Volcanic origin for Little Ice Age

BBC News ^ | 1/30/12 | Richard Black

[NormsRevenge]

The Little Ice Age was caused by the cooling effect of massive volcanic eruptions, and sustained by changes in Arctic ice cover, scientists conclude.

An international research team studied ancient plants from Iceland and Canada, and sediments carried by glaciers.

They say a series of eruptions just before 1300 lowered Arctic temperatures enough for ice sheets to expand.

Writing in Geophysical Research Letters, they say this would have kept the Earth cool for centuries.

The exact definition of the Little Ice Age is disputed. While many studies suggest temperatures fell globally in the 1500s, others suggest the Arctic and sub-Arctic began cooling several centuries previously.

The global dip in temperatures was less than 1C, but parts of Europe cooled more, particularly in winter, with the River Thames in London iced thickly enough to be traversable on foot.

What caused it has been uncertain. The new study, led by Gifford Miller at the University of Colorado at Boulder, US, links back to a series of four explosive volcanic eruptions between about 1250 and 1300 in the tropics, which would have blasted huge clouds of sulphate particles into the upper atmosphere.

These tiny aerosol particles are known to cool the globe by reflecting solar energy back into space.

"This is the first time that anyone has clearly identified the specific onset of the cold times marking the start of the Little Ice Age," said Dr Miller.

[the invisib1e hand]

kewl.

[ETL]

Here's a sunspot chart showing the various peaks and dips throughout the past centuries. Note the "Medieval Max". It corresponds to the "Medieval Warm Period". The "Maunder Minimum" corresponds to the "Little Ice Age", and the "Modern Max" to the recent warming trend we had been experiencing, at least until the past 15 years or so.

"Changes in carbon-14 concentration in the Earth's atmosphere, which serves as a long term proxy of solar activity. Note the present day is on the left-hand side of this figure."

http://en.wikipedia.org/wiki/Solar_activity
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From BBC News [yr: 2004]:
"A new [2004] analysis shows that the Sun is more active now than it has been at anytime in the previous 1,000 years. Scientists based at the Institute for Astronomy in Zurich used ice cores from Greenland to construct a picture of our star's activity in the past. They say that over the last century the number of sunspots rose at the same time that the Earth's climate became steadily warmer."..."In particular, it has been noted that between about 1645 and 1715, few sunspots were seen on the Sun's surface.

This period is called the Maunder Minimum after the English astronomer who studied it. It coincided with a spell of prolonged cold weather often referred to as the "Little Ice Age". Solar scientists strongly suspect there is a link between the two events - but the exact mechanism remains elusive."
http://news.bbc.co.uk/1/hi/sci/tech/3869753.stm
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The Center for Sun-Climate Research at the DNSC (Danish National Space Center) investigates the connection between variations in the intensity of cosmic rays and climatic changes on Earth. This field of research has been given the name 'cosmoclimatology'"..."Cosmic ray intensities – and therefore cloudiness – keep changing because the Sun's magnetic field varies in its ability to repel cosmic rays coming from the Galaxy, before they can reach the Earth." :
http://www.spacecenter.dk/research/sun-climate
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Here's an excellent ~new book out on the subject titled "The Chilling Stars, 2nd Edition: A Cosmic View of Climate Change". It's written by one of the top scientists advancing the theory (Henrik Svensmark, of the above mentioned Danish National Space Center/DNSC).

"The authors explain their theory that sub-atomic particles from exploded stars have more effect on the climate than manmade CO2."
http://www.sciencedaily.com/books/t/1840468157-the_chilling_stars_the_new_theory_of_climate_change.htm

Amazon Books: "The Chilling Stars, 2nd Edition: A Cosmic View of Climate Change"
http://www.amazon.com/Chilling-Stars-2nd-Cosmic-Climate/dp/1840468661 zs90]
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[MadMax, the Grinning Reaper]

I guess the EPA is going to sue those volcanoes.

I much prefer that the EPA be sacrificed to the volcano gods. In my world, that is called “taking out the trash and recycling it”.

I hope that someone sends this article to Al Gore. Oh, I forgot. He can’t read. Well, somebody read it to him, ad tell him to either lay off the twinkies and burgers, or eat all he can and explode.

[factoryrat]

I remember that a volcano erupted in indonesia maybe? In 1990. That year, the summer temperatures in Michigan barely made it above 70 degrees. Wherever it happened, it had a major affect on temperatures for a few years.

[DuncanWaring]

Mt. Pinatubo, Philippines, 1991?

[The_Reader_David]

It seems to me this is an attempt by “atmospheric scientists” to avoid actually having to engage Svensmark’s theory seriously. A volcanic event can trigger a few years worth of cold (as happened late in the Little Ice Age, when the massive eruption of Tambora cause ‘the year without a summer’), but not the longer time-scale phenomenon, so they patch it up with unspecified changes in the Arctic ice pack to stretch the effect.

This looks to me like the usual tactic in defense of an old scientific paradigm (cf. “Vulcan” as an explanation for the precession of the orbit of Mercury, and “gaseous Vulcan” as a patch when no new inner-most planet was observed). Rather than accept that the correlation between sunspot number and earth mean temperature is not spurious, now what we have a causal mechanism to explain it, folks who want the earth’s climate to be explainable in terms of the atmosphere (D*mn! I didn’t have to learn about solar magnetism in grad school and I’m not going to start now, besides if Svensmark is right the grant gravy-train for climate modeling will go to folks who know the new stuff and not us global warming theorists. . .) have to come up with a stretched explanation from within the basis of their existing theories.

[factoryrat]

That sounds about right. All I remember is that it was unseasonably cold and that a volcanic eruption was the cause. The whole summer was cold and the sky was overcast for most of it.