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Scientists unravel 8,200-year-old climate riddle
University of Southampton ^
| April 23, 2005
| PhysOrg
Posted on 03/02/2006 9:54:12 AM PST by SunkenCiv
Palaeoceanographers from the Southampton Oceanography Centre have shed new light on the world's climate behaviour over 8,200 years ago. In an article published this week in Nature, they demonstrate that a sudden drop in temperature lasting 200 years cannot be used as a template for the modern day threat of rapid climate change... Professor Rohling explained: 'Many scientists are using this 200-year-old cold snap to validate their computer climate models when, in fact, many of the global climate changes around that time seem related to the "underlying" longer-term variability. This confusion has complicated efforts to unravel a pattern of climate variability.
(Excerpt) Read more at physorg.com ...
TOPICS: History; Science
KEYWORDS: catastrophism; climate; globalwarminghoax; godsgravesglyphs
While starting to save this file, I found the topic title article already on the drive. Four gigs really is quite a lot. :')
8,200-year-old climate change studied
Mar 1, 2006, 3:02 GMT
Monsters and Critics
UPI
Retreating glaciers opened a route for two ancient meltwater lakes, known as Agassiz and Ojibway, to suddenly and catastrophically drain from the middle of the North American continent. At approximately the same time, climate records show the Earth experienced its last abrupt climate shift -- a drop of average air temperature by several degrees. Scientists believe the massive freshwater pulse interfered with the ocean's overturning circulation, which distributes heat around the globe.
1
posted on
03/02/2006 9:54:17 AM PST
by
SunkenCiv
2
posted on
03/02/2006 9:57:13 AM PST
by
SunkenCiv
(Fiction has to make sense, unless it's part of the Dhimmicrat agenda and its supporting myth.)
To: DaveLoneRanger; redpoll; new yorker 77; blam; FairOpinion; Ernest_at_the_Beach; ...
3
posted on
03/02/2006 9:57:34 AM PST
by
SunkenCiv
(Fiction has to make sense, unless it's part of the Dhimmicrat agenda and its supporting myth.)
To: SunkenCiv
4
posted on
03/02/2006 10:12:03 AM PST
by
Publius6961
(Multiculturalism is the white flag of a dying country)
To: SunkenCiv
That link's URL in null. Was that the intention?
5
posted on
03/02/2006 10:26:44 AM PST
by
Publius6961
(Multiculturalism is the white flag of a dying country)
To: SunkenCiv; blam
My understanding is that the Lake Agassiz surge resulted in the Younger Dryas, 12,900 – 11,500 before the present (or 9900-8500 BC). I think the glacial lake Ojibway formed later, and Lake Agassiz filled up a little bit again, and then both resurged around the 8200 years ago but this didn't lead to as drastic nor as long of a drop in temperatures as the Younger Dryas.
So, the last glaciation reached its peak 20,000 years ago, and the world got lots warmer (and even wetter in some places (like the Sahara and the Middle East) but then when Lake Agassiz (a huge lake, 4 times larger than all the Great Lakes, filled with melted glacier water) burst all that fresh water spilled into the North Atlantic 12,000 years ago--well things got real cold and dry again in a hurry.
See what you and Blam have taught me after all these years on the GGG ping list?!
To: Publius6961
My pleasure.
Abrupt increase in Greenland snow accumulation
at the end of the Younger Dryas event
R. B. Alley, D. A. Meese, C. A. Shuman, A. J. Gow,
K. C. Taylor, P. M. Grootes, J. W. C. White, M. Ram,
E. D. Waddington, P. A. Mayewski & G. A. Zielinski
Nature 362, 527 - 529 (08 April 1993)
THE warming at the end of the last glaciation was characterized by a series of abrupt returns to glacial climate, the best-known of which is the Younger Dryas event. Despite much study of the causes of this event and the mechanisms by which it ended, many questions remain unresolved. Oxygen isotope data from Greenland ice cores suggest that the Younger Dryas ended abruptly, over a period of about 50 years; dust concentrations in these cores show an even more rapid transition (20 years). This extremely short timescale places severe constraints on the mechanisms underlying the transition. But dust concentrations can reflect subtle changes in atmospheric circulation, which need not be associated with a large change in climate. Here we present results from a new Greenland ice core (GISP2) showing that snow accumulation doubled rapidly from the Younger Dryas event to the subsequent Preboreal interval, possibly in one to three years. We also find that the accumulation-rate change from the Oldest Dryas to the Bø11ing/Allerød warm period was large and abrupt. The extreme rapidity of these changes in a variable that directly represents regional climate implies that the events at the end of the last glaciation may have been responses to some kind of threshold or trigger in the North Atlantic climate system.
7
posted on
03/02/2006 10:29:07 AM PST
by
SunkenCiv
(Fiction has to make sense, unless it's part of the Dhimmicrat agenda and its supporting myth.)
To: Publius6961
Oops.
8,200-year-old climate change studied
Mar 1, 2006, 3:02 GMT
Monsters and Critics
UPI
Retreating glaciers opened a route for two ancient meltwater lakes, known as Agassiz and Ojibway, to suddenly and catastrophically drain from the middle of the North American continent. At approximately the same time, climate records show the Earth experienced its last abrupt climate shift -- a drop of average air temperature by several degrees. Scientists believe the massive freshwater pulse interfered with the ocean's overturning circulation, which distributes heat around the globe.
8
posted on
03/02/2006 10:32:39 AM PST
by
SunkenCiv
(Fiction has to make sense, unless it's part of the Dhimmicrat agenda and its supporting myth.)
To: Alas Babylon!
The Younger Dryas ended circa 11K BP; the Lake Missoula flood which produced the Channeled Scablands may be of that earlier date (I found it hard to nail down on the web, one proposed date is 14K BP), but that water went to the Pacific. :')
9
posted on
03/02/2006 10:38:27 AM PST
by
SunkenCiv
(Fiction has to make sense, unless it's part of the Dhimmicrat agenda and its supporting myth.)
The Younger Dryas:
From whence the fresh water?
by T. C. Moore Jr.
Paleoceanography
v 20, PA4021
Oxygen isotopic records of meltwater outflow and records of sea level change do not support the idea that fresh waters derived solely from the melting of Northern Hemisphere ice sheets was likely to have stabilized the upper layers of the North Atlantic Ocean and prevented deep convection during the Younger Dryas. Yet there are paleoceanographic indicators that point to a pause in the formation of North Atlantic Deep Water during the Younger Dryas. This apparent conflict in evidence may be resolved by the existence of large, relatively thick, tabular icebergs that spilled out of the Arctic and into the Norwegian-Greenland Sea and North Atlantic. The melting of large icebergs would have no impact on sea level but combined with meltwater runoff would provide enough fresh water to “cap” the North Atlantic. The timing of the start and the end of the Younger Dryas, however, may not have been directly related to freshwater supply.
10
posted on
03/02/2006 10:40:26 AM PST
by
SunkenCiv
(Fiction has to make sense, unless it's part of the Dhimmicrat agenda and its supporting myth.)
To: Alas Babylon!
"See what you and Blam have taught me after all these years on the GGG ping list?!" That's good. However, I'm learning at the same time as you.
11
posted on
03/02/2006 10:57:32 AM PST
by
blam
To: SunkenCiv
Nope, the Younger Dryas is being blamed on the first Lake Agassiz surge.
from Wikpedia:
The prevailing theory holds that the Younger Dryas was caused by a significant reduction or shutdown of the North Atlantic thermohaline circulation in response to a sudden influx of fresh water from Lake Agassiz and deglaciation in North America. The global climate would then have become locked into the new state until freezing removed the fresh water "lid" from the north Atlantic Ocean. This theory does not explain why South America cooled first.
I'm also reading After the Ice by Stephen Mithen, an excellent account of the Pleistocene/Holocene times. It reads like a novel. Good chapters on the day to day lief of humans in various post ice age settings, as the world grew warmer and wetter, or dryer, in some cases.
Buy Here!
To: SunkenCiv
13
posted on
03/02/2006 8:10:01 PM PST
by
chaosagent
(Remember, no matter how you slice it, forbidden fruit still tastes the sweetest!)
To: Alas Babylon!
Timing of various climate change events after the Ice Age meltdown started aroung 18,000 ya.
There are a lot of interesting conjectures and information, as well as maps in various works by Graham Hancock. There is also a Graham Hancock Forum site, with interesting information.
14
posted on
03/03/2006 6:27:05 AM PST
by
gleeaikin
(Question Authority)
15
posted on
05/14/2006 5:58:05 PM PDT
by
SunkenCiv
(https://secure.freerepublic.com/donate/)
16
posted on
05/14/2006 5:58:23 PM PDT
by
SunkenCiv
(https://secure.freerepublic.com/donate/)
17
posted on
07/04/2010 6:02:34 PM PDT
by
SunkenCiv
("Fools learn from experience. I prefer to learn from the experience of others." -- Otto von Bismarck)
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