Global Signatures and Dynamical Origins of the Little Ice Age and Medieval Climate Anomaly

• Published in: Science (American Association for the Advancement of Science) Vol. 326; no. 5957; pp. 1256 - 1260
• Main Authors: Mann, Michael E, Zhang, Zhihua, Rutherford, Scott, Bradley, Raymond S, Hughes, Malcolm K, Shindell, Drew, Ammann, Caspar, Faluvegi, Greg, Ni, Fenbiao
• Format: Journal Article
• Language: English
• Published: Washington, DC American Association for the Advancement of Science 27-11-2009; The American Association for the Advancement of Science
• Subjects: Atmospheric circulation; Atmospheric models; Climate change; Climate models; Climate proxies; Climatology. Bioclimatology. Climate change; Earth, ocean, space; Exact sciences and technology; External geophysics; History; Meteorology; Proxy reporting; Proxy statements; Radiative forcing; Simulations; Surface temperature; Temperature; Tropical regions; AN, North Atlantic; IS, Tropical Pacific; Neoglacial; Teleconnection; Historical reconstruction; upper Holocene; Quaternary; Arctic oscillation; Surface temperature; climate variability; upper Quaternary; ocean-atmosphere interaction; anomalies; Dynamical climatology; North Atlantic oscillation; Proxy; Spatial distribution; Atmospheric temperature; El Nino; Southern oscillation; Planetary scale; Cenozoic; Phanerozoic; Holocene
• ISSN: 0036-8075; 1095-9203
• DOI: 10.1126/science.1177303

Global temperatures are known to have varied over the past 1500 years, but the spatial patterns have remained poorly defined. We used a global climate proxy network to reconstruct surface temperature patterns over this interval. The Medieval period is found to display warmth that matches or exceeds that of the past decade in some regions, but which falls well below recent levels globally. This period is marked by a tendency for La Niña-like conditions in the tropical Pacific. The coldest temperatures of the Little Ice Age are observed over the interval 1400 to 1700 C.E., with greatest cooling over the extratropical Northern Hemisphere continents. The patterns of temperature change imply dynamical responses of climate to natural radiative forcing changes involving El Niño and the North Atlantic Oscillation-Arctic Oscillation.