President Jefferson Meets Mount Tambora

Guest Post by Willis Eschenbach

In the comments of my last post entitled “Spot The Volcano, 1815 Edition” someone mentioned that Thomas Jefferson had commented on what is often called the “Year Without A Summer”. This was the summer of the year 1816, one year after the eruption of Mt. Tambora in Indonesia, which occurred in April of 1815.

Some research turned up Jefferson’s weather notebook entitled “Analysis of Weather Memorandum Book, January 1817”. All of the data in this post is from his analysis. He opens by saying:

1817. January. Having been stationary at home since Mar.1 1809. with opportunity and leisure to keep a meteorological diary, with a good degree of exactness, this has been done: and, extracting from it a term of seven years compleat, to wit from Jan. 1. 1810. to Dec. 31. 1816. I proceed to analyse it in the various ways, and to deduce the general results which are of principal effect in the estimate of climate. the observations (3905. in the whole) were taken before sunrise of every day; and again between 3. and 4. aclock P.M. on some days of occasional absence, they were necessarily omitted. in these cases the averages are taken from the days of the same denomination in the other years only, and in such way as not sensibly to affect the average of the month, still less that of the year, and to be quite evanescent in their effect on the whole term of 7. years.

In other words, a good and careful observer. In addition, he took the maximum and minimum values at the same times of day, before dawn and between three and four o’clock. Well done, that man.

Since our interest is in the summers, the first graph that I made up from Jefferson’s data is of the May to September growing season in Monticello (see below for growing seasons). Here are the temperature means, minimums, and maximums.

Figure 1. May to September average temperatures at Monticello, Virginia, as recorded by Thomas Jefferson. Horizontal straight colored lines show the averages from 1810 to 1815.

Now, Figure 1 shows some interesting things. The average May to September temperature (yellow line) in 1816 was about the same that of 2015. However, the maximum temperature is about a degree warmer than 1815, and the minimum temperatures were about a degree lower than in 1815. Max goes up, mean unchanged, but the minimum was unusually cold. In particular, the months of July and August had cold minima. So Tambora may have had some effect on temperatures at Monticello.

Jefferson also recorded some other interesting weather data. He wrote down the days of “white frost”, also known as a “killing frost”. He recorded the last day of white frost in the spring, and also the first day of white frost in the fall. This lets us see if 1816, the “Year Without A Summer”, had killing frosts later or earlier than other years. Here’s that information.

Figure 2. Days of the first and last frosts at Monticello, Virginia, as recorded by Thomas Jefferson.

The year 1816 was not at all unusual as regards to frost. The last frost of the spring happened around its usual time. And although it had the earliest fall frost during the period, as Jefferson commented, “but we have seen, in another period, a destructive white frost as early as September.” Not to mention that the growing season was the fourth longest of the seven years of record.

How about rainfall? Here are the month-by-month values:

Figure 3. Monthly rainfall at Monticello, Virginia, as recorded by Thomas Jefferson.

I’ve highlighted the June to August periods because that period was indeed unusually dry in 1816. However, both May and September 1816 were unusually wet, and the year 1816 overall had the fourth highest annual rainfall of the seven years.

Finally, Jefferson considered that when the temperature was below 55°F you’d need a fire. So he listed the number of times that a fire would be necessary, both in the morning and in the afternoon. In his words:

“It is generally observed that when the thermometer is below 55.° we have need of fire in our apartments to be comfortable. in the course of these 7. years the number of observations below 55.° in each year were as follows.”

Here are the number of days per year that Jefferson thought would require a fire either in the morning, the afternoon, or both:

Figure 4. The number of days requiring fires in the morning and the afternoon at Monticello, Virginia, as recorded by Thomas Jefferson. Photo shows one of the many fireplaces in Jefferson’s home at Monticello.

As you can see, 1816 required the least morning fires of the seven years, and it only needed an average number of fires in the afternoon.

So … the growing season of the year of 1816 was dry and had both cold and warm months. In the fall of that year, before he wrote the summary of the data used in this analysis, Jefferson commented in a letter to a friend that “We have had the most extraordinary year of drought and cold ever known in the history of America.” However, his own records show that, as is the habit of humans the world over, he was exaggerating … shocking, I know, that a US President would exaggerate … but I digress.

I say he exaggerated because contrary to his claim, the facts in his meticulous recordkeeping for the year 1816 show less than a half-degree C of May – September cooling, no unusually late or early frosts, an average length growing season, no need for extra fires in the morning, and fewer fires than usual needed in the afternoons. And although June through August was dry, overall the year 1816 was fourth among the seven years in the total amount of rain.

So was there a “Year Without A Summer” at Monticello?

I’d say that the eruption of Tambora may well have some effects at Monticello, with a couple of quite cold months and a couple of quite dry months, but the reports of those effects have been greatly exaggerated, even by Thomas Jefferson himself …

My warmest regards to all,

w.

PS—When you comment, to avoid misunderstandings, please quote the exact words that you are discussing.

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114 thoughts on “President Jefferson Meets Mount Tambora

    • Yes too short, plus that, I’m unsure if we know how he exposed the thermometer. Back then, they didn’t have a standardized instrument shelter, and some readings were taken under trees, or thermometers on the side of buildings.

      It wasn’t until about 1892, with the advent of the Stevenson Screen, that thermometer exposure was standardized.

      • True, but he did take readings over many, many years. And he was always buying the best quality scientific instruments available in his time. Surely this would give a decent reference point vs tree rings, soil cores, etc.

        • That would only help if the cores were taken in the same location. Can’t compare Virginia and California or Ethiopia or Yamal.

      • If he used the same instrument for all readings, dependent errors would cancel out. Independent errors would still be an issue but you end up either believing the data or not believing the data.

    • Disagree, stopped reading here “However, his own records show that, as is the habit of humans the world over, he was exaggerating … shocking, I know, that a US President would exaggerate” Willis took his words claimed they said something they didn’t i.e. Monticello was warming, then basically called him a liar. You do realize that they had newspapers back then so he would have known what the weather was like in”America” not just Monticello. Willis has already proved his point about volcanoes now he is trying to decouple 1815 from volcanoes with one data point.

      • Iron, you may indeed disagree, and you may be right … but if you stop reading every time you disagree with something you’ll never move forwards.

        Best regards,

        w.

  1. Willis

    we dont know for sure the accuracy of the thermometer used:
    +/- 1 (one degree K) different from ours is actually good for that time
    ‘remember they were oblivious of having to re-calibrate [mercury] thermometers every year due to the oxidation of mercury.
    hence my method of looking at the average change from the average over a period of time

    but I don’t think you ever got that hint…

    Click on my name to read my new page on climate change

    • henryp, you say:

      hence my method of looking at the average change from the average over a period of time

      but I don’t think you ever got that hint…

      Um … look again at Figure 1 … change in average over time …

      Also, I looked at your linked page. It starts out by saying:

      It is simple, really. It is warmer during the day than during the night because of the sun. It is warmer in summer than it is in winter because of the sun. So, following simple logic, would you not say that if it is warmer now on earth than it was 100 years ago, it must also be because of the sun?

      The change in insolation from day to night is on the order of 600 watts per square metre.

      The change in insolation from winter to summer is on the order of 250 watts per square metre.

      The average change in insolation over the past hundred years is on the order of 0.25 watts per square metre, if that.

      So no, while your sentence sounds logical, once you look at the actual numbers it makes no sense at all.

      w.

    • Henry, I thought mercury thermometers had a vacuum above the column. Although not a perfect vacuum, surely the oxygen would become depleted on a year or two.

      • True enough. I think it is some other type of degradation of that causes the deviation in mercury thermometers. Must admit that I cannot remember now what it was. I do remember getting irritated by the endless yearly quality checks on theremometers during the relevant audits.

        • Gary
          I think it was the reaction between the mercury and the glass…sorry I forgot.
          Obviously that is the reason why we stopped using them. We are now using thermocouples. I take it that they are used now exclusively in weather stations?

          • I have a JUMO Kontaktthermometer (-5℃ .. 103℃) made in 1949. It is marked “Zum Ultrathermostat” and “hoch belastbar”.

            It is more accurate than a recently calibrated Oakton thermocouple instrument.

            I can see what looks like a smudge of dirt near the bottom of mercury column, but it is right where the static contact is inserted, so it can be an illusion caused by mercury imperfectly wetting the contact. It has no effect on accuracy.

            This instrument is as “hoch belastbar” as anything made in old Germany.

            I had an even older German thermometer (1890s) that was just as accurate.

      • John Tillman–

        Your link to Stothers’ very satisfying study of the great Tambora eruption made my day. Stothers was one of the members of my committee for my Ph.D., in Astrophysics from City University (CUNY). I worked across the hall from him on the 5th floor of the GISS Institute for a year or two. He was the scientist I most admired, for his interest in everything and the depth of his studies. His office was large with a huge table in the middle overflowing with 10 or 20 piles of manuscripts. As he says about his Tambora study, it included elements of volcanology, meteorology, oceanography, glaciology, climatology, astronomy and history. A perfect topic for him.

        While he and I were on the 5th floor, James Hansen was on the 2nd, studying Venus. Stothers thanks him for suggesting the Tambora study. Would that Hansen could have kept studying Venus instead of turning his attention to Earth.

        • You’re most welcome. Thanks!

          Hansen was on the wrong track on Venus, too. But at least the damage he could do was limited to understanding of that planet.

          Sad to say, but it now appears that GISS has outlived its usefulness.

  2. If only the current debate was more reflective of the actual historical data and not using hyperbole in its anecdotal analysis. More like Willis, less like Jefferson. That would make discussions about climate far more productive and informative.

  3. The mistake you appear to be making is assuming his claim “We have had the most extraordinary year of drought and cold ever known in the history of America.” is somehow specific to Monticello. Seems more likely that he’s referring to the weather for the US at the time or at least New England.

    Might help to know who he was writing to. I’m guessing someone in Europe.

    Seems to me you’ve proven that 1815 wasn’t a year without a summer in Monticello.

    • Thanks, Bill. Yes, he could be referring to the weather for New England.

      However, the eruption seems to have had little effect in Monticello itself.

      w.

    • Someone up above said he had bad crops that year, could it be he was just making excuses to his creditors?

      • TJ was hardly alone in suffering crop failure. His letter wasn’t to creditors but to Gallatin for transmission to Mde. de Stael, as noted below, where you can read the missive.

        Adapted from an Irish Times article on the diary of an Irishman who suffered through the consequences of the catastrophe:

        The Mount Tambora eruption lofted huge amounts of volcanic ash into the stratosphere, blocking sunlight and leading to a temperature drop. Prof. John D. Post’s 1977 book, “The Last Great Subsistence Crisis in the Western World”, looked at how northeastern America and parts of western Europe, in particular, were the worst affected by the consequences of the eruption.

        In May 1816, snow and frost killed off crops in the upland areas of Massachusetts, New Hampshire and Vermont, with Atlantic Canada suffering similarly. Snow and especially frost continued into June, July and August, with lake and river ice observed as far south as Pennsylvania and Virginia. The destruction of crops led to food shortages and starvation for many, especially the poor.

        Europe was just emerging from the Napoleonic Wars at the time, and the low temperatures and continuous rain of 1816 led to severe food shortages. There were food riots in Britain and France, with arson and looting in many European cities. Landlocked Switzerland was worst affected by the violence, and the famine caused the government to declare a national emergency.

        There was continuous rain in Ireland for eight weeks during that non-summer; crop failure and famine followed. The famine led to a major typhus epidemic occurring between 1816 and 1819; it is estimated that up to 100,000 people died. With the failure of harvests in Britain, there was also extensive suffering and death.

        Failed harvests caused the price of oats to soar, which made it too expensive for many people to keep horses. The German inventor Karl Drais, looking for alternative methods of transport, invented a type of velocipede, an early form of what we know today as the bicycle.

        On Sumbawa itself and on neighboring Indonesian islands, the violent eruption of Mount Tambora caused catastrophic loss of life. In China and India, the consequent cold weather and floods killed animals and destroyed crops, leading to terrible famine and cholera epidemics.

        • “In May 1816, snow and frost killed off crops in the upland areas of Massachusetts, New Hampshire and Vermont, with Atlantic Canada suffering similarly.”

          May frosts are common in Massachusetts.
          “https://www.plantmaps.com/interactive-massachusetts-last-frost-date-map.php”

          “Snow and especially frost continued into June, July and August, with lake and river ice observed as far south as Pennsylvania and Virginia. The destruction of crops led to food shortages and starvation for many, especially the poor.”

          Based upon current evidence the snow and frosts through the summer appear anecdotal alarmism rather typical of newspapers.

          Lake and river ice in Pennsylvania and Virginia is indeterminate as Ice dams leave piles of ice long after warm weather returns. Plus many of the taller hills, er, Eastern mountains, can have snow in upper elevation shadowed hollows long into summer.

          The Irish Times article is interesting, not definitive.

    • Thanks for the links, John. Per Figure 9 of your first link, the temperature drop in Europe was on the order of two tenths of one degree C, less in most other parts of the world … from the biggest eruption in modern history. The only place in Figure 9 that saw a half degree of temperature drop was upper New England.

      And Jefferson’s debts were mostly related to the War of 1812, the bursting of the property bubble, and the Bank Panic of 1819 …

      w.

      • Crop failures surely didn’t help TJ’s financial situation.

        He also didn’t feel the need to economize. He continued buying wine from France on credit, for instance.

        Globally, the drop in temperature was 0.4 to 0.7 °C, as per my 1984 Stothers link. But marginal agricultural areas were naturally affected more. Please see .PDF link above.

        Stothers, Richard B. (1984). “The Great Tambora Eruption in 1815 and Its Aftermath”. Science. 224 (4654): 1191–1198.

      • Maybe it wasn’t the temperature per se but an effect of weaker sunlight cf the dust in the atmosphere. If there was famine in Europe, China etc then there was some effect.

        Just a layman’s thought.

    • Also, from TJ’s 1816 letter to Mde. de Stael, via Albert Gallatin, linked below:

      “We have had the most extraordinary year of drought & cold ever known in the history of America. in June, instead of 3¾ I. our average of rain for that month, we had only ⅓ of an inch, in Aug. instead of 9⅙ I. our average, we had only 8⁄10 of an inch. and it still continues. the summer too has been as cold as a moderate winter. in every state North of this there has been frost in every month of the year; in this state we had none in June & July. but those of Aug. killed much corn over the mountains. the crop of corn thro’ the Atlantic states will probably be less than ⅓ of an ordinary one, that of tobo still less, and of mean quality. the crop of wheat was midling in quantity, but excellent in quality. but every species of bread grain taken together will not be sufficient for the subsistence of the inhabitants; and the exportation of flour, already begun by the indebted and the improvident, to whatsoever degree it may be carried, will be exactly so much taken from the mouths of our own citizens. my anxieties on this subject are the greater, because I remember the deaths which the drought of 1755. in Virginia, produced from the want of food.”

  4. the decrease in temperatures from volcanic eruptions is nowhere near as large as people claim.

    Strawman fallacy. Scientists know very well the weather effects from volcanoes since decades ago. Do you really think you are going to discover anything of value with your number games?

    The available evidence from El Chichon and Pinatubo eruptions only supports a short-term effect from volcanoes on temperatures, lasting at most a few years. Instrumental temperature records from 19th and 20th century volcanic eruptions indicate a temperature decrease of 0.2-0.3 °C for 3-4 years (Self et al., 1981).

    According to Rampino et al., 1979:
    “The eruption of Tambora in 1815, one of the largest eruptions during the past few thousand years, is associated with a hemispheric temperature decrease of only 0.5° to 1°C for 2 to 3 years. In this case, average global temperatures had already been decreasing since 1810 and then rose again in the 1820s.

    Scientists know very well volcanic eruptions have a small effect on temperature of a few decimals of a degree for a few years. I don’t know who is that people that you talk about.

    Rampino, M.R., et al. 1979. Can rapid climatic change cause volcanic eruptions?. Science, 206, 4420, 826-829.

    Self, S. et al. 1981. The possible effects of large 19th and 20th century volcanic eruptions on zonal and hemispheric surface temperatures. Journal of Volcanology and Geothermal Research, 11, 1, 41-60.

    • What have facts got to do with what people “know”? People are still claiming the little ice age was caused by volcanos. And I don’t just mean know nothings like politicians and reporters. Check back through WUWT alone to see where people have been refuting papers and articles claiming long term effects.

      Mann’s hockystick is still being used to support CAGW as well as the “97%” lie.

      • The effect from volcanoes is too fleeting to explain the LIA and previous cold cycles of the Holocene and prior interglacials. Even a cluster of them over decades wouldn’t cut it to explain a multicentennial scale climatic phenomenon.

        Now, geologically long continuous flood basalt or rifting eruptions, as posited for the end Permian, Triassic and Cretaceous mass extinction events, is more plausible. In the Cretaceous case at least, however, the Yucutan impact is better supported than the Deccan Traps eruptions.

  5. RE comment on figure 1: “Now, Figure 1 shows some interesting things. The average May to September temperature (yellow line) in 1816 was about the same that of 2015. However, the maximum temperature is about a degree warmer than 2015, and the minimum temperatures were about a degree lower than in 2015.”

    Did you intend to say 1815 instead of 2015?

  6. interesting article and observations.

    on the
    ***********
    We have had the most extraordinary year of drought and cold ever known in the history of America
    **********

    statement….w/o knowing whether he meant that since time of colonization or time of COTUS ratification (new hamshire was 1788, US Gov ( ie America) started in 1789) it could have been as short a timeframe as 28 years.

    still, had not read this before and liked seeing it. well done.

      • ok thanks,
        that seems to greatly increase timeframe and negates my thinking of his timeframe possibilities.

      • Dunno when reliable record keeping began in Virginia, Massachusetts or New York, but maybe for a century before 1816. Fahrenheit invented the first mercury thermometer in 1714, and developed his scale for its use.

        Before then, there would have been written records describing the weather and harvests.

        • John — I don’t know for sure, but I infer that there were decent thermometers here and there in the colonies and the early United States. However, except for sea going ships, hardly anyone seems to have been charged with making and recording regular observations until well into the 19th Century. Here’s a link to a pdf with a lot of old weather observations gleaned from the archives at the University of Vermont. http://www.uvm.edu/~epscor/pdfFiles/2013_workshop/dupigny-giroux_backward_seasons.pdf Note the scarcity of the sort of regular temperature and precipitation data that we take for granted nowadays.

  7. Jefferson’s comments raise a question about his subjective impression of the ‘unusual’ Summer of 1816. His crop failure certainly would have been a strong influence on his personal opinion in spite of his meteorological observations. And, while communication was slow, he almost certainly had heard of the problems New England, and especially Vermont, was experiencing.

  8. A sample of one location by a 73 year old man, bright as he was, using early 19th century tools and methods is hardly of much use in determining anything relevant regarding the effects Tambora had on the global or regional climate. He was roughly my age and I can confirm that eyesight, hearing, physical flexibility, and bathroom calls, along with other issues, could have had an effect upon his record keeping in any event.

    • JimG1 January 28, 2019 at 10:56 am

      A sample of one location by a 73 year old man, bright as he was, using early 19th century tools and methods is hardly of much use in determining anything relevant regarding the effects Tambora had on the global or regional climate.

      I didn’t say it was of use on a “global or regional” basis. However, it is one of the best records that we have from the US from that time, and by a very good observer.

      w.

  9. Willis volcano articles are generally of high quality (Dronning Maud etc).
    But this time not so good: “Cherry picking the beginning and end date, 1810-1816.
    This period has to be assessed in a wider context: !808/09 was a hugh volcano
    explosion, which levelled temps 1808-1815 and then, the 1815 event continued the levelling for some more years. Therefore no temp descent for Jefferson, because temps were too low from the very beginning, 1808. Lit: Stenni, B. 2017. The general
    cooling effects of volcanos in Sigl&Winstrup 2015.
    The general background for this 1800++ period and the 62 yr. temp plateau,
    see your, proudly rejected to read:
    http://www.knowledgeminer.eu/climate-papers.html, in PART 8, page 3.
    Sorry mate.

    • JS: There has been a lot of ‘unspecific’ volcanic activity posited by warmologists trying to eradicate, first the Little Ice Age itself, and then a fallback position of eradicating a climatological explanation for the Little ce Age because they don’t want to have a range of natural variation to be that big dwarfing the “control knob” CO2 response. Rhetoric has proved insufficient. Cooking data gives the most satisfactory results.

    • J. Seifert January 28, 2019 at 10:56 am

      Willis volcano articles are generally of high quality (Dronning Maud etc).
      But this time not so good: Cherry picking the beginning and end date, 1810-1816.

      Oh, piss off with your accusations of “cherry picking”—I used every single year that Jefferson had records of in his Weather Memorandum book. Can’t do more than that. It is an interesting and detailed record of an interesting time, a time for which we have very few records even in the GHCN.

      Next, you say:

      This period has to be assessed in a wider context: 1808/09 was a huge volcano
      explosion, which levelled temps 1808-1815 and then, the 1815 event continued the levelling for some more years.

      My last post showed the record of that time … hold on. I’ve gotten better data since then, GHCN V.4 versus V.3, courtesy of Steve Mosher. Here are all of the stations which have 90% data for the period 1800 – 1820.

      So no, the 1809 eruption did NOT “level temps” until 1815. In fact, temperatures ROSE for two years following 1809.

      And no, the 1815 eruption did not “continue the leveling for some more years”. There was a small one year drop, centered in the following spring, and temperatures rose for two years after that.

      Don’t like my data showing such small effects in Europe? Think I just slammed some numbers together for good effect? Here’s the Berkeley Earth data for Europe for the same period:

      Guess what? It shows exactly the same thing my analysis showed. Temperatures rising post 1809, a short drop and two years of rise post 1815.

      And as for your claim that:

      The general background for this 1800++ period and the 62 yr. temp plateau, see your, proudly rejected to read:

      I never “rejected to read” that, proudly or otherwise. I never even heard of it until now.

      And could you be more unpleasant? No, I won’t read your treatise. I just looked at it, and NOW I can say, I’ve proudly rejected to read it. It’s all about how fixed-length cycles rule the temperature … pass.

      w.

      • Your new graphs show exactly the levelling, temps hover around the Zero line, instead of going up as later in the 19 Cty. If you do not see the Zero levelling, well
        who knows why. Also read the Stenni and the Sigl papers, both calculate that those two large eruptions lowered temps for 5 to 7 years max. This lowering is demonstrated in the levelling around zero, otherwise temps, without volcano effects, would go up. You are the champion of not reading, you admitted this many times over. Not more to be said.

      • If you randomly place a vertical line on the graph several times, call it “fantasy eruption” and look for the expected cooling caused by the “fantasy eruption”, sort of a poor man’s Monte Carlo analysis….you reach the pragmatic conclusion that cooling by volcanos is just as likely to be ”confirmation bias” as it is a signal of physical climate effects. Ouch, that’s hurts accepted knowledge….

  10. Whatever these records show, there’s no doubt it was a disastrous year for agriculture globally.

    July 1816 was the coldest in the entire 360 years of the CET (Central England Temperature) series. June and August were also exceptionally cool and the year as a whole was about the 10th coldest.

    It certainly qualifies for the title, and it is no exaggeration.

    • Thanks, Mr. Grim. July 1816 was indeed a whole tenth of a degree colder than July 1802.

      On the other hand, there were twenty-six colder Junes in the CET record, and twenty colder Augusts. So they were not particularly noteworthy.

      It was a bad year for agriculture, but not globally as you claim. From the Smithsonian:

      Researchers today are careful not to blame every misery of those years on the Tambora eruption, because by 1815 a cooling trend was already under way. Also, there’s little evidence that the eruption affected climate in the Southern Hemisphere.

      Here are the years in the CET record that were colder than 1816:

      1675 1688 1692 1694 1695 1698 1740 1784 1814 1879

      As far as I know, none of them were cold because of volcanic eruptions …

      Look, I’m not saying Tambora did nothing. I’m saying that the effects were localized, with the strongest effects in New England, that they didn’t affect much of the planet, that they did not exceed natural variations, and that they didn’t last long.

      w.

      • The 17th century lows were because of the Maunder Minimum. The 1740 event was an historic WX event.

        You forgot the 1784 eruption of Laki and 1814 eruption of Mayon in the Philippines. It would have been easy for you to have checked those years, if you didn’t recall the famous Laki eruption. Mayon was only a VEI4, but it spewed a lot of ash, some of which was still in the air in 1815, when Tambora blew.

        As far as you know doesn’t cut it. Research is easy these days.

        • The Laki eruption began in 1783, and enveloped Europe in low altitude fumes which exacerbated summer heatwaves. Stratospheric aerosols generally tend to slightly warm mid-higher latitude winters. The 1783-84 winter has heliocentric analogues in 1962-63, 1601/03, and the two times the River Nile froze in 829 and 1010 AD. Winters like that would not occur without short term solar changes.

  11. Figure 1 shows some interesting things. The average May to September temperature (yellow line) in 1816 was about the same that of 2015. However, the maximum temperature is about a degree warmer than 2015, and the minimum temperatures were about a degree lower than in 2015.
    Certainly 2015 should be 1815 here?

  12. Once again Willis stumbles into the pit he has dug for himself. His compulsion to ‘measure’, and calculate ‘means’ and ‘averages’, something which he believes gives him the air of a ‘scientist’ has obscured his view to such an extent that;
    a. He makes a global assessment on the basis of a specific locality.
    b. He ignores key factors such as cloud cover which totally affect people’s perception of seasons.
    c. He seems unable to accept that ‘the year without a summer’ was widely observed, felt and discussed all over the world…at the time.|
    He really should have been a ‘climate scientist’!

    • No, he was responding to a comment made by someone about Jeffersons “year without a summer comment” i think he was pretty clear about that. His previous article dealt with a more global (well actually Europe and parts of North America) aspect of the Tambora eruption.

    • charles nelson January 28, 2019 at 11:33 am

      Once again Willis stumbles into the pit he has dug for himself. His compulsion to ‘measure’, and calculate ‘means’ and ‘averages’, something which he believes gives him the air of a ‘scientist’ has obscured his view to such an extent that;

      Charles, when you start out by personal attacks, it is clear that you are a man with an agenda and NOT a man looking for the truth …

      a. He makes a global assessment on the basis of a specific locality.

      I made no “global assessment”. I was discussing Monticello.

      b. He ignores key factors such as cloud cover which totally affect people’s perception of seasons.

      I have no idea what this means.

      c. He seems unable to accept that ‘the year without a summer’ was widely observed, felt and discussed all over the world…at the time.|

      No, it wasn’t. From the Smithsonian:

      From the Smithsonian:

      Researchers today are careful not to blame every misery of those years on the Tambora eruption, because by 1815 a cooling trend was already under way. Also, there’s little evidence that the eruption affected climate in the Southern Hemisphere.

      Half the planet unaffected … not “all over the world” as you claim.

      You’re letting your hatred get the better of you …

      w.

      • ROTFLMFAO @ Willis.



        Anytime someone questions your work you claim: “you start out by personal attacks”

        No Willis, your work sucks and people that know better than you will point it out to you. It’s not personal, it’s just that YOUR WORK SUCKS!!!!!!

        • J. Philip, when someone starts out by claiming “his compulsion to ‘measure’, and calculate ‘means’ and ‘averages’, something which he believes gives him the air of a ‘scientist’ has obscured his view”, that is indeed a personal attack.

          As to my work sucking, I’ve had a peer-reviewed “Brief Communications Arising” published in Nature magazine, so obviously they didn’t agree with you. And I have over 125 citations in the scientific journals to my other published work, so those 125 scientists also don’t agree with you.

          Remind us … do you have anything at all that was peer-reviewed and published in Nature magazine? Mine is only a peer-reviewed “Brief Communications Arising”, but still …

          Best regards,

          w.

          • BTW. . . this J. Philip Peterson is not me. . . love you Willis. . .

            I see that the 3rd “j philip peterson” on google is me, and my website.

            This J. Philip Peterson is new on here, and from what I have seen knows nothing about global warming, or climate change as WUWT has been explaining about for years. . .
            JPP

  13. Well, it might have been dry enough during the prime growing season at Monticello to have a crop failure, which is something a farmer would notice. Rain when the crop is not growing is not worth anywhere near as much, so having average rain for the year is not really important (Fig 3).

    • True, Tom, and much agriculture of the time was rain-fed. It’s interesting in that drought is generally not associated with the “Year Without A Summer”.

      w.

        • John, I say that because of things like this from your second link:

          Dry in the monsoon regions

          In the summer of 1816, large regions covered by the Asian monsoon arguably suffered from severe drought due to a failure of the Asian monsoon – at least this is found in climate model simulations and according to some, but not all, reconstructions

          I fear I’m not easily impressed by “climate models and some, but not all, reconstructions”.

          However, always more to learn,

          w.

          • Because drought was found in models and reconstructions for the Asian monsoon region, and also in the actual rainfall records of other parts of Earth, you conclude that drought wasn’t associated with 1816 and following years?

            How does that work?

  14. Willis,

    Thomas Jefferson made the “official” weather observations for the
    Second Continental Congress while that body was in session.

    They met in Philadelphia 1775 – 1784 +/-.

    I don’t think there’s ever been a synopsis of those observations.

  15. Let’s not give Al Gore any ideas for sciency reporting from a former statesman with UHI effects etc. Of course he would assign it to one of fake video team members who previously worked on the fake science results for high school students.

  16. I found the first newspaper reports in the Java Govt Gazette dated the 29th of April 1815.
    The Dutch East-Indies and other colonies were at the time still under the temporarily British rule because the situation with France had not yet fully been dealt with. Some publications were in Dutch and English.

    ” We have been looking anxiously for-
    ward during the last week, for .some satis-
    factory account of the Volcanic eruption
    that has recently taken place to the East-
    ward, but we are at length obliged to send
    this Paper to the Press with nothing but a
    few Extracts from private letters, to satis-
    fy the anxious curiosity of our Readers.

    It is clear however, that the principal
    explosion took place on the night of the
    10th , and on the morning of the 11th in-
    stant and it may be remembered that on
    this night the inhabitants of Batavia and
    its Environs were -alarmed by what was
    supposed to be a heavy cannonade at sea,
    and which was imagined to be an action
    between two frigates—these sounds were
    more distinctly heard to the Eastward.

    At Tagal and Paccalongan they commenc-
    ed upon the 5th, and the same persuasion
    obtained. Letters from Passarowang and
    •Sourabaya of the 11th instant, mention,
    that for several days past the weather had
    been exceedingly gloomy, but on the
    night of the 10th and 11th instant, the
    houses were shook to their foundations
    by violent explosions from some Volcano
    in the neighbourhood, which they suppos-
    ed to be Gouong Bromo.

    On the 11th instant, the atmosphere was
    so obscured by smoke and ashes, that at 8
    o’clock, there was little or no day-light,
    and at 4 o’clock in the afternoon, it was
    perfectly dark .Many of the accounts we
    have seen may possibly have been exag-
    gerated, but that there has been some tre-
    mendous convulsion to the Eastward, there
    can be no doubt.—”

    Link to this paper , with a few more accounts ,is here: https://resolver.kb.nl/resolve?urn=ddd:011023206:mpeg21:p005

  17. It seems likely that those years occurred during a negative AMO and thus were likely cooler than average even without any eruption.

  18. When I read about killing frosts in the summer, in the year without a summer, it generally had to do with New England, further north. The year without a summer was credited for driving migration of people from the seemingly cursed, stony farms of New England to the Ohio valley. 6 inches of snow on June 6 in much of New England. Cold in early July killed vegetable crops in northern NE. A hard frost in mid-August killed more crops. Another hard frost on August 28 killed more crops. I’ve read various sources about this over the years – here is one:

    http://www.newenglandhistoricalsociety.com/1816-year-without-a-summer/

  19. I read somewhere that eruptions in the tropics don’t have much effect on world temperatures, try a volcano in the high latitudes.

  20. What we are analysing is subjective impressions vs objective recordings. What people remember is the odd extreme event, whereas averages don’t mean very much and are easily forgotten. In a month of days where the weather is slightly warmer, the few cold days will be more memorable – and vice-versa. There is also the issue of outlook: to an optimist a day with mostly sunshine and a shower at lunchtime is a sunny day, to a pessimist it is a wet day. This is particularly relevant when it comes to social pressure to conform – if everyone is saying, “phew what a scorcher” because it was hot at midday are you going to argue that you were cold that night and needed a blanket (OK, some of us ‘ornery types might, but we will get ignored the way that we are doing at the moment!)

    I know we have to use averages to look at the bigger picture of climate, but they are meaningless statistical constructs when it comes to the effect of weather on personal experience.

  21. Instrument measurements and average temperatures don’t tell the whole story. You could do a similar analysis of other major volcanic eruptions and the Little Ice Age and would likely find that temperatures and growing seasons were not unusually different in many places. But in some regions they were significantly different. Just like numerous historical records report unusually cold winters in some places during the Little Ice Age (ice festivals on the Thames), there are historical records of disastrous crop failures in 1816, the “Year Without A Summer,” that resulted in migration to other places in search of better opportunities. The Dust Bowl years were similar. Whether or not average temperatures or temperature extremes were significantly different, there were undoubtedly weather extremes that caused widespread hardship. These may or may not directly correlate to, in the case of 1816, a volcanic eruption; but the misery was widespread and a matter of historical record.

  22. JT:

    It is a common opinion that the climates of the several states of our union have undergone a sensible change since the dates of their first settlements; that the degrees both of cold & heat are moderated. the same opinion prevails as to Europe: & facts gleaned from history give reason to believe that, since the time of Augustus Caesar, the climate of Italy, for example, has changed regularly at the rate of 1.° of Fahrenheit’s thermometer for every century. may we not hope that the methods invented in latter times for measuring with accuracy the degrees of heat and cold, and the observations which have been & will be made and preserved, will at length ascertain this curious fact in physical history?

    1°F per century. There you have it, global warming, the science is settled. Too bad the more accurate modern methods still haven’t adequately explained this “curious fact in physical history.

  23. True enough. I think it is some other type of degradation of that causes the deviation in mercury thermometers. Must admit that I cannot remember now what it was. I do remember getting irritated by the endless yearly quality checks on theremometers during the relevant audits.

  24. Gary
    I think it was the reaction between the mercury and the glass…sorry I forgot.
    Obviously that is the reason why we stopped using them. We are now using thermocouples. I take it that they are used now exclusively in weather stations?

  25. The last killing frost in 1813 was the beginning of Feb???? Think of the warmunists & eco-loons today wringing hands and crying about that. Oh no! The world is going to FRY!

  26. Readers might be interested in reading first person accounts of the Battle of Waterloo which occurred on June 18, 2015 in Belgium. The eruption certainly didn’t negatively affect the crops that year in that area.
    More than one account talks about the height of the grain having an affect on the course of the battle.
    At Quatre Bras “the rye in the field was so high” Llewellyn of the 28th Regiment remembered, that….the enemy…were obliged to make a daring person ride forward to plant a flag as a mark, at the very point of our bayonets”
    “the light company of the 51st Regiment….was fired on by the French infantry which had got unscathed to within forty feet of their line under cover of the standing grain”
    From The Face of Battle by John Keegan

  27. Gene Selkov says

    https://wattsupwiththat.com/2019/01/28/president-jefferson-meets-mount-tambora/#comment-2608368

    Henry says

    please note my comments to Gary just before &

    depending on the height of temperature that the thermometer was eposed to, the amount of reaction of the glass [which also contains oxygen] with the mercury might be variable….?

    Like I said, I also thought the yearly audits were rediculous but my thermometer to determine viscosity was only used ar 25 +/- 0.1 degrees C, constantly. So, I never seeing any differenec I was inclined to think that the deviation as reported was non-existant.

  28. Mary Shelley commented upon the weather of Summer, 1816, in the preface to the 1831 edition of Frankenstein. https://www.rc.umd.edu/editions/frankenstein/1831v1/preface

    “I passed the summer of 1816 in the environs of Geneva. The season was cold and rainy, and in the evenings we crowded around a blazing wood fire, and occasionally amused ourselves with some German stories of ghosts, which happened to fall into our hands. These tales excited in us a playful desire of imitation. Two other friends (a tale from the pen of one of whom would be far more acceptable to the public than any thing I can ever hope to produce) and myself agreed to write each a story founded on some supernatural occurrence.

    “The weather, however, suddenly became serene; and my two friends left me on a journey among the Alps, and lost, in the magnificent scenes which they present, all memory of their ghostly visions.”

    I’d say that account speaks of a summer with extreme cold spells. That sounds like one of John Tillman’s references, http://www.newenglandhistoricalsociety.com/1816-year-without-a-summer/ . Cold, warm, cold, warm ….

    If you’re farming, you don’t need a uniformly-cold summer. A summer with a few really bad frosts can do you in just as well.

  29. President Jefferson was certainly aware of the weather. He had Rumford fireplaces constructed at Monticelli.

    “Jefferson’s remodeling notes for Monticello, begun in November of 1796, contain sketches and notes for “Count Rumford’s fire places in the square rooms”;3 another “Design for Chimney and Flues,” externally dated to 1797, also contains drawings and notes for a Rumford-style fireplace.”

    https://www.monticello.org/site/research-and-collections/sir-benjamin-thompson-count-von-rumford

  30. Ellen

    there is nothing you can do about natural climate change, except be warned about it ahead of time;
    if we can people to stop putting money on this man made climate nonsense and focus on looking at natural solar cycles, like I am saying:
    There is going to be major drought time, on the great plains of north America starting just about this year or next year
    2019-87 = 1932
    [Dust Bowl drought 1932-1939]
    1932-87 = 1845
    https://www.researchgate.net/publication/286971648_Drought_in_the_western_Great_Plains_1845-56_Impacts_and_implications
    that drought period was from 1845 until 1856
    I think I heard somewhere on this page now about a drought that played out in in Virginia from 1755 onward. True?
    Co-incidence?
    Or Gleissberg solar cycle? {the GB cycle is calculated by me and others as being about 87 years].

    The extra record cold [winters] as predicted by me now have already started. The dry summers are lying ahead.
    http://breadonthewater.co.za/henrys-climate/

    I hope you come right:

    moving south, I would say…

  31. I wrote an article that was published back in the early 90s. It was on-line, but has been taken off. I studied Iowa tree ring data, and I remember the extremes into about 1820. Growing conditions for trees in Iowa were terrible just following the 1815 time. I also used monthly average corn prices in that study, and I remember the high being (in 1815 dollars) $1.05/bushel.

    It certainly, from what I saw, had to have been a memorable time.

  32. Dear Willis, thank you for taking the time and converting Jefferson’s weather data into graphic formats, he certainly was a most careful observer and and used the best instruments of his time. Weather observations for a plantation owner was most important, as such his comment (of which you made fun of) needs to be taken seriously and put into context. As of 2009, the Monticello foundation has this letter reprinted in more detail, see below and it becomes clear that he was not simply comparing annual averages but rather commenting on dramatic weather events which directly effected the purse of a land owner in these days.

    In particular your comment “And although June through August was dry, overall the year 1816 was fourth among the seven years in the total amount of rain.” completely ignores that these 3 months are the key months when you try to grow plants.

    https://www.monticello.org/site/research-and-collections/eruption-mount-tambora

    “In September 1816, Jefferson scanned his rainfall records and considered weather reports from elsewhere as he continued to puzzle over the drastic change in weather. From his correspondence with Albert Gallatin, we read:

    We have had the most extraordinary year of drought & cold ever known in the history of America. in June, instead of 3 3/4 I. our average of rain for that month, we had only 1/3 of an inch, in Aug. instead of 9 1/6 I. our average, we had only 8/10 of an inch. and it still continues. the summer too has been as cold as a moderate winter. in every state North of this there has been frost in every month of the year; in this state we had none in June & July. but those of Aug. killed much corn over the mountains. the crop of corn thro’ the Atlantic states will probably be less than 1/3 of an ordinary one, that of tob[acc]o still less, and of mean quality.4

    The eruption of Mount Tambora offers only one instance of the payoff to science from Thomas Jefferson’s passion for collecting basic data on natural phenomena.”

    I guess the “lesson” for “mankind” to this day is this: The annual average temps are less important, what we should care about is precipitation and temperatures during growing season.

    Best,
    Gerhard

    • Gerhard, many thanks for that full quote. I had not seen the full quote before, and I see now that Jefferson was indeed not exaggerating. Instead, he was mostly reporting the states “North of here”, with “here” being Virginia.

      Also, it seems that in locations other than Monticello, in a location he calls “over the mountains”, there were frosts in August. So Monticello seems to have been a favored spot, with no frosts in the summer at all.

      Thanks for the clarification, it highlights both the reality and the spotty nature of the changes.

      w.

    • in every state North of this there has been frost in every month of the year

      I’d be hard pressed to agree with there being frosts in July, except in various very localized places. (My father thinks he saw frozen dew in a depression off I-93 in New Hampshire one July 5th.)

      In my https://wattsupwiththat.com/2016/06/05/summer-of-1816-in-new-hampshire-a-tale-of-two-freezes/ I note:

      Up north in Lancaster, the soil moisture must have been much better, as Adino Brackett logged mid-month “… we have had fine weather every day[?] since about the 25th of June. Vegetables grow remarkably fast.”

      On August 9th he wrote “Through the whole of July the weather continued very warm and growing. It seems as though old times had returned.”

      There is a claim that there was frost or snow every month of the year in New England. While there is no hint of a frost in these reports, Klingaman and Klingaman report “On Monday July 8th, frost struck crops from Maine to Virginia. In Franconia, New Hampshire, the cold snap destroyed the bean crop. … The morning of July 9th brought even colder temperatures and hard frosts across New Hampshire, much of Vermont, and western Massachusetts.”

      Let’s just assume this frost was limited to low lands and depressions where radiational cooling could bring its effects. Oh, just one more thing, Plumer reported wind conditions as “NW high” every day between the 6th and 9th. The wind could still be undercut by a night-time temperature inversion, and allow a weak temperature inversion to bring its extra cooling. I may research these days further, this seems to be the most confusing event of the summer.

  33. While your charts show yearly activity, one also shows monthly – the chart with first and last white frost. Since Tambora blew in April, I found it interesting that the last frost in 1815 was later than usual in the spring, occurring in mid-May 1815. How long after Tambora might the effects have been felt in Monticello? Probably a coincidence, but interesting nonetheless.

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