January 30, 2012
Volcanic Eruptions Caused Little Ice Age?

If lots of volcanoes start erupting better buy good winter clothes.

A new University of Colorado Boulder-led 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 CU-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.

Low sun spot activity to blame? Nope. The big cooling was all about cooling aerosols ejected by volcanoes.

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."

When will nature throw another really big curve ball at us?

Share |      Randall Parker, 2012 January 30 10:08 PM  Climate History

LoboSolo said at January 31, 2012 4:14 AM:

Who needs volcanoes: Met Office releases new figures which show no warming in 15 years

Forget global warming - it's Cycle 25 we need to worry about http://www.dailymail.co.uk/sciencetech/article-2093264/Forget-global-warming--Cycle-25-need-worry-NASA-scientists-right-Thames-freezing-again.html

Figures suggest that we could even be heading for a mini ice age to rival the 70-year temperature drop that saw frost fairs held on the Thames in the 17th Century.

Lyle said at January 31, 2012 5:42 AM:

LoboSolo, I think you need to consider your source before you chalk up a fanciful article in a British tabloid as overwhelming evidence.

1. A halt in the increase does not mean a sudden decrease - it means a plateauing. Of course, that doesn't appear to stop the Daily Mail from getting models from skeptics to assert impending freezing of the Thames.

2. Personally, I prefer to look at the data. NASA’s Goddard Institute for Space Studies has surface temperature data since 1880, and 9 of the 11 years since 2000 (including 2011) have been the warmest years ever recorded. Their analysis, using past data rather than models, is available here: http://1.usa.gov/yDq0Nc

While NASA scientists acknowledge the solar minimum, they believe its effects are only offsetting more rapid warming later this decade. If the data is too much for you, here is the summary at the bottom: "2011 was only the ninth warmest year in the GISS analysis of global temperature change, yet nine of the ten warmest years in the instrumental record (since 1880) have occurred in the 21st century. The past year has been cooled by a moderately strong La Niña. The 5-year (60-month) running mean global temperature hints at a slowdown in the global warming rate during the past few years. However, the cool La Niña phase of the cyclically variable Southern Oscillation of tropical temperatures has been dominant in the past three years, and the deepest solar minimum in the period of satellite data occurred over the past half dozen years. We conclude that the slowdown of warming is likely to prove illusory, with more rapid warming appearing over the next few years."

3. I suggest you reread the Daily Mail article with a skeptical mind rather than one primed to accept it since it confirms your belief. Consider how they started off the article with "consensus" in quotes, who they picked to interview, how they appear to have picked quite carefully what quotes to use from the climate scientists, and a dozen other simple clues that show their bias. Then consider exactly what data they claim to have, and compare it to NASA's.

Then decide for yourself - who is reputable?

f1b0nacc1 said at January 31, 2012 8:14 AM:

Nice try Lobo...

The Daily Mail article was about a report from the UK Met office, which in turn based IT'S report on over 30,000 temperature measurements. NASA (home of James Hansen, among others) hardly has covered itself with glory in this whole AGW debate, so to suggest that they suddenly have some automatic credibility is a rather transparent case of argument by authority...

Care to challenge the UK data on its merits? Or is the data too much for you?

Ryan said at January 31, 2012 1:26 PM:

OT: Randall, what do you think of the recent solar flares and upcoming solar maximum? Your post about the disastrous potential of another Carrington event first alerted me to this danger and now it's all over the news (though never associated with any extreme risk).

Fat Man said at January 31, 2012 1:43 PM:

"Personally, I prefer to look at the data. NASA’s Goddard Institute for Space Studies has surface temperature data since 1880, and 9 of the 11 years since 2000 (including 2011)"

Hansen and his gang at Goddard have been cooking the same land based, UHI polluted, data into trends that far exceed the error bars for years. Being on the Federal rice bowl doesn't make them objective, it makes them politicians pushing bu11$#;+ to justify raising taxes to feed their lazy @$$3$.

John Cunningham said at January 31, 2012 3:06 PM:

Hoaxer Hansen predicted in 1988 that by 2008, rising sea levels would put the West Side Hwy in Manhattan underwater by 2008. Never happened.
Also, Hansen and other warmalists have never explained why they uniformly reduced temperature records prior to 1950 by 2 degrees C. they never
explained how they arrived at this reduction.

Han Ningham said at January 31, 2012 6:19 PM:

Better data suggest that a combination of low solar activity plus volcanic eruptions leads to little ice ages.

Both land and water temperatures are diverging from the IPCC models. That calls for a hysterical all out response. Denial of solar drivers of the climate would certainly qualify.

AC1 said at February 1, 2012 10:14 AM:

So real weather measurements have falsified all the catastrophic increasing temperature trend models.

Also falsified the "hockey stick" which "hid" the medieval warm period...

AC1, proud denier of (impossible) predictive powers of recursive models.

Tantor said at February 1, 2012 10:32 AM:

So the Little Ice Age was not created by medieval SUVs?

tim maguire said at February 1, 2012 10:33 AM:

While Lyle isn't going to win many converts with his reliance on NASA data, I think his main point is valid. There is very little data about how solar cycles effect climate. The solar scientists' prediction about cycle 25 is something to be aware of, maybe concerned about, but we should be willing to bring the same skepticism to their claims as we bring to AGW claims.

sol said at February 1, 2012 10:48 AM:

mini ice ages come every five hundred years. Although thermometers did not exist back in the day, evidence exists in historical records from 3000 bc to the present concerning mass migrations, crop failures, bumper crops, famines, plenty, trade routes and products traded, astrology, the nileometer, paintings, frescos, and sculptures that there is a five hundred year climate cycle.

Given that the Sun is a spaceship - and that the Earth, other planets and other assorted junk is orbitting spaceship Sun as it orbits with our galaxy - it seems likely that every 500 years the Sun passes through a gravity well that distorts the Earth's orbit, drawing it and all the rest of the debris orbiting the Sun further away with the result that less sunshine reaches the Earth and the temperature falls 10C-20C degrees. Just a very small change in Earth's orbit.

LarryD said at February 1, 2012 11:22 AM:

The Maunder Minimum occurred within the LIA. The Dalton Minimum occurred after the LIA was well over.

While Miller's conclusions are plausible, I'd be more confident if he had datable samples of volcanic ash, or some other direct evidence of volcanism, burned vegetation could possibly result from other wildfire causes. And computer models, well GIGO, has he been able to actually test those models against reality?

There was a cooling trend that ended in the 1970s. That had people angsting over the Impending Ice Age. Then the trend turned warming. Now the trend is switching again, but we know about the Pacific Decadal Oscillation, and the Arctic and Atlantic ones as well. Yeah, some people are yelling "Ice Age". Again. Combining oscillations in cooling mode with a solar minimum, I expect it to get more unpleasant than the last cooling phase, maybe as bad as the Dalton Minimum. But not another LIA, let alone the end of the interglacial.

tom beebe st louis said at February 1, 2012 11:37 AM:

Wasn't 1884 or 1885 the year without summer? It's described in Teddy Roosevelt's memoirs about a non-summer spent in Montana. And, as I recall, an eruption of the Indonesian volcano Krakatoa was seen as the cause, blanketing the earth with ash. Can somebody verify my imperfect recollections?

Daniel said at February 1, 2012 11:40 AM:

John Cunnigham:

It's a myth that Hansen categorically predicted that the Westside Highway would be underwater by 2008.


LarryD said at February 1, 2012 12:24 PM:

OK, I'm mistaken. The LIA went from about 1350 to 1850, although exact starting and ending dates are hard to pin down. Events indicating climate change (arctic ice pack expansion, glacial expansion, the end of reliably warm summers in Northern Europe) started as far back as 1250. The Dalton Minimum was from 1790 to 1830, so it was in the LIA too. But this doesn't change my final conclusion.

Krakatoa went off in 1883, to quote Wikipedia "In the year following the eruption, average global temperatures fell by as much as 1.2 °C (2.2 °F). Weather patterns continued to be chaotic for years, and temperatures did not return to normal until 1888."

AMac said at February 1, 2012 12:28 PM:

Daniel (February 1, 2012 11:40 AM) --

In my opinion, the skepticalscience.com website should be cited with considerable caution. They have attracted considerable criticism (justified, I think) for the pro-CAGW-Mainstream bias of a number of their articles (e.g.).

John said at February 1, 2012 12:48 PM:

The year without a summer was 1816. There indeed was a massive volcano, but it was Tambora. Krakatoa was in 1885, but was smaller than Tambora, though still quite large.

1816 was called the year without a summer because there were summertime frosts in New England that destroyed crops, and started the major exodus of farming people to the Ohio valley. This Wikipedia entry says that Europe also had very low temperatures, and that 1816 was the last time there was a subsistence crisis in the western world:


Of course, yes, it is Wikipedia, but they probably don't have this one wrong, it is pretty established history.

1816 was at the tail end of the Daulton minimum, so there might have been a combination of lower solar as well as a massive volcano, reinforcing each other, assuming that the Daulton minimum actually had a meaningful cooling impact. I'm not yet on board with this last idea, but I am open to it, and the next decade might settle the question.

DonM said at February 1, 2012 1:07 PM:

The navier stokes equations describe fluid flow with changes of temperature and density. they are nonlinear, chaotic, and show sensitive dependence on initial conditions. Because of that, long term prediction based on past states is not possible.

Not only the weather on earth, but also the solar weather are described by the NS equations.

What would cause volcanos? Perhaps an increasing mass of ice pressing in on the south pole? Perhaps a decreasing mass of ice on the south pole.

Prediction is not possible. The smart strategy is to be as rich and prosperous as possible so you and yours are ready for the unexpected.

And when things get really bad, your coworkers are edible.

Mike said at February 1, 2012 1:47 PM:

The article does indeed mention sediment cores, but either nobody thought to examine those cores for ash deposits typical of vulcanism or they were indeed examined and nothing was found, and that was somehow deemed not worth mentioning (the cores showed thick annual layers due to increase melting in the warmer weather). So we're left with dead plants = active volcanoes. Not convincing.

Mike Mangan said at February 1, 2012 2:13 PM:

Heh. Skeptical science. SS. Cook's Catechism of Correct Climate Thought. The ultimate data source for CAGW Reavers to maintain a proper level of hysteria and arrogance.

Shelby J said at February 1, 2012 3:29 PM:

Bottom line is humans don't live long enough to see any major climate changes. (Unless they move to some other location on earth.)
Climate change happens over a long, long, long time.
The climate one is born into is going to be the same basic climate they die in.

RebeccaH said at February 1, 2012 3:40 PM:

The real bottom line is that human beings will adapt to whatever the climate chooses to throw at us, just as we have for the last couple or three hundred thousand years or so (I'm including our Neanderthal and Denisovan cousins here). In fact we, as the latest iteration of homo whatever have the advantage of a fairly well advanced technology and culture. Short of an asteroid extinction event or the sun unexpectedly dying, we are not going to disappear, so all this drama over climate is really kind of ridiculous.

Syl said at February 1, 2012 5:08 PM:

We've all known for a long time already that major volcanic eruptions occurred during the Little Ice Age. The important cooling ones are those that occur near or fairly near the equator and are so powerful they reach way way up high so the particulates are scattered around the globe. And the volcanic activity back then certainly meets those criteria. This paper seems to me to bring up something we've already known but with a slant that the sun had little or nothing to do with it. I would posit there would have been a cooling anyway because of reduced radiation from the sun for 70 some years during the Maunder Minimum and that increased volcanic activity of the right type made the cooling deeper.

It's silly to assume it was one or the other when both were obviously involved.

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