The Little Ice Age:
How Climate Made History 1300-1850
by Brian M. Fagan
PaperbackFloods, Famines, and Emperors:
El Nino and the Fate of Civilizations
by Brian M. FaganThe Long Summer:
How Climate Changed Civilization
by Brian M. Fagan
Posted on 02/03/2012 9:32:32 AM PST by null and void
A new study appears to answer contentious questions about the onset and cause of Earth’s Little Ice Age, a period of cooling temperatures that began after the Middle Ages and lasted into the late 19th century.
According to the new study, the Little Ice Age began abruptly between A.D. 1275 and 1300, triggered by repeated, explosive volcanism and sustained by a self-perpetuating sea ice-ocean feedback system in the North Atlantic Ocean, according to University of Colorado Boulder Professor Gifford Miller, who led the study. The primary evidence comes from radiocarbon dates from dead vegetation emerging from rapidly melting icecaps on Baffin Island in the Canadian Arctic, combined with ice and sediment core data from the poles and Iceland and from sea ice climate model simulations, said Miller.
While scientific estimates regarding the onset of the Little Ice Age range from the 13th century to the 16th century, there is little consensus, said Miller. There is evidence the Little Ice Age affected places as far away as South America and China, although it was particularly evident in northern Europe. Advancing glaciers in mountain valleys destroyed towns, and famous paintings from the period depict people ice skating on the Thames River in London and canals in the Netherlands, waterways that were ice-free in winter before and after the Little Ice Age.
“The dominant way scientists have defined the Little Ice Age is by the expansion of big valley glaciers in the Alps and in Norway,” said Miller. “But, the time it took for European glaciers to advance far enough to demolish villages would have been long after the onset of the cold period,” said Miller, a fellow at CU’s Institute of Arctic and Alpine Research.
Most scientists think the Little Ice Age was caused either by decreased summer solar radiation, erupting volcanoes that cooled the planet by ejecting shiny aerosol particles that reflected sunlight back into space, or a combination of both, said Miller.
The new study suggests that the onset of the Little Ice Age was caused by an unusual, 50-year-long episode of four massive tropical volcanic eruptions. Climate models used in the new study showed that the persistence of cold summers following the eruptions is best explained by a sea ice-ocean feedback system originating in the North Atlantic Ocean.
“This is the first time anyone has clearly identified the specific onset of the cold times marking the start of the Little Ice Age,” said Miller. “We also have provided an understandable climate feedback system that explains how this cold period could be sustained for a long period of time. If the climate system is hit again and again by cold conditions over a relatively short period — in this case, from volcanic eruptions — there appears to be a cumulative cooling effect.”
A paper on the subject is being published January 31, 2012, in Geophysical Research Letters, a publication of the American Geophysical Union. The paper was authored by scientists and students from CU-Boulder, the National Center for Atmospheric Research in Boulder, the University of Iceland, the University of California, Irvine, and the University of Edinburgh in Scotland. The study was funded in part by the National Science Foundation and the Icelandic Science Foundation.
As part of the study, Miller and his colleagues radiocarbon-dated roughly 150 samples of dead plant material with roots intact collected from beneath receding ice margins of ice caps on Baffin Island. There was a large cluster of “kill dates” between A.D. 1275 and 1300, indicating the plants had been frozen and engulfed by ice during a relatively sudden event.
Both low-lying and higher altitude plants all died at roughly the same time, indicating the onset of the Little Ice Age on Baffin Island — the fifth largest island in the world — was abrupt. The team saw a second spike in plant kill dates at about A.D. 1450, indicating the quick onset of a second major cooling event.
To broaden the study, the team analyzed sediment cores from a glacial lake linked to the 367-square-mile Langjökull ice cap in the central highlands of Iceland that reaches nearly a mile high. The annual layers in the cores — which can be reliably dated by using tephra deposits from known historic volcanic eruptions on Iceland going back more than 1,000 years — suddenly became thicker in the late 13th century and again in the 15th century due to increased erosion caused by the expansion of the ice cap as the climate cooled, he said.
“That showed us the signal we got from Baffin Island was not just a local signal, it was a North Atlantic signal,” said Miller. “This gave us a great deal more confidence that there was a major perturbation to the Northern Hemisphere climate near the end of the 13th century.” Average summer temperatures in the Northern Hemisphere did not return to those of the Middle Ages until the 20th century, and the temperatures of the Middle Ages are now exceeded in many areas, he said.
The team used the NCAR-based Community Climate System Model to test the effects of volcanic cooling on Arctic sea ice extent and mass. The model, which simulated various sea ice conditions from about A.D. 1150-1700, showed several large, closely spaced eruptions could have cooled the Northern Hemisphere enough to trigger Arctic sea ice growth.
The models showed sustained cooling from volcanoes would have sent some of the expanding Arctic sea ice down along the eastern coast of Greenland until it eventually melted in the North Atlantic. Since sea ice contains almost no salt, when it melted the surface water became less dense, preventing it from mixing with deeper North Atlantic water. This weakened heat transport back to the Arctic and creating a self-sustaining feedback system on the sea ice long after the effects of the volcanic aerosols subsided, he said.
"Our simulations showed that the volcanic eruptions may have had a profound cooling effect,” says NCAR scientist Bette Otto-Bliesner, a co-author of the study. “The eruptions could have triggered a chain reaction, affecting sea ice and ocean currents in a way that lowered temperatures for centuries."
The researchers set the solar radiation at a constant level in the climate models, and Miller said the Little Ice Age likely would have occurred without decreased summer solar radiation at the time. “Estimates of the sun’s variability over time are getting smaller, it’s now thought by some scientists to have varied little more in the last millennia than during a standard 11-year solar cycle,” he said.
One of the primary questions pertaining to the Little Ice Age is how unusual the warming of Earth is today, he said. A previous study led by Miller in 2008 on Baffin Island indicated temperatures today are the warmest in at least 2,000 years.
Other co-authors on the paper include CU-Boulder's Yafang Zhong, Darren Larsen, Kurt Refsnider, Scott Lehman and Chance Anderson, NCAR's Marika Holland and David Bailey, the University of Iceland's Áslaug Geirsdóttir, Helgi Bjornsson and Darren Larsen, UC-Irvine's John Southon and the University of Edinburgh's Thorvaldur Thordarson. Larsen is doctoral student jointly at CU-Boulder and the University of Iceland.
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You and me both. I was in Port Townsend WA. and we heard it blow from there. Fortunately the prevailing winds did not bring any ash our way.
Be it as it may, St Helens was a small eruption with a modest VEI of 5.
The verifiable eruptions listed are posted at Global Volcanism Program, Volcanoes of the World, Large Holocene Eruptions - http://www.volcano.si.edu/world/largeeruptions.cfm
“Massive” in volcano speak is anything above a VEI of 6. St Helens at VEI 5 was a hicup or just large. Keep in mind that a super volcano eruption is anything with a VEI of 9 or above.
I have no idea what the “study” volcanoes are. I only posted the known eruptions around that time which would be considered “massive” - draw your own conclusions.
That the “study” centers around a 50 yr period for an event (LIA), which took place over hundreds of years, leaves one wondering just what the point was. I smell a need for more grant money ...
The Little Ice Age:
How Climate Made History 1300-1850
by Brian M. Fagan
PaperbackFloods, Famines, and Emperors:
El Nino and the Fate of Civilizations
by Brian M. FaganThe Long Summer:
How Climate Changed Civilization
by Brian M. Fagan
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Thanks null and void, and the answer's, definitely. :') |
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——there is little consensus———
It is clear to me that the onset caused massive disruption of human life in North America. The 1275 -1300 dating corresponds to the massive change in the South west and Cahokia.
The Anasazi moved from Aztec hundreds of miles south ti Paquim and split into the present Pueblo and Hopi settlements. Simultaneously, Cahokia fell apart and settlements south developed.
What ever it was that caused the chang turned human culture upside down and produced radical change in the way life was lived.
If I recall correctly from a TV show on Discovery or Green Planet, there’s a lab in Scandinavia that has done groundbreaking work collecting sample cores of tree rings from all over the world and relating the rings to worldwide climate changes and known events.
More reading professor? PFL, I barely have time to read everything I want to as it is.
Sure looks constant to me:
It's probably this guy.
A controversy over Baillie's data. See here:
Climate Sceptic Wins Landmark Data Victory 'For Price Of A Stamp'
"Belfast ecologist forced to hand over tree-ring data describes order from information commission as a 'staggering injustice'
I’ve long wondered if there was any sort of coupling mechanism between the Sun’s and Earth’s magnetic fields, where variations in the solar field could trigger volcanoes or earthquakes.
It is said that 250,000 'took to the sea' at the end of the Shang Dynasty.
I've often wondered because this is about the same time that the Olmec appears (very advanced) in Mexico. Maybe some of those Shang survivors?
* 3195BC
* 2354BC
* 1628BC (Exodus?)
* 1159BC
* 207BC
* 44BC
* 540AD (The Dark Ages)
(The Dark Ages: Were They Darker Than We Imagined?)
Thanks for the info. You may be right that the guy was Irish instead of Scandinavian.
I knew it was a small country and I was within a few hundred miles of being right on target. :-)
I am absolutely amazed and delighted on a daily basis by how much information our Freepers like yourself have at their fingertips.
Me, I just like to read and poke fun at accepted ‘scientific truths’ and shibboleths.
-——What ever it was that caused the chang ——
This is the way things actually get screwed up as the result of poor or miscommunication. I left off the “e”..... I meant to say change. : )
The unintended result was to shift the focus from the North American Indians to something completely different. I read the book you recommended on The Voyages of the Pyramid Builders. Now I guess you are pointing me onward in a more specific direction.
Back in October I visited Cahokia where a very large truncated pyramid is located. The place fell apart during the period noted in this article. Cahokia was contemporary with the Anasazi and the Arizona Hohokam. At the time noted, Cahokia was larger than many European cities especially London
I have been Reading several of the books by Stephen Lekson, especially The History of the Ancient Southwest. He says..... everybody knew everything, distance was not a problem. What he means is that all the various populations knew of the others and were actively involved in trade and the distance covered to trade was not a problem.
Much later, the Spanish wanted to find Eldorado. A western Mexico Indian took them to the pueblos and they were disappointed.He led them on and they killed them in Kansas because they no longer believed him. They had traveled too far. He was surely bound for the long gone Cahokia.
A decent book about this area:
I know that St. Helens was not a huge eruption compared to other volcanic events throughout history. It was still an impressive reminder of the awesome power of nature. I was climbing it with a group of friends just a couple of years before. The day it blew up I was at some friends house that had a perfect view of the entire North Western side of the mountain.
I don't doubt at all that volcanic activity can have a profound effect on the climate for a few years at the least. Studying volcanic activity's influence on the climate may actually be worth a little grant money? The thing that makes me uneasy about this particular study is the cast of characters involved, the study’s reliance on a computer model and at least in this article... the lack of documentation as to which historically documented events that they are referring to, and as you note the time-line that they are referring to.
I also am suspicious of any theory that has simple explanations about a system as complicated as the world's climate.
My wife and I own a small airplane. Many years ago we were flying back from California and we ran into bad weather. We had both been feeling poorly and got off to a slow start. We also had a headwind. In Northern California we found ourselves late at night between two layers of clouds over mountains with thunderstorm activity, heavy rain, turbulence and very poor visibility.
By the time we made it down to where we were flying above I-5 just North of Grants Pass, my wife had become extremely rattled. We were a few hundred feet over the freeway and still getting bounced around pretty severely. It was pitch black, the heavy rain was pelting the windscreen and we could see almost nothing. To top it off we were running low on fuel. She started crying and sobbing that she would rather be giving birth again. It was at that point that I realized at a visceral level that it is generally not one thing that causes a pilot to lose control of his / her airplane... it is all of the factors combined.
I am suspicious of simple explanations for complex systems. Volcanic activity may very well have been a contributor to the start of the Little Ice Age, but I think trying to ignore solar activity and other factors is unwise and most likely motivated by an alarmist agenda and not good science.
I can’t imagine a connection. My understanding is that the main driver for tectonic activity is lunar tides.
:’) I’ve got two of ‘em, have even read one of them. :’)
Thanks blam, looks like a topic or two could be built from those.
Lots of speculation; plenty of scientification, but very little, if any, science.
50-year-long episode of four massive tropical volcanic eruptions.
Which volcanoes, where? Curious minds would like to know.
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