Major volcanic eruptions can have a profound effect on global climate, especially if the volcano is located at a low latitude. The eruption of Tambora in 1815 and of Krakatoa in 1883 lowered temperatures worldwide. I recently saw a PBS documentary suggesting the cold weather around [sub][sup]A.D.[/sup][/sub] 535 may have been caused by an earlier eruption of Krakatoa.
But what about other famous cold snaps: Are there volcanic eruptions associated with them too? (I’m not suggesting that there must be, I’m just wondering if there are.)[ul]
[li]829 the Nile froze over at Cairo.[/li][li]1010, the Nile froze over at Cairo again.[/li]1780: Long Island Sound froze over solid allowing horse-drawn sleighs to pass between New London and Montauk (this was about 3 years before the famous 1783 Laki eruption in Iceland that perturbed the climate of Europe).[/ul]Note: These are three factoids I’ve collected over the years. I can’t vouch for their accuracy.
I’m doing this from memory, so it is sure to be chock full 'o errors. Additionally, the story may not have any truth to it in the first place.
We owe volcanic eruptions for the creation of science fiction in general and Frankenstein in particular. My faulty memory tells me that the “year without a summer” was caused by multiple volcanic eruptions at about the same time. Krakatoa might have been one of the volcanos in question. Mary Shelly, Lord Byron, Percy Byshe Shelly, et al spent that cold summer indoors writing. Mary Shelly wrote Frankenstein during that period, which some say is the first science fiction novel.
I’m sure that the above is not entirely accurate, and I’m also sure that this doesn’t really address the OP. Sorry.
I’ve checked the GISP2 ice-core measurements for SO4 concentrations around your dates. Remember that the dates are estimates, probably accurate to within a year or so for dates these recent, but more inaccurate the longer ago you look at.
The Laki eruption shows up clearly. In fact it’s the fourth-highest SO4 concentration of the last 2000 years (not counting the last 50 years, when industrial pollution causes a MASSIVE jump in SO4 levels) However, there is no sign of an eruption in 1780. Sorry.
In the 1000-1020 range, there is nothing much happening. However, a few years later we find:
Clearly something major happened in the years 820-829 (plus or minus say 10 years). But a sustained SO4 concentration over that length of time is… unusual.
Most of these figures are in the ‘normal’ range, except for 824 and 832-834, which are somewhat elevated. You see concentrations in the 100 ppb range about every 10 years or so. Note that the datings of these measurements were made independently from those for SO4, and may vary by several years. My opinion - no strong particulate signal.
So the eruption(s) were not explosive. This leaves effusive eruptions, like Laki 1782, which can in fact last for decades. That’s my best guess.
[hijack] bibliophage:(signature) Some books are to be tasted, others to be swallowed, and some few to be chewed and digested.
–Francis Bacon (1561-1626)
My 6-month-old daughter tastes and chews her books. Where does that fit in Baconian philosophy? :D:D
Groundskeeper Willie: excellent post. But where the heck did you get all that ice-core data? If it’s online somewhere, I wouldn’t mind perusing it myself.
I used a program called paleoview. It’s a paleoclimate visualisation tool, allowing you to look at paleoclimate data in the form of either lists or graphs. The freeware version includes icecore data from the GRIP2 and GISP sites in Greenland.
…whether or not a volcanic eruption has a subsequent effect on climate will depend not only on the type of eruption, but what latitude the eruption occurs at. The combo with the maximum GLOBAL effect would be an explosive eruption at low-mid latitude.
Why are these two things important? First of all, an explosive eruption is most likely to inject ash and SO2 into the stratosphere, where it can linger for extended periods of time because it will not be precipitated out with rain (rain, snow, etc. are phenomena of the troposphere, not the stratosphere). Second, for ash and SO2 to achieve something close to a global distribution, it has to be injected at a location where the upper level winds can redistribute it widely. This is most easily accomplished in the low latitudes, where connections with higher-latitude winds in both hemispheres can be made. Thus Tambora and Krakatau, both highly explosive eruptions at low latitudes, had a noticeable impact on global climate for years.
In volcanic events that are less explosive but longer lasting, the accompanying outgassing may large enough to have similar effects on a regional or hemispheric scale. That’s true for the 1783 Laki eruption, as well as another Icelandic eruption in 934 (see this link and also the links at the bottom of that page). While the 1783 Laki eruption was extremely disruptive to the Alaskan Inuit, and to varying degrees had disruptive effects elsewhere in the northern hemisphere, the southern hemisphere was effectively untouched because the eruption occurred at too high a latitude.
What this boils down to is: if an eruption is not explosive/gassy enough, OR is at too high a latitude, it will not have an impact on global climate. It may also not leave a mark in ice core records at both poles, but rather just at the closest one. (The publicly available Antarctic ice core data don’t include SO2 or SO4 with dates, so I couldn’t check those for the eruptions mentioned above.)
In an earlier post I had said that a string of successive high SO4 concentrations was unusual. Since 5000 BC there have been 3 times, or once every 2000+ years on average, that there have been 20 or more years of successive high SO4 concentrations:
Interesting data, Groundskeeper Willie. Isn’t it curious that known eruptions, like the 934 AD Iceland eruption, don’t appear in the ice cores as a SO4 spike? I wonder, too, what caused the SO4 increases that do appear.
I’m not so sure… If you took all of the science questions out of GQ, then I’m not sure how well the rest would hold up. Depending on how you define “science and nature” (Does that include mathematics? Technology?), I count up to 24 topics currently on the first page of GQ that would fit. Besides which, if we do add any more fora, we would probably want something which could take some more of the load off of MPSIMS, that being the busiest forum-- I believe that this was the rationale behind IMHO. Then, too, you have crossover topics, like the recent threadspot Astronomy and Poetry, which fit nicely into the current GQ, but would not fit well into either fragment.
Meanwhile, it’s nice to see the internet doing what it’s designed to do for a change: Facilitating the exchange of knowledge:)