Posted by: jnicklin | May 31, 2007

The Medieval Warm Period and the Little Ice Age

Michael Mann produced the Hockey Stick discussed elsewhere on this blog. In doing so, he airbrushed the Medieval Warm Period and the Little Ice Age from the record. Most adherants to anthropogenic global warming call these events localized, that is, they only happened in Europe. While research is not plentiful on what happened outside of Europe during those times, much new evidence is coming out of Europe. Two web sites are of note on this.

First Climate Audit with a thread on Archaeological Finds in Retreating Swiss Glacier By Steve McIntyre and the other at CO2 Science’s Medieval Warm Period Record of the Week

More evidence for a global MWP come from Evidence for a ‘Medieval Warm Period’ in a 1,100 year tree-ring reconstruction of past austral summer temperatures in New Zealand by Cook, Palmer and D’Arrigo. Their conclusion is “…selected temperature proxies from the Northern and Southern Hemispheres confirm that the MWP was highly variable in time and space. Regardless, the New Zealand temperature reconstruction supports the global occurrence of the MWP. GEOPHYSICAL RESEARCH LETTERS, VOL. 29, NO. 14, 1667, doi:10.1029/2001GL014580, 2002

So much for a localized event. If anyone has any other sites, please list them in the comments.

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Another non-European MWP file.

TREE RING EVIDENCE FOR A MEDIEVAL WARM PERIOD IN COLUMBIA BAY, ALASKA
BRADY, Kristina L.1, WILES, Gregory C.1, D’ARRIGO, Rosanne2, and CALKIN, Parker E.3, (1) Geology, The College of Wooster, Wooster, OH 44691, kbrady@wooster.edu, (2) Tree ring Lab, Lamont-Doherty Earth Observatory, Palisades, NY 10964, (3) Institute of Arctic and Alpine Research, Univ of Colorado, Boulder, CO 80309

“Recent dendroclimatic compilations from Northern Hemisphere temperature-sensitive tree-ring sites support a Medieval Warm Period (MWP) spanning parts of the 8th through 12th centuries AD. A newly-compiled, well-replicated ring-width chronology from Columbia Bay is a record of temperature variation along the maritime southern Alaskan coast and now spans the MWP (AD 774-2000). Over the past two decades the tidewater Columbia Glacier has experienced catastrophic retreat exposing almost 15 km of fjord. The ring-width record here is assembled from living trees and subfossil wood killed by a steady, millennium long glacial advance of the iceberg calving Columbia Glacier margin. “

By: John Nicklin on May 31, 2007
at 5:07 pm

Reconstruction of Climate in the Medieval Warm Period

Y.Tagami

“As the results, some characteristics of climate are recognized around the Medieval Warm Period. However it is relatively hot conditions continued until the 8th century, cool condition appeared for short period in the late 9th century. Then warm conditions continued from the 10th century to the former half of the 15th century. After the latter half of 15th century, cool conditions appeared and then considerable cold conditions started from the 17th century. So, between the former and the latter cold ages, the warm condition is clear from the 10th century to the 14th century.”

http://edcgeo.edu.u-toyama.ac.jp/WWWROOT/Geohome/IntN/Abs.htm

By: John Nicklin on May 31, 2007
at 5:50 pm

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