Guest Post by Willis Eschenbach
Richard Muller and the good folks over at the Berkeley Earth Surface Temperature (BEST) project have released their temperature analysis back to 1750, and are making their usual unsupportable claims. I don’t mean his risible statements that the temperature changes are due to CO2 because the curves look alike—that joke has been widely discussed and discounted, even by anthropogenic global warming (AGW) supporters. Heck, even Michael Mann jumped on him for that one, saying
It seems, in the end–quite sadly–that this is all really about Richard Muller’s self-aggrandizement 🙁
And if anyone should know about “self-aggrandizement”, it’s Michael Mann … but I’m not talking about Muller’s claim that humans caused the warming. No, I mean the following statement:
The historic temperature pattern we observe has abrupt dips that match the emissions of known explosive volcanic eruptions; the particulates from such events reflect sunlight and cool the Earth’s surface for a few years.
In support of this statement, Richard Muller offers up the following chart:
Figure 1. BEST claims about temperature and volcanoes. SOURCE
So what’s not to like?
Well, first it appears he has included and excluded volcanoes depending on whether they show up in his temperature record. If we look at big eruptions, eruptions with a “volcanic explosively index” (VEI) of 6 or above, since 1750 we have the following volcanoes:
Mount Pinatubo, 1991
Novarupta, 1912
Santa María, 1902
Krakatoa, 1883
Mount Tambora, 1815
Grímsvötn and Laki, 1783
So Muller has left off Santa Maria and Novarupta, and included El Chichon and Cosiguina. But that’s not the real problem. The real problem is that many of these occurred after or during the temperature drop that they are supposed to have caused … here’s the BEST data including all relevant volcanoes, without the style of overlay that they have used that obscures the actual timing:
Figure 2. BEST temperature data and dates of volcanoes. Red line is a four-year centered Gaussian average of the temperature data. Photo shows Mt. Redoubt in Alaska.
So let’s look at the volcanoes, one by one:
LAKI, 1783: Occurred near the end of the fall in temperature that it is supposed to have caused.
TAMBORA, 1815: Occurred at the end of the fall in temperature that it is supposed to have caused.
COSIGUINA, 1835: Occurred near the middle of the fall in temperature that it is supposed to have caused.
KRAKATOA, 1883: Occurred at the end of the fall in temperature that it is supposed to have caused.
SANTA MARIA, 1902: Occurred in the middle of the fall in temperature that it is supposed to have caused.
NOVARUPTA, 1912: I can see why Muller omitted this eruption, which occurred just before a rise in temperature …
EL CHICHON, 1982: Occurred during the fall in temperature that it is supposed to have caused.
PINATUBO, 1991: This is arguably the only one of the eight volcanoes that could legitimately be claimed to cause a detectable fall in temperature … a whopping fall of 0.15°C or so.
So while volcanoes certainly may cause a minor drop in global temperature, the claim of Richard Muller and the BEST folks that there are “abrupt dips that match the emissions of known explosive volcanic eruptions” is simply not true. There are abrupt dips, but they don’t match up with the volcanic eruptions.
w.
[Update] Further reading:
Prediction is hard, especially of the future discusses the GISS analysis of Pinatubo.
Missing the Missing Summer is about the eruption of Tambora.
Dronning Maud Meets the Little Ice Age investigates a claim that the Little Ice Age was triggered by vulcanism.
Volcanic Disruptions plays the game “Spot the Volcano”
[Update] Another way to investigate the question is to look at the average temperature anomaly during the two years before and the two years after the eruption. Figure 3 shows that result.
Figure 3. Average temperature anomaly two years before and two years after the eruptions. Black lines show the standard error of the mean.
After some eruptions it cooled a bit, after some it warmed a bit, and after some there was no change … go figure.
Discover more from Watts Up With That?
Subscribe to get the latest posts sent to your email.
So temps now are 0.3 degree’s warmer than the 1770’s. Thanks BEST, that’s some scary rise. lol
For those wondering about a series of volcanic eruptions before 1815, my files show:
Urezelina, Sao Jorges, Azores 1808. Leif Svalgaard, WUWT comments, included an article by Michael Chenoweth, 2001 Geophysical Research Letters. From the abstract: “The 1809 eruption is dated to March-June 1808 based on sudden cooling in Malaysian temperature data and maximum cooling of marine air temperature in 1809.” Svalgaard adds the 1814 eruption of Mayon.
In a Science Daily release 12/7/09: :”[Professor Jihong] Cole-Dai [South Dakota SU Dept of Chemistry and Biochemistry] said climate records [ice cores from Greenland and Antarctica] show that not only were 1817 — the so called ‘year without a summer’ — and the following years very cold, the entire decade of 1810-1819 is probably the coldest for at least the past 500 years. Another use of the 500 number elsewhere, Tambora was the largest eruption in the last “500 years”.
There is another interesting article by Catchpole and Hanuta, U Manitoba, Climate Change 1989. From sailing ships log-books in the Hudson Strait, 1751-1889: “The number of concurrences between the years with severe ice in Hudson Strait and the years with major eruptions was significant at the 99.5% level. In the western part of Hudson Bay this significance level was 95%. The years with severe ice in eastern Hudson bay did not concur with major eruptions.”
Willis, great catch., Now let the real “peer review” begin.
This morning’s Los Angeles Times front page headline: “Climate change skeptic is now believer. [Sub-head] A Berkeley professor makes a surprise ‘total turnaround’ in a study funded by doubters of global warming.” The study from that marxist center, UCB, in the “fair and balanced” Chicago Tribune of Los Angeles.
What would be more interesting would be a plot showing the leading moving average based on the next 2-4 years (i.e., what happens after the eruption).
As usual, the devil is in the details and Willis is a master at digging out basic data. The bottom line here is that, at most, volcanic eruptions may result in a couple of cooler years, but only temporarily affect weather, not climate. Now Willis has shown even that is questionable.
Good job Willis!
A remarkable post in which you display ignorance of statistics, climate and volcanoes. Are you not even aware that volcanoes are not the only climate variable? Do you not realise that your centred average line inevitably displays the influence of major volcanic eruptions before they have occurred? Do you not understand that the VEI is not the primary variable which determines influence on climate? That would be the amount of stratospheric aerosol injection, which depends on the nature of the eruption and its latitude, and is only partially correlated with VEI.
And obviously you have no familiarity at all with the literature on attribution of climate change. People far cleverer than you have been studying this in far more sophisticated ways than you can imagine, for quite some time. The influence of volcanoes on climate is very well established.
Beyond the volcanic non-dips, Willis:
The error bar/max-min of old records wrt new records has bothered me in that the median value is taken to reflect climatic conditions for all times, so that we can say the “actual” temp average is comparable. But this assumes that the natural VARIATION is constant. If former times had a LARGER variation, comparisons of the median temperature would misrepresent the climate of the time.
Is it possible that a lot, or at least much greater portion than today, of the former max-mins were, in fact, true representations of the world? That “stability” of the climate is much greater now than in the recent past? Is it possible that a more accurate representation of the last few thousand years is to set the temperature variation vis-a-vis max and min values? If so, then warm times and cold times were both greater in the near-past, and today’s “extremes” are, in fact, much less than previously.
If it can be show than climatic variations are at a recent period low, then there is no substance for saying that climatic “weirdness” is a sign of pre-CAGW instability.
If Willis had Muller’s flair for hyperbole:
“Temperature Drops Cause Volcanic Eruptions!”
Clearly, the cooling of the atmosphere sucks hot volcanic gas to the surface, causing eruptions. I have the charts to prove it!
TYPO: Pinatubo wasn’t at 1912
Confirmation bias leads to selection bias. I’ve never bought volcanic forcings. Declines in solar cycle frequency caused these coolings.
Thank you ob for explaining the Galeras and the Mout St Helen eruptions , and why they are not in the charts !
It would appear that their is a good case for speculating that their might be a common cause that could produced both large (VEI > 5) volcanic eruptions (mostly located in the tropics) and significant drops in world temperature, as well.
Willis is right in using causality arguments to point out that the eruption themselves are most likely not the cause of the drops in temperature, while conceding that they may have an effect at reducing world temperatures by a small amount in some cases.
However, there is a case that large Plinarian volcanic eruption [VEI > 4] located in the tropics can have an observable effect upon the general circulation patterns in the mid-latitudes of the Southern Hemisphere.
Recently, I published a paper that showed a significant correlation between long-term changes in the lunar tidal forces and the interannual to decadal variability of the peak latitude anomaly of the summer (DJF) subtropical high pressure ridge over Eastern Australia (LSA), between 1860 and 2010.
http://astroclimateconnection.blogspot.com.au/2012/03/open-atmospheric-science-journal-2012-6.html
If you go to this page and look at the main graph you will see that there is actually quite a good match between the number of days the nearest Full/New moon is from perihelion and the peaks in
yearly variability of the peak latitude anomaly of the summer (DJF) subtropical high pressure ridge over Eastern Australia (LSA). In fact, the correspondence between the peaks in the data sets are (generally) so good, that it is possible to identify peaks in LSA that are caused by large Plinarian [> 4] volcanic eruptions to the near north of Australia. (i.e. in the Indonesian Archipelago and New Britain (e.g. Krakatoa in 1883)).
Note: that this data is presented for speculative purposes only and is not being used to claima “rock-solid” connection between these two phenomenon.
Remember when Muller was the darling of the anti-AGW community?
Good times, those. Good times.
If anything, according to the timings, volcanoes caused warmings.
Volcanoes emit far more CO2 than warmist-corrupted science admits. Maybe the putative cooling depends on the relative amounts of ash and CO2. Or maybe the CO2 itself. causes temporary cooling.
Since the ice core data (often cited as proof that CO2 is linked to warming) shows that warming proceeds CO2 increases by hundreds of years, why can’t future volcanic eruptions cause cooling in the past?
Hey, Jorge! Do you have a source for that “volcanoes emit far more CO2….” comment?
Just curious. Because that sounds like kind of a big deal.
Nick Stokes says:
July 30, 2012 at 4:11 am
Thanks, Nick and Ian. With a four-year filter, you’d start to see effects two years before the drop in temperature. But while a short timespan Gaussian average does react slightly before the drop, the Gaussian nature of the average makes the effect much smaller than you’d expect. Here, for example, is the same data, with a Gaussian filter of half the size (2 years).
As you can see, none of my comments or conclusions are affected by the change.
My own sense is that yes, volcanoes do have an effect. However, it is minimized by both the “nearly equal but opposite” responses of the climate to such a change (such as decreased tropical clouds), and by the noise in the climate system. As a result, the volcanic signal in the data ends up being quite small.
Here’s another way to look at it, this is the average temperature anomaly for the two years prior to the eruption, compared with the temperature anomaly for the two years following the eruption:
As you can see, sometimes it warmed after an eruption, sometimes it cooled, sometimes temperatures were unchanged within the error of the measurements … not a ringing endorsement for Muellers claims, quite the opposite in fact.
w.
Stew says:
July 30, 2012 at 4:42 am
In that case, you might be interested in my post, “Missing the Missing Summer“. I’ll add a link to it in the head post as well.
w.
Tried running a correlation with sunspot numbers, known volcanic eruptions and temperature datasets once (Figures from 1780-2000AD). Just to satisfy my own curiosity. I’m no statistician or scientific researcher, merely an interested layman, but I couldn’t see any obvious connection simply using publicly available historic data. At least not globally.
Paul Matthews says:
July 30, 2012 at 4:35 am
Nice catch, I’d missed that entirely … teach me to trust Mueller even in the most elementary matters.
w.
There is ice core evidence that the Tambora eruption was preceded by another, six years earlier so that the Tambora eruption intensified and extended the existing coolng trend:
Dai, J.; Mosley-Thompson and L.G. Thompson (1991). “Ice core evidence for an explosive tropical volcanic eruption six years preceding Tambora”. Journal of Geophysical Research (Atmospheres) 96: 17,361–17,366.
Willis,
Not to argue your major conclusion, however:
1. Though these may have coincidentally occured during a temperature decline which had already begun for other reasons, this does not mean there was no significant impact to exacerbate that fall.
2. To say as a result that “volcanos certainly may cause a minor drop in global temperature” is probably an over statement :
a. You cannot be sure how much something like Tambora increased a temperature drop already under way.
b. Even Tambora, a relatively major event in the list, was minor compared to some of the historic eruptions of, say, Yellowstone. Better to say ‘THESE volcanos may….’
pyromancer76 says:
July 30, 2012 at 8:03 am
I love how climate science these days is reduced to “probably” … it may or may not be the coldest decade in the last 500 years, but if you don’t know, don’t guess and call it science.
In fact, according to BEST, the ten years before the Tambora eruption in 1815 were COLDER than the decade following the eruption, so the BEST data disagrees strongly with Professor Cole-Dai:
1755-1764, -0.89°C
1765-1774, -0.29°C
1775-1784, -0.54°C
1785-1794, -0.75°C
1795-1804, -0.51°C
1805-1814, -1°C
1815-1824, -0.82°C
1825-1834, -0.48°C
1835-1844, -0.78°C
1845-1854, -0.4°C
1855-1864, -0.52°C
1865-1874, -0.25°C
1875-1884, -0.39°C
1885-1894, -0.46°C
1895-1904, -0.28°C
1905-1914, -0.36°C
1915-1924, -0.25°C
1925-1934, -0.06°C
1935-1944, 0.09°C
1945-1954, -0.01°C
1955-1964, -0.01°C
1965-1974, 0°C
1975-1984, 0.17°C
1985-1994, 0.36°C
1995-2004, 0.7°C
w.
What is that black central curve. It does not look like an average, sometimes it follows the wiggles, sometimes not, it looks more like hand-drawn ?