From NCAR/UCAR, they’re still trying to stamp out solar influence as a potential cause of the Little Ice Age. One of the things I wonder about is that during low sunspot activity, does the reduced solar-magnetic influence have any effect on Earth’s plate tectoncs and vulcanism? Does a reduced solar-magnetic influence prompt more volcanism? We may get the answer to this question in the coming years as the Ap solar-geomagnetic activity index is at an all-time low in the records.
Study may answer longstanding questions about Little Ice Age
BOULDER — A new international study may answer contentious questions about the onset and persistence of Earth’s Little Ice Age, a period of widespread cooling that lasted for hundreds of years until the late 19th century.
The study, led by the University of Colorado Boulder with co-authors at the National Center for Atmospheric Research (NCAR) and other organizations, suggests that an unusual, 50-year-long episode of four massive tropical volcanic eruptions triggered the Little Ice Age between 1275 and 1300 A.D. The persistence of cold summers following the eruptions is best explained by a subsequent expansion of sea ice and a related weakening of Atlantic currents, according to computer simulations conducted for the study.
The study, which used analyses of patterns of dead vegetation, ice and sediment core data, and powerful computer climate models, provides new evidence in a longstanding scientific debate over the onset of the Little Ice Age. Scientists have theorized that the Little Ice Age was caused by decreased summer solar radiation, erupting volcanoes that cooled the planet by ejecting sulfates and other aerosol particles that reflected sunlight back into space, or a combination of the two.
“This is the first time anyone has clearly identified the specific onset of the cold times marking the start of the Little Ice Age,” says lead author Gifford Miller of the University of Colorado Boulder. “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.”
“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 study appears this week in Geophysical Research Letters. The research team includes co-authors from 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, NCAR’s sponsor, and the Icelandic Science Foundation.
Far-flung regions of ice
Scientific estimates regarding the onset of the Little Ice Age range from the 13th century to the 16th century, but there is little consensus, Miller says. Although the cooling temperatures may have affected places as far away as South America and China, they were particularly evident in northern Europe. Advancing glaciers in mountain valleys destroyed towns, and paintings from the period depict people ice-skating on the Thames River in London and canals in the Netherlands, places that were ice-free 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,” says Miller, a fellow at CU’s Institute of Arctic and Alpine Research. “But the time in which European glaciers advanced far enough to demolish villages would have been long after the onset of the cold period.”
Miller and his colleagues radiocarbon-dated roughly 150 samples of dead plant material with roots intact, collected from beneath receding margins of ice caps on Baffin Island in the Canadian Arctic. They found a large cluster of “kill dates” between 1275 and 1300 A.D., indicating the plants had been frozen and engulfed by ice during a relatively sudden event.
The team saw a second spike in plant kill dates at about 1450 A.D., indicating the quick onset of a second major cooling event.
To broaden the study, the researchers 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.
“That showed us the signal we got from Baffin Island was not just a local signal, it was a North Atlantic signal,” Miller says. “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.”
The team used the Community Climate System Model, which was developed by scientists at NCAR and the Department of Energy with colleagues at other organizations, to test the effects of volcanic cooling on Arctic sea ice extent and mass. The model, which simulated various sea ice conditions from about 1150 to 1700 A.D., showed several large, closely spaced eruptions could have cooled the Northern Hemisphere enough to trigger the expansion of Arctic sea ice.
The model showed that 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 created a self-sustaining feedback on the sea ice long after the effects of the volcanic aerosols subsided, according to the simulations.
The researchers set solar radiation at a constant level in the climate models. The simulations indicated that the Little Ice Age likely would have occurred without decreased summer solar radiation at the time, Miller says.
About the article
Title: Abrupt onset of the Little Ice Age triggered by volcanism and sustained by sea-ice/ocean feedbacks
Authors: Gifford Miller, Áslaug Geirsdóttir, Yafang Zhong, Darren J. Larsen, Bette L. Otto-Bliesner, Marika M. Holland, David A. Bailey, Kurt A. Refsnider, Scott J. Lehman, John R. Southon, Chance Anderson, Helgi Bjornsson, Thorvaldur Thordarson,
Publication: Geophysical Research Letters
=============================================================
Here’s the paper abstract, the actual paper is not yet available (another science by press release that we can’t check).
http://www.agu.org/pubs/crossref/pip/2011GL050168.shtml
GEOPHYSICAL RESEARCH LETTERS, doi:10.1029/2011GL050168
Abrupt onset of the Little Ice Age triggered by volcanism and sustained by sea-ice/ocean feedbacks
- Little Ice Age began abruptly in two steps
- Decadally paced explosive volcanism can explain the onset
- A sea-ice/ocean feedback can sustain the abrupt cooling
Gifford H Miller
Aslaug Geirsdottir
Yafang Zhong
Darren J Larsen
Bette L Otto-Bliesner
Marika M Holland
David Anthony Bailey
Kurt A. Refsnider
Scott J. Lehman
John R. Southon
Chance Anderson
Helgi Björnsson
Thorvaldur Thordarson
Northern Hemisphere summer temperatures over the past 8000 years have been paced by the slow decrease in summer insolation resulting from the precession of the equinoxes. However, the causes of superposed century-scale cold summer anomalies, of which the Little Ice Age (LIA) is the most extreme, remain debated, largely because the natural forcings are either weak or, in the case of volcanism, short lived. Here we present precisely dated records of ice-cap growth from Arctic Canada and Iceland showing that LIA summer cold and ice growth began abruptly between 1275 and 1300 AD, followed by a substantial intensification 1430-1455 AD. Intervals of sudden ice growth coincide with two of the most volcanically perturbed half centuries of the past millennium. A transient climate model simulation shows that explosive volcanism produces abrupt summer cooling at these times, and that cold summers can be maintained by sea-ice/ocean feedbacks long after volcanic aerosols are removed. Our results suggest that the onset of the LIA can be linked to an unusual 50-year-long episode with four large sulfur-rich explosive eruptions, each with global sulfate loading >60 Tg. The persistence of cold summers is best explained by consequent sea-ice/ocean feedbacks during a hemispheric summer insolation minimum; large changes in solar irradiance are not required.
Received 29 November 2011; accepted 30 December 2011.
Citation: Miller, G. H., et al. (2012), Abrupt onset of the Little Ice Age triggered by volcanism and sustained by sea-ice/ocean feedbacks, Geophys. Res. Lett., doi:10.1029/2011GL050168, in press.
@ur momisugly rossbrisbane says:
Perhaps you need to read my papers before criticizing them. There are a little bit more complicated than simply curve fitting. And there exists a long discussion about the parameters adopted there.
As shown in my papers, in particular in the latest one, the issue is that all GCMs adopted by the IPCC fail to properly reconstructing thae main patterns observed in the climate system including the steady temperature since 2000.
Tell me, which GCM model agrees with the data? Which GCM passes proper scrutiny?
Name one model, at least! You can look at the appendix of the paper and tell us your best choice.
N. Scafetta, “Testing an astronomically based decadal-scale empirical harmonic climate model versus the IPCC (2007) general circulation climate models” Journal of Atmospheric and Solar-Terrestrial Physics, in press. DOI: 10.1016/j.jastp.2011.12.005.
http://www.fel.duke.edu/~scafetta/pdf/Scafetta_models_comparison_ATP.pdf
Studying the data and tring to understanding the dynamics they contain is the way science works. Science does not start with a fully understood mechanism, but with the data and their anaysis.
@ur momisugly Hi Leif, are you sure you did not miss something while in Japan? 🙂
About the paper we are discussing in this post, thanks to Leif who put the paper of his web-site, I invite to look at their figure 2A,B and C.
The increase of Ice cap expansion (figure 2C) between 1270 and 1500 is clearly in agreement with the solar pattern with two cool periods (maximum cap expansion) during the two prolonger solar minima Wolf (1270-1300) and Sporer (~1435) minima and a partial recovery between the two low solar mimima periods.
About the volcano activity, please note the large vocano spike around 1258 and around 1460 (figure 2B). The 1258 volcano is presented at the precurson of the Little Ice age because it occurred a few decades before the large cap expansion peak between 1270 and 1300. However, the large volcano spike in 1460 occurred while the cap expansion was rapidly “decreasing” and it does not appear to have had any effect on climate.
Thus, it is evident that the strong ice cup increase peak around 1430-1440 is related to the grand minima of the solar activity, and not to the volcano occurence, which happened after it around 1460. What do you think, Leif, about this point?
Nicola Scafetta says:
January 30, 2012 at 8:32 pm
What do you think, Leif, about this point?
I think you don’t need to try to hijack this thread too. We have already discussed the flaws of your papers, so no need to wallop in them again.
Nicola Scafetta says:
January 30, 2012 at 8:32 pm
Doesn’t matter whether you think your models are crunching data in a meaningful way. If you have 20 equations with 24 unknowns, the best and most powerful computers with the most innovative algorithms ain’t gonna solve that baby.
Leif, are you sleeping?
I am talking about the paper currently addressed here. About my papers yo need some update.
They claim that the large Ice cup increase during the LIA was caused by volcano activity and that the sun does not matter at all.
Now, look at their figure 2A, 2B and 2C. In particular at the strong ice cup increase peak around 1430-1440. This occurred excactly at the minima of the grand solar Sporer Minimum. On the contrary, the major volcano activity peak occurred around 1460.
So, my question is: was the strong ice cup increase peak around 1430-1440 caused more likely by the solar low activity of that time or by the great Volcano eruption of 20 years later?
Note that no significant volcano eruptions occurred between 1350 and 1450
Anthony, if you can, would you like to show Figure 2 in the paper by magnifying figure 2A, 2B and 2C between 1400 and 1500 with some arrow to indicate the points I am talking about?
The author of the paper say:
“The PDF peak between 1430 and 1455 AD corresponds with a large eruption in 1452 AD, although the ages of the three largest 5-year bins appear to precede the eruption date. In contrast to the earlier 13th Century peak, the second PDF peak occurs at the end of a 150-year interval of variable but falling snowline (Figure 2c), raising the possibility that the PDF peak plausibly reflects a brief natural episode of summer cold that preceded the large 1452 AD eruption.”
“a brief natural episode of summer cold that preceded..”? Brief?, it was 20 years. Cased by what? by the volcano activity of 1452?!
Nicola Scafetta says:
January 30, 2012 at 9:14 pm
that the sun does not matter at all.
They probably got that right. But beware of your weasel words “at all”. Of course, the sun matter somewhat, like a little bit, but it is clear that the sun is not a major driver and that therefore the LIA has other, natural causes.
“Based on computer simulations.” There they go again.
Nicola Scafetta says:
January 30, 2012 at 9:14 pm
Now, look at their figure 2A, 2B and 2C. In particular at the strong ice cup increase peak around 1430-1440. This occurred excactly at the minima of the grand solar Sporer Minimum. On the contrary, the major volcano activity peak occurred around 1460.
http://en.wikipedia.org/wiki/Sp%C3%B6rer_Minimum 1460-1550
“Because the energy involved is so small. It is like judging a billionaire’s wealth by the varying loose change in his pocket.”
Thanks Leif for quantifying that for me! 🙂
Paul Wanamaker says:
January 30, 2012 at 9:55 pm
“Because the energy involved is so small. It is like judging a billionaire’s wealth by the varying loose change in his pocket.”
Thanks Leif for quantifying that for me! 🙂
The EUV is less than 1/10,000 of the visible energy:
http://lasp.colorado.edu/sdo/meetings/session_1_2_3/presentations/session2/2_01_Viereck.pdf
and is absorbed above 100 km altitude where the density is less than 1/1000,000 of that at the surface. So up there there is a large effect [on a very small total mass] but it has no effect on the climate below. There is simply not enough stuff up there to make any difference.
Paul Wanamaker says:
January 30, 2012 at 9:55 pm
“Because the energy involved is so small. It is like judging a billionaire’s wealth by the varying loose change in his pocket.”
Thanks Leif for quantifying that for me! 🙂
Instead of taking obscure comments from a scientist with obvious AGW bent, as gospel, I suggest you research the topic more thoroughly. EUV impacts the atmosphere directly down to 70 km as well as producing species that filter down to lower levels that control ozone production. FUV is responsible for ozone production down to 30km. EUV varies by 100% and FUV by 30% over the solar cycle.
http://tinyurl.com/2dg9u22/?q=node/236
Leif Svalgaard says:
January 30, 2012 at 9:41 pm
http://en.wikipedia.org/wiki/Sp%C3%B6rer_Minimum 1460-1550
A poor reference from someone who should know better. 10Be and 14C records clearly show the drop off in solar activity occurs long before 1460.
http://tinyurl.com/2dg9u22/images/solanki_sharp.png
http://upload.wikimedia.org/wikipedia/commons/5/5c/Carbon14_with_activity_labels.svg
Geoff Sharp says:
January 30, 2012 at 10:31 pm
EUV impacts the atmosphere directly down to 70 km
slide 16 of: http://lasp.colorado.edu/sdo/meetings/session_1_2_3/presentations/session2/2_01_Viereck.pdf
as well as producing species that filter down to lower levels that control ozone production.
The density is so low [less than a 1/1000 of that in the stratosphere] that it doesn’t matter what ‘filters down’. The ozone is produced below 50 km in concentrations thousands of times larger than what is up there in the thermosphere. EUV has no influence on the climate.
Geoff Sharp says:
January 30, 2012 at 10:41 pm
10Be and 14C records clearly show the drop off in solar activity occurs long before 1460.
Now you are down to dueling cherry picking. The LIA is a broad event lasting several hundred years and has likely nothing to do with solar activity anyway: http://www.leif.org/research/Global-Temperatures-2000-yrs.png
So four massive tropical volcanic eruptions (may have) triggered the Little Ice Age between 1275 and 1300 A.D, “…our simulations showed that the volcanic eruptions may have had a profound cooling effect…”
Then again maybe not, “…frequent volcanic eruptions from 1100 to 1260 A.D. may have added to regional warming. Volcanic eruptions may have resulted in mild winters in northern and western Europe during High Medieval time…”.
http://www.sciencedaily.com/releases/2003/10/031020055353.htm
Authors of these papers may be laughing all the way to the bank.
Leif Svalgaard says:
January 30, 2012 at 11:09 pm
————————-
perhaps you are using the wrong reconstructions, what do you think about this ?
http://img.photobucket.com/albums/v207/neuralnetwriter/GlobalWarming/JK_Austrian_Speleothem.jpg
http://www.uibk.ac.at/geologie/pdf/spa12.pdf
Leif Svalgaard says:
January 30, 2012 at 10:58 pm
as well as producing species that filter down to lower levels that control ozone production.
The density is so low [less than a 1/1000 of that in the stratosphere] that it doesn’t matter what ‘filters down’. The ozone is produced below 50 km in concentrations thousands of times larger than what is up there in the thermosphere. EUV has no influence on the climate.
I noticed you are now limiting your argument to EUV only and forget FUV. You have already been shown to be incorrect in this area and your opinion is in opposition to atmospheric scientists that are considered expert. This is not your field, how many papers have you written dealing with UV modulation in our atmosphere?
Now you are down to dueling cherry picking. The LIA is a broad event lasting several hundred years and has likely nothing to do with solar activity anyway:
I am merely pointing out your weak wiki statement is irrelevant and incorrect. Nicola is showing the growth in ice happens at the time of solar grand minimum (sporer) well before the volcanic event listed in the paper. There are 4 grand minima during the LIA, you need to be specific with the timing, the whole period was not cool.
Manfred says:
January 30, 2012 at 11:46 pm
perhaps you are using the wrong reconstructions, what do you think about this ?
“wrong”?
You show a reconstruction from Austria. Is that supposed to be valid as Global Temperature?
And BTW, the cosmic ray variation is not correct. The cosmic rays that reach the atmosphere vary foremost with the strength of the geomagnetic field rather than with solar activity. Here is the real cosmic ray variation: red curve at bottom: http://www.leif.org/research/INTCAL-Jasper.png and here for the past 10,000 years: http://www.leif.org/research/CosmicRays-GeoDipole.jpg The solar modulation are the small wiggles.
Perhaps I should note that I’m not pushing the volcano idea. Just remarking that it is something that could be in the mix.
Leif Svalgaard says:
January 31, 2012 at 12:01 am
Manfred says:
January 30, 2012 at 11:46 pm
perhaps you are using the wrong reconstructions, what do you think about this ?
“wrong”?
You show a reconstruction from Austria. Is that supposed to be valid as Global Temperature?
———————————————————
The author claims it is global and from what he says, I think this is far superior to any other reconstruction. Here is my translation from a German TV discussion:
Question: So you say we did have warmer times and colder times within those 10000 years ?
Mangini: Yes, what we see from our data is indeed, that within 300 years it can go up and down, relatively or very fast, and there is variability in the temperature between 1 and 3 degrees, and I am very conservative here, it may well be within that range.
Rahmstorf interrupting: locally
Mangini: No, it is not local. We see this from the Alps up to Norway, all correlated and synchronous.
Rahmstorf interruptung: This is local for me.
Mangini: North-Atlantic synchronous, China synchronous, Chile synchronous, they are all synchronous, this is the great thing about stalagmites, because, as we can date them so well, we really see those peaks happening at all places at the same time.
We have been working for about 10-15 years intensively on stalagmites and we even got now a research group from the DFG in Heidelberg to extract precipitation and temperature from stalagmites from the signals we see in them.
Stalagmites grow layer upon layer and every layer is approximately 1 year and you can, if you measure the stable isotopes in a stalagmite, extract a formation over the growth period of a stalagmite. Stalagmites can be dated very well, there a many stalagmites, spread over all continents and these are very beautiful archives.
Geoff Sharp says:
January 30, 2012 at 11:48 pm
I noticed you are now limiting your argument to EUV only and forget FUV.
The FUV is absorbed in the E-layer and also does not get lower down and varies a lot less.
You have already been shown to be incorrect in this area and your opinion is in opposition to atmospheric scientists that are considered expert.
Nonsense. You misunderstand their papers. The FUV doesn’t have a significant climate signature either.
This is not your field, how many papers have you written dealing with UV modulation in our atmosphere?
Don’t fall in the trap believing that fields are so narrow that only somebody that doesn’t know anything can span them all. FUV absorption and its creation of the E-layer is something I have studied for decades. I use that for calibration of the sunspot number via the diurnal variation of the geomagnetic field.
There are 4 grand minima during the LIA, you need to be specific with the timing, the whole period was not cool.
The timing doesn’t matter as the temperature was low for hundreds of years and not related to solar activity: http://www.leif.org/research/Global-Temperatures-2000-yrs.png
Geoff Sharp says:
January 30, 2012 at 11:48 pm
the growth in ice happens at the time of solar grand minimum (sporer) well before the volcanic event listed in the paper.
If you care to actually read the paper you’ll learn that it does not claim that the LIA started in 1460:
“Sea ice was rarely present on the North Iceland shelf from 800 AD until the late 13th Century, when an abrupt rise in sea-ice proxies suggests a rapid increase in Arctic Ocean sea ice export, followed by another increase 1450 AD, after which sea ice was continuously present until the 20th Century [Massé et al., 2008] (Figures 1 and 2e). The increase in sea ice north of Iceland at the start of the LIA, and its persistence throughout the LIA, supports our modeling experiments suggesting explosive volcanism and associated feedbacks resulted in a self-sustaining expanded sea-ice state beginning 1275–1300 AD. Additional support for regional cooling beginning in the late 13th Century comes from the inversion of temperatures measured in a borehole through the south dome of the Greenland Ice Sheet (Figure 1).”
Translation were excerpts from this TV discussion in German
http://klimakatastrophe.wordpress.com/2008/03/02/latif-rahmstorf-schonwiese-meinungsmache-gegen-klimaskeptiker/
Nicola Scafetta says:
January 30, 2012 at 9:14 pm
Anthony, if you can, would you like to show Figure 2 in the paper by magnifying figure 2A, 2B and 2C between 1400 and 1500 with some arrow to indicate the points I am talking about?
http://tinyurl.com/2dg9u22/images/miller.png
“Does a reduced solar-magnetic influence prompt more volcanism?”
There has been speculation for some years that the rates of nuclear decay throughout the Earth may be modulated by varying solar neutrino fluxes.
Leif Svalgaard says:
January 30, 2012 at 8:06 pm
eyesonu says:
January 30, 2012 at 7:54 pm
Homage to the ‘Team’?
You can pay your own homage to whomever you like. How about some substance instead?
===================
After reading your response and reviewing what I wrote, well……It does read quite different than what I meant. Sorry. This was a moment of ‘open mouth and insert foot’ on my part. It should have carried a ‘sarc’ tag.
The other part of the original comment that I made would have better been stated as “If one only knows how to use a hammer, would one only seek nails to work with?” This was perhaps an ad hom directed at the ‘Team’s’ obsession with CO2.
The paper by Miller et al is very interesting and appears to be very well supported.
Effects of forcings on climate appears to take very long periods of time before the results reach an ‘equalibrium’ again or return to a normal, if there is such a thing as a normal. It’s a chaotic world we live on / in and I don’t think we have much to do with affecting it’s climate. There are much greater forces at work.