Guest essay by David Archibald
This post drew attention to the similarity between the recent warm decades and the period leading up to the extremely cold year of 1740. Now let’s investigate how a 1740-type event might play out. This graph shows the average of the monthly temperatures for the years 1736 to 1739 plotted with the monthly temperatures of the year 1740:
With respect to growing conditions, the 1740 season was a month later than the average of the previous five years and the peak months of the season were 2.5°C cooler. To get a perspective on how a repeat of 1740 might affect growing conditions in the Corn Belt, Bill Fordham, advising the grain industry in the Midwest, has kindly provided an update on the current season:
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“So far here in the center of the Midwest, the 2013 growing season is almost identical to 2009 in regards to Growing Degree Days (GDD).
In 2009 48% of the corn was planted by May 12 and 62% was planted by May 19.
In 2013 18% of the corn was planted by May 12 and 71% was planted by May 19.
In 2009, we never received a killing frost until November 5 when the low was at 28F. The Midwest had a huge crop that was wet and light test weight, but never got killed by a frost. In 2009, the total GDD accumulation from May 15 thru September 30 was 2,530 GDD.
The bulk of the corn planted in the Midwest ranges from 2,300 to 2,700 GDD (based on Fahrenheit). With the volcanoes that have been erupting in Alaska and Russia, especially with Mt Sheveluch erupting to 7.4 miles on June 26, I will be surprised if we get through the month of September in 2013 without an early killing frost. If the heat dome and high pressure ridge stays centered in the west and over Alaska until Labor Day, the clockwise rotation will pump the cold air south over the Midwest along with the ash. There are millions of acres at risk in IA and MN, that are 2-3 weeks behind normal.
After silking, it takes 24-28 days to reach the Dough Stage when kernel moisture is about 70% and about 50% of the total dry matter has accumulated in the kernel.
After silking, it takes 35-42 days to reach the Dent Stage when kernel moisture is about 55% and about 70% of the total dry matter has accumulated in the kernel.
It takes about 55-65 days after silking for a corn plant to mature and for the kernel to reach black layer, normally at 30-35% moisture.
A killing frost, <30F, will do damage whenever it occurs before black layer, the earlier the frost, the more severe the damage. A hard killing frost <28F can reduce the yield up to 25%, or more depending on the variety, even a week before black layer.
In 1974 I experienced severe loss on some late planted corn when I got rained out on May 7 and didn’t get back in to finish planting for 3 weeks. The May 7 corn yielded 190 bushels per acre and the May 28 corn yielded 90 bushels per acre, same variety.”
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Based on Bill Fordham’s experience of 1974, planting three weeks later reduced the crop yield by 50%. If the peak growth months of June, July and August are 2.5°C (4.5°F) cooler as per the CET record of 1740, that would reduce the GDD by 414.
A repeat of the climate of 1740, with a late planting and reduced heat in the three months prior to harvest can be expected to reduce crop yield by well more than 50%.
tchannon says:
July 6, 2013 at 6:44 am
lsvalgaard says:
July 5, 2013 at 7:48 pm
tchannon says:
July 5, 2013 at 7:25 pm
http://lasp.colorado.edu/sorce/data/tsi_data.htm
Is based on an obsolete paper by Wang, Lean, and Sheeley from 2005.”
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The TSI data on that page has been adjusted to conform with the new understanding provided by Kopp and Lean 2011.
So it is the most accepted current version.
http://www.dtic.mil/dtic/tr/fulltext/u2/a535690.pdf
vukcevic says:
July 6, 2013 at 4:31 am
Tectonics is indirect positive forcing acting via ocean currents
You have not explained how that works. Or even defined what you call ‘tectonics’. Here is the scientific definition: “Tectonics (from the Vulgar Latin tectonicus, meaning “building”) is concerned with the orogenies and tectonic development of cratons and tectonic terranes as well as the earthquake and volcanic belts”. That is ‘how are structures formed and do they develop’.
Dr. S, your observation is wrong, dogmatic and contrary to the good science practice.
To invoke more and more causes is contrary to science.
climatereason says:
July 6, 2013 at 4:34 am
I am not sure there is much evidence of long lived volcanic effects apparent in any archives I have seen.
Presumably because the immediate effect has the most impact and subsequently people are either dead or have adapted to the changed situation.
Do you have a view of the eruption noted by DR Mann in the middle of the 1200′s?
Some people have assumed that the LIA began with that eruption. Could well be.
Also in my previous link I had noted annual, decadal and fifty year figures. (Figure 4) The purpose was to examine this data not, on this occasion to plot a 5 year running figure.
Even so, running means should be centered.
Using the 40 year figures give the impression of much greater climate stability than actually exists in the real world. I would be pleased to have your comments on this.
Since climate is defined as average weather over 30 years that ought to be the proper smoothing window. 40 years window is a bit too long. I would have been happier with 30. But clearly the variation of the average over 30 [or 40] years has a lot less variation than that from year to year, so climate is more stable than weather.
AndyG55 says:
July 6, 2013 at 4:44 am
“Why can’t we skeptics get that?”
scientific illiteracy, perhaps?
Is with the same ‘tongue-in-cheek’ as the question.
Bill Illis says:
July 6, 2013 at 5:30 am
So, we are down about 0.3 W/m2 from what would be expected, but it is stil 0.17 W/m2 higher than normal given the solar cycle.
We are 0.25 higher than expected http://www.leif.org/TSI-not-following-SSN-F107.png
Stephen Walters says:
July 6, 2013 at 5:37 am
Very poor graph for a man of your talents, very hard to see any detail.
Because no cycles are alike on a day-to-day basis, so the details don’t matter much http://www.leif.org/research//SC14-and-24.png.
SC24 does not have the big swings that SC14 had
Did SC5? Perhaps you can show us. The big swings in SC14 began about the point of the cycle where we are at now in SC24, so watch for them from now on.
Now, you evade the direct comparison:
A recent reconstruction of the number of sunspot groups is not sensitive to the Waldmeier sunspot weighting and thus has no issue with ‘corrected’ data. It also has error bars that reflect the 1-sigma confidence. We can compare SC5, 6, 12, 14, 16, and 24 http://www.leif.org/research/Sunspot-Groups-Small.png and you can judge for yourself how SC24 compares and report here what you found.
tchannon says:
July 6, 2013 at 6:44 am
Simply look at the plot. It contradicts what you claimed.
The plot shows that almost all the increase took place since 1900. This is contradicted by much evidence, e.g. the magnetic field of the Sun. From http://www.leif.org/EOS/Foukal-2012.pdf :
“iv) Arguments for a sharp TSI rise in the first half of the twentieth century require complete disappearance of the photospheric magnetic network going back in time from the 1950s toward 1900. Such a disappearance is contradicted by the presence of a fully developed network in Ca K spectroheliograms obtained at Mt.Wilson and Meudon Observatories since the 1890s.”
And by the heliospheric field [which is the Sun’s field as dragged out by the solar wind]: http://www.leif.org/SC14-SC24-HMF-B.png
Caleb says:
July 6, 2013 at 6:45 am
I wonder, was the AMO was warm, and the volcano prompted a surge of that warmth north?
The Sun was in a funk then [some say] so the temps should have been way low.
Bill Illis says:
July 6, 2013 at 8:09 am
The TSI data on that page has been adjusted to conform with the new understanding provided by Kopp and Lean 2011.
That pertains to the average level only, which was simply adjusted by 4.6 W/m2, not to the variation.
So it is the most accepted current version.
The model is still from 2005 and is not the most accepted current version [there isn’t any at the moment – as Greg Kopp said to me in email from February “I suspect we don’t really know the TSI during MM nearly as well as we’d like…”]. See also reply to tchannon above.
lsvalgaard says:
“..and likely more important for England temperatures: Bárdarbunga Iceland, 1739]”
These were eruptions under the glacier:
“Studies of tephra layers have shown that a number of eruptions have occurred beneath the glacier itself, probably in the northeast of the crater or in Bárðarbunga. These eruptions appear to follow a cycle, several eruptions were in the glacier between 1701–40..”
http://en.wikipedia.org/wiki/B%C3%A1r%C3%B0arbunga#Eruptions
Can you provide a link showing that 20% of the population of Iceland died then?
Ulric Lyons says:
July 6, 2013 at 9:36 am
Can you provide a link showing that 20% of the population of Iceland died then?
As I said earlier:
Although Bárdarbunga [Iceland] also erupted strongly in 1739, perhaps the real damage was due to Hekla in the the same year. [ http://runeberg.org/univers/0476.html ]:
Translating from the Swedish:
“One of the most violent eruptions known on Iceland happened in 1739, when lava flows filled the Skapt-ons and Herrfirflojts valleys to a thicknes of 125-190 meter and flowed on for 84 and 34 km and buried [with their estimated volume of 12-15 cubic km] a 500 square km land area. The eruption lasted four months and due to it and the ensuing famine 9,288 people perished or nearly 1/5 of the total population of Iceland, in addition to 53% of the cows, 82% of the sheep and 77% of the horses”
Ulric: As you may know, the devastating eruptions were in 1783-85. Consequent famine killed an estimate 25% of Iceland’s population:
http://en.wikipedia.org/wiki/Laki
Dr. Svalgaard:
I have not found a record of Hekla’s erupting in 1739. The Swedish source may be incorrect:
http://www.volcano.si.edu/volcano.cfm?vn=372070
Hekla erupted at VEI 1 or less in 1725 & at VEI 4 in 1766 (both in April under the calendars then in use).
http://en.wikipedia.org/wiki/Hekla#1725_and_1766.E2.80.931768
Leif says
S [=TSI] = a T^4 [Stefan-Boltzmann law]
dS = a 4 T^3 dT [differentiate]
dS/S = (a 4 T^3 dT)/(a T^4) = 4 dT/T
dT/T = 0.1/289 [Kelvin] [289K is average global temperature]
dS/S = 4*0.1/289 = 0.001384
dS = 0.001384*1361 W/m2 = 1.88 W/m2 which is about what TSI varies during a solar cycle.
Ah, but the 0.1 C temperature variation is at ocean surface level where the average heat flux variation reaching the surface is only about 70% of 1/2 of 1/2 of the TSI variation at the cloud tops.
There is 30% reflected, one factor of two for day-night averaging and a factor of 1/2 for latitude averaging. So only 17.5% of the TSI variation is effective for raising the ocean surface temperatures. Now what say you?
@lsvalgaard
Lava from Hekla does automatically mean there was significant ash in the air, which would not have reached the UK anyway with strong easterlies blowing through the cold winter period.
milodonharlani says:
July 6, 2013 at 9:57 am
I have not found a record of Hekla’s erupting in 1739. The Swedish source may be incorrect
We go to war with the sources we have [to paraphrase Rumsfeld]. This is the reference to the source:
http://runeberg.org/univers/
Now, there were large eruptions elsewhere in 1739, e.g. Tarumae and Shikotsu both in Japan.
The other side of that coin is that there was nothing unusual about the Sun in 1740.
bones says:
July 6, 2013 at 10:02 am
Now what say you?
I say that the albedo and round Earth are all automatically accounted for by computing dT/T and dS/S because those effects occur both above and below the division sign and thus cancel out.
There are many variables not possible to predict. The sun has the most obvious effect on daily temps just by day and night variance. So, if the solar wind and other conditions of the sun decline or increase then it is reasonable to expect some changes on earth temperature in line with other planet temperatures. Now, it we had some history of temperatures on Mars that varied similarly to Earth, could we say it was due to solar output and not a local event i.e. eruptions, metero strikes, CO2 levels, and so forth? One could be more concerned about an earth orbit changing event, or strike from the vast number of astorieds and comets. I think we have shown we can survive the solar changes of the last 12,000 years.
By the way, how are the ski areas fairing?
Ulric Lyons says:
July 6, 2013 at 10:06 am
Lava from Hekla does automatically mean there was significant ash in the air, which would not have reached the UK anyway with strong easterlies blowing through the cold winter period.
We actually do not know if Hekla blew during Winter 1739. That many people and animals died due to famine hints that the eruptions were later in the year when the animals were out in the fields and the harvest failed. During winter there would have been a much smaller effect because crops were not growing and animals were generally in shelters.
We could look at live stock deaths from cold and other death events that coincide with winters. Like the Amazon event a few years back? And China? Or how about humane death related to cold as apposed to heat. But, then again there are circumnstanse to define.
lsvalgaard says:
July 6, 2013 at 10:15 am
The supposed 1739 eruption in Iceland is what Rummy might have called a known unknown. IMO the Swedish source is wrong, since no record appears to exist upon which it’s based. Its description of catastrophe fits the known known of 1783, et seq, due to the Laki & associated eruptions. If Iceland had been as devastated after a 1739 eruption as following Laki, it would show up in documents. However I found no record of catastrophic famine in Icelandic history of 1739-40, however there was one in Ireland, of unknown cause, associated with the year under discussion here, 1740.
http://en.wikipedia.org/wiki/Great_Irish_Famine_%281740%E2%80%931741%29
Steve says:
July 5, 2013 at 1:33 pm
I”ve never seen the crops this far behind. Corn was not knee-high by the fourth of July, but it has always been waist to shoulder high in my lifetime…..
>>>>>>>>>>>>>>>>>
Corn in my area (Mid North Carolina) was planted very late ~ mid May now we have had two weeks of rain so it is starting to catch up but like you say Steve it is only shoulder high and not silking yet.
What is really weird is my buck goat has gone into rut in the last two weeks. Goats rut at the same time a buck deer does, Mid September.
highflight56433 says:
July 6, 2013 at 10:38 am
We could look at live stock deaths from cold and other death events that coincide with winters.
In Iceland the weakest animals [and the bulls – they ate too much] were slaughtered just before the winter [such as not needing to be fed]. The rest wintered over indoors in shelters eating hay stored up for that purpose.. So live stock did not die from cold, but rather from the butcher’s knife.
Here’s a description of Laki’s big blow 230 years ago (the link title has the wrong year):
http://www.wired.com/wiredscience/2013/06/local-and-global-impacts-1793-laki-eruption-iceland/
It probably would have taken a similar eruption to produce a catastrophic famine in 1739, of which there is no record then in Iceland, other than the Swedish source cited by Dr. Svalsgaard.
Leif, did I mention Iceland? Why redirect the statement to Iceland when the point is global?
milodonharlani says:
July 6, 2013 at 10:42 am
The supposed 1739 eruption in Iceland is what Rummy might have called a known unknown. IMO the Swedish source is wrong, since no record appears to exist upon which it’s based.
Absence of Evidence is not Evidence of Absence. There is also no evidence that the Sun was acting up [the previous statement not withstanding]: SSN-1730-1750.png
http://www.leif.org/research/SSN-1730-1750.png
The red curve is based on too few records.
highflight56433 says:
July 6, 2013 at 10:58 am
Leif, did I mention Iceland? Why redirect the statement to Iceland when the point is global?
Didn’t I mention Japan too? In any event the Central England Temperature is not global and is likely to be influenced by volcanism in Iceland as we saw in 2010 http://en.wikipedia.org/wiki/Air_travel_disruption_after_the_2010_Eyjafjallaj%C3%B6kull_eruption
so why whine?
Leif, the point is you intentionally deminished my coment to Iceland.
highflight56433 says:
July 6, 2013 at 11:07 am
Leif, the point is you intentionally diminished my comment to Iceland.
Every thing I say is intentional. And I cannot alter your comment, but am I not allowed to disagree?
lsvalgaard says:
July 6, 2013 at 11:00 am
milodonharlani says:
July 6, 2013 at 10:42 am
The supposed 1739 eruption in Iceland is what Rummy might have called a known unknown. IMO the Swedish source is wrong, since no record appears to exist upon which it’s based.
Absence of Evidence is not Evidence of Absence. There is also no evidence that the Sun was acting up [the previous statement not withstanding]: SSN-1730-1750.png
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But there is evidence that the Swedish source confused 1783 with 1739, since its details correspond to the Laki eruption-induced famine. Also, there must be some original source for the Swedish statement, but its absence from the Net suggests it doesn’t exist, other than for 1783. If the 1740 Irish famine had been caused by an Icelandic eruption, the “fog” of 1783 would have been noted in the British isles. Also, had Hekla or another Icelandic volcano erupted in 1739, there would be a record of it, especially if of 1783 Laki magnitude. In an instance that extreme, absence of evidence is evidence of absence. The minor eruption of 1725 was noted.
You do have the Japanese eruptions, so IMO the jury is still out on volcanic cause for the cold of 1740.
lsvalgaard says:
“During winter there would have been a much smaller effect because crops were not growing and animals were generally in shelters.”
125-190 meters of lava in the valleys would bury them nicely. So what happened to European winter warming following eruptions? http://bit.ly/13si2Ae