According to Wikipedia, the Medieval Warm Period was a time of warm weather around AD 800-1300 during the European Medieval period. Initial research on the MWP and the following Little Ice Age (LIA) was largely done in Europe, where the phenomenon was most obvious and clearly documented. It was initially believed that the temperature changes were global. However, this view has been questioned; the 2001 IPCC report summarises this research, saying
“…current evidence does not support globally synchronous periods of anomalous cold or warmth over this time frame, and the conventional terms of ‘Little Ice Age’ and ‘Medieval Warm Period’ appear to have limited utility in describing trends in hemispheric or global mean temperature changes in past centuries”.
Of course, there’s many researchers, such as Michael Mann and his thoroughly discredited “hockey stick” that try mightily to make the MWP disappear.
News flash to IPCC. Now a scientist has linked the MWP to success of the Inca civilization in the southern hemisphere. It is not going away any time soon, it is spreading.
The new study is called “Putting the Rise of the Inca within a Climatic and Land Management Context” and was prepared by Alex Chepstow-Lusty, an English paleo-biologist working for the French Institute of Andean Studies, in Lima. Link to paper (PDF) is here (h/t to WUWT reader Corey)
Here is the abstract:
The rapid expansion of the Inca from the Cuzco area of highland Peru produced the largest empire in the New World between ca. AD 1400–1532. Although this meteoric rise may in part be due to the adoption of innovative societal strategies, supported by a large labour force and standing army, we argue that this would not have been possible without increased crop productivity, which was linked to more favourable climatic conditions. A multi-proxy, high-resolution 1200-year lake sediment record was analysed at Marcacocha, 12 km north of Ollantaytambo, in the heartland of the Inca Empire. This record reveals a period of sustained aridity that began from AD 880, followed by increased warming from AD 1100 that lasted beyond the arrival of the Spanish in AD 1532. These increasingly warmer conditions allowed the Inca and their predecessors the opportunity to exploit higher altitudes from AD 1150, by constructing agricultural terraces that employed glacial-fed irrigation, in combination with deliberate agroforestry techniques. There may be some important lessons to be learnt today from these strategies for sustainable rural development in the Andes in the light of future climate uncertainty.
Here is a news article about it that talks of the findings. (h/t to WUWT reader “cotwome”) – Anthony
Opportunity knocks, again, in the Andes
The four centuries coincided directly with the rise of this startling, hyper-productive culture that at its zenith was bigger than the Ming Dynasty China and the Ottoman E
mpire, the two most powerful contemporaries of the Inca.
“This period of increased temperatures,” the scientists say, “allowed the Inca and their predecessors to expand, from AD 1150 onwards, their agricultural zones by moving up the mountains to build a massive system of terraces fed frequently by glacial water, as well as planting trees to reduce erosion and increase soil fertility.
“They re-created the landscape and produced the huge surpluses of maize, potatoes, quinua and other crops that freed a rapidly growing population to build roads, scores of palaces like Machu Picchu and in particular the development of a large standing army.”
No World Bank, no NGOs.
The new study is called “Putting the Rise of the Inca within a Climatic and Land Management Context” and was prepared by Alex Chepstow-Lusty, an English paleo-biologist working for the French Institute of Andean Studies, in Lima. Alex led a team that includes Brian Bauer, of the University of Illinois, one of today’s top Inca-ologists. The study is being published in Climate of the Past, an online academic journal.
Alex spends a lot of time in Cuzco and he told me the other day that the report “raises the question of whether today’s global warming may be another opportunity for the Andes.”
The core samples from the sediment of the little lake, Marcacocha, in the Patakancha valley above Ollantaytambo, show that there was a major cold drought in the southern Andes beginning in 880 AD lasting for a devastating century-plus through into 1000AD. This cold snap finished off both the Wari and the Tiahuanaco cultures which had between them dominated the southern Andes for more than a millenium.
It was at this same time that the Classic Maya disappeared in Yucatan. It was also a time, on the other side of the Pacific when major migrations from East Asia took place into Polynesia, an indication of a major Niño event; a Niño sees western Pacific currents switch to flow from West to East.
Core samples from glaciers and from the mud beneath lakes in the Andes, the Amazon and elsewhere have built up a history of the world’s climate and the message is crystal clear. It is that changes have taken place in the past, during the six or seven thousand years of our agriculture-based civilizations, that are just as big as the ones we are facing from today’s CO2 warming.
The message may be, too, that climate change is especially forceful in the Andes. Here we are, sandwiched thinly between the world’s biggest ocean and the world’s biggest jungle. The peaks are so high that they have had until just a few years ago deep ice on or near the Equator.
The valleys and surrounding hills have formed the roof of the human world for at least three millennia, according to Alex Chepstow-Lusty’s core samples. Nowhere else do millions of people live at or even near 4,000ms above sea level where it is cold, but getting warmer.
Today’s warming is also following on a colder spell that started, the core samples say, not long after the arrival of the Spaniards in the 16th century.
For instance, the pollen in the cores says that there was maize being grown under the Incas around the lake at 3,300ms a.s.l. Until recently the upper level for maize around the Urubamba valley was 3,000-3,100ms. In the past few years the maize level has moved up and today there is maize being grown again above Marcacocha.
Alex’s records show that hundreds of terraces were being built around the lake between 1100 and 1150 AD -“lots of mud followed by the heavy pollen of maize.”
Enrique Mayer, at Yale, tells me that “the question of the expansion of maize together with the Inca state is now a proven archeological fact, notably in the Mantaro Valley (Tim Earle).
“The question of why terraces are not worked now as intensively as they could has been worked on (Bill Devevan) in the Colca Valley where the terraces are actually in franco retroceso.
“Also, you have John Treacy’s book on Coporaque which is probably the most technically accessible to the argument that terraces are, like flower pots, expensive to maintain.”
There is also, of course, the work of John Earls on the terracing at Moray.
Today there are thousands upon thousands of fine flights of Inca terraces all over the upper ends of the valleys of Central and Southern Peru but few of them are used on a regular basis.
Efforts have been made, among them by Ann Kendall, the English archaeologist, to rescusitate the old irrigation channels and the use of the terraces in the valleys above Machu Picchu. But most have been re-abandoned.
In the same vein the great forests of polylepis, the world’s highest tree, which capture and conserve moisture, have mostly been cut down for firewood.
As they say, you only have to look in the mirror to see where the problem is.
Any ideas why the MWP started around 800 AD in Europe, but didn’t reach South America until 300 years later (1100 AD)? Or why the MWP ended around 1300 AD in Europe, and at 1450+ AD in South America.
Curious.
Barry Foster
I think Hawaii is one of those places that has not shown warning (and the States generally)
http://www.wrcc.dri.edu/cgi-bin/cliGCStT.pl?hi6198
A good book on past civilisations around the world who flourished in warmer times than today and fell when the climate cooled is called ‘Earth in the Balance’ published in 1992. The examples were being used to demonstrate what could happen if we much up our climate (rather than let nature take its course).
The author of this very well researched book? Al Gore. Too bad he didn’t get too speak to Michael Mann before they both went mad
Tonyb
Ummmm … ahhhhhh …. Ah! Yeah, that’s it! The MPW was ONLY IN THE NORTHERN HEMISPHERE!!
Meanwhile, G8 bans Climate Change
How much disinformation the people at the UN need to spit out in order to get more of our money? If Global Warming always made Empires rise because it enhanced agriculture to feed the people and the armies, why would it be different today?
UN Official Seeks G-8 Cash for Climate Change Fund
Top UN climate official to AP: G-8 should help poor countries now with global warming: http://abcnews.go.com/International/wireStory?id=8008662
Conservative&denialist (14:30:59) :
The Inca culture was an advanced culture
Agreed.
to which you owe most of the food you ate today.
Please explain.
I hate to go OT Charles; but the above is on continuous play now, and this does seem an appropriate place to put this; I hope you’ll forgive me.
George
So from the 15 May 2009 issue of SCIENCE (is this a peer reviewed Journa ?); on page 888, under the heading “Ocean Science”.
“Ice Sheet Stability and Sea Level.” by Erik R. Ivins. A reference #19 for which there is no precedent says; “This work was performed at the Jet Propulsion Laboratory, California Institute of Technology- (which is well known to be on Colorado Blvd in Pasadena CA; and not in Antarctica.)-and funded by the Solid Earth and Surface Process Focus Area within NASA’s Earth Science Program.”
I need to quote some verbatima; but not too much. My EMPHASES will be additive.
“How much will sea levels rise IF the West Antarctic Ice Sheet becomes unstable.”
“Volume changes in the Antarctic Ice Sheet are poorly understood, despite the importance of the ice sheet to sea-level and climate variability. Over both millenial and shorter times scales, net water influx to the ice sheet (mainly snow accumulation) NEARLY BALANCES water loss through ice calving and basal ice shelf melting at the ice sheet margins (1). However there MAY BE TIMES when parts of the West Antarctic Ice Sheet (WAIS) are lost to the oceans thus raising sea levels. ”
Well that is the very beginning of the paper, and I need cite no more, because it continues in a like mode.
Notice the work was done in sunny Southern California, and not in Antarctica. One may infer that not a jot of measured observation data is included in this paper which is fullof IF, or MAYBE, and similar jargon of SCIENCE FICTION; rather than experimental observation of normal research science.
There’s not a jot of science in this paper; it is 100% Science Fiction; what MIGHT happen IF this DID happen. About once full page paper with 18 reference numbers, of which I only copied #(1); which just happens to refer to an eartlier SCIENCE paper.
You can bet on the mainstream media if they stumble across this drivel; will cite a model study, as actual observational science; instead of the completely made up WHAT IF scenario of a science fiction “Star Trek” episode.
This is just an example of wht is printed in SCIENCE in lieu of science.
On another web site today, I learned that some Aussie bloke (oceanographer)says the whole Great Barrier Reef will be gone in 20 years. I say good riddance to that graveyard of ships; I’m sure I won’t be here to see it off, but maybe My sons can go and fish for some wonderful new species, when all that bric-a-brac is outa there.
So we have studies of what will happen IF the entire gret barrier reef disappears in 20 years; or what will happen IF the whole West Antarctic Ice Sheet (WAIS) suddenly falls in the southern ocean.
I haven’t yet seen a paper on what will happen IF the Moon falls into the Pacific Ocean; but you can bet that some taxpayer funded research grant has some fool woking on such a paper.
Frankly I’m getting tired of “Studies” (done in the local bars) on WHAT MIGHT HAPPEN IF some as yet never before observed SCIENCE FICTION SCRIPT should happen to get played out.
As a taxpayer, I don’t actually begrudge paying for scientists to actually do experimental science to observe something; or for theoretical scientisst to devise plausible theories for some phenomenon that someone else actually did observe.
But I am tired of paying for ersatz “scientists” to write SCIENCE FICTION for Hollywood film makers to consider for release to a GULLIBLE PUBLIC.
As a paid up AAAS reader of SCIENCE; I now have an alarm bell that goes off , everytime i come across one of these movie scripts masquerading as actual science.
You guys need to get a life, and you should be ashamed of yourselves for this charade.
George
Thank you Charles for considering this OT (on topic)
Reply: It is funny that on topic and off topic have the same acronym. A source of endless confusion for moderators and the potential conflagrations, both flammable and inflammable, which may ensue. ~ charles the moderator
Come on people. You just don’t get it.
It is really well known that the MWP was only a local phenomenon. It was local in Europe, Asia, Australia, South America, North America and Africa.
It was a local phenomenon in those places ONLY.
Kind of like Steve Martin in “Pink Panther”, when he tells a suspect to stay in the local vincinity:
“Do NOT leave Europe, Asia or the Americas”.
Some subtleties of the above SCIENCE paper; and that cited piece is actually the opening paragraph or part of it, with nothing removed in betweeen.
Did you catch that disclaimer about the snow pileup NEARLY BALANCING the ice calving over short and millenial time scales; in otherwords pretty much always so far as we know. See how cleverly they don’t say which way that nearly balance tips. Izzere more snow pileup than calving; or verse vicea.
They use the form that leads you by the nose to conclude that it is out of whack since it is only NEARLY balanced; and that the whack is in favor of the calving outdoing the snow pileup.
Clearly over the millenia, the darn balance is pretty fine, because if it tipped too far one way; there would be ice all over El Camino Real in silicon Valley; while if it tipped too far the other way, the Hudson River would be halfway up the Empire State Building.
Anybody want to wager that there is some feedback mechanism involved; Le Chatalier’s Principle in action or some facsimile thereof.
Too much ice calving, and losss of sea ice from the Antarctic perimeter, exposes a heap of new open sea surface; which is somewhat hotter than the ice; whcih would promote a massive increase in oceanic evaporation, and an increasing deposit of snow on top of that sheet ice that always seems to be in delicate balance with the snow, and that increased mass accelerates the march to the sea to stop the pileup getting too large.
Too much sea ice, and growing ice shelves, and the ocean evaporation slows down depriving the southern continent of its snow resupply, so the warmer ocean can work on melting some of that excess ice perimeter ice.
Yeah I plan to hang around to see what happens when the Moon crashes into the Pacific Ocean.
George
The Man 98 ‘Hockey Stick’ (as illustrated) showed a drop in temperature from the medieval warm period to the little ice age of 0.3 degree.
The ‘skeptic approved’ Loehle reconstruction and the graph shown here show a drop of about 1.2 degrees.
The revised Mann 08 reconstruction now shows a drop of about 0.8 degrees. The difference is 0.4 degrees.
One of the big factors in the ‘hockey stickness’ of the Mann 08 reconstruction and the lack of ‘hockey sitckness’ of the Loehle reconstruction appears to be how the modern record period is treated. To get a hockey stick Mann 08 creates a reconstruction for the northern hemisphere only. The modern temperature trend for the northern hemisphere shows a steeper increase than for the whole globe.
In contrast Loehle creates a global temperature series, and with a slightly stronger medieval warm period, and a less steep modern global increase (less steep than NH increase), arrives at more of a U shape, with the modern increase a little lower than the medieval period, but not enough to be sure the difference is significant.
In contrast the ‘non hockey stick’ version of the temperature record posted above shows an increase of only about 0.2 degrees since 1900. My guess is that the temperature record ends around 1980 so loses another 0.4 degree or so increase between 1980 and today.
As I’ve stated priorly, and here again: If CO2 was supposed to be any kind ‘warming agent,’ then I must enquire as to how it was that during the warming spell of the MWP —when MORE people were born and thence MORE CO2 was released in that period of time as a result of more carbonaceous materials (dung, wood, peat and coal) being used by more people, very much less efficiently than now— that with all the carbon in the atmosphere, the Earth suddenly got colder at the end of said MWP?
.
Further, with the advent of the Little Ice Age, how was it —again with INCREASED use of said carbonaceous materials because of the ensuing cold— that releasing yet MORE CO2 into the atmosphere caused the climate to become EVEN COLDER?
.
If CO2 is supposed to be some kind of ‘warming gas,’ then someone PLEASE explain how it was that releasing more of it caused the Earth’s climate to get colder?
.
I await a ‘learned’ reply which to date has NOT been forthcoming.
.
I am patient. How long must I wait?
.
Chris V. (14:58:13) :
Any ideas why the MWP started around 800 AD in Europe, but didn’t reach South America until 300 years later (1100 AD)? Or why the MWP ended around 1300 AD in Europe, and at 1450+ AD in South America. Curious.
Smaller continental surface and thicker ice cap in the Southern Hemisphere. That’s the possible explanation.
RE: Philip_B (13:23:45) :
I believe significant population collapse is imminent, the worst ever. We are seriously overextended in our reliance on marginal growing regions both at high and low latitudes. High latitudes of course will succumb rapidly the moment the full crash from the Twentieth Century Warm Period sets in – we may well be experiencing warning waves of this presently. The double whammy comes from the knock on effect in the higher latitudes of the tropics (e.g. 15 – 25 deg – SE US, Southern / SE Asia, etc) as the Monsoonal moisture flows of summer and early fall fail due to colder temps in continental interiors. That of course will bring mega droughts to the impacted regions. Imagine the effect of a mega drought in South and SE Asia.
“Any ideas why the MWP started around 800 AD in Europe, but didn’t reach South America until 300 years later (1100 AD)? Or why the MWP ended around 1300 AD in Europe, and at 1450+ AD in South America.”
The answer lies in the huge thermal inertia of both Oceans surrounding South America, acting as a buffer to both the warmth and the cold.
However, the cold must have fallen quite fast in the central or ‘mediterranean’ part of the continent, away from the buffering effect of oceans, as the Spanish chroniclers state that at the time of Santa Cruz de la Sierra’s (Bolivia) foundation in 1591, they describe terrible frosts that split in half huge tree trunks. It is possible because those 200-year-old trees grew during the previous much warmer period. Santa Cruz is at about 32ºW and 15ºS coordinates, in the border of the Amazon jungle, hot tropical climate.
The MWP is a unique period in the last few thousand years. Normally the Sun has a slowdown of activity every 172 years (roughly), during the MWP it missed a beat causing a longer period of good solar activity, like we have experienced over the last 200 years but lasting longer.
The length of the MWP in this report differs from northern hemisphere records by about 300 years, did the Wolf & Sporer minima have no effect in the southern hemisphere?
Any ideas why the MWP started around 800 AD in Europe, but didn’t reach South America until 300 years later (1100 AD)? Or why the MWP ended around 1300 AD in Europe, and at 1450+ AD in South America.
See Craig Loehle’s multi proxy reconstruction (link below and download the pdf).
It shows the MWP lasting from 650 AD to 1450 AD (approx) with a significantly warmer and shorter period from 800 AD to 1000 AD. Both are referred to as the MWP.
The graph above showing a steady warming then cooling in the MWP is an over-simplification. Loehle’s reconstruction shows multiple warming peaks with cooling in between, before a steep temperature fall into the LIA around 1500 AD.
http://www.ncasi.org/publications/Detail.aspx?id=3025
SteveSadlov,
I genuinely worry about the effect of a major volcanic eruption producing another Year Without A Summer or worse. Millions died even though at the time people kept food supplies for 12 months.
In our Just In Time world the effect would be awful. The YWAS happened less than 200 years ago and we know for certain it will happen again and without warning. It could happen tomorow and no government anywhere is remotely prepared.
Yet they are spending prodigous resources on AGW, a problem that may not even be real and even if it is, we have decades to prepare for.
Philip_B (19:30:39) :
See Craig Loehle’s multi proxy reconstruction (link below and download the pdf).
Indeed, Craig Loehle’s multiproxy reconstruction on the variability of temperature during the last 2000 years is the most reliable source on this issue. I have used his database in some comparisons of temperature, solar irradiance and carbon dioxide concentration. Loehle’s database comprehends the period from 16 AD to 1980 AD; however it can be easily complemented with UAH/AMSU2 database.
The length of the MWP in this report differs from northern hemisphere records by about 300 years, did the Wolf & Sporer minima have no effect in the southern hemisphere?
I can think of a reason. The water. The South is dominated by ocean which is a lot slower to heat up and cool down.
You know for the purposes of finding a climate signal it would be smart to treat the two halves as separate entities. Like take all the climate stations from south of the equator and average that, draw your graphic. Do the same with the north. So instead of the one world graph, present two.
The South should be the last to warm up, the North the first to cool off.
RE: Philip_B (19:58:41) :
RE: “It could happen tomorow and no government anywhere is remotely prepared”
Here is the quantity of faith I currently have in governments and main stream culture, to understand risks and develop appropriate contingency plans: .
Careful, if you blink you might not see the full stop I typed there …
This statement applies not only to sudden climate change, a well known issue, but also, to other mega disasters and things like severe geopolitical, global scale miltary and economic matters.
papertiger (21:09:28) :
I can think of a reason. The water. The South is dominated by ocean which is a lot slower to heat up and cool down.
You cant have your cake and eat it too.
Conservative&denialist (14:30:59) : The Inca culture was an advanced culture to which you owe most of the food you ate today.
Wow! They invented tea, milk, sugar, eggs, pancakes and wheat, berry syrup, ravioli (beef), whole wheat bread, butter, pink lemonade, beets (pickled), chicken, penne pasta, alfredo sauce, sauted vegetables with italian seasoning, olives, olive oil, coffee and cheese? Who knew! 😎
BTW, I did have tomato sauce on the ravioli and there was some yellow crook neck squash in with the onions and and a couple of tomatoes in the sauteed vegetables. And I do know that we owe a great deal to corn aka maize and common beans… but there was food pre-inca contact and I still eat lots of it… Peas, fava beans, lentils, soy, garbanzos, mung, adzuki … not all beans are from America, not even most beans.. Wheat, barley, oats, spelt, rice, rye, triticale, buckwheat: there were plenty of grains before corn/maize. Squash / pumpkin are nice, but so are radishes, turnips, kale, sweet potatoes and cabbage. Potatoes are a nice starchy root, but there are lots of nice starchy roots (Parsnips are one of my favorite, as are yams or sweet potatoes) and while marinara is a nice sauce, so is Pesto…
We could happily live without the bounty of new vegetables that came from the Americas. It is better with them, but not in any “bow down and say a prayer of thanks” way.
FWIW, I’m allergic to corn. Not dramatically, just enough that I have to avoid it. I’ve done just fine putting millet flour into “corn bread” recipes and sorghum does a fine job substituting in other contexts. Common beans are nice, but I’ve made a dandy lentil chili and even mung bean chili. Green beans are nice, but so are “yard long beans” and snow peas.
My point?
Substitution.
We can substitute a large number of food species for each other. The land would still be there growing a crop if corn (maize) were gone tomorrow. (In Texas, the alternate crop when the rain is expected to be a bit light is Sorghum. In Africa it tends to be millet.) Potatoes are a good cool season crop, but so are many other starchy foods such as short stem grains, winter wheat, beets, turnips, parsnips, root parsely, salsify, … We grow something because it is a little cheaper to grow or a little better flavor, or sometimes it’s just a bit more familiar (and sometimes because it is different); not because there is no alternative.
So yes, be thankful for all the variety of plants we can use, but realize that we’d be fine if we’d never seen an American species…
Philip_B (19:58:41) : I genuinely worry about the effect of a major volcanic eruption producing another Year Without A Summer or worse. Millions died even though at the time people kept food supplies for 12 months.
And well you ought… Chaiten is still blowing in Chili and the ring of fire is edging to an active state. There is a historical correlation of more vulcanism with low sunspots (ie. it may not be accidental that you get a big volcano right in the middle of the low solar activity periods “confusing” causality…)
The quake storm around Chaiten showed the magma pool to be very very large. Folks are just hoping it does not blow as a supervolcano and they are hoping that it stops venting and the magma pool cools all on it’s own… “Hope is not a strategy”…
In our Just In Time world the effect would be awful. The YWAS happened less than 200 years ago and we know for certain it will happen again and without warning. It could happen tomorow and no government anywhere is remotely prepared.
I have some comments about that here:
http://chiefio.wordpress.com/2009/04/06/food-storage-systems/
We know for certain that it will happen again. We just don’t know if it will be caused by a volcano, a rock fall from space, or some other cause; or exactly when.
During the 1800’s folks commonly stored the produce from one whole year for use in the following year. We now ship grains world wide, producing and consuming with as little storage as possible. A couple of months at most. Very silly. One big rock from space into the ocean and the shipping is sunk. It would take several years to rebuild enough ships; for example.
All you need to do is buy 8% more food each month of what you normally would eat (in storable forms, like dried fruit and canned goods) and you will have a “one year storage system” in about one year… It takes about 1 “dry pound” to feed a person for a year. 365 lbs of food is not very much space. About the size of a large filing cabinet or small desk. You will save more money by reduced prices buying in bulk and avoiding trips to the store than it costs to make happen. All it takes is the desire to do it.
We are in the early stages of a crop failure in wheat right now in Argentina and Canada. It’s not going to be better any time soon. We have drought lining up in the “dust bowl” (hmmm… and that was about 80 years ago… when the sun was quiet… ) parts of Texas and Oklahoma. California has shut off water to a large chunk of crop land and rainfall is low. It’s mostly about the water, and trends this year are “not good”.
So I’m encouraging my friends to start a food storage system and make sure they are prepared for “bad times”; even if those bad times are just a lost job or an earthquake or hurricane…
(While I don’t recommend it – since folks tend not to actually eat the stuff – you could make a ‘dirt cheap’ food storage system out of a couple of 50 lb sacks of beans and rice along with some vitamin pills. It’s about $300 for 300 lbs of such foods even bought at places other than the bulk sellers. I think it is better to buy what you already eat, since then you WILL eat it and not waste it… but if things go “bump in the night”, well, $100 at Costco or WalMart buys a lot of beans & rice in a hurry…)
You don’t need to depend on your politicians and government weenies to do the right thing, you can just go do it yourself a lot cheaper…
SteveSadlov,
I get my history from first person accounts by people who were there at the time.
I recall a particularly harrowing account from a young Finnish girl who described roads choked with starving people searching desperately for food and lined with the dead and dying (in the winter after the Year Without a Summer).
It may not be like that in America or Australia, but the Indian sub-continent and China are an entirely different matter.
FWIW I think the likeliest use of nuclear weapons is blackmail of food haves by food havenots after a repeat of the Year Without a Summer.
Highlander
/// As I’ve stated priorly, and here again: If CO2 was supposed to be any kind ‘warming agent,’ then I must enquire as to how it was that during the warming spell of the MWP —when MORE people were born and thence MORE CO2 was released in that period of time as a result of more carbonaceous materials (dung, wood, peat and coal) being used by more people, very much less efficiently than now— that with all the carbon in the atmosphere, the Earth suddenly got colder at the end of said MWP? ///
Possibly for the very same reason that volcanoes that emit CO2 also cause temporary cooling if they also spew out sulphur, ash and other materials that blot out the sun.
And possibly because greenhouse gases are only one factor that affect climate.
And possibly because the number of people alive back then were insignificant compared to the 6 billion alive today.