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.
If cosmic changes affect the atmosphere, it’s likely they affect magma.
Cosmic rays ionize molecules in the atmsphere. Why not magma?
With both changes to fluid and magnetic field, I’d think there would be changes to pressures and circulation paterns in fluids.
Leif Svalgaard says:
January 31, 2012 at 11:34 pm
TomRude says:
January 31, 2012 at 11:16 pm
You are putting your own words (the 1450 date) in my mouth
this is what you said:(..)
===
Leif here is YOUR original post:
Leif Svalgaard says:
January 31, 2012 at 11:14 am
Nicola Scafetta says:
January 31, 2012 at 11:02 am
that a 20-year large ice cover increase peak from 1430 to 1450 was induced, according to the authors, by a volcano eruption occurred in their data in 1452 instead that by the great solar Sporer minimum in 1420-1450 so evident in their own data? Does it make sense?
The eruption in 1452 was not the cause of the LIA [which started a long time before], and they don’t claim that. The LIA [according to the paper] is a self-sustaining event over hundreds of years, helped along by the occasional eruption during the centuries.
==
You wrote this not me. EOM
Geoff Sharp says:
January 31, 2012 at 11:58 pm
But most these days refer to the Lyman-alpha portion (125.6nm) as the top end of the EUV scale with 10 being the baseline and XUV below 10. This is certainly the scale that NASA has adopted.
NASA don’t ‘adopt’ things. Individual scientists write that stuff, e.g. [ http://www.archive.org/details/nasa_techdoc_19970004842 ] “We observed the Io torus from 820-1140 A on universal time (UT) 20.25 July 1994 from a sounding rocket telescope/spectrograph. These observations serve as only the fourth published spectrum of the torus in this wavelength range, and the only far ultraviolet (FUV) data documenting the state of the torus during the Shoemaker Levy 9 Impacts.” saying that 82-114 nm is FUV. Just don’t claim that someone is ‘wrong’ on this just because they prefer a different boundary.
EUV and FUV are major players and if there are changes in the output of these parts of the spectrum, there are downstream changes that affect the mesosphere,stratosphere AND troposphere. You can resist the accepted science, but it only makes you look silly.
The energy in EUV and FUV is too minute to have any significant effects on the troposphere and no climate effects have been demonstrated. ‘Accepted science’ has to do with effects in the thermosphere and upper mesosphere. There is no ‘accepted science’ that EUV and FUV are major players in climate.
BTW, FUV during the 20th century was the same as FUV in the 18th century. Perhaps you are also claiming that the climate was the same, firmly adhering to the AGW view that there was no LIA at all.
Edim says:
February 1, 2012 at 4:21 am
Those who know know that they don’t know. And vice versa.
arguing from a position of ignorance does not seem very fruitful, but suit yourself.
TomRude says:
February 1, 2012 at 9:29 am
So what’s the title of Miller’s paper for? It’s called “Abrupt onset of the Little Ice Age triggered by volcanism and sustained by sea-ice/ocean feedbacks” is this not?”
Provided you will acknowledge that you wrote the above, could you please parse it and explain what it means.
This paper is mostly discredited here by a volcanologist: http://www.wired.com/wiredscience/2012/01/volcanoes-and-the-little-ice-age-not-the-smoking-gun/#more-94336
Leif Svalgaard says:
February 1, 2012 at 10:00 am
The energy in EUV and FUV is too minute to have any significant effects on the troposphere and no climate effects have been demonstrated. ‘Accepted science’ has to do with effects in the thermosphere and upper mesosphere. There is no ‘accepted science’ that EUV and FUV are major players in climate.
We are not talking about energy as you well know…we are talking chemical changes that affect ozone etc.
I have referenced Hood, Solomon, Marsh, Baldwin and many other authors who are considered experts in this field. They all disagree with Dr. Svalgaard, who has no expertize in this area. I rest my case.
Geoff Sharp says:
January 31, 2012 at 11:58 pm
EUV and FUV are major players and if there are changes in the output of these parts of the spectrum, there are downstream changes that affect the mesosphere,stratosphere AND troposphere. You can resist the accepted science, but it only makes you look silly.
This is what ‘accepted science’ says:
Solar Output Signals in Troposphere:
Visible/IR: small “bottom up” signals in reported in troposphere
UV: clear heating effects in stratosphere (ozone layer) – may have subtle “top down” effects on troposphere
EUV: dominates thermosphere, no evidence nor credible mechanism for coupling to the troposphere
X-Rays: major effects in thermosphere, no evidence or credible mechanism for coupling to the troposphere
Solar wind: same as for EUV and X-rays
Cosmic Rays: proposed modulation of cloud cover
SEPs: destroy ozone so may have similar effects to UV
Slide 8 of http://www.rmets.org/pdf/presentation/20111207-lockwood.pdf
As you say: resisting accepted science only makes you look silly.
Geoff Sharp says:
February 1, 2012 at 2:13 pm
We are not talking about energy as you well know…we are talking chemical changes that affect ozone etc. […] I rest my case.
The chemical changes have very little influence on the ozone layer and no known or accepted climate effects. You misread and misinterpret your references. But it is time anyway to rest your sorry ‘case’.
Geoff Sharp says:
January 31, 2012 at 11:58 pm
You can resist the accepted science
From http://www.nature.com/nature/journal/v467/n7316/full/nature09426.html
“our findings raise the possibility that the effects of solar variability on temperature throughout the atmosphere may be contrary to current expectations”
The reason for this is the recent finding that “using the SIM data, solar radiative forcing of surface climate is out of phase with solar activity” due to the unexpected large variation in middle ultraviolet [not FUV or below]. Time for you to get up to speed on this…
E.M.Smith says:
January 31, 2012 at 10:31 pm
================
That is the best point made in this discussion and I fully agree.
Leif Svalgaard says:
February 1, 2012 at 2:46 pm
Keep trying Leif, your references are weak. Lockwood is certainly no expert.
REPLY: IMHO he’s more of an expert than you are Geoff. Take a time out from WUWT for a couple of days, I don’t want another one of your fights breaking out. – Anthony
Jon says:
February 1, 2012 at 10:44 am
This paper is mostly discredited here by a volcanologist: http://www.wired.com/wiredscience/2012/01/volcanoes-and-the-little-ice-age-not-the-smoking-gun/#more-94336
Some interesting extra facts presented in this link. Miller has used the global or southern hemisphere SO2 record in his study, but when looking at the northern hemisphere the profile looks very different, esp around 1452. If the NH ice core records didn’t see the 1452 eruption, how was the northern ice sheet affected according to Miller’s theory?
Geoff Sharp says:
February 1, 2012 at 6:56 pm
REPLY: IMHO he’s more of an expert than you are Geoff. Take a time out from WUWT for a couple of days, I don’t want another one of your fights breaking out. – Anthony
I am not saying I am an expert. I have been posting peer reviewed papers from the top atmospheric authors that cover decades of research. Lockwood is not renown for his work in atmospheric science. I am happy to take a couples of days break, but I feel you are playing the censor.
REPLY: Last time when you got fiery feisty, you ended up with a couple of months ban. I’m seeing the same pattern beginning to emerge again. I’m suggesting you take a break so I don’t HAVE to play censor – Anthony
Geoff Sharp says:
February 1, 2012 at 7:18 pm
I have been posting peer reviewed papers from the top atmospheric authors that cover decades of research. Lockwood is not renown for his work in atmospheric science.
One does not need to be renowned, only to know the science, and he is just [as I] reporting on ‘accepted science’ in a talk given at the Royal Meteorological Society. The papers you refer to are alright as they go, but are irrelevant for lower atmospheric physics and neither the energy deposited nor the chemical changes in the upper atmosphere are large enough to materially affect the lower. In the next talk at that meeting, Joanna Haigh [who is renowned] confirms that http://www.rmets.org/events/abstract.php?ID=4649
“neither the energy deposited nor the chemical changes in the upper atmosphere are large enough to materially affect the lower”
Any change in the stratospheric temperature will affect the height of the tropopause such that if the gradient between equator and pole is affected then the surface air pressure distribution including the permanent climate zones will slide poleward or equatorward beneath the tropopause.
Hence the significance of this:
“our findings raise the possibility that the effects of solar variability on temperature throughout the atmosphere may be contrary to current expectations”.
I have previously analysed one of the possibilities in some detail here:
http://climaterealists.com/index.php?id=6645
“How The Sun Could Control Earth’s Temperature”
Is there a killer point in the current ongoing research that suggests an alternative scenario ?
Re: Jon
I took a look at the paper you referenced and found it basically making much the same point I have been making and even references one of the same websites. Thanks.
In the midst of this side argument about solar influence, I think key points have missed about the fundamental flaws in this paper.
For one thing, the LIA is, according to Wikipedia, occurred from 1550 to 1850 and this paper is discussing events occurring up to almost 300 years before that as triggering sea-ice changes that were sustained by further eruptions. Aside from dramatically changing the time frame of the LIA and expanding it by about 300 years, there is no evidence of an ongoing level of eruptions throughout the entire period to sustain the changes or any diminution of eruptions to cause the changes to stop. As a matter of fact, the 19th century was extremely active in terms of volcanic eruptions which is period when the LIA ends. That a strong eruption can cool the Earth for a number of years isn’t a question, but whether it can set in motion a self-sustaining cooling trend without additional more or less equivalent eruptions (which clearly didn’t happen) is mostly conjecture. Also needing clarification is how warm periods could occur during this self-sustaining trend.
Stephen Wilde says:
February 2, 2012 at 4:08 am
Any change in the stratospheric temperature will affect the height of the tropopause such that if the gradient between equator and pole is affected then the surface air pressure distribution including the permanent climate zones will slide poleward or equatorward beneath the tropopause.
Any large enough change will affect …
This is the key. Clearly a change of 0.00000001K will not affect anything measurably. So your word ‘any’ has to be suitable quantified.
Leif Svalgaard said:
“Any large enough change will affect …
This is the key. Clearly a change of 0.00000001K will not affect anything measurably. So your word ‘any’ has to be suitably quantified.”
It seems large enough to many. Your quantification is way out when chemically induced changes in ozone amounts at different levels are taken into account.
The very papers that you link to concede larger changes than that and that there is a top down effect and that in some layers of the atmosphere (above 45km) the sign of the solar effect is the opposite of that expected from established science.
My suggestion is the only one that seeks to account for that reverse sign effect. In fact my article was written before that reverse sign effect was actually publicised. I felt obliged to assume that the reverse sign effect existed because of other real world observations.
Some of what I see from the claims in the paper:
(1). M. Mann is aware that there was in fact a little ice age.
(2). Ice receeding as of ‘today’ shows that there was none in the past as evidenced by plant growth now being revealed under the ice.
(3). The title of the paper is deceptive with regards to its content.
(4). Climate can change abruptly without the forcing of manmade CO2.
(5). The effect of a forcing event can last for a long time. Is the Earth still recovering from the little ice age?
There are a lot of solid arguments presented contrary to claims made in the paper and contrary to the title of the paper.
So what does all this mean? Probably nothing important.
I have been saying for some time that solar variability affects the vertical temperature profile of the atmosphere so as to alter the gradient in the height of the tropopause between equator and pole.
That allows the permanent climate zones to shift poleward or equatorward as part of a global energy balancing exercise.It is the relative tropopause heights at equator and poles that matter. Generally the oceans most affect the heights at the equator and the sun affects most the heights at the poles and each effect can suppement or offset the other at an given time.
It is a pair of see saws, one in each hemisphere, with the tropopause as the cross piece and the fulcrum around 45 degrees north and south though that position is affected by sea and landmass distribution such that the climate system is slightly unbalanced leading to a tendency for the Arctic to warm when the Antarctic is cooling and vice versa.
The papers at the RMS talk that Leif has referred to are generally supportive of that proposition though as far as I can see none of the contributors has drawn it all together to arrive at that conclusion.
The reason for such shifting of the climate zones is to maintain as far as possible the baseline adiabatic lapse rate as set by atmospheric pressure and solar irradiation. Anything that seeks to disturb that lapse rate is automatically offset by a change in the rate of energy flow from surface to space INSTEAD of any change in system energy content.
I have been saying for years that what we see as climate change is simply a redistribution of surface energy as the rate of flow from surface to space changes over time.
The manifestation of that process is poleward and equatorward climate zone shifting which gives the largest regional effects in the middle latitudes.
It is likely that every planet with an atmosphere does much the same thing which is why it has been observed that for both Venus and Earth the atmospheric temperature at a given pressure is the same subject only to an adjustment for the distance of each planet from the sun.
In so far as GHGs have any effect it is simply negated by a miniscule such shift as compared to the large shifts from solar and oceanic causation.
Similar effects occur as a result of volcanic outbreaks.
As far as I can tell my proposals are consistent with all the papers in that RMS talk.
Stephen Wilde says:
February 2, 2012 at 9:02 am
As far as I can tell my proposals are consistent with all the papers in that RMS talk.
As long as the proposals are not quantitative [giving numbers] no such claim can really be made.
“As long as the proposals are not quantitative [giving numbers] no such claim can really be made”
As I’ve pointed out before, there are lots of phenomena that could invalidate my proposals.
For example:
i) If the ozone quantities in the region above 45km had NOT increased at a time of quiet sun.
ii) If the stratosphere were STILL cooling at the pre 1995 rate.
iii) If the polar air masses were NOT surging across the middle latitudes more often.
iv) If temperatures had NOT stopped rising around 1998.
v) If the record negative AO had NOT coincided pretty neatly with the low solar minimum between cycles 23 and 24.
and lots more are possible.
So, quantification isn’t necessary if the direction of trend is used as a diagnostic indicator.
Stephen Wilde says:
February 2, 2012 at 12:22 pm
So, quantification isn’t necessary if the direction of trend is used as a diagnostic indicator.
Your bar is a lot lower than mine. For example: “i) If the ozone quantities in the region above 45km had NOT increased at a time of quiet sun.” What time precisely [year, months]? Not increased by how much? including error bars, and so on.
“i) If the ozone quantities in the region above 45km had NOT increased at a time of quiet sun.” What time precisely [year, months]? Not increased by how much? including error bars, and so on.”
See Joanna Haigh’s papers for the period 2004 to 2007 and possibly subsequently.
I know you are aware of them.
Stephen Wilde says:
February 2, 2012 at 1:44 pm
See Joanna Haigh’s papers for the period 2004 to 2007 and possibly subsequently.
Not good enough as she does not give any estimates of how well her results match your theory. Again, without numbers you have nothing.
Stephen Wilde says:
February 2, 2012 at 9:02 am
Thanks Stephen.
The papers at the RMS talk that Leif has referred to are generally supportive of that proposition though as far as I can see none of the contributors has drawn it all together to arrive at that conclusion.
The Haigh presentation that Leif referenced is all about solar effects on Earth’s climate. Many references to varying ozone production , planetary waves and jet stream changes as a result. Of note she also clearly displays that EUV and FUV are the prime part of the spectrum used in ozone production
http://tinyurl.com/2dg9u22/images/haigh.png
Haigh, Hood and Baldwin are also pushing in the same direction, ozone changes from UV modulation at solar min, affect atmospheric weather patterns.