Guest essay by David Archibald
There is now consensus that the Sun has now entered a quiet period. The first paper from the solar physics community predicting the current quiet period was Schatten and Tobiska’s 2003 paper “Solar Activity Heading for a Maunder Minimum?”. To date, Solar Cycle 24 has shown similar maximum SSN amplitudes to that of Solar Cycle 5, the first half of the Dalton Minimum:
Figure 1: Solar Cycle 24 relative to the Dalton Minimum
But what comes beyond that? Predicting the amplitude of Solar Cycle 24 was big business in the solar physics community with a total of 75 forecasts. There is only one forecast of the amplitude of Solar Cycle 25 to date. That forecast is Livingstone and Penn’s prediction of a maximum amplitude of seven. The first forecast, by Libby and Pandolfi, of the current quiet period is now over 40 years old. The fact that Libby and Pandolfi’s prediction got the detail of temperature changes to date right gives great credibility to it. Written in 1979, they forecast a warming trend for the rest of the 20th century followed by a cold snap that might well last throughout the first half of the 21st century. Specifically, Dr Libby is quoted by the Los Angeles Times as saying,
“we see a warming trend (by about a quarter of 1 degree Fahrenheit) globally to around the year 2000. And then it will get really cold – if we believe our projections. This has to be tested.” How cold? “Easily one or two degrees,” she replied, “and maybe even three or four degrees.”
The Libby and Pandolfi forecast was based on isotope ratios in tree rings and dates from a time before the corruption of tree ring science.
One commercial consequence of lower solar activity is that satellites will last longer in their orbits. Another is that agricultural production in the mid-latitudes will be affected. One of the most productive agricultural regions on the planet is the Corn Belt of the United States. Modern corn hybrids are tuned around maximizing the yield from the growing conditions experienced in the Corn Belt over the last 30 years with Growing Degree Days (GDD) to maturity ranging from 2200 to 2700. GDD is calculated from the day of planting by adding the maximum and minimum daily temperature in Fahrenheit, dividing by two and then subtracting 50 to produce the result. If the overnight minimum is less than 50°F, 50°F is used. The maximum is capped at 86°F as corn plants don’t grow any faster above that temperature. Daily temperature records for the Corn Belt start about 1900. The following graph shows the accumulation of GDDs for the periods 1901 – 1910 and 2001 – 2010 for Whitestown just northeast of Indianapolis in the southeast end of the Corn Belt:
Figure 2: Cumulative GDD for Whitestown, Indiana 1901 – 1910 and 2001 – 2010
The graph assumes a common planting date of 27th April. The blue lines are the years 1901 – 1910 and the red lines are the years 2001 – 2010. They all stop on the date of first frost. Most of the growing seasons last decade had plenty of heat to get to maturity with up to 1,000 GDD in excess of the requirement at 2,500 GDD. A century before, the margin of safety was far less. Normal first frost for Whitestown is 10th October. A century ago the earliest frost was five weeks before that on 3rd September, 1908. Similarly, in the latter period the earliest date to get to 2,500 GDD was 15th August. In the earlier period the last date to get to 2,500 GDD was almost six weeks later at 28th September.
Farmers can adjust the type of crop they grow to suit their climatic expectations. Yield is directly proportional to GDD though as shown by the following graphic of corn and soybeans:
Figure 3: Yield relative to GDD (CHU) for Corn and Soybeans Source: Andy Bootsma, 2002: Potential Impacts of Climate Change on Eastern Canada
If a farmer plants a 2,200 GDD corn crop in the expectation of a cool or short season and the season turns out to have been capable of growing a 2,500 GDD, then he has foregone about 12% of the value of the later maturing variety. If he plants a 2,500 GDD variety and the season falls short though, most of the value of the crop will be lost. Wheat and barley require about 1,600 GDD and 1,400 GDD respectively. The highest wheat yield in Indiana in 2012 was 74 bushels/acre whereas the highest corn yield was 159 bushels/acre. Another factor in predicting grain output is the ability to switch to winter wheat in which a crop is planted in early September, germinates and then lies dormant under the snow blanket until the following spring.
A study in the 1980s of the effect of lower temperatures on Canadian wheat production found that a 1°C decrease would reduce the frost-free period by 15 days and that a 2°C decrease would not allow the crop to ripen before the first frost. Canadian wheat farmers have assured me though that they could switch to winter wheat and have a higher yield. In Manitoba, for example, the yield might be 71 bushels per acre for winter wheat compared to 51 bushels per acre for spring wheat. Growing winter wheat is riskier than spring wheat in that a hard frost before the first snow could kill the crop.
A further complication in trying to determine what the coming decline in temperature will do to grain production is that the area of the Corn Belt approximates to the region that was scraped flat by the Laurentide ice sheet. After the Wisconsin Glacier receded, the glaciated soils of the Midwest that are primarily north of Interstate 70 were covered with several feet of wind-blown loess deposits that came from the Great Plains that lie east of the Rockies. In Northern Illinois for example, in an area north of I-80, six to eight feet of loess deposits overlie glacier till. These soils are all primarily silt loam, silty clay loam, clay loam and clay. The water holding capacity of these soils are about 2 inches per foot. The counties in the Corn Belt with the highest productivity have deep fertile soils. Most of these soils were covered with prairie grass that over time raised the organic matter levels to between 2% and 5%. The resulting biological activity that developed in these soils made them very productive. These counties are also watered by natural rainfall that results from the Gulf of Mexico Pump. As the weather fronts move from west to east across the Rockies, we have the Great Plains that are mostly arid, but by the time the fronts reach eastern Nebraska, the moisture from the Gulf of Mexico is sucked north by the counter-clockwise flow of air that rotates around the low pressure fronts and drops the rain on the Midwest when it hits the cooler air from the north. Therefore the Corn Belt has the optimum combination of soil type, temperature and moisture. As growing conditions shift south, the soil types won’t be as good.
Friis-Christianson and Lassen theory enables us to predict temperature for a solar cycle if we know the length of the solar cycle preceding it. Thus Solheim et al have been able to predict that the average global temperature over Solar Cycle 24 will be 0.9°C lower than it was over Solar Cycle 23. Polar amplification also plays a part such that Svalbard, for example, in winter will experience a 6°C decline in temperature. Work on temperature records in the northeast United States suggest that the temperature decline in prospect for the Corn Belt is 2.0°C for Solar Cycle 24.
We can cross-check this expectation against modelled historic Total Solar Irradiance (TSI) data. Lean et al produced a reconstruction of TSI back to 1610. That is shown in Figure 4 following. Also shown is Livingstone and Penn’s prediction for Solar Cycle 25 amplitude converted to TSI by scaling against the Maunder Minimum. Shaviv in 2008 found empirically that a 1 watt/m2 change in TSI was associated with (as opposed to cause directly) in a 0.6°C change in global average temperature. A fall in solar activity to levels reached in the Dalton Minimum, as per Lean’s data, would result in a decline of global temperature of 1.2°C, a little more than what Solheim’s group is projecting. Solar Cycle 4, the cycle preceding the Dalton Minimum, was 13.6 years long, about a year longer than Solar Cycle 23. Libby and Pandolfi’s prediction of a temperature decline of up to 4°F translates to 2.2°C. Through TSI, this would require a fall of 3.7 watts/m2 which is greater than the range in Lean’s modelled data for the period since 1610. This may mean that Libby and Pandolfi are correct and Lean’s model needs adjusting.
Figure 4: Projecting the decline in Total Solar Irradiance
Working through the effect on GDDs, a return to TSI conditions of the Dalton Minimum can be expected to reduce US corn production by perhaps 20% to 25%. This equates to the increase in corn production over the last ten years from mandated ethanol. US grain and soybean production of about 500 million tonnes per annum is sufficient to feed 1.2 billion vegetarians. The amine profile of wheat can be approximated by a diet of 70% corn and 30% soybeans, otherwise those things are fed to animals at about a 25% protein conversion efficiency. Corn and soybeans would be the diet of involuntary vegetarianism. The rest of the world does not have the luxury of US agriculture’s latent productivity.
Figure 5: US Corn and Wheat Prices 1784 to 2013
Figure 5 shows the effect of the low temperatures of the Dalton Minimum on corn and wheat prices in the United States. The absolute peak was associated with the eruption of Mt Tambora. Also evident is the period of high and volatile prices associated with the cold temperatures of the mid-19th century.
Figure 6: Major wheat exporting countries
A return to the climatic conditions of the Dalton Minimum is likely to take Russia, Kazakhstan and the European Union out of the export market. The other countries will have some reduction in wheat available for export. Colder is also drier and thus a number of major grain producers such as India and China, currently largely self-sufficient, will experience shortfalls from their requirements.
Figure 6: Imports and exports of grain by continent
Figure 6 above shows net exports of grain by continent with the Arab countries as a separate region. Those countries are the biggest grain importing block on the planet. Soybeans are not included in this graphic. China has become the major soybean importer at 60 million tonnes per annum. In terms of protein content, that equates to about 180 million tonnes of wheat per annum. The Chinese convert those soybeans to animal protein in the form of pig meat.
Countries in the Middle East North Africa (MENA) region have been in the news recently. Further detail on their import dependency is shown in Figure 6 following.
Figure 6: MENA region domestic and imported grain by country
In Figure 6, the population size of each country is shown by the size of the bar. The blue component of the bar shows how much of each country’s grain requirement is grown domestically and the red component denotes the imported share. Countries are shown from west to east as per the map. A proportion of the Egyptian population already suffers from malnutrition. A current wheat prices, it costs about $1 per day to keep someone fed in terms of bulk grain. The oil exporting countries in the graphic can afford to feed their populations, with some countries feeding others as well. Saudi Arabia has been keeping Yemen above water and more recently took on Egypt too.
Figure 7: An animal model of population growth and collapse
All the countries of the MENA region have seen their populations grow to well in excess of their inherent carrying capacity. A combination of deteriorating climate and ongoing world population growth can be reasonably expected to cause a spike in grain prices to levels last seen in the 19th century. It is also possible that sufficient grain may not be available at any price in some regions. Populations models from the animal kingdom provide some guidance as to how events might unfold. A good example is the snowshoe hare and lynx of North America. The snowshoe hare population collapses to less than 10% of its peak on a roughly ten year cycle, followed by the lynx. Taking the example of Egypt, the current population is twice the level that can be supported by its grain production. If the food supply to that country falls below the minimum required to maintain public order, then the distribution system for diesel and fertiliser will break down and domestic grain production would also be affected.
The starving populations of Egyptian cities will fan out into the countryside and consume whatever they can chew which will include the seed grain. That will ensure that domestic grain production will collapse. The population of Egypt might fall to 10% of its carrying capacity which would be 5% of its current level. Any starvation in the MENA region is likely to trigger panic buying by other governments in the region and beyond with consequent effects on established trade patterns.
UPDATE:
The Excel spreadsheet for the Whitestown data used in this essay is here Whitestown-all-years (.xlsx file)
rgbatduke says:
“As far as the climate is concerned, we’re trying to extrapolate the shape of an elephant by carefully examining the tiny patch of skin we can see with remarkably good instrumentation, one perhaps a centimeter square. We see a zit and conclude that it is major feature on the elephant’s skin. With our dim, short-sighted eyes, we can make out a big, grey blur that could be the elephant’s ass or the back of its neck equally easily off in the distance. We cannot view the entire elephant in detail, not ever — most of it is completely invisible to us and will remain so forever, and we cannot explain its shape because other elephants, and other animals of similar sorts (e.g. other planets) are very distant indeed and don’t look much like our very own elephant. We can only wait for the one centimeter to become two, three, four as the flea of time on whose back we ride moves relentlessly along.”
True, if you only see the weather in your own village and ignore all the vast amount of surface and satellite data, but then it’s a pink elephant not a grey one.
“Oh, please. Nobody has the capacity to determine where “truth lies” in climate science.”
Solar based forecasts at the scale of weather can readily map the climate for decades ahead. Would you deny the use of such a essential tool because the mechanisms are not understood?
“..where I would assert that as a physicist who has studied this issue now for a fairly long time albeit as a hobby of sorts rather than a profession I expect that my guess would be better than your guess as a general rule —”
David has an estimate based on weaker solar activity, you have a blind guess (slight warming for the next two decades you said on an earlier post), which is completely in the wrong direction.
Thanks for another interesting and thought provoking contribution Mr. Archibald.
I do find amusing the response of certain of your critics that we’ve nothing to worry about because of hybrid genetics and unlikely volcanic activity versus the Dalton minimum given a drop in global average temperature of just 1.2 degrees F.
It would seem that your prediction accounts for those factors and predicts a fall in temperature more than double the rise experienced over the past century.
“And lean, ugly cows ate up the seven fat cows that came before them.” One will note that 1800 BC experienced a similar Solar decline.
Ulric,1879-1909 was lower then normal solar activity but it was not sustained enough in my opinion to be a true prolonged solar minimum, still it did have a climatic effect as you point out.
This current solar situation loooks to be evolving into a much more serious down turn in solar activity in contrast to the 1879-1909 time period in my opinion.
What we need going forward to see if solar/climate connections do exist is for the sun to slump into a very prolonged quiet period and see the climate reaction.
I am saying based on past history if the degree of solar quiet approaches the Dalton ,or better yet the Maunder Minimum conditions there will be a climatic impact.
What we have now is potentially the first true prolonged solar minimum since the Dalton ,and I think if this prolonged solar minimum (following several years of sub-solar activity in general,started in year 2005) meets it’s potential that the solar /climate correlations will start to manifest themselves in the climatic system of earth.
Those being in response to direct changes in solar parameters and the associated secondary effects to those earth originating climatic items that influence the climate of the earth through random changes, absent any extreme solar changes which I feel will exert an influence on those earth originating random earth climatic items.
Items, such as clouds, volcanic activity, enso etc. etc.
If(IF) the degree of magnitude change and duration of time of the solar changes meets certain criteria.
THOSE BEING AS FOLLOWS:
solar flux sub 90.
solar wind 350 km/sec.
cosmic ray count north of 6500 per minute.
ap index sub 5 ,98+% of time.
solar irradiance off .015% or more.
EUV light wavelengths 0-105nm, intensity of sub 100 or lower.
All of the above sustained. If these conditions are acomplished going forward I am of the strong opinion they will be exerting an ever increasing influence on the climate of the earth going forward both through the direct solar changes and the secondary effects from those direct solar changes.
Salvatore Del Prete says:
“Ulric,1879-1909 was lower then normal solar activity but it was not sustained enough in my opinion to be a true prolonged solar minimum, still it did have a climatic effect as you point out.
This current solar situation loooks to be evolving into a much more serious down turn in solar activity in contrast to the 1879-1909 time period in my opinion.”
As ever, it is the weather event periods that are critical, and particularly in which season they fall, as cold conditions through the growing seasons are potentially far more parlous than a very cold winter, which is what this topic is all about.
Now, there are two main factors, firstly is the 110.7yr (on average) cycle of solar minimum’s, of which solar cycles 12-14 were such an episode, and secondly, the short term heliocentric configurations that are responsible for the daily-weekly scale changes in AO/NAO etc. The effective heliocentric analogue for the short term is at 179.05 years back, which shows a very strong and long cluster of very cold events from 1836 to 1845: http://climexp.knmi.nl/data/tcet.dat
This was during a much stronger solar cycle: http://www.solen.info/solar/cycl8.html
Yet these short term events are occurring in a much weaker solar cycle this time, so would tend to be colder, as we have already seen in December 2010 and March 2013, and that is despite a now warmer global temperature.
Make your own mind up, to me it looks very bleak indeed until the mid 2020’s.
We have unknowns biggest being volcanic activity or lack of it going forward.
But over 80% of all major volcanic eruptions since 1600ad have been associated at or around solar minimums.
I agree bleak going forward ,how bleak is the question.
Salvatore Del Prete says:
“I agree bleak going forward ,how bleak is the question.”
Very severe for agriculture as many of the cold shots will through late Spring and Summer time.
Salvatore Del Prete says:
September 11, 2013 at 11:28 am
Indeed, the Dalton kicked off with the VEI 6 Arctic eruption of Laki.
gary gulrud says:
“Indeed, the Dalton kicked off with the VEI 6 Arctic eruption of Laki.”
The start of that cold event cluster is in 1782: http://climexp.knmi.nl/data/tcet.dat
The eruption is triggered by the sharp rise in temperature after the long cold 1782-3 winter. Maybe JJA of 1784 could have been cooled from remaining high altitude SO2, but I don’t see any other cool seasons there that can be attributed to stratospheric aerosols, they are supposed to be warming in the north hemisphere winters. The 1783/4 winter is classic, it’s the same heliocentric configuration as in 1962/3, and in 1009/10 when the River Nile froze. It has done that twice in the last 2Kyrs, the previous was ~179yrs earlier on the same configuration type.
Ulric global temperatures versus volcanic activity correlate very well. The higher the volcanic activity the lower the global temperatures will be.
Take the year without a summer around 1815ad, that came shortly after a massive volcanic eruption of Mt Toba
In addition if the volcanic activity is in the higher latitudes it will enhance a more meridional atmospheric circulation due to the warming of the stratosphere.
So2 from volcanic eruptions causes incoming sunlight to be absorbed in the stratosphere ,which is then reflected out to space never reaching the surface, of the earth causing cooling. No doubt about that.
EXAMPLES OF GLOBAL COOLING IN THE AFTERMATH OF HISTORIC ERUPTIONS:
Observational evidence shows a clear correlation between historic eruptions and subsequent years of cold climate conditions. Four well-known historic examples are described below.
LAKI (1783) — The eastern U.S. recorded the lowest-ever winter average temperature in 1783-84, about 4.8OC below the 225-year average. Europe also experienced an abnormally severe winter. Benjamin Franklin suggested that these cold conditions resulted from the blocking out of sunlight by dust and gases created by the Iceland Laki eruption in 1783. The Laki eruption was the largest outpouring of basalt lava in historic times. Franklin’s hypothesis is consistent with modern scientific theory, which suggests that large volumes of SO2 are the main culprit in haze-effect global cooling.
TAMBORA (1815) — Thirty years later, in 1815, the eruption of Mt. Tambora, Indonesia, resulted in an extremely cold spring and summer in 1816, which became known as the year without a summer. The Tambora eruption is believed to be the largest of the last ten thousand years. New England and Europe were hit exceptionally hard. Snowfalls and frost occurred in June, July and August and all but the hardiest grains were destroyed. Destruction of the corn crop forced farmers to slaughter their animals. Soup kitchens were opened to feed the hungry. Sea ice migrated across Atlantic shipping lanes, and alpine glaciers advanced down mountain slopes to exceptionally low elevations.
KRAKATAU (1883) — Eruption of the Indonesian volcano Krakatau in August 1883 generated twenty times the volume of tephra released by the 1980 eruption of Mt. St. Helens. Krakatau was the second largest eruption in history, dwarfed only by the eruption of neighboring Tambora in 1815 (see above). For months after the Krakatau eruption, the world experienced unseasonably cool weather, brilliant sunsets, and prolonged twilights due to the spread of aerosols throughout the stratosphere. The brilliant sunsets are typical of atmospheric haze. The unusual and prolonged sunsets generated considerable contemporary debate on their origin.They also provided inspiration for artists who dipicted the vibrant nature of the sunsets in several late 19th-century paintings, two of which are noted here.
Krakatau sunset
In London, the Krakatau sunsets were clearly distinct from the familiar red sunsets seen through the smoke-laden atmosphere of the city. This is demonstrated in the painting shown here of a sunset from the banks of the Thames River, created by artist William Ascroft on November 26, 1883.
The vivid red sky in Edvard Munch’s painting “The Scream”
The vivid red sky in Edvard Munch’s painting “The Scream” was inspired by the vibrant twilights in Norway, his native land.
For a more thorough description of the 1883 eruption, see Krakatau.
PINATUBO (1991) — Mt. Pinatubo erupted in the Philippines on June 15, 1991, and one month later Mt. Hudson in southern Chile also erupted. The Pinatubo eruption produced the largest sulfur oxide cloud this century. The combined aerosol plume of Mt. Pinatubo and Mt. Hudson diffused around the globe in a matter of months. The data collected after these eruptions show that mean world temperatures decreased by about 1 degree Centigrade over the subsequent two years. This cooling effect was welcomed by many scientists who saw it as a counter-balance to global warming.
Salvatore Del Prete says:
“Ulric global temperatures versus volcanic activity correlate very well. The higher the volcanic activity the lower the global temperatures will be.”
In most cases the worst cold is before the eruption. Winter 1783/4 has nothing to do with volcanic cooling. Summer 1816 would have suffered weak solar conditions too to be that cool, a stronger short term solar signal will completely hide the volcanic cooling effects in the mid-upper latitudes, as in summer 1884 after Krakatau. Global temp’s will not drop appreciably from volcanic cooling because of the ENSO response.
Salvatore Del Prete says:
“In addition if the volcanic activity is in the higher latitudes it will enhance a more meridional atmospheric circulation due to the warming of the stratosphere.”
An enhanced zonal wind driven by heating of the tropical stratosphere by the volcanic aerosols is responsible for the regions of warming:
http://onlinelibrary.wiley.com/doi/10.1029/92GL02627/abstract
http://climate.envsci.rutgers.edu/pdf/RobockMaoWinterWarming92GL02627.pdf
I disagree totally with you on that point. The article I sent verifies this as well as the recent global cooling associated with MT.PINATUBO eruption.
In fact I have never seen a global warm up following a volcanic eruption, not even once.
Volcanoes
“The sun was dark and its darkness lasted for eighteen months; each day it shone for about four hours; and still this light was only a feeble shadow; the fruits did not ripen and the wine tasted like sour grapes.” As this Michael the Syrian quote regarding the weather of 536 A.D. demonstrates, a climate catastrophe that blots out the sun can really spoil your day. Procopius of Caesarea remarked: “During this year [536 A.D.] a most dread portent took place. For the sun gave forth its light without brightness. and it seemed exceedingly like the sun in eclipse, for the beams it shed were not clear.” Many documents from 535 – 536 A.D.–the time of King Arthur in Britain–speak of the terrible “dry fog” or cloud of dust that obscured the sun, causing widespread crop failures in Europe, and summer frosts, drought, and famine in China. Tree ring studies in Europe confirm several years of very poor growth around that time, and ice cores from Greenland and Antarctica show highly elevated levels of atmospheric sulfuric acid dust existed.
“Volcanic Winter” resulted. Sulfur dioxide reacts with water to form sulfuric acid droplets (aerosol particles), which are highly reflective and reduce the amount of incoming sunlight. The potential eruption that led to the 535 – 536 A.D. climate calamity would have likely been a magnitude 7 event on the Volcanic Explosivity Index (VEI)–a “super colossal” eruption that one can expect to occur only once every 1000 years. The Volcanic Explosivity Index is a logarithmic scale like the Richter scale used to rate earthquakes, so a magnitude 7 eruption would eject ten times more material than the two largest eruptions of the past century–the magnitude 6 eruptions of Mt. Pinatubo in the Philippines (1991) and Novarupta in Alaska (1912).
Figure 1. An 18 km-high volcanic plume from one of a series of explosive eruptions of Mount Pinatubo beginning on 12 June 1991, viewed from Clark Air Base (about 20 km east of the volcano). Three days later, the most powerful eruption produced a plume that rose nearly 40 km, penetrating well into the stratosphere. Pinatubo’s sulfur emissions cooled the Earth by about 1°F (0.5°C) for 1 – 2 years. (Photograph by David H. Harlow, USGS.)
Super-colossal eruptions
There has been only one other magnitude 7 “super-colossal” eruption in the past 1500 years–the massive eruption of the Indonesian volcano Tambora in 1815. The sulfur pumped by this eruption into the stratosphere dimmed sunlight so extensively that global temperatures fell by about 2°F (1°C) for 1 – 2 years afterward. This triggered the famed Year Without a Summer in 1816. Killing frosts and snow storms in May and June 1816 in Eastern Canada and New England caused widespread crop failures, and lake and river ice were observed as far south as Pennsylvania in July and August. The Tambora eruption was about 40% smaller than the 535 – 536 A.D. event, as measured by the number of sulfur aerosol particles deposited in Greenland ice cores.
In an article published in 2008 in the American Geophysical Union journal EOS, Dr. Ken Verosub of the University of California, Davis Department of Geology estimated that future eruptions capable of causing “Volcanic Winter” effects severe enough to depress global temperatures by 2°F (1°C) and trigger widespread crop failures for 1 – 2 years afterwards should occur about once every 200 – 300 years. Even a magnitude 6 eruption, such as the 1600 eruption of the Peruvian volcano Huaynaputina, can cause climatic change capable of killing millions of people. The Huaynaputina eruption is blamed for the Russian famine of 1601-1603, which killed over half a million people and led to the overthrow of Tsar Boris Godunov. Thankfully, the climatic impacts of all of these historic magnitude 6 and 7 eruptions have been relatively short-lived. After about two years, the sulfuric acid aerosol particles have settled out of the stratosphere, returning the climate to its former state.
Mega-colossal eruptions
Even more extreme eruptions have occurred in Earth’s past–eruptions ten times more powerful than the Tambora eruption, earning a ranking of 8 out of 8 on the Volcanic Explosivity Index (VEI). These “mega-colossal” eruptions occur only about once every 10,000 years, but have much longer-lasting climatic effects and thus are a more significant threat to human civilization. According to the Toba Catastrophe Theory, a mega-colossal eruption at Toba Caldera, Sumatra, about 74,000 years ago, was 3500 times greater than the Tambora eruption. According to model simulations, an eruption this large can pump so much sulfur dioxide gas into the stratosphere that the atmosphere does not have the capacity to oxidize all the SO2 to sulfuric acid aerosol. The atmosphere oxidizes as much SO2 as it can, leaving a huge reservoir of SO2 in the stratosphere. This SO2 gradually reacts to form sulfuric acid as the OH radicals needed for this reaction are gradually produced. The result is a much longer-lasting climate effect than the 1 – 2 years that the magnitude 6 and 7 events of 535, 1600, 1815, and 1991 lasted. A magnitude 8 eruption like the Toba event can cool the globe for 6 – 10 years (Figure 3), which may be long enough to trigger an ice age–if the climate is already on the verge of tipping into an ice age. Rampino and Self (1992) argued that the sulfur aerosol veil from Toba was thick and long-lasting enough to cool the globe by 3 – 5°C (5 – 9°F), pushing the climate–which was already cooling and perhaps headed towards an ice age–into a full-scale ice age. They suggested that the response of Canada to the volcano played a particularly important role, with their model predicting a 12°C (22°F) reduction in summer temperatures in Canada. This would have favored the growth of the Laurentide ice sheet, increasing the reflectivity (albedo) of the Earth, reflecting more sunlight and reducing temperatures further. The controversial Toba Catastrophe Theory asserts that the resulting sudden climate change reduced the Earth’s population of humans to 1,000 – 10,000 breeding pairs. More recent research has shed considerable doubt on the idea that the Toba eruption pushed the climate into an ice age, though. Oppenheimer (2002) found evidence supporting only a 2°F (1.1°C) cooling of the globe, for the 1000 years after the Toba eruption. Zielinski et al. (1996) argued that the Toba eruption did not trigger a major ice age–the eruption merely pushed the globe into a cool period that lasted 200 years. Timmereck et al. (2010) used a model to show that the sulfate particles inthe stratosphere would have clumped together after the eruption, limiting the colling effect to four years, with a maximum global reduction in temperature of 3.5°C. Interestingly, a previous super-eruption of Toba, 788,000 years ago, coincided with a transition from an ice age to a warm period.
Salvatore Del Prete says:
“I disagree totally with you on that point.”
I made a few points, so I cannot tell which you refer to.
“The article I sent verifies this as well as the recent global cooling associated with MT.PINATUBO eruption.”
It’s rubbish, no way was it 1°C cooling:
http://www.woodfortrees.org/plot/hadcrut4gl/from:1990/to:1995
“In fact I have never seen a global warm up following a volcanic eruption, not even once.”
Probably because you have not looked well enough. It’s surprising that no one, that I am aware of, noticed the stronger cooling before the eruptions.
The above article proves beyond a shadow of a doubt that volcanic eruptions equate to global cooling, although some parts of the globe during certain seasons can warm,but the overall effect is for lower temperatures.
True LOW LATITUDE volcanos may promote (EL NINO), but when PROLONGED LOW solar activity takes place it is thought not only does volcanic activity increase in general but the biggest increases in volcanic activity are in the higher latitudes , which have no effects on ENSO, and warm the stratosphere at those latitudes enhancing solar effects which both serve to promote a more meridional atmospheric circulation.
Of note, global temperatures did drop despite El Nino conditions when Mt. Pinatubo errupted in the early 1990’s.
I have presented to you the data in black and white if you don’t believe it so be it.
Salvatore Del Prete says:
“I have presented to you the data in black and white if you don’t believe it so be it.”
Just postulates from folk without even the foggiest awareness of short term solar factors. The coldest of events have no volcanic eruption to be connected to, and most of the large eruptions have the most severe cooling BEFORE the event.
Past history says what I say to be true ,not what you are saying.
On this one I think we should agree, to disagree.
It’s rubbish, no way was it 1°C cooling:
http://www.woodfortrees.org/plot/hadcrut4gl/from:1990/to:1995
and it shows a cooling following the PINATUBO eruption of about-.4c, I did not say 1c due to pinatubo, but I did say cooling and your chart verifies it and makes my point.
Ah, but look at the last two volcanoes: The very distinct, very sharp changes in the transmission in the past thirty years are much smaller than what the 536 year statements quoted above seem to indicate.
http://www.esrl.noaa.gov/gmd/webdata/grad/mloapt/mlo_transmission.gif
(That image is from WUWT Solar page.)
Super-colossal eruptions
There has been only one other magnitude 7 “super-colossal” eruption in the past 1500 years–the massive eruption of the Indonesian volcano Tambora in 1815. The sulfur pumped by this eruption into the stratosphere dimmed sunlight so extensively that global temperatures fell by about 2°F (1°C) for 1 – 2 years afterward. This triggered the famed Year Without a Summer in 1816. Killing frosts and snow storms in May and June 1816 in Eastern Canada and New England caused widespread crop failures, and lake and river ice were observed as far south as Pennsylvania in July and August. The Tambora eruption was about 40% smaller than the 535 – 536 A.D. event, as measured by the number of sulf
You don’t BELIEVE this ? I am just curious.
I do believe this.
but nevertheless transmission was lower and so were global temperatures for a time.
Salvatore Del Prete says:
“LOW LATITUDE volcanos may promote (EL NINO), but when PROLONGED LOW solar activity takes place it is thought not only does volcanic activity increase in general but the biggest increases in volcanic activity are in the higher latitudes”
Where are Toba, Tambora, Krakatau and Pinatubo then?…..
“..which have no effects on ENSO, and warm the stratosphere at those latitudes enhancing solar effects which both serve to promote a more meridional atmospheric circulation.”
Laki was mostly not a stratospheric event, the ash clouds increased surface temperatures through summer 1783. Have you any examples of “increases in volcanic activity in the higher latitudes” ?