Paintings, sunspots and frost fairs: Rethinking the Little Ice Age

The whole concept of the ‘Little Ice Age’ is ‘misleading’, as the changes were small-scale, seasonal and insignificant compared with present-day global warming, a group of solar and climate scientists argue.

Explanations for the cooling to Earth’s climate, thought to have occurred between the 16th and 19th centuries, include low solar activity, volcanic eruptions, human changes to land use and natural climatological change.

But in a new paper in Astronomy & Geophysics, the house journal of the Royal Astronomical Society, Professor Mike Lockwood, of the University of Reading, and his collaborators, note that the temperature shift was smaller than that seen in recent decades resulting from the emission of greenhouse gases, and that although low solar activity may have been one driving factor, it certainly was not the only one.

Professor Lockwood said: “Commentators frequently refer to the Little Ice Age in discussions on climate change. We wanted to carry out a comprehensive study to see just how reliable the evidence is for a cooler climate, how big an impact it really had and how strong the evidence for a solar cause really was.

“On the whole the Little Ice Age was a manageable downturn in climate concentrated in particular regions, even though places like the UK had a larger fraction of cold winters. Our research suggests that there is no single explanation for this, that warm summers continued much as they do today and that not all winters were cold.”

Researchers scrutinised historical records, such as the accounts of ‘frost fairs’ when the River Thames froze solid, and looked at the paintings from the era, such as the landscapes of Pieter Bruegel the Elder, with ‘Hunters in the Snow’ depicting a cold winter scene. Both of these are cited in support of the Little Ice Age concept.

From around 1650-1710, and to a lesser extent from 1790-1825, periods respectively known as the Maunder and Dalton Minima, sunspot numbers were unusually low, an indication that the surface of the Sun was slightly cooler. This external influence is often suggested as an explanation for the colder conditions.

Analysis of extreme temperatures in the Central England Temperature (CET) thermometer record.
Part (b) shows the lowest monthly average in each winter whereas part (c) shows the hottest monthly average in each summer. In both cases blue shows lower temperatures, and red shows higher temperatures than the long-term average.
The cold winter months match up very well with the years in which frost fairs were held (vertical mauve lines) or years when the Thames was reported as frozen solid (vertical orange lines). However these years are not usually also associated with colder summers, unless there was a large volcanic eruption (measured from the sulphates that it deposited in polar ice sheets) such as Tambora in 1815.
The top panel (a) shows the level of solar activity as seen in sunspot numbers (from telescopic observations and deduced from Carbon-14 stored in tree rings). It can be seen that, contrary to common claims, the Thames did not freeze more often during the Maunder minimum (c.1660-1710). Thames freezing events ceased after the demolition of the old London bridge in 1825 and the installation of the embankments, completed in 1870 (both dates marked with black lines): the faster flow meant that the river no longer froze, even when temperatures fell to values that had previously caused freezing. CREDIT M. Lockwood

 

The Reading-led team looked at the various pieces of evidence in more detail. They compared direct temperature records and proxy data such as ice records, with the years when the Thames was frozen over (whether or not a frost fair took place), and with the indications of solar activity.

Historical climate change is assessed through a variety of means. The Central England Temperature (CET) dataset tracks temperature from 1659, making it the oldest and longest running meteorological instrumental data sequence in the world. This direct record is supplemented by studies of biological proxies such as tree rings, corals, insect numbers and molluscs, all sensitive to climate change.

The authors draw comparisons with the ice ages proper. Cores taken from Antarctic ice allow global temperatures to be inferred, by measuring the proportions of deuterium (2H), a heavier atom of hydrogen, and of the heavier oxygen atom 18O, compared with their lighter ‘normal’ counterparts. It takes more energy to evaporate water with a higher proportion of these atoms, and they are more easily lost from rainfall, before they are deposited in ice found nearer the poles. The changing proportion of these atoms then allows researchers to assess how the temperature has changed over millions of years.

From these comparisons, the scientists argue that the description of the period as an Ice Age is misleading, as temperatures in that period fell far less than in a glaciation. During the Little Ice Age (LIA), the average temperature in the northern hemisphere fell by around 0.5 degrees. In contrast, in the most recent major glaciation that came to an end around 12,000 years ago, global temperatures were typically 8 degrees Celsius colder than today.

Frost fairs also seem to be a poor indication of overall climate, as they often did not take place despite the Thames freezing, partly for many reasons including puritanical authorities or safety as lives were lost when the ice melted. The ending of the frost fairs had nothing to do with climate change or solar activity, instead being due to the increased river flow when the original London Bridge was demolished in 1825, and the first Victoria embankment opened in 1870. Both of these prevented the river from freezing completely, despite many subsequent cold winters.

Selective use of art historical evidence appears to reinforce the illusion of a prolonged cold spell. Yet ‘Hunters in the Snow’, depicting a January scene, is part of a series by Bruegel known as ‘The Twelve Months’. Seven of these paintings may have been lost, but ‘The Gloomy Day’ (February), ‘Haymaking’ (July), and ‘The Return of the Herd’ (November) all give no indication of unusually cold conditions. Consistent with this, Lockwood and his team note that even at the height of the LIA period, colder European winters were still accompanied by many warm summers.

Pieter Bruegel the Elder – Hunters in the Snow (Winter) – Google Art Project Created: 31 December 1564

For example, 1701 is close to the lowest point of the Little Ice Age, yet in both Paris and London the summer was reported as being unbearably hot and the CET for July that year is the 10th hottest on record, with average temperatures for the month reaching 18.3°C. The year 1676 is the second hottest June on record at 18.0°C, yet it too was in the middle of a run of cold winters. Such high summer temperatures do not fit at all with the name “Little Ice Age”.

Much more dramatic variations can result from large volcanic eruptions. Samalas, a volcano which erupted in 1257 in what is now Indonesia, ejected large amounts of dust into the atmosphere, causing a temporary cooling effect. The years between 1570 and 1730, corresponding to the coldest part of the LIA, also saw continuous lower level volcanic activity that may have suppressed temperatures. Volcanic eruptions undoubtedly cause both cold winters and cold summers. One of the clearest examples was the Tambora eruption of July 1815, which caused the next year to be called “the year without a summer”.

Professor Lockwood said: “This study provides little solace for the future, as we face the challenge of global warming. Solar activity appears to be declining at present, but any cooling effect that results will be more than offset by the effect of rising carbon dioxide emissions, and provides us with no excuse for inaction.”

###

The paper: (paywalled)

https://academic.oup.com/astrogeo/article-abstract/58/2/2.17/3074082/Frost-fairs-sunspots-and-the-Little-Ice-AgeSOLAR?redirectedFrom=fulltext

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We must get rid of the Little Ice Age.

Bryan A

Absolutely.
The LIA was a sporadic (only lasting for a few tens of decades) and transient event (eventually ending) that was only felt in a few regions (like only in those regions where most people lived) and only had a minor effect on growing seasons (what famine)

jorgekafkazar

Yes, and Napoleon’s troops on their way home from their Russian excursion often took off their uniforms to enjoy the balmy weather.

1696-1697; one out of every three people in Finland starved to death.

Nothing to see here, folks. Please move along.

jbird

Looks like a case of assuming the conclusion then coming up with information to support it. Haven’t the proponents of AGW been doing that all along? Nothing new here.

Henry Galt

“We must get rid of the Little Ice Age” … for our masters and betters. So as to enable their agenda(s). Fly, my Pretties, fly …

Sheri

And we do that by refusing to use the term “global” unless it fits our hypothesis. “Global”=proves AGW

M Seward

Now that the Hockey Schtik has been discredited the Little Ice Age really must go by other means L&G & LGBTQI peeple it really is an Inconvenient Truth. Fineagling the thermometer record by mathematical adjustment reduces its magnitude by comparison especially when you only look at anomalies but more must be done. Pal Reviewed Papers shall be our primary Weapon of Mass Misinformation.

rogerthesurf

Who claimed that it was anything near to a full glaciated ice age?
I also wonder if the authors took any heed of the winters in the new world at the time?

Menicholas

I wonder if they took any heed of that time the guy in charge of it altered the entire temperature series, then destroyed the original one, and refused to give anyone a look at his methodology because they might want to “find something wrong with it”?
Anything based on that time series is worthless warmista crap…the opposite of scientific, like everything the warmistas do.
May sound harsh, but that is the truth.

The author suggests that the cooling effect averaged 0.5 degrees. Why would anybody expect that 0.5 degrees would seriously affect occasional very hot summers? A little perspective when you write, please.

Rascal

I take it that Prof. Lockwood is unfamiliar with Valley Forge, and the painting of Washington crossing the Delaware river.
Probably also has no idea why Greenland is so named.either!

“I take it that Prof. Lockwood is unfamiliar with Valley Forge, and the painting of Washington crossing the Delaware river.”
The painting is not a photograph. In fact, He painted the wrong boat. Weather than night was snow/ rain.
Not very cold for that location at that time of year
You can check Thomas Jeffersons weather Diary as well to see what that winter was like.

2hotel9

Yep, according to the eyewitness account you list it was a harsh winter, beginning early and lasting well into spring. Thanks for pointing that out!

Jaap T

https://en.wikipedia.org/wiki/Pieter_Bruegel_the_Elder
Lived 1520/1530 until 1569, all his paintings are before 1570 … So this little Ice Age was quite a bit longer than many people seem to think.

1701 wasn’t the coldest year AFAIK. But more importantly one consequence of the climate change of that time for Western Europe may very well have been that the Gulfstream effect was lessened. That means much colder winters but also somewhat warmer summers, because then the Western Europe climate starts to look more like that of Russia (Continental Climate) or North-Western US.
Check out how far North a city like say Amsterdam is, quite similar to New York, but Amsterdam never has winters as cold as they are in the NYC area, nor summers like it, because of the Gulf stream effect.

Anyways that LIA period is known to be much colder by many, many degrees, and for a much longer period than our current winters.
We know this because the great rivers of Western Europe froze over, including the big ones that basically NEVER freeze in winter (at least not since 1830 or so, nor between 900-1500), like the Rhine or the Meuse.

The Rhine only froze during the extreme cold periods like during the time of the mass migrations at the end of the Roman Empire (crossing of the frozen Rhine by the Goths in 405/406) and during LIA.

That’s why those Dutch/Belgian paintings are important. Not that they show people skating, but because they are skating on the Rhine, the Waal, the Meuse, the Scheldt etc.

To get an idea of how much colder it must have been: recently we had a record winter in NL, I think it was 2009. It reached -20 degrees Celsius. It was much colder than normal for many months. Yet none of the rivers froze, at least not enough to carry people.
It was almost that cold in 2010 (-18), again no rivers froze and we couldn’t even have the Frisian skating event ‘Elfstedentocht’ (Eleven ‘City’ Tour).
Normal winters in NL means temperatures around zero, maybe some snow, maybe cold enough to skate.
Maybe even cold enough for long enough to have the Frisian Eleven ‘City’ Tour, which is mostly on small streams and some ditches that easily freeze; biggest problem area’s are in places where the route is crossing bridges and some places in or near cities. The event was held in 1909, 1912, 1917, 1929, 1933, 1940, 1941, 1942, 1947, 1954, 1956, 1963, 1985, 1986, 1997. Coldest temperatures in those years are around -10 C… And these are typical solar minimum years.
The event was cancelled just before start in 1987, 1996 and 2012, all very cold years. It could have taken place in 1939 and 1979 (according to estimates), but for various reasons didn’t. The event didn’t happen in 2009, it wasn’t cold enough for long enough, perhaps also due to too much snow (hence bad ice buildup).

Compared to that the climate in which a river like the Rhine would freeze is hard to imagine. How much colder must that have been and for how long?

Jaap T

Hmm, it seems that the Rhine did freeze as far downstream as Nord Rhein Westfalen (Mainz area even) in 1929.
See https://www.uni-mainz.de/presse/15622_ENG_HTML.php and
http://newatlas.com/rhine-freezing-solar-cycle-weather/23886/
Funny that they mention that Frisian event and the 11-year cycle.

The crossing of the Rhine in December 405 is considered to have taken place in the Mainz area. So it need not have been as cold as during the LIA.

The LIA must have been colder still because of the fact that people could skate on the big rivers in the Netherlands, and that certainly was not possible in 1929 (nor in 1917 or 1933 or ….).

Interesting perspective. I see the same kind of disconnect for the medieval warm period. In Greenland, soil was farmed that is now permafrost. That doesn’t seem to agree with the idea that temperatures were only one degree or so warmer than now (laughably, on Wikipedia the MWP is actually shown as colder than now).

crosspatch

I believe the LIA was probably marked by more meridional jets causing more extremes in both cold and hot. I don’t KNOW this to be a fact, but it seems consistent with what was seen.

About CO2, people need to understand that the more CO2 you put into the atmosphere, the more difficult it is to have additional climate impact by adding more. If we were to increase atmospheric CO2 to 600ppm, to give the same additional climate impact, we would have to increase it to 1200ppm and I doubt we would ever get there. And to have the same impact again, we would need to increase it to 2400ppm.

The crux of the hysteria is the claimed 6x amplification of climate impact due to “positive feeback”. Rather than 1 degree of warming per doubling, they claim a doubling could produce 6 degrees of warming. It is pretty obvious by now that isn’t happening or we would have seen most of it by now. They also imply that all warming is human caused and none of it is natural. Climate hysteria only makes sense if you “believe in” the positive feedbacks AND believe none of the warming we have seen is natural variation. I think those two assumptions are nonsense.

Just a question(maybe an ignorant one) for anyone to answer :Who decided that CO2 is a ‘ greenhouse gas’, O2&N2are more than 99.9 percent of the atmosphere while CO2 is , about 400 parts per million .Its possible effects would indeed appear to be ‘astronomical ‘, really??

Bryan A

Is CO2 a greenhouse gas?
Easily and quickly verifiable
2 greenhouses side by side of equal size and space and placed for equal sun exposure.
1 has ambient atmospheric concentrations of CO2 (400ppm) the other has enriched CO2 (800ppm)
Measure the daily temperature differencess over the course of a year.
Same temperature = neglegible effect
Enriched temp higher = Positive effect
Enriched showing Higher winter time night time temp = comfirmation AGW Theory WRT Warmer winters
Most any other (opposite) change = AGW theory debunked

MarkW

Small problem. That’s not how a greenhouse gas works.

Ken

Bryan A. Wrong. There will, indeed, be a difference in the two greenhouses, but it will not be the temperature. The difference will be that in the greenhouse with a greater concentration of CO2, the plants will show more growth and will need less water.

Right string. Wrong yoyo.

Thomas Englert

Argon ~0.93% of atmosphere by volume.

Gloateus

O2 and N2 are “only” 99.04% of earth’s atmosphere, not counting water vapor.

Menicholas

Correct.
Those figures are true for dry air ( I guess, i did not cross check them).
They are not true of the atmosphere, which contains water…and over the tropical and equatorial zones, which constitute the largest part of the surface (about 40% of the Earth lies between the Tropic of Capricorn and the tropic of Cancer), the air has as much as 5% water in it.

Bryan A

Ken,
Not necessarily wrong, if there is a temperature difference, and the effect is more pronounced at night in winter
Now this still doesn’t spell catastrophe but would indicate that CO2 is a greenhouse gas.

Shoot, the simple fact that it is used to enrich the atmosphere in greenhouses says it’s a greenhouse gas

AGW is not Science

Indeed the assumption that all of the (supposedly, since the data, scientifically speaking, is utter crap) measured warming is human caused is sheer nonsense, especially when the underlying hypothesis has NO empirical evidence to support it, just the endless insistence that the hypothesis is fact. AND there is plenty in the paleoclimate record to indicate that the notion that CO2 drives temperature is closer to complete nonsense than it is to fact.

Menicholas

Consider this: Even during the full blown ice age advances, the sun was just as strong as it is now, just a little farther away, and the Sun angle got lower in Winter (but higher in Summer, with the tilt of the Earth higher), and perihelion came closer to midsummer than in midwinter in the NH, as it does now.
So near the Equator it was just as hot…solar heating was likely reduced by a small amount most of the time, and during Summer at high latitudes the Sun angle was higher than now, although the sun was farther away then I bet any amount of money anyone wants that it still felt like the Sun on a hot day.
So, whenever the wind was from the South, it would be darn hot.
It was an ice age because Winters were longer and colder and darker, and the ice reflected a lot of solar energy. But not in the tropics…not by much.
The average temp was lower, but I bet the equatorial weather was just as hot as now, or close to it.
Which means higher temp gradients. And the oceans were smaller…large amounts of land surface lie at a depth which was exposed during the periods of high ice extent…which would tend to make Summers hotter and Winters colder overall.
Then as now, during Summer large high pressure systems could get locked into place and pump tropical air northwards…and it would be hot…very hot.
It was still the frickin Sun after all!
There was a mile of Ice in new England back then…but it never made it to Philly…because it was melting all the time at the edges! Because it was still hot down South!
The people that author studies like this are not curious scientists and fair minded analysts…they are hacks, political hacks, spewing political propaganda.
If they stopped it with the propaganda…they would be incommunicado…completely unable to say anything.

BallBounces

Agenda-driven, confirmation-biased science.

Karl Compton

Hot periods in summers in the LIA? That would be weather,not climate, right?

Windy Wilson

You got it! Just like unusually cold or wet winters during the current period of Catastrophic Anthropogenic Global Warming (The claiming of every unseasonably hot day as evidence for CAGW should have gone down the memory hole long ago).

Bryan A

Nope, remember, Cold is weather and Warm is climate

BCBill

No, no! Current hot is CAGW and current cold is climate change. Past hot is weather, past cold is climate. You have to keep your 88 straight (88 rationalizations that is, not keys)

I wrote a long article about the Little Ice age a couple of years ago seen through the perspective of CET

https://judithcurry.com/2015/02/19/the-intermittent-little-ice-age/

The take home message for me was that the period was not one long monolithic period of centuries of cold and that the term ‘Intermittent Little Ice age’ was more accurate.

We can capture its worst period during extended CET from around 1538. (my extension)

There were undoubtedly very severe winters and also blazing hot summers the equal of today, although one would rarely follow the other. Perhaps the best way to look at it was that there was often marked seasonality, more so than we get these days in the UK.

What is also clear is that temperatures have been rising for the last 300 years or so, making Giss a staging post, and not the starting post, for warming.

Perhaps most intriguing of all is that CET has been declining slightly all this century (although only 16 years of course-not a meaningful climatic period) although the apparent plateau is at a relatively high temperature.

The modern warm period appears to have similarities with the MWP, in as much it was a long period of (relative) warmth, but peppered with some colder spells. There were many extreme events during both the MWP and LIA which appear to be more severe than their modern equivalents

tonyb

Gloateus

Tony,

Since three decades are generally deemed the smallest unit of climate, what is the 30-year trend in the CET, ie 1988-2017? Neatly, 1988 is also the Year of Hansen, when climate doom was proclaimed.

And do you trust the Met to maintain it honestly?

Gloateus

There is a flat trend starting from 1993 to the end of 2016.

That includes a sharp peak around 1998 . That temperatures have remained flat, albeit with many ups and downs, for some 23 years is interesting as is the slight declne during this century.

Having met many of the met office scientists including David Parker who compiled the cet version from 1772 , yes I do trust them.

Tonyb

Gloateus

Thanks very much, Tony. The 1998-99 El Nino spike is to be expected, as with the super El Nino just past.

IOW, it reflects trend analysis in global “data” sets (not that they all qualify as actual data).

Makes drawing broader inferences from the CET justifiable.

Menicholas

I am not so sure that the hot Summers and cold Winters would be any less likely to follow one another than now.
In 1936, the US had both the coldest Winter on record, and the hottest Summer on record.
Coincidence?
Or were both a consequence of the same conditions?
What might that be?
Dry air!
Anyone who goes to the desert a lot and stays there at night knows what happens to temps when the air is very dry.
It takes comparatively little energy to heat up dry air, and also nighttime radiational cooling is very rapid un dry air, and the lower dewpoint means it gets colder before H2O saturation slows radiational cooling.
During such a year, we might expect string springtime storms, as the tropics were likely just as hot and humid as now, so when cold air and warm air clashed, there would be stronger storms and more precipitation.
And we saw, during that year, the entire East coast flooded, and a very bad tornado season.

I think it would be not such a stretch to think that the LIA and even the big ice ages saw similar years.

Those ice sheets would have been very good at wringing all the snow out of any air that moved over them from the South…where the Sun was just about the same.

My understanding is that what led to the LIA famines that killed people with starvation, or left them weak and unable to fight off illness, was not winters, but cold and very wet summers that ruined crops in sodden fields. (Moldy grain contaminated with ergots had an effect like LSD and led to odd outbreaks of “dancing plauge”). In Finland the people who survived learned how to subsist on the inner bark of fir trees. There were no large reserves of grain, and to have a single bad summer put everyone in jeopardy.

Menicholas

Imagine what would happen even today, if a nice hard freeze occurred in Summer of the major growing regions of the northern hemisphere?
Perhaps especially today…back then a lot fewer people lived in cities.
There are currently billions of people with zero ability to produce or hunt one single days worth of food for themselves.
And a surprisingly low stock of food on hand, considering the world as a whole and yearly consumption rates.

so funny Gloat asks who to trust.. And he trusts tonyb, who he doesnt know, to tell him who to trust.
Clue bird Gloat. Science aint about trust.
Its about not trusting what you yourself beleive.
Here is clue. IF you are unwilling or unable to do the work yourself, or check the work yourself.
Then you have no grounds to trust or not to trust.

richardscourtney

Steven Mosher:

People gain reputations from their ‘track records’ so it is very reasonable that Gloateus would seek information from tonyb when wondering about the veracity of the Met. Office.

Similarly, as is confirmed by your post I am answering, your ‘track record’ says that nobody in their right mind accepts anything you say as being reasonable.

Richard

Gloateus

Steven,

I have read enough of Tony B’s work to trust him.

Yours, not so much.

He conducts paleoclimate research without taxpayer support. Yours should be cut off. Indeed, it should be right up there with Gavin and Kevin’s “work”, if what you do can be so dignified by that term.

Gloateus

Steven,

My previous reply still hasn’t appeared, so I’ll repeat it.

I’ve read Tony’s work and admire it. Why should I reproduce it, when he has done so well.

Your “work”, not so much. If what you, Schmidt, Karl, Jones, etc perpetrate can be dignified by that term.

Here’s hoping that your funding gets cut. Tony does his excellent work free of charge to the taxpayers.

pochas94

“During the Little Ice Age from the 15th century to the 18th century, famines in Europe became more frequent. This often led to a rise in conspiracy theories concerning the causes behind these famines, such as the Pacte de Famine in France.[73]
The 1590s saw the worst famines in centuries across all of Europe.”

https://en.wikipedia.org/wiki/Famine#Europe

If we didn’t have the paintings, the Little Ice Age would already have been purged from history by Mann and and Pachauri’s Ministry of Truth.

The Badger

Some of us have libraries with old books and periodicals in them (and a few paintings on the walls) but I spend more time looking at the more accurate and detailed stuff in the books than the painings.

aaron

I’m diehard against CAGW, but I do like this paper, mostly. Warm summers occurred then as now? OK, so what’s the big deal now? A top ten hot summer several centuries ago – no it can’t be, the present warming is unprecedented, right? Sarcasm aside, this paper isn’t a typical hysteria rag.

Pop Piasa

But a shame that all that reasonably carried-out research ended with such a PC assumption in the last paragraph.

Auto

Pop,
Funding.
Publishing, even.
You don’t put that in – you don’t get published.
Swamp draining might have started, but it is, emphatically, not yet complete.

Auto

I would like to see a bit more even-handedness in the paper, too. For example, when it says ““On the whole the Little Ice Age was a manageable downturn in climate concentrated in particular regions, even though places like the UK had a larger fraction of cold winters.”, it should also say ““On the whole the late 20th century warming was a manageable upturn in climate concentrated in particular regions, even though places like the Arctic had a larger fraction of warming in the climate models.”.

aaron

I agree Mike, well-written.

Ian Magness

Oh, it was insignificant was it? How about showing us (if they exist) the deaths from cold figures for these and later times. Further, how about the ENSO figures – do they exist? There is some evidence that many of the world’s, say 10 to 50 year, surface temperature cycles derive, at least in part, from times when there were net El Nino periods (warmer, resulting from more heat energy being released into the atmosphere from the deep oceans), and net La Nina periods (cooler due to net absorption into the oceans). Why is this potential explanation not mentioned?
Answer: the authors simply want to bury the LIA as a trivial irrelevance that we do not need to understand in the context of understanding the present, slightly warmer, period – which we must all understand in man’s fault and man’s fault alone. More grant money please.

Tom O

Actually, they are trying to “bury” the quiet Sun hypothesis of causing cooling so they can continue to say that more carbon dioxide will eventually cause a catastrophic temperature increase. This quiet sun idea of causing drops in temperature over prolonged periods is not going to matter, so forget it.

tabnumlock

The millions of people who starved to death will be glad to hear it.

subtle2

This review does not mention comments about how cold it was as entered in journals or diaries of the day. Ink in the inkwells in the study frozen solid.
Somewhere there is a note that cabinet makers lost their supplies of hardwood, because the intense cold split the trees.

Windy Wilson

I remember what you mention from James Burke’s “Connections”, published in (IIRC) 1978, in the interregnum between Catastrophic Anthropogenic Global Cooling and Catastrophic Anthropogenic Global Warming (Either during the Ozone Hole Catastrophy or the Acid Rain Catastrophy).

MarkW

“Unbearably hot” is hardly a scientific measure as people measure what is hot and cold based on what they are used to, not on some absolute scale.

Gabriel

First of all Prof. Lockwood seems to be a warmist since he believes AGW/CO2 is responsible for any warming without any question. He may be part of the group who calls themselves ‘the consensus’. It is a discredit for his work at the beginning. Secondly and according to this report from WUWT it definetely seems to rely just on UK-based information. There are reports from other places in the world and written in other languages which also reenforces the idea of a very cooling period. And it also must be reminded the problems with plagues in the European crops which was a main drive for europeans to cross the oceans (then finding America). Recently I’ve found some excerpts from reports included in documents from South America regarding the Dalton period which depicts very cold temperatures even at latitudes of 20° or less (which is absolutely out of question nowadays).

My editorial opinion as “borrowed” from Webster’s Online:
Definition of simplism
: the act or an instance of oversimplifying; especially : the reduction of a problem to a false simplicity by ignoring complicating factors.

aelfrith

“For example, 1701 is close to the lowest point of the Little Ice Age, yet in both Paris and London the summer was reported as being unbearably hot” Isn’t that weather extrapolated as climate?

Sheri

Climate is always an extrapolation from weather, or more accurately, it’s the average of weather. They are intrinsically bound.

Menicholas

An ice free Arctic is an extrapolation.
But the cyclic nature of Arctic Ice tells us that an extrapolation will not lead us to the average, in fact exactly the opposite will occur if one merely extrapolates whatever trend is currently occurring.

There is overwhelming evidence that the Little Ice Age was global, for instance from glaciers in Alaska, S America, New Zealand and Antarctica.

It is also well established that temperatures began declining around the 13thC, so that a cooler climate was already well established long before the coldest phases around 1700, and again in the mid 19thC.

If anyone is in any doubt, I suggest they read HH Lamb

GeologyJim

The Idso team has also compiled an extensive list of “peer reviewed” studies documenting LIA conditions all over the globe [yes, southern hemisphere too]

http://www.co2science.org

Lockwood et al are trying to artificially trivialize the evidence by focusing only on England and northern Europe. Also using the straw-man argument that LIA was not as climatically significant as the full-blown Last Glacial Maximum. So what? The LIA coincides with worldwide advances of mountain glaciers, meaning snow/ice accumulation was greater than ablation/melting over decadal/centennial timescales

sheesh

Gentle Tramp

Quite so, Paul !

One must only study the pictures of the Rhone Glacier in the 19th Century and compare them with the modern pics:

https://en.wikipedia.org/wiki/Rh%C3%B4ne_Glacier#Evolution

Why then was the Rhone Glacier so much longer and thicker around 1870 if there should have been no significant LIA compared with today or the similar warm periods of the MWP and the Roman era? Furthermore, many Alpine passes which are still ice covered today, like e.g. the Theodul pass near Zermatt, were ice-free during the MWP. That means, the LIA was quite real compared with both sides of its history…

This documentation is quite interesting as well:

https://youtu.be/YF8AAJSTJoM

Javier

Exactly

http://i.imgur.com/fa9yhHJ.png

Like it never happened. What is wrong with science when charlatans publish in journals articles about the climate based on paintings.

“There is overwhelming evidence that the Little Ice Age was global, for instance from glaciers in Alaska, S America, New Zealand and Antarctica.”
I’m laughing
Suddenly people who think 40000 temperatures stations are enough to get an idea of global temperature, think they can establish a Global LIA by finding 3 cold locations.
But hey the idea of a global temperature itself makes no sense, so we cant say the LIA was colder.

Gloateus

Steven,

Do you seriously imagine that manipulating station data to manufacture a global average temperature since 1850 accurate and precise to fractions of a degree is the same as observing the actual response of the planet to average colder temperatures over a period of centuries, as shown by paleoproxy data?

It’s not only the fact that most glaciers grew everywhere during the LIA. The same picture emerges from thermometers, historical records, ice cores, sea and lake sediments, insect remains, trees, pollen, stalagmites, you name it. There is no source of climatic data which does not show a global LIA.

And no one is stepping on the data and cooking the books, as do the bureaucratic gatekeepers to please their political masters.

Robert Craigen

This is an important point. I can’t speak to motivation but I suspect the reason they started the timeline in the 16th Century is to avoid the dramatic shift in temperature from the MWP. How did they arrive at the 0.5 degree change? Apparently by ignoring the first 3 centuries of change, including the most dramatic change during what historical climatologists call the “1300 event”. Further, those who actually study this professionally (whom these authors might have done well to ask about this before choosing a timeframe for their study) have thoroughly documented parallel effects around the world, in North and South America and in the pacific rim. It ain’t a case of a few cold winters in London. Here’s a pretty authoritative source https://books.google.ca/books?id=tzjomalYtNgC&pg=PA98&lpg=PA98&dq=storm+activity+during+the+medieval+warm+period&source=bl&ots=OYO9_WN1lW&sig=XdyJZNh50n0RVuIfkRVosdrzEZU&hl=en&ei=1LFHSrfRGpOEtwen1ISWBg&sa=X&oi=book_result&ct=result&redir_esc=y#v=onepage&q=storm%20activity%20during%20the%20medieval%20warm%20period&f=false

2hotel9

So, this boils down to a “potato-potatoe” issue. Just like DJT calling it “wiretapping” makes Obama Admin surveillance of American citizens not really surveillance. I am certain all those people who suffered and died during the LIA feel so much better, now.

AndyG55

This Lockwood guy is just following the money.

Changes his ideas on the flip of a $100 note.

https://wattsupwiththat.com/2010/04/14/lockwood-demonstrates-link-between-low-sun-and-low-temps/

troe

The intended takeaway is at the end ‘ worse than we thought’ and “no excuse for inaction”

Political statements made in a politcal document. All here know that this is the machine we are fighting at work. In raw power politics we are not that interested in the details. Was Mann? This faction of the coalition is out to squash your malign influence on current events. Be paranoid.

Menicholas

It aint paranoia if everything said about these political propagandists is true.

I prefer the paintings of Hendick Avercamp

Hendrick

jorgekafkazar

As rare as hen’s teeth? Not any more, say scientists:
https://www.theguardian.com/education/2006/feb/23/research.highereducation

Insignificant compared to the CAGW? I was looking at the latest temp updates. The tropics have NOT warmed (that is the area where warming could possibly cause problems), and the warming that has happened is hardly noticeable. Compare that to glaciers eating villages, hypothermia and starvation.

The author of the press release said “On the whole the Little Ice Age was a manageable downturn…” But somehow todays small warming (less than 1°C) is unmanageable? Even with all of our technological advances?

MarkW

Furthermore, much, perhaps even most of that 1C warming is due to the planet recovering from the LIA. It has nothing to do with increased CO2.

MarkW

enargpia, nice attempt at deflection. You are getting better, I hope your in line for a raise.
Regardless, as you well know, nobody knows, just as nobody knows for certain what caused the LIA.
Not knowing what caused it does not disprove the well known fact that it happened.

MarkW

As always, energia, you dance with exquisite precision, yet you never manage to actually say anything.
If we have warmed up, then we have recovered from the LIA. Perhaps we will shortly plunge into another LIA, perhaps we won’t.
So freaking what?
The fact remains that we have warmed up and that most of the warming since the start of the Industrial revolution is the result of that warming.
This paper tries to imply that all of the warming since the bottom of the LIA is due to CO2, and that is patent nonsense.

MarkW

Noting that we went into a LIA and then recovered from it is a claim that the climate is steady state?
I’m going to guess that not even you believe the nonsense you spew.

the 11 year signal shows up. I don’t buy the TCR the authors derive from the solar signal, but their statistical analysis finding it looks valid.
The effect is very small. And a small effect is expected, so no surprise there.

It is, however, so small [even if real] that it has no effect [also being cyclic] on the climate [one 30-yr period used to define climate contains three solar cycles].

Gloateus

However there do appear to be supercycles of the ~11-year cycle which operate in the climate bands of 30 and more years, such as grand solar minima. The Maunder is generally considered to have lasted about 70 years, or six cycles.

Dunno how well this comports with your rejiggering of the sunspot count, but ought at least to remain illustrative:
comment image

The difference between the minima during the LIA and the Modern Maximum is pretty stark in this graph.

Look at the graph in my first comment.

Check out the view of some of the best solar physicists in world [Lockwood is not one]:
http://www.leif.org/EOS/2011GL046658.pdf
“We argue that there is a minimum state of solar magnetic activity associated with a population of relatively small magnetic bipoles which persists even when sunspots are absent, and that consequently estimates of TSI for the Little Ice Age that are based on scalings with sunspot numbers are generally too low. The minimal solar activity, which measurements show to be frequently observable between active‐region decay products regardless of the phase of the sunspot cycle, was approached globally after an unusually long lull in sunspot activity in 2008–2009. Therefore, the best estimate of magnetic activity, and presumably TSI, for the least‐active Maunder Minimum phases appears to be provided by direct measurement in 2008–2009. The implied marginally significant decrease in TSI during the least active phases of the Maunder Minimum by 140 to 360 ppm [parts per million] relative to 1996 suggests that drivers other than TSI dominate Earth’s long‐term climate change”.

MarkW

energipia, do you take lessons in how to be-clown yourself?
First off, we have been talking about the recovery period since the LIA. Now you want to talk about the last year.
One thing I’ve noticed about you, the further behind you fall, the more desperate you are to change the subject.
Regardless, over the last year, the temperature is down, about 0.6C, not up.
Before that, the increase was due to the El Nino.
Since you aren’t smart enough to figure it out for yourself, I’ll give you a break and point out that the drop in temperature is also due to the El Nino. It’s fading to be specific.

MarkW

To put it another way.
I know that the planet has warmed since the bottom of the LIA because that is what all the records and all the science says.
I do not need to postulate a reason for this warming in order to recognize that it has occurred.

MarkW

As always energpia, you use words without knowing what they mean.
If I note that when I release a ball it falls.
That’s not circular reasoning, it’s just an observation of a fact.
Just as noting that it is a fact that the world has warmed up since the bottom of the LIA is not circular reasoning.

Gloateus

lsvalgaard April 4, 2017 at 12:44 pm

Thanks for the up to date information.

Gloateus

Besides which, you misuse the term “falsification”. That applies to hypotheses, not the observations which test their predictions. The hypothesis of CACA has been repeatedly falsified, indeed was born falsified.

Your citing a datum from one glacier in Canada doesn’t some how cancel out all the contrary observations from everywhere else in the world. It’s a local exception, if valid. There could be lots of reasons for trees from warm periods since the Holocene Optimum not to have survived or have grown there.

The hypothesis that nothing unusual has happened in climate recently has been repeatedly confirmed by observations from around the world. It is not falsified by a local exception.

Javier

Gloateus,

It is quite well established in the glacierology field that current global glacier retreat since the LIA is unusual and out of trend for this time in the Holocene. Most glacierologists are convinced that globally glaciers have not been this short since the Holocene Climatic Optimum ended about 5500-5200 years ago. I am also convinced that they are right. The evidence has to be accepted. The question is what does it mean? Does it mean that the world is as warm as it was 5500 years ago? That is not the only explanation. CO2 theory is that the effect of CO2 is maximal the least H2O there is in the air, and the air above glaciers is very dry due to its low temperature. We could be looking at a place that it is specially sensitive to CO2 and therefore not a good thermometer for the rest of the planet. I believe that due to the high CO2 content of the atmosphere, it is compatible to have very reduced glaciers and yet temperatures still within Neoglacial bounds.

Samuel C Cogar

Javier – April 4, 2017 at 3:52 pm

It is quite well established in the glacierology field that current global glacier retreat since the LIA is unusual and out of trend for this time in the Holocene. Most glacierologists are convinced that globally glaciers have not been this short since the Holocene Climatic Optimum ended about 5500-5200 years ago. I am also convinced that they are right. The evidence has to be accepted.

Javier, given your above “ignorant based comments” …… I have to assume that the “glacierologists” you speak of in your above commentary were educated in the “same era” public school systems that you were …… therefore you all have a pretty damn good excuse for being utterly ignorant of historical “events” that were factually recorded at the time they occurred and have been verified and attested to by world renown researchers and historians for the past 2,000 years.

And the historical “event” that completely debunks your above “glacierology” claims is/was …….. Hannibal’s crossing of the Alps in 218 BC …. when he, Hannibal, led over 90,000 soldiers, 10,000 horses and 37 war elephants across the Alps …… to attack and defeat the Romans.

http://i.dailymail.co.uk/i/pix/2016/04/04/16/32D6EC9700000578-0-image-a-23_1459783189796.jpg

Javier, try getting either one (1) horse or one (1) elephant across the Alps now days, by following Hannibal’s route, ….. let alone 10,000 horses or 37 elephants.

MarkW

energpia, since you insist on continuing to make a fool of yourself.
It has warmed about 1C since the bottom of the little ice age.
About 0.7C of that warming occurred prior to 1950 when CO2 levels started rising.
That is all I’ve said, it is a proven fact. Nothing circular at all about the logic.
You really ought to quite and stop trying to hijack threads with your patented nonsense.

“energpia, since you insist on continuing to make a fool of yourself.
It has warmed about 1C since the bottom of the little ice age.”
1. That means you have knowledge of the temperature of the LIA
2. That means you trust at some level the measurement of temperature today.
3. It also means you accept sparse sampling as the sampling in the LIA is very sparse and not
even thermometers
4. It also means you accept the notion of a global temperature.
As we know, tonyb will tell you, all records except the CET and diaries he has read are not credible.
It hasnt warmed since the LIA because there was no LIA, just weather. Nothing out of the ordinary.

jorgekafkazar

Everything is manageable to the man who doesn’t have to do it himself.

Menicholas

Yes, unmanageably huge increases in agricultural outputs, unmanageable increases in global greening, unmanageable dearth of famines on a decadal timescale the world over, and unmanageably unimportant fluctuations in Arctic sea ice.

Resourceguy

The time span of the LIA is vast compared to the era of post-modern climate narcissism.

Lockwood: “no excuse for inaction”
Here are some good excuses for inaction.
Except for the now cooled 2015-16 El Nino blip, no global warming this century (except by Karlization). Yet about 35% of the increase in CO2 sinve 1958 (Keeling curve) took place this century.
No acceleration of SLR.
Greening.
Polar bears thriving.
No increase in weather extremes.
Renewables not viable without subsidies, and intermittent.
Models falsified by tropical troposphere temperature (Christy testimony last week).
According to the new Mckinsey report, Germany’s Energiewende a ‘success’ (higher cost, less reliable) except in one detail—German Utility CO2 emissions are rising.

There is no excuse for action .

jorgekafkazar

Follow the money.

Menicholas

Ristvan wins the internet yet again!

Maunder Minimum cold may have been somewhat exaggerated, the CET (at latitude 51.5 to 53.5N) the only realistic temperature record available from the MM period, shows that it was cold and lasted a dozen or so years.
http://www.vukcevic.talktalk.net/CET-latest.gif
In this graf you can see in more detail the CET’s seasonal temperatures since 1659.
“Climate change is a large-scale, long-term shift in the planet’s weather patterns or average temperatures.”
Approximately 0.17% change in the global temperature over period of the last 30 years, and may be the case for the LIA temperature drop or the subsequent temperature rise (1720-30), none of these may qualify as “a large-scale, long-term shift”.
Accordingly the ‘climate change’ occurred at the time of Younger Dryas and at the interruption of the Ice Age by the present interglacial.

Unfortunately, Lockwood still uses his own home brew sunspot record. I have superposed the official record [average curve is the red one]. Fortunately, it doesn’t change his argument a whole lot, regardless if you agree with it or not:
http://www.leif.org/research/Lockwood-LIA-Graph.png

Gloateus

Paul Homewood on globally advancing glaciers during the LIA:

https://notalotofpeopleknowthat.wordpress.com/2015/01/25/glacial-advance-during-the-little-ice-age/
comment image?w=756&h=1248

Image from Lamb’s “Climate, History and the Modern World”.

This sort of revisionism of history is like the unpersons in Soviet historiography. They are the unperiods.

First they came for the Medieval Warm Period. Then they came for the Little Ice Age. Next they will come for Dark Ages Cold Period. Then they will come for the Roman Warm Period, the Greek Dark Ages Cold Period, the Minoan Warm Period, the Bronze Age Collapse Cold Period, the Egyptian Warm Period, the Sahara Desertification Cold Period and the Holocene Climatic Optimum.

Menicholas

Lie big, keep it simple, keep repeating it.
These jokers are students of the wrong period of history.

Matt Owens [Lockwood colleague] gave this talk at a workshop I co-organized in 2014:
http://www.leif.org/EOS/Owens-MM-Talk.pdf
Slide 9: “No Little Ice Age”

Gloateus

Looks to me as if there are lower lows during the interval before c. 1850 than after it.

And that is what is wrong with Lockwood’s home brew series.
Some of my comments here:
http://www.leif.org/research/Confronting-Models-with-Reconstructions-and-Data.pdf

jorgekafkazar

Fascinating links, Dr. S.

Gloateus

Leif,

Thanks for the link to your team’s work. Dunno why Lockwood just didn’t use your 2003 reconstruction in 2014, if not before. Not Invented Here, I guess.

It is worse than that. We were critical of him:
http://www.leif.org/research/Reply%20to%20Lockwood%20IDV%20Comment.pdf

Gloateus

Well, by 2014 he was coming around to your reconstruction bit by bit, regardless of what he thought in 2006. Might be too much to expect for him to admit that fact.

Yes, he will never admit that. In fact is still claiming that his old ‘result’ from 1999 is still valid [it is not]. He claimed that the statistical significance was at 99.999999999996%….

whiten

lsvalgaard
April 4, 2017 at 10:11 am
——————

Sorry Isvalgaard…..most probably this is not correct and out of topic, but I have to ask at this point.

Any time soon that you may decide to get your hands “dirty” and get to really rumble on this mud fighting AGW thingy?

From my point of view you may just have the most significance of “evidence” and knowledge to engage.
Apart from Jupiter thingy, am I right or wrong with this?!? Please let me know if not much of asking…..

No trying to spoil anything, but could not resist it, if you know what I mean!

cheers

Any time soon that you may decide to get your hands “dirty” and get to really rumble on this mud fighting AGW thingy?
I don’t quite know what you question or problem is. You can read about my view on the matter here:
http://www.leif.org/research/Climate-Change-My-View.pdf

Gloateus

lsvalgaard April 4, 2017 at 12:00 pm

Wonder what statistical significance level he attaches to his discovery that the LIA didn’t really exist.

does it matter?

Gloateus

No. Probably the canonical 97%.

It is the CET’s winters that are often quoted as the Maunder Minimum period’s exceptional, while the summers were more mixed affair.
For better understanding what has happened in the winters during and since the MM it might be of interest to compare the three CET’s winter months
http://www.vukcevic.talktalk.net/CET-DJF.gif
At the first glance it appears that the MM was less exceptional than the 1760-1840 period.

Gloateus

Washington crossed the Delaware in a particularly icy December. Napoleon picked a bad year to invade Russia.

Gloateus

I’m surprised that the allegedly worst European winter of at least the past 500 years doesn’t show up in central England, ie 1708-09:

https://en.wikipedia.org/wiki/Great_Frost_of_1709

William Derham, at Upminster near London, recorded a low of −12 °C (10 °F) on the night of 5 January 1709, the lowest he had ever measured since he started taking readings in 1697. His contemporaries in the weather observation field in Europe likewise recorded lows down to −15 °C (5 °F). Derham wrote in the Transactions of the RS that, “I believe the Frost was greater (if not more universal also) than any other within the Memory of Man”.

That doesn’t sound all that low, I admit, but outside the cities where these readings were taken, it might well have been colder. This past winter in the Pacific NW, it got below zero F. In 1968, the mercury dipped to -35 °F in my town.

Gloateus

Vuk,

Thanks. So in the CET, 1708-09 wasn’t nearly as bad as the winter of 1684, in the very depths of the Maunder Minimum.

The conclusion that 1709 was the worst in 500 years thus isn’t supported by the CET. Tell that to the freezing Swedes in the Ukraine before Poltava, and to French aristocrats huddled around their ceramic heating furnaces.

On the annual basis the CET isn’t representative of continental Europe, but one would expect similar long term trend, but that is not case either
http://www.vukcevic.talktalk.net/2CETs.gif
Between 1825 and 1975 (150 year period) if the data is to be believed Central Europe was about 0.5C colder (?!)

Note: Central European temperature graph is anomaly centred at the CET’s 9 degree C.

Gloateus

Vuk,

As would be expected of a continental rather than marine climate.

IMO the issue isn’t whether the absolute temperature anomaly per se is representative of any larger area, but if the ups and downs reflect a world average.

Menicholas

“Washington crossed the Delaware in a particularly icy December. Napoleon picked a bad year to invade Russia.”
Anyone care to comment on how rare it is these days for the Delaware to be frozen near Trenton by Christmas?
OK, I will…it never happens.

Menicholas April 4, 2017 at 6:33 pm
“Washington crossed the Delaware in a particularly icy December. Napoleon picked a bad year to invade Russia.”
Anyone care to comment on how rare it is these days for the Delaware to be frozen near Trenton by Christmas?
OK, I will…it never happens.

It didn’t happen in 1776 either, they crossed by boat. Slightly after Christmas it frequently does (as it did then), here’s a photo from 2014comment image

Once during the annual reenactment during the last 50yrs the Delaware was sufficiently frozen that the troops marched over the river.

Gloateus

Yup, the Delaware has been icier than normal lately. In fact, in the allegedly warmest year on record, it had more ice than in at least 20 years. In March!:

http://wnep.com/2015/03/11/keeping-an-eye-on-the-frozen-delaware-river/

Menicholas

Phil. posts an undated picture of a frozen river and claims it is the Delaware river near Trenton in December.
I call BS.
Prove it.
I lived there most of my life.
February is not unheard of, but ice choked in December? Near Trenton?
No.

Menicholas April 4, 2017 at 9:08 pm
Phil. posts an undated picture of a frozen river and claims it is the Delaware river near Trenton in December.

I said ‘slightly after Christmas’, it was 7th Jan.
I call BS.
Prove it.
I lived there most of my life.
February is not unheard of, but ice choked in December? Near Trenton?
No.

Then you’ll recognize this view then, dated 9th Jan, 2014:
http://image.nj.com/home/njo-media/width960/img/the-times/photo/2014/01/-79bc643ae36a2e22.jpg
and these:
http://image.nj.com/home/njo-media/width960/img/the-times/photo/2014/01/-1397dfede76dc3e9.jpg
http://image.nj.com/home/njo-media/width960/img/the-times/photo/2014/01/-4fd114736d03b29f.jpg

Menicholas

Golly Phil. I think you need a new calendar.
Cuz the one most of us are using have that date almost 3 weeks after Christmas. If you lived in the Northeast you know that it commonly gets cold around the week of Christmas and the beginning of January.
Cold as in very cold… tens of degrees below freezing. Which is what it takes to freeze a river solid or even to cause it to be choked with ice as it was on Christmas that year.. question isn’t does the river freeze in the middle of January its is it already Frozen by Christmas.
So tell us again how what the river is doing on January 10th has anything to do with what the river was doing at Christmas?

Menicholas April 5, 2017 at 5:24 am
Golly Phil. I think you need a new calendar.
Cuz the one most of us are using have that date almost 3 weeks after Christmas.

Which calendar are you using, 7th Jan isn’t even two weeks after Christmas?

If you lived in the Northeast you know that it commonly gets cold around the week of Christmas and the beginning of January.
Cold as in very cold… tens of degrees below freezing. Which is what it takes to freeze a river solid or even to cause it to be choked with ice as it was on Christmas that year.

If by “Christmas that year” you mean 1776, it wasn’t “choked with ice”, there were a few ice floes but it did start to snow and was blowing a gale (a classic Nor’easter). It did clear up a few days later and froze hard allowing some troops to walk across the river on Jan 1 1777.

question isn’t does the river freeze in the middle of January its is it already Frozen by Christmas.
So tell us again how what the river is doing on January 10th has anything to do with what the river was doing at Christmas?

More trouble with numbers, who mentioned Jan 10th and since when is it the middle of January?

whiten

lsvalgaard
April 4, 2017 at 12:23 pm.

Thank you for the reply and the link offered….

Went through it very superficially and maybe due to that probably missed in the Sun’s section the later method you apply for the the Sun’s short term variability reconstructions by relying in 14C and delta18….. some thing seen quite often, and offered by you in these comments!

Just checking if maybe there was some thing in that respect included in your view of this matter…just checking…nothing more…….
That was the most of my question was about…probably not even worth it…

The link Mosh offered the other day about some work of yours was more interesting to me and I did not have a superficial go at it…just to be honest.

Thank you again for your reply, and hopefully I am not been noisy and bothering here.

cheers

Looking at the monthly CET record one can see that winters were cooler back at the start. However if you look at the monthly CET records for June one finds a total absence of warming over the whole record. The warming appears to be seasonal.

brianjohn

“Manageable Downturn”. Hmmm. Tell that to the Tlingits who had to shut down their habitation of Glacier Bay during the LIA. Expressing my own non scientific biases, can I refer to this as an “evacuation”. Where’s my funding?

Clyde Spencer

When Sir Francis Drake visited the west coast of North America, he found that the natives were not wearing clothes to suitably protect them from the cold, presumably because they were not used to the colder weather.

What was happening with alpine glaciers during this time? That got left out.

Gloateus

Please see the link I posted to Paul’s article above.

Glaciers advanced globally. Alpine villages were threatened and parts of Switzerland had to be evacuated by climate refugees no longer able to farm the upper valleys. Some passes in the Alps are open only during warm periods. Those just emerging now were also open during the Medieval, Roman, Minoan and Egyptian Warm Periods and Holocene Optimum, as shown by, among other evidence, the presence of artifacts from those intervals but not the cold ones. Oetzi the Iceman is from the end of the Holocene Optimum.

Gabriel

Charrua and Guarani indians from South America used to wear heavy ‘overcoats-like’ dresses known as ‘palas’ or ‘ponchos’ at latitudes between 25° and 40° in the 16th and 17th centuries according to documents sent to the kings of Spain and Portugal. These documents mention very cold temperatures in Southeastern South America.

rtj1211

British winters are controlled by the competing claims of mild and wet southwesterly Atlantic storms, wild, stormy and potentially snowy northwesterly depressions competing against the influence of cold Siberian highs extending to Western Europe, with snow potentially coming either from the NE, the east or even the SE. Much can be deduced about the nature of the winter patterns depending on precipitation distribution, both solid and liquid.

Britain can have a very mild winter even if the Alps and Germany have an incredibly cold one, but it is unlikely to have a cold one if Germany is mild. For that to happen, you need Mediterranean air reaching Bavaria but arctic air streaming down to Britain……

Given the obvious differences between California and the UK (the winter patterns do not cosegregate), I would be very wary of extrapolating a highly local temperature record across the globe.

Perhaps proxies across the globe should also be evaluated in the period 1350-1750?

Gloateus

Proxies around the globe have been evaluated for that interval and for those before and after it.

They show that not only the LIA and MWP were world-wide phenomena, but that so were the warm and cool periods before them during the Holocene and previous interglacials.

The LIA can be largely explained by its frequent, deeper and longer-lasting solar minima compared to the warm periods which preceded and followed it. There were some big volcanic eruptions then, too, but not much more so, if at all, than during the Medieval and Current WPs.

Going without clothes in the temperate zones of the Precolumbian Americas was common. The people were hardy. Darwin encountered naked Fuegians during the colder than present 1830s of subantarctic Tierra del Fuego. Indians not only in California but Virginia were often naked, as was then eleven year-old Matoaka “Pocahontas” Powhatan when the English first met her in 1609, doing cartwheels (without benefit of having seen a cart). If nothing else, it upped vitamin production in the skin.

The LIA (1300-1850) was a period of weather extremes and a shifting of climate from the Medieval Warm Period to very cold winters and wet, cold springs. The years of the Great Famine, 1315 to 1319, were the wettest in some 50 years. Interspersed in these periods of extreme cold and wet were also periods of warmth and relatively benign weather. Unprecedented weather changes — where have we heard that before? During the LIA, glaciers advanced and destroyed whole villages.

Dr. Mann tells of of recent weather extremes but the extremes in the LIA would make anything today seem like child’s play. The population expanded during the favorable years of the MWP and crop failures in the LIA caused widespread starvation and subsequent disease. It was thought that “weather making” witches were responsible for the fiendish weather and general misery, and literally thousands were burned at the stake. See Brian Fagan, “The Little Ice Age” and the haunting paper by Behringer: https://drive.google.com/file/d/0B8k_TGrJSc67a1lIZ25WamhabXc/view?usp=sharing.

Taphonomic

Why do teleconnections work for a larch in Yamal or bristlecones inn the White Mountains but not for the Thames freezing?

Coldest CET winter was in 1684 with average temperature below –1C, but two years later in 1686 the average winter temperature rose to above +6C see here. That is weather not climate change.
“Climate change is a large-scale, long-term shift in the planet’s weather patterns or average temperatures.”

You can read the whole article (open access) here:
http://www.climate-lab-book.ac.uk/files/2017/04/343_AandG_MMandLIA.pdf

Isn’t this like the Karl paper where they are explaining away something that they previously denied existed at all?

Lockwood says: On the whole the Little Ice Age was a manageable downturn in climate concentrated in particular regions…

The whole article has twisted the narrative by suggesting that the Little Ice Age started in 1650. In fact it started a lot earlier: Look at: Miller, Gifford H., et al. “Abrupt onset of the Little Ice Age triggered by volcanism and sustained by sea‐ice/ocean feedbacks.” Geophysical Research Letters 39.2 (2012).

They say: “Here we present precisely dated records of ice-cap growth from Arctic Canada and Iceland showing that LIA summer cold and ice growth began abruptly between 1275 and 1300 AD, followed by a substantial intensification 1430–1455 AD. Intervals of sudden ice growth coincide with two of the most volcanically perturbed half centuries of the past millennium.”

This coincides with other historical information: Such as the Great Famine, from Wiki: “The Great Famine of 1315–1317 (occasionally dated 1315–1322) was the first of a series of large-scale crises that struck Europe early in the fourteenth century. Most of Europe (extending east to Russia and south to Italy) was affected.[1] The famine caused millions of deaths over an extended number of years and marked a clear end to the period of growth and prosperity from the eleventh to the thirteenth centuries.”…and the Black Death: again wiki: “The Black Death was one of the most devastating pandemics in human history, resulting in the deaths of an estimated 75 to 200 million people in Eurasia and peaking in Europe in the years 1346–1353.”

Millions of deaths due to famine and 200 million dead due to plague – not what I’d call a manageable downturn in climate.

So, back to Lockwood’s new study: It should be entitled: “Frost fairs, sunspots and the period several hundred years after the Little Ice Age called the Maunder Minimum”.

Gloateus

Lockwood might start in the 1650s because of the CET, but of course the LIA began much earlier than that, regardless of precise date.

The onset of the LIA is debatable. There was extreme weather in parts of the 13th and 14th centuries, but the second half of the 1300s was warm. I’d suggest AD 1400 as a good start date, although some consider the Wolf Minimum to have occurred in the LIA rather than the MWP:
comment image

Javier

I consider 1257 as the start date of the LIA. I don’t think you can consider to be in the Medieval Warm Period after that, and there is no need to add more transition periods.

http://i.imgur.com/dLwwN4e.png

Gloateus

Tony can correct me, but IIRC the 14th century was as warm as the 13th in Manley’s reconstruction of CET for the centuries preceding its thermometer record beginning in the 17th century.

If however you do want to start the LIA in the mid-13th century, I’d base it on the Wolf Minimum rather than a volcanic eruption. The two might not be independent events, anyway.

Thanks for the glacial advance and retreat study you cited below, BTW.

Gloateus

The world was set up for the Black Death because population had grown so rapidly during the Medieval WP. War was also made easier by the increase in fodder for animals and food for fighters. War horses in particular needed lots of not just grass but grain.

But by my reckoning both the first outbreaks of plaque (1347 et seq) and most of the Hundred Years’ War (1337-1453) occurred during the Medieval WP. The Wars of the Roses, a dynastic conflict in England, did however happen during the early LIA. Weather and climate affected it. Towton, “probably the largest and bloodiest battle ever fought on English soil” (Gravett, 2003), was waged in a snowstorm on Palm Sunday, 29 March (Old Style) 1461.

Gloateus,

Interesting points. But when you say: “But by my reckoning both the first outbreaks of plaque (1347 et seq) and most of the Hundred Years’ War (1337-1453) occurred during the Medieval WP. ” Did you base that opinion on a specific piece of information or a general impression from a wide group of sources? Because the reference I cited above seemed pretty clear about when it started, and it fits with the known facts of geographically widely dispersed extreme famines (a whole series of them) and the black death, both of which seem highly likely to be associated with the stresses to people and animals caused by rapid cooling, and crop failure after many unusually warm years.

Gloateus

I base it mainly on the temperature record, whether instrumental or proxy.

If you want to go by famines, then the LIA should start in 1315.

https://en.wikipedia.org/wiki/Great_Famine_of_1315%E2%80%9317

In the 1250s-80s there was some bad weather, typically associated with volcanic eruptions. There was also the Wolf Minimum, c. 1280-1350. But the second half of the 14th century generally once again enjoyed MWP-style good weather. Conditions naturally varied on different continents and in the oceans.

So start and end dates of warm and cool intervals can be fairly arbitrary. And of course they contain decadal cycles counter to the centennial secular trends. Thus the MWP had some cooler intervals, the LIA some warmer cycles, as in the early 18th century coming out of the Maunder Minimum, and the Current WP some cool cycles, as in the 1940s-70s.

Auto

Gloateus
Do be aware that cricket – eminently a summer game – has, occasionally, been disrupted by snowfall. Certainly in May. And probably also in June, July and possibly August, IIRC. And (Pre-winter) September.
Snowstorm – very rarely . . . .

This is the British Isles.
Don’t like the weather? – well, hang on a couple of hours, and we can show you two more seasons . . . .

As for forty day forecasts – words fail me.

Auto

Stevan Reddish

“the temperature shift was smaller than that seen in recent decades resulting from the emission of greenhouse gases”

Since the temperature shift in the last 2 decades is negligible, the portion allocatable to emission of greenhouse gasses must be sub-negligible. If the authors reason that greenhouse gas emissions are a problem, I have reason to doubt their ability to reason. If they can falsely attribute changes in late 20th century climate to the single explanation of CO2, I have reason to doubt their ability to claim anything was or was not caused by a single factor:

“Our research suggests that there is no single explanation for this, that warm summers continued much as they do today and that not all winters were cold.”

Crop failure during the LIA was due to cold summers, by the way.

Do they realize they just claimed summers today are no warmer than during the LIA? They are simultaneously arguing against the existence of the LIA and global warming.

SR

Menicholas

It is a tangled web they weave.
The big problem with lying all the time about everything, is keeping the story straight.
It cannot be done…not well enough to fool a careful listener.

Bruce Cobb

Lockwood was on a mission: to straighten that hockey stick shaft, to make the blade look even scarier. Gravy trains don’t run by themselves. They need help from sciencestitutes.

don penman

The low solar radiation would have been noticed much more in the winter months (January) in the UK than in the summer months because solar radiation is at its lowest in January and would have been even lower than ,we are actually tilted towards the Sun in the summer at higher latitude . I read this nonsense and despair.

The low solar radiation would have been noticed much more in the winter months (January) in the UK than in the summer months because solar radiation is at its lowest in January
On the other hand we are closest to the Sun in January, so solar radiation over the globe is 7% higher than in Northern summer.

BCBill

So the millions of people who died from cold and starvation did that unnecessarily? The beech forests that froze and disappeared from the landscape were overreacting. If somebody at the time had pointed out that the LIA was just an illusion, it would have saved a lot of heartache. Possibly the models in use at the time showed that world was warming so people attributed the dying forests to heat stroke. Speaking of which, we haven’t had such a cold miserable spring for a long time here in BC. Let me get this straight- warm summers negate the LiA, and cold springs are caused by CAGW? Turtles all the way down.

Javier

In their 2015 review, Olga Solomina and col. divided world glaciers in 17 regions, 13 of them in the Northern Hemisphere, 1 in low latitudes, and 3 in the Southern Hemisphere. the LIA saw glacier advances in 12 of those regions, including all from the Southern Hemisphere, the biggest number in the entire Holocene. Most glaciers that advanced during the LIA reached their record lengths for the entire Holocene.

http://i.imgur.com/NvESsyd.png

So yes, it was that cold. The coldest period in the entire Holocene. If glaciers are proof of global warming, they were proof of global cooling. You cannot have it any other way. That weather was more variable then than now is to be expected. We all know that global warming reduces the frequency of extreme weather events. Global cooling does the opposite obviously.

Solomina, Olga N., et al. “Holocene glacier fluctuations.” Quaternary Science Reviews 111 (2015): 9-34.
http://www.geo.umass.edu/climate/papers2/Solomina_QSR_2015.pdf

Since we are the way towards a new glaciation [in a few tens of thousands of years], colder periods will tend to become still colder, so no surprise there.
Ont the other hand, the number of glacier advances quoted is small [~5] and the statistics of small numbers must always be taken with a grain of salt.

Javier

“Ont the other hand, the number of glacier advances quoted is small”

You didn’t read properly. Solomina et al., represent glacier regions not individual glaciers. Most glacier regions have around 10 records (yellow points in figure 1 of the paper), and most records are composite from several glaciers (Supplemental information table 2). They have looked literally at hundreds of glaciers worldwide. It is the biggest meta-study on glaciers ever.

The glaciers within a region are not independent and so do not improve the statistics. It is like if you had 10 weather stations in Belgium and computed an average temperature. Now increase the number of stations to 100, 1000, 10000, 100000 1000000, etc. You still get the same mean but the statistical uncertainty does not decrease by a factor of 1000, because nearby stations are not independent.

MarkW

If 12 of 13 are advancing or retreating that is meaningless because 12 is too small a number to use for statistical purposes?

Depends, on how many 12s there are. If only one, then not.

Javier

“The glaciers within a region are not independent and so do not improve the statistics.”

Again talking with authority about what you don’t know Leif. Glaciers within a region can be independent and as such are analyzed. Within the Alps region, Eastern Alps and Western Alps present quite different profile of advances and recessions that receive different names, like the Rotmoos advance in the Austrian Alps and the Piora advance in the Swiss Alps. And to top it, Solomina et al. regions are diverse. The Low Latitudes region comprises glaciers from tropical South America, Eastern Africa, and New Guinea. It would be quite hard to get a more complete analysis than what Solomina et al., 2015 have done. The paper is full of prominent authors from all over the world.

Menicholas

One might hope you are correct when you speculate that the current interglacial will turn out to be several times longer than the last bunch of them have been.
I would not bet the house on it…then again…at a span of several times longer than all of recorded history, we may only know it if you are wrong.
I would feel better if there was a more complete explanation of why the glacial advances and declines are as precipitous as they are, rather than gradual cycles like the Milankovich oscillations.

One might hope you are correct when you speculate that the current interglacial will turn out to be several times longer than the last bunch of them have been.
I didn’t say that. The slow decline of temperature into the depth of a glaciation generally takes on the order of 50,000 years. Now, there are people who believe that CO2 will save us from the next glaciation.

Javier

This is a small statistical sample according to Leif:

http://i.imgur.com/IUkHWAs.png

I shall ignore your usual misguided denigration and just remark that there is nothing wrong with the paper, only with your wide-eyed biased view of it. If there is variation within a region that just adds to the noise and decreases the significance.

Javier

“I shall ignore your usual misguided denigration”

You should not ask what you don’t give.

“If there is variation within a region that just adds to the noise and decreases the significance.”

There is nothing wrong with their statistics. When most glaciers from a region show advances then the region shows advances. When 12 out of 17 regions show advances, then most glaciers on the planet show advances. The number of glaciers considered in the study is staggering because they are doing a meta study. When you said “the number of glacier advances quoted is small [~5]” you were wrong, but you are unable to recognize it. They have to work with regions because a lot of the information they use has been published that way. Most glacier studies are individual or regional. They consider both.

Does not change the statistical facts. If in each regions the glaciers behaved the same way, they are only count for one. If they didn’t, the variation would just add noise and diminish the statistical significance. It doesn’t matter how many glaciers there were in each region. This is elementary.

Javier

“If in each regions the glaciers behaved the same way, they are only count for one.”

Data binning is a pretty standard procedure. There is nothing wrong with that study.

As I said: there is nothing wrong with the study. The fault is with you.

Javier

“The fault is with you.”

Yes I know. You have a problem with my «wide-eyed biased view of» the article, which happens to coincide with the view of the authors, many of them as prominent in their field as you are in yours, yet somehow you seem to think that your opinion carries more weight than theirs.

You only have to read the article to see how many of the glacier regions of the world experienced their maximum extent at the LIA. There is no other time in the Holocene that features that distinction.

And regarding forcing, they have this to say:

“Our results suggest that solar activity may have played a role in the large scale climatic transformations, at least in the second half of the Holocene.”

Ouch. Their «wide-eyed biased view of» their own work is also at fault according to you. How do they dare to provide evidence that solar variability affects climate so much as to move glaciers on a global scale? Luckily for us we have Dr. Svalgaard that will quickly and swiftly reject their evidence with a cute remark.

suggest and may
Are the usual weasel words showing that this is still an open question.

Javier

“this is still an open question.”

As most things in science. But it is a question on which they have taken an opposite side to you.

They suggest that maybe the sun had something to do with it, at least in the 2nd half of the Holocene. All reasonable caveats considering the low significance of small number statistics [all three in the Southern Hemisphere, wow]

Javier

“suggest and may
Are the usual weasel words showing that this is still an open question.”

The answer to this one is pretty easy:

This is the disadvantage for science communication. Do you listen to the scientific analysis – which is full of probably, maybe, possibly, roughly, estimated, hypothesised – or do you just agree with someone who sounds convincing and shouts down/shuts down dissenting opinions?

https://judithcurry.com/2017/04/05/science-needs-reason-to-be-trusted/

ACK

Evidence supporting the view that LIA glacial advances were greater than during older Holocene cold periods is overwhelming and irrefutable. Various techniques can be employed (including written records) to date the furthest down-valley Holocene terminal moraines. [A terminal moraine, or end moraine forms at the snout of a glacier and marks the point of the glacier’s maximum advance. Any earlier Holocene terminal moraines will be destroyed as a later glacier advances over them]. Invariably the oldest Holocene terminal moraines from glaciers worldwide are of LIA dates – commonly mid 1700s). If older cold periods had caused glaciers to extend further down valleys than the LIA glaciers, their terminal moraines would still be present further down valley than the LIA terminal moraines. They are absent. The evidence stares you in the face in every glaciated region. The fact that even older Pleistocene terminal moraines survive in the valleys even further down valley removes the remote possibility that early Holocene moraines were present but have subsequently been destroyed.

Javier

That’s why the surprising position by a group of climatologists that the LIA was local and didn’t have much global effect is only a reflection of the sad situation of climatology, when authors that defend that position without presenting any evidence and ignoring all the available evidence against get to publish in scientific journals. The loud message is that climatology is no longer about evidence, and scientists, scientific societies, and journals have abandoned the scientific method in pursuit of activism. This is a sad time for science indeed.

don penman

the amount of solar radiation is still smaller because the day is shorter and room temperature drops to a low level with reduced solar radiation during January an observation.

That is true every year. The LIA was not special in that regard.

Macha

No mention of the bray or devries cycles in these comments…..Where is Javier to chart them.

Javier

At the LIA there was the coincidence of the lows of the Eddy (~1000 year) cycle, the Bray (~2400 year) cycle and the oceanic (~1500 year) cycle. Together with the progressive cooling of the Neoglacial period for the previous 4500 years and on top of that elevated volcanic activity, made the LIA unusually cold, even if it wasn’t cold all the time.

http://i.imgur.com/AXYL8f1.png

Several authors have demonstrated that the distribution of grand solar minima is not random, and that the probability of them occurring at the lows of the ~2400 year Bray cycle is significant.

Gloateus

https://wattsupwiththat.com/2016/11/24/the-bray-hallstatt-cycle/

For more on the Bray Cycle from Andy and Javier.

Gloateus

From when NASA still practiced the scientific method:

https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19910003157.pdf

Stephen Richards

this is a good site for historical weather across france from 1850

http://www.meteo-paris.com/chronique

coolclimateinfo

Expectations of what low solar activity does to temperatures on short to long terms are part of the problem.

The solar influence on decadal scale temps is incremental, solar min to min.

The low solar conditions and cold and snow records of this winter go together like a hot sun and warm temps, and it was no different back during the LIA. Obviously we’ve seen records set in either direction – so is the climate really any different now than during the LIA except maybe a degree or two warmer?

It took many many successive high solar cycles to drive a net temperature increase, and the reverse is going to be true as well. It will require several low cycles to eat away at decades of high solar OHC buildup.

Can’t we agree the climate oscillates over long periods and therefore will always be ‘changing’?

“On the whole the Little Ice Age was a manageable downturn in climate … Our research suggests that there is no single explanation for this,…”
There you go, insert Global Warming for LIA and you have the same stiuation today, and a very manageable upturn.

Ed Zuiderwijk

Lockwood is a closet warmist. He will play down and pooh-pooh any evidence for the little ice age.

On another issue. If you enlarge the part of the Brueghel painting with the group of three people on the frozen pond, about one third up on the righthand side, you will notice that they play a game that looks like curling. This is two centuries before that game was played in Scotland and casts doubt on the claim by the Scots to have invented it.

taxed

Here in England the cold winters mixed with warm summers during the LIA. Suggests that there was a increase in blocking patterns during this time. Not only that but it also hints to where this blocking was happening during the year. During the winter months this blocking was largely forming somewhere to the north of England. Anywhere from the NW to the NE of England. So as to bring colder air down from the Arctic or across from the east. But during the summer this pattern changed. In the summer months this blocking was now forming to the south of England. Most likely coming up from the Azores and then settling over Britain or mainland europe. So allowing warm air to be drawn up from the south and so leading to these warm summers.

Sheri

Question: If the AGW theory had never been put forth, would anyone one have questioned the nature of the LIA?

Gloateus

No, nor the MWP or previous cycles.

Menicholas

That is the crux of it Sheri…historical revisionism tailored to a propaganda-based narrative which is being foisted on us for political reasons.
Science got nothing to do with it.
Like Mae West’s diamonds…”goodness had nothing to do with it”.

https://youtu.be/u7ekAQ_Plxk?t=39s

Pop Piasa

So from these studied conclusions, If a supervolcano should suddenly explode, it would fix AGW (and global population numbers) all at once?

Kalifornia Kook

I’m confused. The authors claim that the LIA resulted in temperatures falling a mere 0.5 degrees is not big thing. Rep Beyer at the House Climate Science hearing mentioned the error between observed and modeled temperature was a mere 0.5 degrees, which Mann agreed was no big thing. Yet, a rise in temperature of 0.5 degrees is cause for alarm, and no amount of money is too much to spend to correct it. What am I missing?

MarkW

The author seems to be claiming that the 0.5C cooling of the LIA is a non-event.
However the 1.0C warming since the bottom of the LIA is going to kill us.

John Harmsworth

I will point out that where I live in Western Canada, several crops which are exported worldwide require about a 90 day growing season and it is not unusual for crops to be lost to frost. I’m sure this applies to Russia and Ukraine as well and I believe frost is a risk in Argentina and to a slightly lesser degree in the Northern U.S. A shortening of the growing season by just a few days can be disasterous as a tremendous amount of the world’s food is grown in these areas. Colder years often mean later seeding and slower crop development as well.

Rob

Really need to look at the well documented (H.H. Lamb) enhanced atmospheric “blocking”
in the NH. From proxy data, this is coincident with the onset of a true Glacial Epoch.

Pop Piasa

Their graph seems to show a minor correlation between solar inactivity and larger eruptions. Has this anything to do with the solar activity/temperature relationship? Where these eruptions occurred would also change their impact on global climate, as well as the composition of the volcanic effluent and its plume height, rate of dissipation, etc.

Gloateus

A study conducted in 2008 by Jann-Yeng Liu, from the Center for Space and Remote Sensing Research in Chung-Li, Taiwan, found a connection between high energy charged particles in the ionosphere and earthquakes. The paper examined more than 100 earthquakes with magnitudes of 5.0 or larger in Taiwan over several decades. The results indicate that almost all of the quakes down to a 35 km depth were preceded by distinct electrical disturbances in the ionosphere.

I looked at the N. Atlantic area. Curve fitting shows something reminiscent of a ‘correlation’, but
don’t tell Dr. S.
http://www.vukcevic.talktalk.net/NAT-GSN.gif

Gloateus

Contrary to common opinion, the LIA didn’t have a higher frequency of large eruptions than has the Current Warm Period so far, although the latter of course is still much shorter in duration than the Little Ice Age Cool Period.

It did however have at least one VEI 7 event, which the modern warming hasn’t experienced yet. There were two if you start the LIA in AD 1257 instead of the early 15th century.

https://en.wikipedia.org/wiki/List_of_large_volcanic_eruptions

Current Warm Period (c. AD 1850 to present)

VEI 6

Krakatoa, 1883
Santa Maria, 1902
Novarupta, 1912
Pinatubo, 1991

Little Ice Age Cold Period (c. AD 1400 to 1850)

VEI 7

Tambora, 1815

VEI 6

Unknown, 1808/09
Grímsvötn, 1783-85
Long Island (New Guinea), 1660
Kolumbo, Santorini, 1650
Huaynaputina, 1600
Billy Mitchell, 1580
Bárðarbunga, 1477
Kuwae, 1452-53

Medieval Warm Period (c. AD 900 to 1400)

VEI 7

Baekdu, ~946
Samalas, 1257

VEI 6

Ceboruco, 930
Katla, 934-940
Quilotoa, 1280

There were also VEI 6 eruptions in AD 800, 710 (both in the Bismarck volcanic arc, like Long Island) and 700 (Alaska), should you consider the Dark Ages Cool Period to have ended earlier and the MWP to have begun sooner. The Rabaul caldera in the Bismarck arc also blew in 540, but that’s definitely in the DACP (also called the Migrations CP, due to the barbarian invasions by cold climate refugees).

If you transfer the 13th century eruptions from the MWP to a lengthened LIA, then the MWP features just one big eruption and two smaller ones. The record might not be as good as for more recent events, however.

The Current WP had four VEI 6 eruptions, while the LIA had nine VEI 6 & 7 eruptions. Adding the two 13th century eruptions gives the LIA rate eleven.

If you date the LIA from AD 1257 to 1850 and the Current Warm Period from 1851 to now, then the rates are one VEI6/7 per ~54 and 41.5 years. If the LIA lasted only from 1401 to 1850, then its rate was one per 50 years.

So the Current Warm Period so far has seen more frequent big eruptions per century than the LIA, but lacks a VEI 7.

Gloateus

There is but One!

–The Exorcist