Roman Warm Period

The Roman Warm Period has been proposed as a period of unusually warm weather in Europe and the North Atlantic that ran from approximately 250 BC to 400 AD.^[1] Cooling at the end of this period in south west Florida may have been due to a reduction in solar radiation reaching the Earth, which may have triggered a change in atmospheric circulation patterns.^[2]

Theophrastus (371 – c. 287 BC) wrote that date trees could grow in Greece if planted, but could not set fruit there. This is the same situation as today, and suggests that southern Aegean mean summer temperatures in the fourth and fifth centuries BC were within a degree of modern temperatures. This and other literary fragments from the time confirm that the Greek climate during that period was basically the same as it was around 2000 AD. Dendrochronological evidence from wood found at the Parthenon shows variability of climate in the fifth century BC resembling the modern pattern of variation.^[3] Tree rings from Italy in the late third century BC indicate a period of mild conditions in the area at the time that Hannibal crossed the Alps with elephants.^[4]

The phrase "Roman Warm Period" appears in a 1995 doctoral thesis.^[5] It was popularized by an article published in Nature in 1999.^[6]

Proxies

• Pollen: A high resolution pollen analysis of a core from Galicia concluded in 2003 that the Roman Warm Period lasted from 250 BC-450 AD in northwestern Iberia.^[7]

• Glaciers: A 1986 analysis of Alpine glaciers concluded that the 100 AD to 400 AD period was significantly warmer than the immediately preceding and following periods.^[8]

• Deep ocean sediment: A 1999 reconstruction of ocean current patterns based on the granularity of deep ocean sediment concluded there was a Roman Warm Period that peaked around 150 AD.^[6]

• Mollusk shells: An analysis of oxygen isotopes found in mollusk shells in an Icelandic inlet concluded in 2010 that Iceland experienced an exceptionally warm period from 230 BC to 40 AD.^[9]

See also

• Holocene climatic optimum
• Medieval warm period
• Hubert Lamb
• Maunder minimum

Notes

References

• Moberg, Anders; Sonechkin, Dmitry M.; Holmgren, Karin; Datsenko, Nina M.; Karlén, Wibjörn; Lauritzen, S. E. (10 February 2005), "Highly variable Northern Hemisphere temperatures reconstructed from low- and high-resolution proxy data", Nature 433 (7026): 613–617, Bibcode:2005Natur.433..613M, doi:10.1038/nature03265, PMID 15703742 . Corrigendum: Moberg et al. 2006.
• Moberg, Anders; Sonechkin, Dimitry M.; Holmgren, Karin; Datsenko, Nina M.; Karlén, Wibjörn; Lauritzen, Stein-Erik (23 February 2006), "Corrigendum: Highly variable Northern Hemisphere temperatures reconstructed from low- and high-resolution proxy data", Nature 439, Bibcode:2006Natur.439.1014M, doi:10.1038/nature04575 .
• Jansen et al. (2007), "Chapter 6: Palaeoclimate",  , in IPCC AR4 WG1 2007.
• IPCC AR4 WG1 (2007), Solomon, S.; Qin, D.; Manning, M.; Chen, Z.; Marquis, M.; Avery, K.B.; Tignor, M.; and Miller, H.L., ed., Climate Change 2007: The Physical Science Basis, Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, Cambridge University Press, ISBN 978-0-521-88009-1  (pb: 978-0-521-70596-7).
• Huang, S.; Pollack, H. N.; Shen, P. Y. (4 July 2008), "A late Quaternary climate reconstruction based on borehole heat flux data, borehole temperature data, and the instrumental record", Geophysical Research Letters 35 (L13703): L13703, Bibcode:2008GeoRL..3513703H, doi:10.1029/2008GL034187 .
• Mann, Michael E.; Zhang, Zhihua; Hughes, Malcolm K.; Bradley, Raymond S.; Miller, Sonya K.; Rutherford, Scott; Ni, Fenbiao (9 September 2008), "Proxy-based reconstructions of hemispheric and global surface temperature variations over the past two millennia", Proceedings of the National Academy of Sciences of the United States of America 105 (36): 13252–13257, Bibcode:2008PNAS..10513252M, doi:10.1073/pnas.0805721105, PMC 2527990, PMID 18765811 .
• Black, Richard (1 September 2008). "Climate 'hockey stick' is revived". BBC News. Retrieved 2011-05-18. 
• Arctic Warming Overtakes 2,000 Years of Natural Cooling, University Corporation for Atmospheric Research, 3 September 2009, retrieved 19 May 2011 .
• Bello, David (4 September 2009), "Global Warming Reverses Long-Term Arctic Cooling", Scientific American [webpage], retrieved 19 May 2011 .
• Kaufman, Darrel; Schneider, David P.; McKay, Nicholas P.; Ammann, Caspar M.; Bradley, Raymond S.; Briffa, Keith R.; Miller, Gifford H.; Otto-Bliesner, Bette L.; Overpeck, Jonathan T.; Vinther, Bo M.; and Arctic Lakes 2k Project Members (4 September 2009), "Recent warming reverses long-term arctic cooling", Science 325 (5945): 1236–1239, Bibcode:2009Sci...325.1236K, doi:10.1126/science.1173983, PMID 19729653  Cite uses deprecated parameters (help).
• Mann, Michael E.; Zhang, Zhihua; Rutherford, Scott; Bradley, Raymond S.; Hughes, Malcolm K.; Shindell, Ddrew; Ammann, Caspar M.; Faluvegi, Greg et al. (27 November 2009), "Global Signatures and Dynamical Origins of the Little Ice Age and Medieval Climate Anomaly", Science 326 (5957): 1256–1260, Bibcode:2009Sci...326.1256M, doi:10.1126/science.1177303, PMID 19965474  |displayauthors= suggested (help).
• Ljungqvist, F. C. (September 2010), "A New Reconstruction of Temperature Variability in the Extra-Tropical Northern Hemisphere During the Last Two Millennia", Geografiska Annaler: Series A, Physical Geography 92 (3): 339–351, doi:10.1111/j.1468-0459.2010.00399.x .
• Ljungqvist, F. C.; Krusic, P. J.; Brattström, G.; Sundqvist, H. S. (2012), "Northern Hemisphere temperature patterns in the last 12 centuries", Climate of the Past 8: 227, Bibcode:2012CliPa...8..227L, doi:10.5194/cp-8-227-2012 .