Posted on 12/17/2004 2:27:50 AM PST by Exton1
A 1240-Year Record of Arctic Temperatures
Reference
Moore, J.J., Hughen, K.A., Miller, G.H. and Overpeck, J.T. 2001. Little Ice Age recorded in summer temperature reconstruction from varved sediments of Donard Lake, Baffin Island, Canada. Journal of Paleolimnology 25: 503-517.
What was done
Lake sediment cores from Donard Lake, Baffin Island, Canada (approximately 66.25°N, 62°W), were analyzed to produce a 1240-year record of average summer temperatures for this region.
What was learned
Over the entire 1240-year period from 750-1990 A.D., summer temperatures averaged
2.9°C. Anomalously warm decades with summer temperatures as high as 4°C occurred around 1000 and 1100 A.D. At the beginning of the 13th century, Donard Lake witnessed "one of the largest climatic transitions in over a millennium," as "average summer temperatures rose rapidly by nearly 2°C from 1195-1220 A.D., ending in the warmest decade in the record" with temperatures near 4.5°C.
The rapid warming of the 13th century was followed by a period of extended warmth that lasted until an abrupt cooling event occurred around 1375 A.D. The decade following 1375 A.D. was one of the coldest in the record and represented the onset of the Little Ice Age on Baffin Island, which lasted for 400 years. At the modern end of the record, a gradual warming trend occurred over the period 1800-1900 A.D., followed by a dramatic cooling event in 1900 that brought temperatures back to levels consistent with the Little Ice Age, which lasted until about 1950. Temperatures warmed during the 1950s and 1960s, whereupon they have trended toward cooler conditions to the present.
What it means
Large abrupt swings in temperature appear to be a consistent feature of climate in this region of the world, with temperatures rising and falling by as much as 2°C in as short a time period as a decade. Such natural temperature variability demonstrates the high degree of difficulty associated with attempting to separate effects of anthropogenic climatic forcing from those of natural causes.
In contradiction of politically-correct climatology, the study also demonstrates the existence of both the Medieval Warm Period and Little Ice Age on Baffin Island. And it stands in stark contrast to the climate alarmist claim that the latter part of the 20th century experienced "unprecedented" warming, at least in this part of the world, which is, however, where such anthropogenic phenomena are supposed to be most evident.
Page printed from: http://www.co2science.org/journal/2001/v4n32c1.htm
In other words, any 'global warming' evidence thus far presented is within this range andf therefroe NO MEANINGFUL CONCLUSION can be drawn.
End of science lesson.
First of all, I think you're mixing up two terms. There was a "Holocene Climate Optimum" -- the period you're referring to is most commonly called the "Medieval Warm Period" or MWP.
Can you show provide references that indicate the MWP was truly global? The main problem is that there is so little data from the Southern Hemisphere.
By the way, Baffin Island is in the Northern Hemisphere.
For a bit of help, there is decent data showing that the cold period from 1400 - ~1850 was global, but most intense in Europe and the northern Atlantic region. Is that what you're thinking of?
You also might like to read this:
Climate in Medieval Time (PDF)
Excerpt of interest:
"There is evidence for widespread hydrological anomalies from 900 to 1300 A.D. Prolonged droughts affected many parts of the western United States (especially eastern California and the western Great Basin) (14). Other parts of the world also experienced persistent hydrological anomalies (15). For this reason, Stine (14) argues that a better term for this period is the Medieval Climatic Anomaly, removing the emphasis on temperature as its defining characteristic."
In the single figure in this reference, the Baffin Island record is #15, indicating that the warmest 30 year period in that record occurred about A.D. 1200. In the figure, records 4-6 are Southern Hemisphere, showing the warmest 30-year period between 1400-1500 -- which in Europe was the start of the Little Ice Age!
See reply 63 for your edification.
No, I didn't, because it's not true.
As I said, "the globalwarmingwhackos have steadfastly maintained that the Medieval Warming was not world wide is that the Science showing the warming there is Absolutely Irrefutable. When someone devises an equally good way of establishing that it was, in fact, worldwide, they'll figure out some other way to lie and obfuscate to their moronic target masses. I've yet to hear any of their vaunted "models" demonstrate any possible methodology for maintaining a warm Arctic for centuries without other major climactic ramifications, but their "faith" allows them to simply 'know' that earth is warmer now than ever before - because man's activities 'clearly' makes it that way."
Keep up your faith mission.
On the other hand, when issues of science are approached in the manner of advocacy, it's hard to change a viewpoint, because the holders of the viewpoint are ideologically bound to the way that they think things should be -- not necessarily the way that things actually are.
Noooo, now wait a second this could be series, if it's lower in cities it would explain the large urban vote for Kerry; they're not brain dead, only oxygen deprived.
ping
bump
bump
Yeah, you're right. Brain-fart on my part.
"Can you show provide references that indicate the MWP was truly global? The main problem is that there is so little data from the Southern Hemisphere."
No--I'm past the point of keeping references on this stuff--got other stuff to keep me busy. I just keep seeing different studies from widely separated geographic areas all pointing to the "globalality" of the "Medievel Warm Period". One I "do" recall was from Australia. Used proxy oxygen isotope measurements on some shellfish in sediment.
This one is a UNCPBA/GSA report.
Actually lake sediments and ice cores are very accurate at determining climatic conditions at the time the layer was put down.
Fascinating Bump.
cogitator worships at the alter of the IPCC. I really can't see how an intellectually honest person can defend the hockey stick theory.
Or so you say. The lost squadron crash landed during WWII.. By the time it was relocated, it was necessary to tunnel down to the planes which after 50 years were buried in 250 feet of ice and snow pack with more than 250 "annual rings". Accurate my eye. By practice and dead brained assumptions, we'd have to tell the world everyone was mistaken, WWII actually happened more than 200 years in the past beyond what is recorded in history books. You'll excuse me if I have problems with the subject or the claimed result.
Ice cores for dating, are taken in stable ice, not in or near a glacier.
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