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-- Vladimir Ilyich Lenin - See more at: http://thepeoplescube.com/lenin/lenin-s-own-20-monster-quotes-t185.html#sthash.aTrSI3tG.dpuf
A lie told often enough becomes the truth.
-- Vladimir Ilyich Lenin - See more at: http://thepeoplescube.com/lenin/lenin-s-own-20-monster-quotes-t185.html#sthash.aTrSI3tG.dpuf
A lie told often enough becomes the truth.
-- Vladimir Ilyich Lenin - See more at: http://thepeoplescube.com/lenin/lenin-s-own-20-monster-quotes-t185.html#sthash.aTrSI3tG.dpuf

Monday, February 18, 2013

Little Ice Age a global event

The IPCC scientists have constantly claimed that the Medieval Warm Period (MWP) and the Little Ice Age (LIA) were Northern Hemisphere (NH) events. For example, from IPCC TAR: (link)
Mann et al. (1998) and Jones et al. (1998) support the idea that the 15th to 19th centuries were the coldest of the millennium over the Northern Hemisphere overall. However, viewed hemispherically, the "Little Ice Age" can only be considered as a modest cooling of the Northern Hemisphere during this period of less than 1°C relative to late 20th century levels (Bradley and Jones, 1993; Jones et al., 1998; Mann et al., 1998; 1999; Crowley and Lowery, 2000). 

However a  paper published in a peer review journal contradicts the IPCC's theory that the Little Ice Age was restricted to the Northern Hemisphere. The study was carried out on temperature data from the West Antarctic Ice Sheet.

From Geophysical Research Letters:
We present temperature data from a 300 m borehole at the West Antarctic Ice Sheet (WAIS) Divide. Results show that WAIS Divide was colder than the last 1000 year average from 1300 to 1800 C.E.
The temperature in the time period 1400-1800 C.E. was on average 0.52 {plus minus} 0.28{degree sign}C colder than the last 100-year average.

As reported by CO2 Science:

Reference
Orsi, A.J., Cornuelle, B.D. and Severinghaus J.P. 2012. Little Ice Age cold interval in West Antarctica: Evidence from borehole temperature at the West Antarctic Ice Sheet (WAIS) Divide. Geophysical Research Letters 39: 10.1029/2012GL051260. 



Background
The authors write that "the Northern Hemisphere experienced a widespread cooling from about 1400 to 1850 C.E., often referred to as the Little Ice Age (hereafter LIA)," which they describe as "the latest of a series of centennial scale oscillations in the climate," citing Wanner et al. (2011). However, they say "it is still unclear whether the Southern Hemisphere high latitudes had a temperature response synchronous to that of the Northern Hemisphere," noting that "changes in the solar forcing" - which many scientists believe were responsible for driving the sequential climatic progression from Roman Warm Period to Dark Ages Cold Period to Medieval Warm Period to Little Ice Age to Current Warm Period - "would call for hemispheric synchroneity."


What it means
Orsi et al. feel confident in stating that their result "is consistent with the idea that the LIA was a global event, probably caused by a change in solar and volcanic forcing, and was not simply a seesaw-type redistribution of heat between the hemispheres as would be predicted by some ocean-circulation hypotheses."


Read more at CO2 Science:

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