Interesting Change of Season Length

Changing Seasons length

Changing Seasons length

Original from this site:

There are several interesting things about this chart. The first one is just that at the “2000” point (now) we have summer (the red line) having gotten steadily longer in the N. Hemisphere while winter ( blue line) is steadily shorter. Think that might, just maybe, have something to do with the N. Hemisphere getting warmer? Looks to me like about one whole day more summer and one whole day less winter since the birth of Christ. This trend continues (if very very slowly) for the next 2000 years. (At which time we have 94 days of summer (instead of about 93.5 today) and 88.75 days of winter ( instead of about 89 today).

So today the Summer / Winter ratio is 1.05 and in 2000 years it will be 1.06 while about 7000 BC it was 88.25 / 94.5 or 0.934 at the peak.

Somehow “I think that matters”.

So we have the South Pole staying really nice and cold while the North Pole is cooking a few extra days and getting snow a few less. And we’re surprised the North Pole isn’t freezing up as much as the south?

Much further forward, our seasons become nearly equal again. As we can stay out of an ice age glacial only as long as the North Pole gets excess warming from longer summers, this says we eventually freeze up. While our present insolation 65 North is below the self melting range, and in a ‘metastable’ range of 428 W/m^2; we ARE above the “guaranteed to enter a glacial” rate of 416 W/m^2 (so we just need to avoid a sharp surprise downturn). Details here:

So this implies, strongly, that if we can just avoid some kind of surprise “big cold swing” (think “big rock from space” or “big ass volcano” or possibly “Maunder Minimum and Gulf Stream takes a break”…) we’ve got about 9,000 years before we are back at real risk of a guaranteed plunge into a glacial. Unfortunately, there are a couple of other factors that come into it, including axial tilt, that are pushing the other way. But still, it is very nice to have a ‘big one’ in our corner.

FWIW, having the seasons be ‘equal length’ in about 20,000 years is “not good”. When summer is not extra long and seasons are equal length, we cannot get out of a glacial once one starts. In fact, from about 9000 AD to 20,000 AD, any “cold bump” and we are pretty much glaciating. That big summer peak length in about 18,000 BC is the only reason we left the glacial in the first place. That extreme extra summer / short winter; that is the only case when you can melt the ice at the north pole and exit a glacial. That time is past and does not return for about 100,000 years. So it’s pretty much guaranteed we have a new glacial by that 30,000 AD equal seasons point, and then can’t get out of it for another 70,000. All we are arguing about, really, is how soon the ice comes and doesn’t leave “up north”. Our present insolation levels would allow that to happen right now. We are “whistling past the grave yard” as it is. But it is very comforting to see some ‘longer summers’ on the cards for the next few thousand years as a bit of help keeping the ice away.

Unfortunately for folks in the Southern Hemisphere, you get shorter summers. Then again, folks in hot places like Australia and Chile might like that ;-)

Update: Added Obliquity Chart

Obliquity (tilt) graph for the Earth

Obliquity (tilt) graph for the Earth

Original Image

Down in comments I do some “hand waving” about this graph and it becomes much more clear what I’m talking about if you have the graph to look at. We are going to less obliquity, so less summer warming when the North Pole is pointed AT the sun as it is pointed less. We are about 1/2 way to the minimum. We only exit a glacial when at the Maximum AND summer happens when we are furthest from the sun (as that part of the orbit takes longer, so we get longer summers) AND the orbit of the earth is more elliptical (so the added days of summer are the most they can be). The orbit is becoming LESS elliptical (more circular) at the same time that the tilt is becoming less. So now you can see both of them on the graphs. But we do get one “last hurrah” of longer summers for the next couple of thousand years. The swing from longer to shorter summers happens as precession of the perihelion moves into / out of the summer season. (Chandler wobble enters into it too…) So the “fast” cycling is perihelion precession, the longer change of envelope is due to changes of eccentricity of the orbit, and we then have to add in the generally cooler or warmer summers as the tilt changes.

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About E.M.Smith

A technical managerial sort interested in things from Stonehenge to computer science. My present "hot buttons' are the mythology of Climate Change and ancient metrology; but things change...
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23 Responses to Interesting Change of Season Length

  1. John Robertson says:

    Save global warming, northern hemisphere version anyway, time we put those orbiting mirrors into polar orbit, warming the arctic islands to a nice tropical glow.
    Or do we kick start that volcano under the north pole?
    Does 1 or 2 days more really make that much difference?
    Here I get winter and summer at a ratio of 2:1.
    Yet it is possible to grow some vegetables outdoors and most in a greenhouse, the long days help.

  2. E.M.Smith says:

    @John Robertson:

    Yes, a day or two more summer matters a lot. See Milankovich. At 92 days of summer, we CAN have a glacial, at 94 we WILL exit a glacial. (At 91 and decreasing polar tilt, we WILL have an ice age glacial…)

    Once the ice forms, then we can only exit again when three things line up Just Right. High “tilt” or obliquity (so the N. Hemisphere points more at the sun in Summer), High eccentricity ( the orbit has to be not so round) so that we CAN have longer summers. The right stage of the precession cycle (so the N. Pole points AT the sun when the planet is furthest out in the elliptical orbit so that it is Summer that is longest and at the North Pole.)

    Two of those things (eccentricity and precession state) determine the length of summer, (so that above graph combines those two ). The only one left is change of obliquity. (That is getting less each year… headed toward glacial again…) Graph here:

    where we are about 1/2 way between the 24.5 degree max and the 22.0 min at 23.4 and a bit. Much longer term graph here:

    showing wider ranges over millions of years. (the red dot near the middle at the right edge is us now) So we are headed toward less, which means the N. Pole can freeze and stay frozen more easily.

    So over the next 4000 years we lose about 1/2 degree of “tilt” but gain some longer summer (though a bit less brightly lit due to that tilt change). Hopefully about a ‘wash’ and we stay unfrozen.

    From 4000 AD to about 10,000 to 12,000 AD we go back to short summers AND we have only about 22.5 degrees of tilt. Shorter AND less warmed summers at the North Pole. That will pretty much guarantee a plunge into a new ice age glacial at some point during that transition. (IFF we don’t drop in sooner due to some ‘cold excursion’ starting the cold albedo feedback before then…)

    In short, we have a decent hope of getting about 3000 more years of “interglacial”, but not much more. We have a risk of less if some cold excursion event whacks us (as they do from time to time… “Year without a summer” anyone?). Once the cold / snow comes and stays, we can’t get back out of it as we are not at the peak of that summer warmth curve any longer. (We are ‘metastable’ and stay in whatever state we are in – warm or frozen).

    So every one of those “added days of summer” matters. A Lot.

  3. E.M.Smith says:

    Hmmm… It’s about 10,000 years for a “most to least” change, and that is about 5 days shift. So about 2000 years per “day” of change. That means that the folks using StoneHenge (as it was in use for more than that long) would have measured at least one whole day of change of season lengths… (More if they had been doing it starting earlier using earlier structures / methods.)

    I think that pretty much means “they knew” that season lengths could change, if very slowly, as the solstices / equinoxes changed alignment…

    I think this also explains why they tended to “pick one” to sync the annual calendar. (Typically the Winter Solstice or the Summer Solstice). That way the calendar doesn’t need to continually change (well, once every couple of thousand years ;-) as the solstice / equinox change position and the lengths between them changes. Even if not by much and very slowly…)

    This does have an implication for Smith’s Calendar, too. Can’t have all 4 of the solstice and equinox days on exact quarters with 3 x 30 day months between them IF the actual solstice and equinox days are used for each one… ( I wonder it that is why so many old societies had a Lunar Month calendar for most things and only did a ‘sync’ to the solar calendar once a year?…)

    So a bit more ‘polish’ needed on how to keep the solar calendar regular, yet simple to construct, while not being exactly in sync with all 4 solstice / equinox dates… We either have variable number of days in the months to allow for the different season lengths between solstice / equinox points (and change month length every couple of thousand years); or we have ‘formal’ seasons and months that only ‘sync up’ with the actual sun position once per year (and never needs to change)… It looks to me like the ancients chose “sync once” and lunar months. (Egyptian agricultural IIRC, Jewish, Muslim, Celtic Lunar, and a few others including some Asian).

    If I’m reading that graph correctly, the time solstice to solstice ought to be a constant (even though only 1/2 a cycle) as each is 1/2 of the ellipse… have to think about that a bit.

  4. Petrossa says:

    You are all wrong, this is proof of global warming, ask any climatologist. Everybody knows the sun has absolutely no influence on earths climate.

  5. Bill McIntyre says:

    warmer in the north doesn’t do us much good since the bulk of the oceans are in the south……..
    hotter land – – cooler oceans ? ?
    we are getting more circulation of the Arctic Ocean which isn’t helping that situation.

    interesting correction to Milankovitch cycles here:

    the speed changes caused by this orbit must show up somehow on our thermometers???
    your observation of what I call, “ghost Cycle”, about half way through our 1500 yr. cycle is a help in estimating one of the parameters of the orbit to help solve the “150 ma problem”

  6. adolfogiurfa says:

    We need to revisit the actual Solar activity/cycles which are the cause of any changes down here on our Earth:
    Here, the latest from our friend M.Vukcevic:

  7. adolfogiurfa says:

    This is really remarkable:

  8. Ulric Lyons says:

    So summers were 4-5 days shorter in through the Holocene Optimum ?

  9. KevinM says:

    On the first chart, is zero now, or the calendar year zero AD?

  10. adolfogiurfa says:

    Changes in the Earth´s wobble.

  11. adolfogiurfa says:

    Interesting times indeed! A New Kid?:

  12. E.M.Smith says:


    The second graph shows zero as “now” (2000). The first graph had me hitting the link.

    Re-reading the link, it looks like the zero line is not now, but is 0 AD, so I need to adjust some of the text a bit: The graph is marked from BC to AD so zero is the transition:

    A numerical integration from 30000 BC to 30000 AD, showing the relationship between the perihelion cycle and each of the equinoxes, solstices and seasons. Points are plotted at 200-year intervals, without any averaging, connected with straight line segments. Refer to the description above of the effect of the perihelion cycle on season lengths.

    In this longer-range view, spanning nearly 3 perihelion cycles, the relationship between Earth orbital eccentricity (lavender curve, secondary y-axis) and the variations of season lengths is evident.

  13. E.M.Smith says:

    @Ulric Lyons:

    Yes, but we had a steeper ’tilt’ so hotter summers. Also we had just come off of melting all that glacial ice during the longer summer days of the prior peak, so had some ‘overshoot’ warming available to work with.

    Prior interglacials have more of a ‘spike up’ and drop where this one has a shallower ‘spike’ (that I think was ‘peak clipping’ by a meteor impact into the ice sheet at the Clovis Event) and flatter out of that. So we likely had lots of extra solar heating north (due to obliquity / eccentricity – also peaked then) and the overshoot got a bit clipped, then there was enough ice gone that the shorter summers were still catching up with the albedo changes (so we were more ‘flat’).

    Now we are into decreasing eccentricity and obliquity and have ice reforming at the N. Pole (that the looney folks want to be many-year-all-the-time-start-the-next-glacial conditions…) In that context, going into longer summers is holding us, again, flat. But as soon as we are past that peak in about 4000 AD, we start down the tubes as all three prime drivers are moving toward cold. Obliquity, eccentricity, precession.

    So by a pleasant run of events, we had ‘offsetting directions’ on some of those that prevented the usual “spike and plunge” (even if it did kill off the megafauna of N. America and the Clovis People…) and gave us a very stable period for 10,000 years. But those times are ending. The really good news, though, is that it has about 2000 to 3000 years of “about like now” before we are into “too cool” and below 416 W/m^2 at 65N…

  14. Wayne Job says:

    I do hope you are right E.M. about our time remaining before cooling kicks in. It is the extraneous factors that may cause us some pain. Our sun is behaving badly and when it is not powering our earth as it should history and proxies shows increased siesmic and volcanic activity. A few big ones over a decade or two could see some serious reductions in growing seasons on a permanent basis. Leading to worser.

  15. E.M.Smith says:

    @Wayne Job:

    One of THE most nerve wracking things has been trying to figure out exactly that. There are major forces in opposition, and we are balanced right on the edge between holocene warm and ‘next glacial’. The Milankovich cycles have us at a point where we are declining and below the stable insolation level 65N

    but we’d just had a hot cycle, then a cold one, then another hot one. It looked a lot like we had a ‘lining up’ for another Bond Event. It wasn’t until a lot of digging was done that it became clear the driver is lunar / tidal and it isn’t exactly a 1470 cycle (that bought a few hundred more years right now for ongoing warm…)

    But that’s also a very long cycle. The moon has many, and while on the 10,000 range we are in a clear down trend, and on the 1800 we have been warming (and are at a peak) the sub-cycles of the 700 and 350 can be going in other directions…

    Then, there’s that very short 60 year / PDO kind of thing that was running hot and now is turned quite cold:

    Trying to sort all those ‘wheels within wheels’ into something rational had a ‘missing bit’ somewhere. That lead to this posting. The realization that there was a ‘couple of thousand’ year oscillation between N. Hemisphere and S. Hemisphere. That would explain some of the ‘non-fit’…

    So the “what we know” largely breaks into:

    1) We are cooling from the Holocene Peak.
    2) It has a ‘couple of thousand year ripple’, especially in the N. Hemisphere from summer day length changes (that is presently offsetting the cooling trend on Milankovich long cycle)
    3) The lunar tidal long cycle that brings us Bond Events has been in a warming run. We are near a peak, so it will take about 300 years to ‘go low’ on that scale.
    4) That puts TWO cycles near warming peaks. That’s why we are warm, not iced over, now.
    5) We are just barely over the W/m^2 for icing over, but in the “unstable zone”. I would have expected a ‘cold dip’ to freeze us up, but the LIA didn’t. “Why” turns out to be those longer summers the last couple of thousand years… that start getting shorter ‘soon’. But we ARE still in an unstable insolation range 65 N.
    6) The sun has gone all sleepy and we are getting some large and problematic cooling effects.

    Now #6 would have had me all worried (and, in fact, did have me thinking we were lining up for a new Bond Event due to a cold spike coming on top of 1 & 5) but then I found 3 and that it was on top of 2.

    You bring all that together, we are on the edge of a non-recoverable plunge into the next glacial. It will happen when insolation is low enough N 65 and a ‘cold bump’ starts. But, the insolation 65 N total / year is still rising for a few hundred years as we have been getting longer summers AND the lunar tidal cycle has been warming, so will take about 300 to go cold on that longer cycle. Those offset 1 for a while and hopefully have enough to offset 6. As we have had similar sleepy sun events ‘lately’ when other cycles were more cold ( Maunder, Dalton) and didn’t ‘get stuck’ in the cold; the reasonable conclusion is that those forces are too small to push us off the edge into a cold trap.

    The only ‘downside’ with this reasoning is that the season length turns against us in a few hundred, as does the lunar tidal medium / long term. So the next ‘solar dip’ is going to arrive in a context of “all cooling all the time” on the other cycles. THAT inside a ‘non-stable zone’ of W/m^2 N of 65 pretty much guarantees that’s going to be a long slow plunge into the start of the next glacial. ( IMHO, of course).

    So the ‘good news’ is we have 300 to 500 years of continued warm. Possibly longer. Before the cycles are headed into the ‘much colder’ and ‘N. Hemisphere shorter summers’. So that puts us a solar cycle or two further out before a cold spike tickles the unstable Gulf Stream state.

    Just leaving the question this 60 year PDO turn on top of a ‘Minimum’ type sun: Will it be enough to quash the AGW fantasy? Since things warm up again in 30 years, we need to get it gone and buried in 10 or less.

    Oh, also, since many of these cycles are rather sin wave like shaped, at peak excursions rate of change is minimal. So those ‘inflecting’ cycles of season length and lunar tidal long cycle forcing ought to have ‘couple of hundred’ year slow onset. Nice and gentle. (It’s just the 60 year stir and Saros that can be fast with the lunar tidal and the solar ‘take a break’ seems to happen in weeks… or months…)

    So while there is an element of “guess work” in it, and while we ARE in an unstable mode for W/m^2 N 65 so things like big volcano or rock fall from space could knock us to cold now; the best bet is ‘continued a lot like now for a few hundred years with ripples like historical for the last 300 years’.

    Hope that helps give some comfort and foundation for “why” and that it’s not just a feeling about things…

    I know I ought to be more worried about the fact that in 500 years we’re headed into iceberg land and that by 2000 Europe and Canada / New England are headed for frozen disaster. But frankly, it’s way beyond my personal planning horizon and that of my kids, any future grand kids, and THEIR future grandkids. Won’t even know what race they will be or what language they will be speaking by that time horizon. All of 300 years ago ALL my ancestors were living in Europe. Now their descendants are scattered over the entire globe.

    Just not seeing the thing to worry about at the moment…

    Though I suppose it would be better to put sizes and numbers on all those cycles and ‘model’ them… I think that we don’t have good enough numbers and sizes. So IMHO it is ‘just fine’ to look at the existence proof of the last 2000 years and make ‘good guesses’ as to relative sizes and likely offsets.

    THE big question is just: IFF the Gulf Stream does that instability pause and starts descending further south so a new L.I.A. starts; then we have entered the ‘cold instability trap’ and we might, or might not, recover; so what can cause that?

    Likely a major volcano or rock from space. Otherwise we have more modest conditions than during the last L.I.A. ( slightly less insolation 65 N, but significantly more days for it to work) so it ought not to be a problem.

    Oh, and the other bit, that paper (in one of those links…) that showed that WHEN that happens, the “Desert Southwest” gets more rains and Florida is nice. That the heat ‘backs up’ in the source of the warming currents. That means that if “Shit Happens” you may not want to be living in Scotland, but Florida and Texas are just dandy…

    What happened in the L.I.A.? A whole lot of folks from Ireland, Scotland, England, France, Sweden, Germany, etc. packed up and moved to the USA and folks from Main and Vermont headed down to Texas and Oklahoma. We got room… Just bring your boots with ya’…

    So even if the Aw Shit happens, there’s an easy fix and the problems are regional. Heck, in California I’m unlikely to even notice anything. It’s mostly folks at the end of the Gulf Stream that get the worst of it. Well, and it looks like the Middle East and Lavant get a mega drought … so likely to be food riots and wars there… but that is different from ‘now’ exactly how?….

    So that’s where I’ve reached so far, and I’m not seeing a whole lot of remaining unwoven threads or loose ends. Just avoid the places that were sucky in the L.I.A. and “Year without a summer” along with the Muslim World and neighbors. Be a little south, preferably in the Americas or Australia / New Zealand / Pacific islands (though watch out for volcanoes and giant rock tsunami on the islands…). The whole S. Hemisphere is highly water moderated, so just don’t move to frozen mountain tops… Oh, and China tends to drought / frozen cycles so probably not a great idea to be in Siberia / China / Mongolia… unless you are a local. South Asia ought to be fine. (Modulo that whole ‘coming nuclear war Jihad thing’…) Japan too. Philippines would be a great place. Sub-Sahara Africa too, if it were not such a social basket case.

    So, other than our usual human failings, the ‘cold whack’ is not much of a ‘big deal’ in the S. Hemisphere nor Oceana, and not much along the temperate coastal areas either. It’s mostly just a high latitudes N. America and Eurasia thing. With emphasis on the ‘end of the Gulf Stream nations’ when it deflects away. I think we can cope with that. And that it isn’t likely for a good long while.

  16. Gail Combs says:

    Actually whether or not we heading into glaciation is still a hotly debated subject.

    The Antithesis
    [A] landmark paper by Lisieki and Raymo (Oceanography, 2005), an exhaustive look at 57 globally distributed deep Ocean Drilling Project (and other) cores (Figure 1), which stated:

    “Recent research has focused on MIS 11 as a possible analog for the present interglacial [e.g., Loutre and Berger, 2003; EPICA community members, 2004] because both occur during times of low eccentricity. The LR04 age model establishes that MIS 11 spans two precession cycles, with 18O values below 3.6o/oo for 20 kyr, from 398-418 ka. In comparison, stages 9 and 5 remained below 3.6o/oo for 13 and 12 kyr, respectively, and the Holocene interglacial has lasted 11 kyr so far. In the LR04 age model, the average LSR of 29 sites is the same from 398-418 ka as from 250-650 ka; consequently, stage 11 is unlikely to be artificially stretched. However, the June 21 insolation minimum at 65N during MIS 11 is only 489 W/m2, much less pronounced than the present minimum of 474 W/m2. In addition, current insolation values are not predicted to return to the high values of late MIS 11 for another 65 kyr. We propose that this effectively precludes a ‘double precession-cycle’ interglacial [e.g., Raymo, 1997] in the Holocene without human influence.”

    Others think we will see a prolonged interglacial like M11.

    11 August 2005 A late Eemian aridity pulse in central Europe during
    the last glacial inception

    “The onset of the LEAP occurred within less than two decades, demonstrating the existence of a sharp threshold, which must be near 416 Wm2, which is the 65oN July insolation for 118 kyr BP (ref. 9). This value is only slightly below today’s value of 428 Wm2. Insolation will remain at this level slightly above the glacial inception for the next 4,000 years before it then increases again.”

    The deal breaker may be the newest paper This new paper says we are already into the slide towards glaciation. Perspective by Dr. William McClenney on the paper Can we predict the duration of an interglacial?
    NASA on Earth’s bipolar sea ice behavior
    What the return of the bipolar seesaw means.

    ,,,,This IS the debate we should be having. So far, the Holocene has been quite the historically stable little interglacial, so far not exhibiting the normal climate instabilities of the typical end extreme interglacial.

    But “Can we predict the duration of an interglacial?”

    This, now week-old paper, explores a fascinating linkage concept, the inception and disintegration of the bipolar seesaw

    “We propose that the interval between the “terminal” oscillation of the bipolar seesaw, preceding an interglacial, and its first major reactivation represents a period of minimum extension of ice sheets away from coastlines.”….

    “…thus, the first major reactivation of the bipolar seesaw would probably constitute an indication that the transition to a glacial state had already taken place.”

    …“With respect to the end of interglacials, the MIS 5e– 5d transition represents the only relevant period with direct sea-level determinations and precise chronologies that allow us to infer a sequence of events around the time of glacial inception (Fig. 2).”…

    “Thus, glacial inception occurred ~3 kyr before the onset of significant bipolar-seesaw variability.”… Comparison with MIS 19c, a close astronomical analogue characterized by an equally weak summer insolation minimum (474Wm−2) and a smaller overall decrease from maximum summer solstice insolation values, suggests that glacial inception is possible despite the subdued insolation forcing, if CO2 concentrations were 240±5 ppmv (Tzedakis et al., 2012).”

    the raw and highlighted versions. A bloody good read.
    (PDF raw)
    (PDF highlighted)

    In other words as the brain-dead idiot politicians are stripping us of our ability to generate plentiful energy, we are betting the last 2005 paper is correct and not the first 2005 paper I cited as well as the 2012 bipolar seesaw paper. Given the climate at the end of an interglacial is ‘wild’ this is not the time to do away with grain stocks and electric generating capacity.

    Also see Dr. William McClenney’s comments at The Conversation

  17. E.M.Smith says:

    @Gail Combs:

    Yes. And that “debate” was part of what sent me down this path of investigation.

    It IS possible for us to go into the next glacial now (as we are in the unstable range of W/m^2 at 65 N) or for us to stay out for a long time ( as the present orbital status is not extreme so not guaranteed to whack us, then it gets a tiny bit warmer / better).

    Basically, things are, and will remain, unstable for the next 20,000+ years. That’s why it will be an endless debate (until the ice comes…) and why this is my best guess but not a guarantee.

    We are one big ass volcano or one big rock from space away from a non-recoverable cold excursion.

    But if nothing changes from present, we could stay like this for a few thousand years… if nothing changes…. at all… no bad thing… no ‘flash bang’ in the night…

    My guess is we get one of those every couple of thousand years and in a couple of thousand we are in much worse orbital / sunlight position, so ‘the way to bet’ is ‘couple of thousand years’ with possible of ‘in a few hundred’ as the lunar tidal and solar line up in the next ‘both cold’ turn.

  18. Gail Combs says:

    Right now we have the sun going “quiet” with a possible Maunder minimum within the next decade or two. We just had the Iclandic volcano Eyjafjallajökull erupting. Every time in recorded history that Eyjafjallajökull volcano has erupted, the much larger Katla volcano has also erupted a short time later. Iceland’s Laki volcano began erupting on June 8, 1783, and continued doing so for months..

    …The summer of 1783 saw heat waves, extreme cold, widespread famines, crop failures and livestock losses — a crisis that might have even hastened the French Revolution. The following winter, record cold was seen around the North Atlantic. Temperatures in Europe were about 3.6 degrees Fahrenheit (2 degrees Celsius) below average for the late 1700s, and the winter was also one of the coldest of the past 500 years in eastern North America.

    The Laki eruption has been blamed for that exceptionally deadly winter. But the new findings now may exonerate the volcano. Instead of its ashes and gas triggering a colder winter, scientists suggest that the cold snap might have been caused by an unusual combination of climate effects that apparently are similar to those that made the 2009 to 2010 winter so bitter in western Europe and eastern North America.

    Then and now

    In the winter of 2009 to 2010, the North Atlantic Oscillation (NAO), a climate phenomenon in the North Atlantic sector, went through a negative phase, meaning less warm air flowed into Europe and more cold Arctic air headed toward North America. At the same time, the El Niño–Southern Oscillation (ENSO), a climate pattern in the tropical Pacific Ocean, went through a warm phase, which can potentially cause wetter, cloudier winters in northern Europe and enhanced storms to hit the central and southern latitudes of the United States.

    After analyzing 600 years’ worth of data in tree rings, which preserve details about the climate in which the trees grew, the scientists found that NAO and ENSO conditions during the 1783 to 1784 winter were similar to those seen in the 2009 to 2010 winter. In ranking this kind of combined NAO-ENSO events, the researchers found that the 2009 to 2010 winter showed the strongest combined effects and the 1783 to 1784 winter the second strongest in the past 600 years.

    The really worry some problems are in Africa, Southern Asia, South America and Central America where a volcano would have a much bigger effect on the world climate and seismic activity has accelerated in northeastern Africa as the continent breaks apart in slow motion.

    In the last five years, the geologic transformation of northeastern Africa has “accelerated dramatically,” says Wright. Indeed, the process is going much faster than many had anticipated. In recent years, geologists had measured just a few millimeters of movement each year. “But now the earth is opening up by the meter,” says Lorraine Field, a scholar at the University of Bristol who also attended the conference.

    papers on African rift: link 1 and Magmatic Rifting and Active Volcanism Conference (links to a lot of papers)

    Dabbahu Eurption 2005

    South America and Japan are the most active volcano regions of the Holocene followed by Central America. In the years 1975-85, only Japan, Indonesia, and Melanesia reported more volcanism

    Large Holocene eruptions link

    I agree the glaciation trigger will be a combination of events so it will be a crap shoot as to when.

  19. Tim Clark says:

    I can’t find the link to Northern Hemisphere snow cover. It’s high.
    Cold and snow-covered here in Kansas with another blizzard expected tonight. I haven’t been to work since last Tuesday. But, that’s because of CO2.

    The low temperature at Salina, KS was 2 below zero this morning.
    This broke the previous record of 1 below zero set in 1899.

  20. E.M.Smith says:

    @Tim Clark:

    ref in:

    It’s a bit slow to respond, and doesn’t cover fast thin snow cover (so not showing the snow down to near Mexico in California nor the other ‘way south’ snow… I think it has to stay on the ground for a good long while to be ‘cover’…)

    Yup, we’re having a cold turn. “New Little Ice Age” maybe. But as we didn’t tip into a glacial in the LAST LIA, it’s just going to be cold, not a glacial start.


    Please don’t remind me about Katla… I’m doing everything I can to put a Smiley Face on this cold turn. Being reminded that we frequently get major volcanic “Double Taps” just as the cold has really gotten rolling and that they then cause global cold disasters is not helping my OOOOoommmmmm centeredness…. /sarc; ;-)

    That the magma gets stirred in similar ways by the tidal forces so there is likely a direct causal link between cold and more volcanoes, well, that just blows my whole “as long as we avoid a major volcano” into the stratosphere… Now I need to find some new Smiley Face sand to stick my head into … wonder if volcanic ash works? ;-)

  21. E.M.Smith says:

    @Tim Clark:

    This link looks like it has more snow and more variations of measurements:

    Picked it up from this article:

    It is looking “mighty white” out there…

  22. Jason Calley says:

    @ E.M. “that just blows my whole “as long as we avoid a major volcano” into the stratosphere… ”

    And with lowered UV the stratosphere is not quite so far up as it used to be…

  23. adolfogiurfa says:

    Our Sun external diameter shrinks (as the POWER from the galaxy decreases) when it feels cold:Variaciones en el RADIO SOLAR, Habibullo Abdussamatov, Dr. Sc.(Head of Space research laboratory of the Pulkovo Observatory, Head of the Russian/Ukrainian joint project Astrometria):

    Click to access abdu2009.pdf

    Click to access abduss_apr.pdf

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