Remote cave study reveals 3000 years of European climate variation
SYDNEY — University of New South Wales Australia-led research on limestone formations in a remote Scottish cave has produced a unique 3000-year-long record of climatic variations that may have influenced historical events including the fall of the Roman Empire and the Viking Age of expansion.
The study of five stalagmites in Roaring Cave north of Ullapool in north-west Scotland is the first to use a compilation of cave measurements to track changes in a climate phenomenon called the North Atlantic Oscillation.
‘Our results also provide the longest annual record of this important phenomenon, which has a big impact on the climate in Europe,’ says study leader, UNSW Professor Andy Baker.
‘It confirms that the during the Medieval Warm Period between 1080 and 1430 the oscillation index was in an unusually prolonged positive phase, which brings increased rain to Scotland and drier conditions in the western Mediterranean,’ says Baker, of the UNSW Connected Waters Initiative Research Centre.
‘Our results also reveal there was another persistent positive phase between 290 and 550, which coincides with the decline of Rome and a period of intensified human migration in southern Europe during the Dark Ages.
‘This was followed by a persistent negative phase between 600 and 900 which may have provided warm and dry conditions in northwestern Europe that made it suitable for westward expansion by the Vikings, although the precise timing of this event is contested.’
The study is published in the journal Scientific Reports.
The North Atlantic Oscillation climate index measures the air pressure difference between Iceland and the Azores islands off the Portuguese coast, and is a record of the strength of the westerly winds in the North Atlantic.
Roaring Cave, or Uamh an Tartair, in northwest Scotland, is a shallow cave beneath a blanket of peat that has accumulated during the past 4000 years.
Rainfall levels in this region closely correspond with the strength of the oscillation index in winter, with higher precipitation when it is positive. And the upward rate of growth of stalagmites in the cave is very sensitive to rainfall — the more water in the peat, the more slowly the stalagmites grow.
‘We painstakingly measured the thickness of each annual growth ring in five stalagmites taken from the cave, including one that provides a continuous annual record spanning more than 1800 years,’ says Baker.
By overlapping the five stalagmites they obtained a proxy record of the climate at the cave during a 3000-year period from about 1000 BC to 2000 AD.
‘Our research provides a climate context for some of the big human migration events in Europe and allows us to start building hypotheses about the impact of environment on societal change,’ says Baker.
The team includes researcher from UNSW, the University of Lausanne in Switzerland and the University of Arizona in the U.S.
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The paper: http://www.nature.com/srep/2015/150611/srep10307/full/srep10307.html
Abstract:
Annually laminated stalagmites can be used to construct a precise chronology, and variations in laminae thickness provide an annual growth-rate record that can be used as a proxy for past climate and environmental change. Here, we present and analyse the first composite speleothem annual growth-rate record based on five stalagmites from the same cave system in northwest Scotland, where precipitation is sensitive to North Atlantic climate variability and the winter North Atlantic Oscillation (NAO). Our 3000-year record confirms persistently low growth-rates, reflective of positive NAO states, during the Medieval Climate Anomaly (MCA). Another persistently low growth period occurring at 290-550 CE coincides with the European Migration Period, and a subsequent period of sustained fast growth-rate (negative NAO) from 600-900 AD provides the climate context for the Viking Age in northern and western Europe.
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Whether there was a MWP or not has little to do with the extent of AGW since 1950 as per the IPCC but as Mark Steyn has said many times, Mann et al. effectively eliminated the notion of natural climate variation:
http://www.atmos.albany.edu/deas/atmclasses/atm305/figspm-10b.jpg
He hilariously quipped that the contention was that nothing at all had happened in the world until 1950.
pished me keks.
Why do you think that the PAST will recycle !!! The only real variable is the Sun !! The Sun has had increased energy output for the last 350 years. If the Solar Cycle is an indication, cooling is upon us; it will just take three years for the oceans to give up their energy….
What ever you do, don’t look at Antarctica and the massive increase in ice sheets over the last 30 years. Do you really think that this doesn’t matter ????
Nonsense. The % change in solar irradiance caused by fairly regular (every century or so) solar diminution creates a statistical decrease in global temperatures that is less than that caused by both noise and sensor error. That said, understanding solar changes measured at the Top Of the Atmosphere is ongoing.
http://phys.org/news/2015-03-fluctuations-solar.html
If the MWP is dismissed for not being completely global (primarily due to lack of data), then how can they say we have global warming now, since we DO have thirty-year climate records for Antarctica that show absolutely no warming? Of course, then they would have to explain how a well-mixed gas in the atmosphere can result in only local warming.
jtom, you misunderstand. The MWP is not global because we haven’t measured everywhere. And AGW is global because we haven’t measured everywhere. This is perfectly consistent. For various values of ‘consistent.’
Yes. Not measured = cooler or warmer depending of on what answer is required to ensure nature is conforming to the known truths of the climate models.
You understand well how the process of how CAGW works, my son. I see fame and fortune in your future.;-)
I met a guy who lived in a cave for 2 years. Curiously interesting.
Read about this in The Scotsman early this morning.
http://www.scotsman.com/news/environment/ullapool-cave-stalagmites-reveal-historic-secrets-1-3802540
Anyone else reporting this in mainstream media?
OK, but in the Climate Science board game one tree ring trumps 50 stalagmites. Just sayin’.
seems the Pope might have dicovered the Medeval Warm Period!
10 June: Catholic Sun: Pope’s encyclical to have medieval Italian, not Latin, title
http://www.catholicsun.org/2015/06/10/popes-encyclical-to-have-medieval-italian-not-latin-title/
oops meant to type Medieval, not medeval…
‘It confirms that the during the Medieval Warm Period between 1080 and 1430 the oscillation index was in an unusually prolonged positive phase, which brings increased rain to Scotland and drier conditions in the western Mediterranean,’ says Baker, of the UNSW Connected Waters Initiative Research Centre.
‘Our results also reveal there was another persistent positive phase between 290 and 550, which coincides with the decline of Rome and a period of intensified human migration in southern Europe during the Dark Ages.
‘This was followed by a persistent negative phase between 600 and 900 which may have provided warm and dry conditions in northwestern Europe that made it suitable for westward expansion by the Vikings, although the precise timing of this event is contested.’
Okay, now I’m confused. The Dark Ages was a time of cooler temperatures, right? So a persistent positive phase of the NAO produced both the Medieval Warm Period and the cool Dark Ages? Warm and dry conditions have been produced by both “prolonged positive” and “persistent negative” phases?
You are quite justified in your confusion. I made the same point above @ur momisugly 2:47pm, but nobody seems to react to my comment. Are you and I the only ones who read this piece critically?
It could mean that NAO in negative phase produces more rain in SUMMER time (growth season and still warm enough) and the opposite with positive phase, although negative NAO means harsher winters in northern Europe? It depends where you are in Europe…
Did we really need confirmation of the Medieval Warm Period?
In other news, re cent research has confirmed the existence of the number four, the color red, oceans, and cable television.
You’ll find that this “recent research” was funded by the oil industry, so wont be believed by journalists or “progressive” types.
A globally sinchronised MWP peaking during the high Middle Ages (ie after 1000 AD) has never been (to my knowedge) demonstrated. Sadly, this has become a common dogma of sceptics. I explain here:
https://enthusiasmscepticismscience.wordpress.com/2013/09/09/millennium-idols-smash-the-hockey-stick-but-smash-the-others-too/
See especially this much touted graph truncated to the millennium:
https://enthusiasmscepticismscience.wordpress.com/2013/09/22/hubert-lamb-and-the-assimilation-of-legendary-ancient-russian-winters/2008_loehlemccullock_truncated/#main
The current warming episode is not uniformly global, the northern latitudes generally and certain N H regions showing more warming than the overall global average.
I’m an interested layman but it’s my impression that the Lamb graph was necessarily a broad indication of a MWP and not adopted as an “icon” of scepticism whereas the Mann et al. ‘hockey stick’ definitely was, by the alarmists.
Its noteworthy that the cooler temperatures during 600-900 AD drove the Vikings to aggressively colonise warmer countries. This could well be a sneak preview of that will happen on a much larger scale once the Holocene ends for good. Time to hone boat-building skills?
‘It confirms that the during the Medieval Warm Period between 1080 and 1430 the oscillation index was in an unusually prolonged positive phase..’
In fact there was a sharp downturn in northwest Europe temperatures from around 1200 which would have to be increased negative NAO:
http://www.nature.com/ngeo/journal/v6/n5/images_article/ngeo1797-f2.jpg
‘Our results also reveal there was another persistent positive phase between 290 and 550, which coincides with the decline of Rome and a period of intensified human migration in southern Europe during the Dark Ages.’
Probably ~380 to 540 AD, and would have to be increased negative NAO as it was colder in NW Europe.
‘This was followed by a persistent negative phase between 600 and 900 which may have provided warm and dry conditions in northwestern Europe that made it suitable for westward expansion by the Vikings, although the precise timing of this event is contested.’
The 8th century was likely the warmest part of the MWP for Europe, and would naturally have been increased positive NAO, but the century ended in an extreme cold event at 793 AD that would have emptied the Viking larders, with further cold periods in the late 10th and early 11th centuries:
Also worth noting is the extraordinarily severe cold events in the 1100’s, as noted in the Chronicle of Michael the Syrian, with frequent freezing of the Euphrates and severe frosts.
When faced with hard facts like this, or the ancient dairy farms and vineyards in far north climes that now barely support lichen, Warmists wave off the data by claiming these were just bubbles of warmth, around which was freezing climates raged. Madness.
LarryFine
Well, more troubling in their hypocrisy is the fact that – this year! – when satellites detected ONE single area over the middle of the north Pacific Ocean – undetectable until satellites started surveying the whole earth! – the climastrologists “averaged” that 5 month isolated single-hot-spot-over-the-north-Pacific-Ocean into the “hottest global average temperature of all time!” hyperbolic propaganda.
Here is the best NH reconstruction which shows clearly the MWP.
http://2.bp.blogspot.com/-4nY2wr6L-WY/U81v9OzFkfI/AAAAAAAAATM/NA6lV86_Mx4/s1600/fig5.jpg
This is Fig 9 from
http://climatesense-norpag.blogspot.com/2014/07/climate-forecasting-methods-and-cooling.html
In conjunction with Figs 5 and 14 and 13 at the same link it is clear that we are now on the cooling side of the millennial temperature peak at 2003. see
http://www.woodfortrees.org/plot/rss/from:1980.1/plot/rss/from:1980.1/to:2003.6/trend/plot/rss/from:2003.6/trend
Reblogged this on Public Secrets and commented:
Here’s one to upset the climate alarmists: the theory behind the fraudlent “hockey stick” was that the Earth’s climate was relatively stable until recently, when man began pouring CO2 into the atmosphere. That required the denial (oh, irony!) of cyclic warm and cool periods in the past, since such cycles challenge the theory of runaway warming. This study provides more strong evidence of one of these warm phases, the Medieval Warm Period. Perhaps the Pope should read this, too.