) Surface Temperature Reconstructions for the Last 2,000 Years (Natl Acad Press, Washington, DC).], we reconstruct surface temperature at hemispheric and global scale for much of the last 2,000 years using a greatly expanded set of proxy data for decadal-to-centennial climate changes, recently updated instrumental data, and complementary methods that have been thoroughly tested and validated with model simulation experiments. Our results extend previous conclusions that recent Northern Hemisphere surface temperature increases are likely anomalous in a long-term context. Recent warmth appears anomalous for at least the past 1,300 years whether or not tree-ring data are used. If tree-ring data are used, the conclusion can be extended to at least the past 1,700 years, but with additional strong caveats. The reconstructed amplitude of change over past centuries is greater than hitherto reported, with somewhat greater Medieval warmth in the Northern Hemisphere, albeit still not reaching recent levels.

Citations

• Climate reconstruction using ‘Pseudoproxies’
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• Evaluation of proxy-based millennial reconstruction methods
• Northern hemisphere temperatures during the past millennium: Inferences, uncertainties, and limitations
• Robustness of the Mann, Bradley, Hughes reconstruction of Northern Hemisphere surface temperatures: Examination of criticisms based on the nature and processing of proxy climate evidence
• Climate over past millennia
• 'Little Ice Age' summer temperature variations: their nature and relevance to recent global warming trends
• How Warm Was the Medieval Warm Period?

Cited by

• A Reconstruction of Regional and Global Temperature for the Past 11,300 Years
• Recent Warming Reverses Long-Term Arctic Cooling
• A new reconstruction of temperature variability in the extra‐tropical northern hemisphere during the last two millennia
• Proxy inconsistency and other problems in millennial paleoclimate reconstructions
• A Bayesian Algorithm for Reconstructing Climate Anomalies in Space and Time. Part I: Development and Applications to Paleoclimate Reconstruction Problems
• Reconstruction of the Extratropical NH Mean Temperature over the Last Millennium with a Method that Preserves Low-Frequency Variability
• A Bayesian Algorithm for Reconstructing Climate Anomalies in Space and Time. Part II: Comparison with the Regularized Expectation–Maximization Algorithm
• The extra-tropical Northern Hemisphere temperature in the last two millennia: reconstructions of low-frequency variability
• Northern Hemisphere temperature patterns in the last 12 centuries
• Caribbean cyclone activity: an annually-resolved Common Era record
• Hockey stick graph (global temperature) [wikipedia]

Related

• Northern Hemisphere temperature patterns in the last 12 centuries
• The extra-tropical Northern Hemisphere temperature in the last two millennia: reconstructions of low-frequency variability
• A new reconstruction of temperature variability in the extra‐tropical northern hemisphere during the last two millennia
• A statistical analysis of multiple temperature proxies: Are reconstructions of surface temperatures over the last 1000 years reliable?
• A Reconstruction of Regional and Global Temperature for the Past 11,300 Years