The conveyor belt is like a thermostat on a car engine. The fresh water acts like a coolant by slowing the flow of warm air , lowering the atmosphere's temperature. When it freezes the leakage of fresh water into the Greenland basin slows, allowing for it to start back up as the salinity increases. Thus the cycle is seen in the geologic record or through ice cores. BUT, a man made warming is artificially induced unless you think hunter gatherers made enough fires to induce the last ice age. Other natural factors such as volcanoes can also induce mini cooling periods or even asteroid hits. The demise of the Anastazi might be liked to an unnaturally cool and damp period following Mt Pinatubo's eruption of 1312. They also knew about stellar events such as the re-appearance of Halley's Comet (Blue Star) at regular 86 year intervals. I heard myths that the Priests gave orders for dispersal prior to Halley's return for fear of collision. They probably knew about the crater's at four corners. Furthermore, damp storage sites fosters the growth of ergot poisoning as in the Salem witch trials. At about this time the bubonic plague may have crossed over from Europe. Desert squirrels still carry a remnant strain.

Recent research suggests that this period coincides with an impact of some sort. If so, that easily explains the quick cool down.

Before the AGW alarmists get all worked up about this, it is important to recognize that the Lake Agassiz release probably raised the level of the world's oceans by a meter in just a couple of years. The ice had already melted and was trapped in a massive inland lake that covered a couple of Canadian provinces and a couple of US States. It was far larger than any existing lake complex today and was in a fairly unstable state as it was accumulating more meltwater and was temporarily dammed by melting ice sheets and terminal moraines.

Most glacial meltwater these days has a normal route to the seas which is why we have seen a steady, slow rise of sea levels for millenia now. The controls on the flow from lakes etc are also typically very resistant bedrock, such as the Canadian Shield that governs the St Lawrence flow and the Lockport Dolomite that governs the Niagara River flow (Niagara Falls).

There are currently no bodies of water on the planet that could accomplish more than a millimeter. Even the "accelerating pace" of the Greenland ice sheet melting is less than 1 mm per year.

In this article about this recent research, it is interesting to see the discussion about the roller coaster of temperatures discussed in the Greenland area over the past 100,000 years. Once again, we have lived in a period of remarkable climate stability over the past 5,000 years, the likes of which has probably not been seen for a hundred thousand years or more. The global temperature variations that the AGW scientists are trumpeting as disastrous would have simply been data noise in the previous 100,000 years.

http://www.timesonline.co.uk/tol/news/science/earth-environment/article6917215.ece

It is always impressive to travel through the various major meltwater channels in eastern and central North America to see the wide, deep valleys that were carved by these meltwaters with just a small lazy stream or river wandering along in the valley bottom today. That was a time when there were were huge changes in the landscape due to climate change.

""Some climate scientists have suggested that the Greenland ice sheet could have the same effect if it suddenly melts through climate change""

LOL... Sounds Like Gore!

If that suddenly went!!!!!.

And If the Core of the planet suddenly stopped....

What utter nonsence.

I don't know if the NewScientist article discussed it or not, since you did not mention it Brett, but there is a theory with a lot of supporting evidence (documentary on one of the science channels) that the area was hit by a significant meteor which caused almost instant melting of much of the Laurentide Ice Sheet and ultimately causing an ice dam to fail, dumping the meltwater into the St. Lawrence river basin rather than the Mississippi basin where the edge-melt was draining to. It was this rapid influx of cold, freshwater which dramatically gummed up the Gulfstream works.

So unless a large meteor crashes into the middle of Greenland, there won't be a repeat of the the Younger Dryas. The relatively minescule amount of meltwater (compared to the Laurentide Ice Sheet Collapse) coming from the edges of the Greenland Ice Sheet will never be able to affect the the Gulfstream flow in any meaningful way !

Great post!

Climatologists Baffled by Global Warming Time-Out
http://www.spiegel.de/international/world/0,1518,662092,00.html

"It cannot be denied that this is one of the hottest issues in the scientific community," says Jochem Marotzke, director of the Max Planck Institute for Meteorology in Hamburg. "We don't really know why this stagnation is taking place at this point."

Ok MarkB ,If the climatologists don't know why the stagnation is taking place,how reliable is their AGW theory? It's not!
What a bunch of fools these so called scientists are!

Given how quickly an ice age can transpire wouldn't it be prudent to plan for one? An ice age would be deadly and would likely halt civilization as we know it. Since anthropogenic global warming doesn't exist it would be wise to plan for prolonged cooling. There is nothing unprecedented or alarming about the slight rise in temperature (which was not linear) from the end of the Little Ice Age to the end of the 20th Century. We live in a warm interglacial period that is still cold enough for snow so we can go skiing. It's paradise. But as history shows the ice sheets will march again.

Breaking News Story:

Hadley CRU has apparently been hacked – hundreds of files released

Sample from one e-mail:

“I’ve just completed Mike’s Nature trick of adding in the real temps
to each series for the last 20 years (ie from 1981 onwards) amd from
1961 for Keith’s to hide the decline.”

The so-called Clovis Comet did not directly melt very much ice. It does appear responsible, according to some, for the sudden change of drainage of Glacial Lake Agassiz
http://en.wikipedia.org/wiki/Lake_Agassiz
from towards the Gulf of Mexico to (probably) the northwest into the Arctic Ocean and simultaneously the draining of other North American proglacial lakes down the Hudson River while at the same time promoting the first major drainage of the Baltic Ice Lake
http://en.wikipedia.org/wiki/Baltic_Ice_Lake

This onslaught of fresh water and probably ice being pushed out of the Arctic Ocean was enough to set off the Younger Dryas.

(Many details of the above are still considered conjectural and so contentious.)

Thank you, all, for the provocative and apolitical comments! I actually enjoyed reading and learning from the comments to this post because they weren't antagonistic.

Considering that the oldest evidence of human habitation in the Americas dates to this time period, I have to wonder whether the immediacy of this event spurred migrations. A more gradual change would allow people to adapt. Such a sudden change might call for desperate measures, such as picking up and moving to another continent. Also noteworthy after this event are the rise of agriculture and urban settlements.

Some climate scientists have suggested that the Greenland ice sheet could have the same effect if it suddenly melts through climate change, but the 2007 report of the Intergovernmental Panel on Climate Change (IPCC) concluded this was unlikely to happen this century.

I guess that would be the dumb climate scientists. There is no massive freshwater lake ready to rush into the North Atlantic waters near Greenland so there is no mechanism to justify the scary scenario being sold to the gullible.

By the way Brett, are you going to cover the results of the ? It seems to me that when 50% of meteorologists disagree or strongly disagree with the statement, "Most of the warming since 1950 is likely human induced," it deserves mention. That is double the percentage of meteorologists who agreed or strongly agreed with the statement.

Reply: I will consider it.

"Some climate scientists have suggested that the Greenland ice sheet could have the same effect if it suddenly melts through climate change, but the 2007 report of the Intergovernmental Panel on Climate Change (IPCC) concluded this was unlikely to happen this century."

Thank God for that declaration from the IPCC. I feel much better now.

The Younger Dryas mini ice age was brought about when a glacial lake covering most of north-west Canada burst its banks and poured into the North Atlantic and Arctic Oceans. The huge flood diluted the salinity-driven North Atlantic Ocean mega-currents, including the Gulf Stream, and stalled it.

I know you're writing for the general public, Brett, and the description above is vague enough to be generally correct, but it should be made clear that the main thing that happened when the freshwater inundation entered the North Atlantic was the cessation of deep-water formation. Deep-water formation is the ocean-atmosphere system's way of shunting extreme polar cold into the deep ocean (where it belongs) rather than having it stay, well, atmospheric. Deep-water formation is a fascinating subject, happening via the formation of short-lived downwelling "chimneys" (only a few square km in surface extent) when there has been sufficient heat loss from the water to make it dense enough to sink rapidly and massively (somewhat loosely akin to a thunderstorm downburst). The water in the chimney sinks until it reaches a stable density depth and then spreads out. Since density is critical, the freshwater made the North Atlantic too "light" for deep-water formation, and literally the freshwater surface lens had to be diluted with more saline waters until it was of sufficient density to re-enable deepwater formation -- and that's what took 1000 years. Without a mechanism to shuttle the cold out of the atmosphere, the atmosphere stayed cold -- creating the potent cooling at the end of the terminating glacial period warming phase. When deep-water formation re-initiated, the temperatures ramped up in less than a decade -- wasn't there something on TV about an ice core where they pinned down the start of the Holocene to a single year?

Its over guys move on
http://wattsupwiththat.com/2009/11/19/breaking-news-story-hadley-cru-has-apparently-been-hacked-hundreds-of-files-released/
Hadley has confirmed it...
http://www.investigatemagazine.com/australia/latestissue.pdf
This WILL hit mainstream media Brett:you will not regret having posted both sides of the argument

Can someone help me with this. Hate to say it, Am I stupid or is this double speak

November 19, 2009
Mini Ice Ages can happen Fast!

Some climate scientists have suggested that the Greenland ice sheet could have the same effect if it suddenly melts through climate change, but the 2007 report of the Intergovernmental Panel on Climate Change (IPCC) concluded this was unlikely to happen this century.

Wednesday, November 18, 2009
Greenland Ice Sheet Losing Mass at an Accelerating Rate

I have also read that during warm periods, additional snow accumulates in arctic regions, thickening the ice packs and reaching a point at which there is a rather sudden cooling or even the onset of an ice age.