Large volcanic eruptions were responsible for cold temperature extremes recorded since early Roman times

July 8, 2015, Desert Research Institute
A freshly drilled ice-core from TUNU, Greenland containing a history of volcanic eruptions is pushed out of the core barell. Credit: Olivia Maselli

It is well known that large volcanic eruptions contribute to climate variability. However, quantifying these contributions has proven challenging due to inconsistencies in both historic atmospheric data observed in ice cores and corresponding temperature variations seen in climate proxies such as tree rings.

Published today in the journal Nature, a new study led by scientists from the Desert Research Institute (DRI) and collaborating international institutions, resolves these inconsistencies with a new reconstruction of the timing and associated radiative forcing of nearly 300 individual extending as far back as the early Roman period.

"Using new records we are able to show that large volcanic eruptions in the tropics and high latitudes were the dominant drivers of climate variability, responsible for numerous and widespread summer cooling extremes over the past 2,500 years," said the study's lead author Michael Sigl, Ph.D., an assistant research professor at DRI and postdoctoral fellow with the Paul Scherrer Institute in Switzerland.

"These cooler temperatures were caused by large amounts of volcanic sulfate particles injected into the upper atmosphere," Sigl added, "shielding the Earth's surface from incoming solar radiation."

The study shows that 15 of the 16 coldest summers recorded between 500 BC and 1,000 AD followed large volcanic eruptions - with four of the coldest occurring shortly after the largest volcanic events found in record.

This new reconstruction is derived from more than 20 individual ice cores extracted from ice sheets in Greenland and Antarctica and analyzed for volcanic sulfate primarily using DRI's state-of-the-art, ultra-trace chemical ice-core analytical system.

These ice-core records provide a year-by-year history of atmospheric sulfate levels through time. Additional measurements including other chemical parameters were made at collaborating institutions.

"We used a new method for producing the timescale," explained Mai Winstrup, Ph.D., a postdoctoral researcher at the University of Washington, Seattle. "Previously, this has been done by hand, but we used a statistical algorithm instead. Together with the state-of-the-art ice core chemistry measurements, this resulted in a more accurate dating of the ice cores."

"Using a multidisciplinary approach was key to the success of this project," added Sigl.

In total, a diverse research group of 24 scientists from 18 universities and research institutes in the United States, United Kingdom, Switzerland, Germany, Denmark, and Sweden contributed to this work - including specialists from the solar, space, climate, and geological sciences, as well as historians.

Narrow and distorted tree-rings from long living bristlecone-pines (Snake Mountains, Nevada, USA), indicating extreme cooling after a large volcanic eruption in 44 BCE, the year of Julius Cesar's death. Credit: Matthew Salzer

The authors note that identification of new evidence found in both ice cores and corresponding tree rings allowed constraints and verification of their new age scale.

"With the discovery of a distinctive signature in the ice-core records from an extra-terrestrial cosmic ray event, we had a critical time marker that we used to significantly improve the dating accuracy of the ice-core chronologies," explained Kees Welten, Ph.D., an associate research chemist from the University of California, Berkeley.

A signature from this same event had been identified earlier in various tree-ring chronologies dating to 774-775 Common Era (CE).

"Ice-core timescales had been misdated previously by five to ten years during the first millennium leading to inconsistencies in the proposed timing of volcanic eruptions relative to written documentary and tree-ring evidence recording the climatic responses to the same eruptions," explained Francis Ludlow, Ph.D., a postdoctoral fellow from the Yale Climate & Energy Institute.

Throughout human history, sustained volcanic cooling effects on climate have triggered crop failures and famines. These events may have also contributed to pandemics and societal decline in agriculture-based communities.

Together with Conor Kostick, Ph.D. from the University of Nottingham, Ludlow translated and interpreted ancient and medieval documentary records from China, Babylon (Iraq), and Europe that described unusual atmospheric observations as early as 254 years before Common Era (BCE). These phenomena included diminished sunlight, discoloration of the solar disk, the presence of solar coronae, and deeply red twilight skies.

Tropical volcanoes and large eruptions in the Northern Hemisphere high latitudes (such as Iceland and North America) - in 536, 626, and 939 CE, for example - often caused severe and widespread summer cooling in the Northern Hemisphere by injecting sulfate and ash into the high atmosphere. These particles also dimmed the atmosphere over Europe to such an extent that the effect was noted and recorded in independent archives by numerous historical eyewitnesses.

Climatic impact was strongest and most persistent after clusters of two or more large eruptions.

Strong and widespread cooling occurred in the immediate aftermath of large volcanic eruptions as indicated by ice cores from Greenland. Credit: Michael Sigl

The authors note that their findings also resolve a long-standing debate regarding the causes of one of the most severe climate crises in recent human history, starting with an 18-month "mystery cloud" or dust veil observed in the Mediterranean region beginning in March, 536, the product of a large eruption in the high-latitudes of the Northern Hemisphere.

The initial cooling was intensified when a second volcano located somewhere in the tropics erupted only four years later. In the aftermath, exceptionally cold summers were observed throughout the Northern Hemisphere.

This pattern persisted for almost fifteen years, with subsequent crop failures and famines - likely contributing to the outbreak of the Justinian plague that spread throughout the Eastern Roman Empire from 541 to 543 CE, and which ultimately decimated the human population across Eurasia.

"This new reconstruction of volcanic forcing will lead to improved climate model simulations through better quantification of the sensitivity of the climate system to volcanic influences during the past 2,500 years," noted Joe McConnell, Ph.D., a DRI research professor who developed the continuous-flow analysis system used to analyze the ice cores.

"As a result," McConnell added, " observed during more recent times can be put into a multi-millennial perspective - including time periods such as the Roman Warm Period and the times of significant cultural change such as Great Migration Period of the 6th century in Europe."

This reconciliation of ice-core records and other records of past environmental change will help define the role that large climatic perturbations may have had in the rise and fall of civilizations throughout human history.

"With new high-resolution records emerging from ice cores in Greenland and Antarctica, it will be possible to extend this reconstruction of volcanic forcing probably all the way back into the last Ice Age," said Sigl.

Explore further: Rewriting the history of volcanic forcing during the past 2,000 years

More information: Nature, DOI: 10.1038/nature14565

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26 comments

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MR166
1.6 / 5 (13) Jul 08, 2015
So is it safe to assume that during periods of low volcanic activity there could be a temperature increase? How much has average volcanic activity changed over the last 50 years?
Maggnus
4.8 / 5 (16) Jul 08, 2015
So is it safe to assume that during periods of low volcanic activity there could be a temperature increase? How much has average volcanic activity changed over the last 50 years?
Even safer to assume is the fact that you didn't take 2 minutes and look it up yourself. The fallacy of "I don't understand it, so it must be wrong."

antigoracle
1.7 / 5 (12) Jul 08, 2015
The initial cooling was intensified when a second volcano located somewhere in the tropics erupted only four years later. In the aftermath, exceptionally cold summers were observed throughout the Northern Hemisphere.
This pattern persisted for almost fifteen years, with subsequent crop failures and famines - likely contributing to the outbreak of the Justinian plague that spread throughout the Eastern Roman Empire from 541 to 543 CE, and which ultimately decimated the human population across Eurasia.

This is the fate, the AGW Cult of doom and gloom, has in store for us.
denglish
1.7 / 5 (12) Jul 08, 2015
MR, it looks like you'll be off to a good start if you google "volcanic eruption timelines"

Its interesting to see this type of study. MIT was swinging around a similar one (for god knows what reason, he couldn't decipher a simple passage) in another thread.

Articles like this make me hopeful that climate science is maturing.

Even safer to assume is the fact that you didn't take 2 minutes and look it up yourself. The fallacy of "I don't understand it, so it must be wrong."

And as usual, the AGWites come in asses high.
JonnyMcA
5 / 5 (7) Jul 08, 2015
Not to detract from the excellent work of the authors of the Nature article, but what the PhysOrg article doesn't mention is that Baillie and McAneney previously pointed out that the ice cores were dated too old by 7 years in the first millennium AD.

Baillie, M.G.L and McAneney, J "Tree ring effects and ice core acidities clarify the volcanic record of the first millennium" Clim. Past, 11, 105-114, 2015

http://www.clim-p...2015.pdf
hrfJC
1 / 5 (5) Jul 08, 2015
Clearly proves that cooling is strongly related to atmospheric dust particles of optimume size for visible light scattering. Similar but in this case man made cooling was observed after madman Saddam torched numerous Iran oil wells before retreating.
Possible fix for reversing man made global green warming, if indeed global not regional, could be achieved by switching to dirtier and less costly fuel fractions yielding bigger plumes of solar reflective carbon particles from less complete combustion, thereby blanketing the global hemispheres within a few days to a desired umbrella density and lowering surface temperatures in either hemisphere during summer less so in winter.
howhot2
4.4 / 5 (7) Jul 08, 2015
So true @JonnyMcA. The deniers should be freaking-out over that 7 year of 2515? That falls well below the 5% scientific error doctrine of human physical measurements.

Of course the wingnut denier monkeys all go; "uuuuhhh ooohhh uuuhh" as they always do.
@Denglberry; you need to get a life and read UN policy on global warming. It would do you good. The @goremister needs to just watch "An Inconvenient Truth" over and over again until he gets it.

ThomasQuinn
3.5 / 5 (8) Jul 09, 2015
Possible fix for reversing man made global green warming, if indeed global not regional, could be achieved by switching to dirtier and less costly fuel fractions yielding bigger plumes of solar reflective carbon particles from less complete combustion, thereby blanketing the global hemispheres within a few days to a desired umbrella density and lowering surface temperatures in either hemisphere during summer less so in winter.


...just too bad that you'd be poisoning people and/or land in the process. Not a good idea.
zz5555
5 / 5 (6) Jul 09, 2015
could be achieved by switching to dirtier and less costly fuel fractions yielding bigger plumes of solar reflective carbon particles from less complete combustion, thereby blanketing the global hemispheres within a few days to a desired umbrella density and lowering surface temperatures

There's enormous problems with geoengineering as your suggesting. As ThomasQuinn points out, your asking to poison the earth to save it, which is odd. Plus, aerosols precipitate out in short periods of time, so you need to keep at it forever. And, by continuing to burn fossil fuels, your releasing more CO2, leading to more warming, and, therefore, requiring an increase in the aerosols to reflect sunlight.

There's also the problem that not all countries will want this and will fight to stop it. So suggestions of geoengineering really require one strong world government with the power and authority to force nations to do things (including the USA).
denglish
1.5 / 5 (8) Jul 09, 2015
@Denglberry; you need to get a life and read UN policy on global warming. It would do you good.

First, big boys know that insult is the last refuge of an exhausted intellect. In discourse, you would be well served to show respect instead of contempt. Not only does it create an air of non-credibility, proclivity toward the negative will lead you to poor outcomes, which many times, can only be gained through intellectual dishonesty.

On to your statement: I have. There's a big problem, that will give any scientist pause: the observations do not meet the AGW predictions. Therefore, policies based on falsified science are very poorly founded, and in practice, destructive.
jwozniak
4 / 5 (2) Jul 09, 2015
Sigh. Volcano porn, lol.
gkam
2.7 / 5 (7) Jul 09, 2015
Wow, what we put into the atmosphere really does affect climate?

Who'd have guessed?
gkam
3.2 / 5 (9) Jul 09, 2015
We get these from denglish:
"First, big boys know that insult is the last refuge of an exhausted intellect."

Then,
"Regardless, that's what happens when false credentials are put to the test, and political hatred is one's only attribute."

Know thyself, denglish.
denglish
1.5 / 5 (8) Jul 09, 2015
Wow, what we put into the atmosphere really does affect climate?

Who'd have guessed?

No, the article is about Volcanic eruptions affecting the climate; making it cooler.

We get these from denglish:
"First, big boys know that insult is the last refuge of an exhausted intellect."

Then,
"Regardless, that's what happens when false credentials are put to the test, and political hatred is one's only attribute."

Know thyself, denglish.

You are a sad, hateful person, using scientific articles to pick internet fights. I pity you.

gkam
3.2 / 5 (9) Jul 09, 2015
"You are a sad, hateful person, using scientific articles to pick internet fights. I pity you."
-----------------------------

Best laugh I've had all morning.

Thanks.

It ain't pity you feel denglish, it is embarrassment, from such ignorance of the topic. Now, go find out how many kW in a MW.

Thanks.
Eddy Courant
1.5 / 5 (8) Jul 09, 2015
So less than one half of one percent of the atmosphere doesn't control the climate? Surprise! Surprise! Surprise!
gkam
3 / 5 (8) Jul 09, 2015
Thanks Eddie for confirming of our suspicions of your education. Apparently Eddie is unaware of the differences between particulates and a visually-clear, thermally-opaque gas.

And unaware they can change the weather conditions in different directions.
howhot2
4.4 / 5 (7) Jul 09, 2015
@Denglberry; you need to get a life and read UN policy on global warming. It would do you good.

First, big boys know that insult is the last refuge of an exhausted intellect. In discourse, you would be well served to show respect instead of contempt. Not only does it create an air of non-credibility, proclivity toward the negative will lead you to poor outcomes, which many times, can only be gained through intellectual dishonesty.

On to your statement: I have. There's a big problem, that will give any scientist pause: the observations do not meet the AGW predictions. Therefore, policies based on falsified science are very poorly founded, and in practice, destructive.

Eat me. You are the one being dishonest. I have no moral problem with insulting you and belittling you until you turn into the turnup you are. May your AGW predictions of a happy cool world come true. They won't and your one neuron brain say so.

In the meantime, go read a physics book.
denglish
1.5 / 5 (8) Jul 10, 2015
Eat me. You are the one being dishonest. I have no moral problem with insulting you and belittling you until you turn into the turnup you are. May your AGW predictions of a happy cool world come true. They won't and your one neuron brain say so.

In the meantime, go read a physics book.

You haven't presented a very convincing argument for your case. From what I can discern, your post is nothing but vitriol.

I find it very sad that a post with no intellectual content, defending AGW beliefs via employing the tactic of censorship via humiliation would get up votes. This seems to be indicative of the population on these forums that support AGW, and does not bode well should they be seeking current or future credibility.

Regardless, it is good to see climate science maturing. This article lends hope to one-day truly understanding climate change.
howhot2
4.3 / 5 (6) Jul 10, 2015
You haven't presented a very convincing argument for your case. From what I can discern, your post is nothing but vitriol.

I find it very sad that a post with no intellectual content, defending AGW beliefs via employing the tactic of censorship via humiliation would get up votes. This seems to be indicative of the population on these forums that support AGW, and does not bode well should they be seeking current or future credibility.

Let me explain a few things dingleberry; First deniers of AGW are moron idiots and twits like you that post contrary to AGW have no credibility. So I expect that you want abuse. You might as well just admit your credibility is the one in question not mine. That is why I'm voted up and your not.

Your ideas on global warming are as stupid as shit and really don't deserve comment. Anyway, if you want to debate climate change, go to hell. It's already been explained. Only the paid trolls have a need to debate it. Cheers.
Eddy Courant
1.8 / 5 (5) Jul 11, 2015
Thanks Eddie for confirming of our suspicions of your education. Apparently Eddie is unaware of the differences between particulates and a visually-clear, thermally-opaque gas.

And unaware they can change the weather conditions in different directions.

----------------------------------------
"You are a sad, hateful person, using scientific articles to pick internet fights. I pity you."
gkam
2.3 / 5 (6) Jul 11, 2015
"You haven't presented a very convincing argument for your case. From what I can discern, your post is nothing but vitriol."

"You are a sad, hateful person, using scientific articles to pick internet fights. I pity you."
-------------------------------------

Your penchant for projection is interesting.
Returners
1.8 / 5 (5) Jul 11, 2015
The AGWites on this thread should be arrested for cyber-bullying.
denglish
1.8 / 5 (5) Jul 12, 2015
Let me explain a few things dingleberry;

You haven't presented a very convincing argument for your case. From what I can discern, your post is nothing but vitriol.

This seems to be indicative of the population on these forums that support AGW, and does not bode well should they be seeking current or future credibility.

Regardless, it is good to see climate science maturing. This article lends hope to one-day truly understanding climate change.

Captain Stumpy
4.2 / 5 (5) Jul 12, 2015
This seems to be indicative of the population on these forums that support AGW, and does not bode well should they be seeking current or future credibility
funny you, of all people, should mention this.

Your idea of "credibility" is to post opinion and then claim it is equivalent to validated studies... of which you still haven't been able to refute except to stick your fingers in your ears and say "LALALALA i can't hear you!" and then post out of context graphics, more opinion, fraudulent "official looking" studies which are not published or peer reviewed, or political lies and vitriol.

This is the very definition of intellectual dishonesty.
your attempts to use it as "refutation" and argue about credibility is ironic
Bongstar420
2.3 / 5 (3) Jul 12, 2015
Terrestrial volcanism (the smoky kind) = global cooling
Oceanic volcanism = global warming

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