At https://wattsupwiththat.com/2016/12/19/a-bad-day-for-younger-dryas-comet… … is one of those headlines that seem to say the debate is over and the Younger Dryas boundary event did not involve a cosmic detonation in the atmosphere. A bad day for the younger dryas comet theory – which seems to refer to disagreements over nano diamonds and what they are (a technical dispute if you like). Either the nano diamonds are real – or they are not. How do one group of laboratory scientists see one thing and another group in another laboratory see something else – or say they could not see what the first group saw? The implication is that one group of scientists is incompetent. Is that feasible – or is it all a case of the old guard fighting a rearguard action and attempting to smother the upstarts?
Two articles in the Journal of Quaternary Science (December 19th 2016) which include another review of the nano diamond question by Tyrone Daulton and pals (see also www.eurekalert.org/pub_releases/2016-12/wuis-tco121916.php). Daulton is presented as an authoritive figure on nano diamonds as he has previously been involved in finding nano diamonds in star dust. He is an establishment figure it would seem and was brought into the debate by Richard Kerr, a science journalist with a reputation for looking down on anything not toeing the consensus science view. Interesting times but no doubt the other side will respond – and perhaps a new paper is being prepared even as you are reading this post. What is certain though is that this story will run for a long time to come. It is also interesting to note that Watts Up is toeing the orthodox line here (are they seeking a bit of credibility with the establishment for long years of opposing global warming?) The comments today are down to 68 pages and growing and some interesting info is emerging. The anti-comet group are in the ascendancy but there are some efforts at counter attack but a general analysis of them would seem to show how embedded the idea of the ocean current system switching has become – mainly because this is what is being taught in education institutions. It relies over heavily on an injection of cold water from glacial melt and this is the weak spot as you need lots of ice released into the North Atlantic. Xavier, who comments way down the thread, says that the Younger Dryas was not a return to glacial conditions – but a temporary cold period that was never as cold as it was in the last Ice Age. This point has several repercussions which is spoilt by suggesting that because sea levels were not as low as they were in the LGM this means the YD was not as cold. If the YD was not a glacial what was it. Some summers in the YD were quite warm so on average it would not have been as cold as the earlier Late Glacial Maximum (which was very cold). The evidence from Britain is ambiguous. Glaciers reformed, or expanded, on high mountains in Scotland, such as Raanoch Moor, but there is no evidence of glaciation in lowland areas. The YD was a different beast to the Ice Age proper – which makes me wonder why some scientists insist on dating the end of the Ice Age to the end of the Younger Dryas. Why do they do that? One reason is that they are repeating what other people say and the end of the Younger Dryas is a convenient perch to bring the Pleistocene to a close and drum in the Holocene (an interglacial episode). It is also interesting to note that when this meme began, decades ago, interglacials were thought to last around 10,000 years in length. In reality the interglacial began around 18 to 15,000 years ago, but here again we have the Oldest Dryas episode (another cooling event as the Ice Age itself came to an end) and a key to what brought it to an end (along with evidence of mass die-off in some parts of the world but not so much in western Europe as you don't get a lot of herbivores in a glaciated region). Another reason perhaps for insisting the Ice Age ended with the end of the Younger Dryas is that it allows some obfuscation on the idea of the preservation of a body of cold water to remain in the Great Lakes region during several thousand years of warming and subsequently pour into the sea as a result of a collapsing ice dam (a dodgy theory by itself as the ice dam had to remain unmelted through the warm episodes between the Oldest, the Older, and the Younger Dryas events. Is that really tenable – or just a convenient theory. What the comments show is that the origins of the Younger Dryas (and the Oldest and Older Dryas events) are still up for grabs and the comet theory is not going away anytime soon.
One other point worth bearing in mind (usually side stepped by claiming the Antarctic region warmed up at a different time than the Arctic) is the Oldest Dryas event. It would have required the release of a lot of cold water into the North Atlantic. This must be so if the Younger Dryas was caused by such a process so must the Oldest, and the Older Dryas events have involved lots of cool formerly ice water locked up in the ice sheet. As far as the Oldest Dryas this is obvious as lot of meltwater would have been available as a result of the retreating ice sheets. It is the timing that is the problem. The Oldest Dryas occurred with no evidence of warming at the end of the Late Glacial Maximum. A small movement at the poles is one idea that is never seriously explored and has never been subject to computer simulation by mainstream scientists. It's a bit like comets at the Younger Dryas boundary – to be opposed at all costs and the debate shut down as preposterous. The Oldest and Younger are so similar that a common cause must connect them. Is it feasible to think a cold body of fresh water was released on the cusp of the end of the Late Glacial Maximum which caused a cool period when the temperatures were already very cold as a result of the Late Glacial Maximum. I suppose you could jiggle around with the ice core and foraminifera data and suggest the LGM was gradually warming up – but as it was an icy environment would it have warmed up enough to melt ice into water, summer and winter? The ocean circulation system model is contradicted by the Oldest Dryas period which is why we have had the additional theory, designed to prop it up, and computer simulated, that the Antarctic warmed up slightly earlier, and this changed the circulation system in the Atlantic. No doubt if there was pole shift of some kind the ocean circulation would also change – allowing the currents to extend further north than they did in the Late Glacial Maximum. Is this what the data is showing – the onset of ocean currents to more northerly climes at the end of LGM? What we know is that in the LGM the ocean circulation was inhibited from reaching the northern zone of the Atlantic as sea ice extended too far to the south. It would require something like a warming in the southern region to send warmer waters northwards – which serves to keep the ocean circulation model alive and kicking. Is it a reality? What caused the ocean water in Antarctic waters to warm up? Pole shift in the north would have been accompanied by the same in the south. As in all these debates the arguments are complex and some people argue from mainstream science articles as if these are the facts rather than theories. Just because some theories are repeated more than others doesn't mean they are any more real than the lesser argued theories. Theory is theory. Facts require the burden of proof – not a computer simulation. We may note that the southern temperature changes have been debunked in any case as Xavier actually relates on the comments thread. None of the evidence so far contradicts the comet theory – unless the nano diamonds are not nano diamonds (which is what one of the new papers alleges). We need to wait and see how the other side respond.