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‘Little Ice Age’ which froze the River Thames caused by Americas genocide, study finds

February 9, 2019

By Paul Homewood


Competition will be fierce, but we have an early contender for the Junk Science of the Year Award:


Colonisation of the Americas at the end of the 15th Century killed so many people, it disturbed Earth’s climate.

That’s the conclusion of scientists from University College London, UK.

The team says the disruption that followed European settlement led to a huge swathe of abandoned agricultural land being reclaimed by fast-growing trees and other vegetation.

This pulled down enough carbon dioxide (CO₂) from the atmosphere to eventually chill the planet.

It’s a cooling period often referred to in the history books as the "Little Ice Age" – a time when winters in Europe would see the Thames in London regularly freeze over.

"The Great Dying of the Indigenous Peoples of the Americas led to the abandonment of enough cleared land that the resulting terrestrial carbon uptake had a detectable impact on both atmospheric CO₂ and global surface air temperatures," Alexander Koch and colleagues write in their paper published in Quaternary Science Reviews.

What does the study show?

The team reviewed all the population data it could find on how many people were living in the Americas prior to first contact with Europeans in 1492.

It then assessed how the numbers changed in following decades as the continents were ravaged by introduced disease (smallpox, measles, etc), warfare, slavery and societal collapse.

It’s the UCL group’s estimate that 60 million people were living across the Americas at the end of the 15th Century (about 10% of the world’s total population), and that this was reduced to just five or six million within a hundred years.

The scientists calculated how much land previously cultivated by indigenous civilisations would have fallen into disuse, and what the impact would be if this ground was then repossessed by forest and savannah.

The area is in the order of 56 million hectares, close in size to a country like modern France.

This scale of regrowth is figured to have drawn down sufficient CO₂ that the concentration of the gas in the atmosphere eventually fell by 7-10ppm (that is 7-10 molecules of CO₂ in every one million molecules in the air).

"To put that in the modern context – we basically burn (fossil fuels) and produce about 3ppm per year. So, we’re talking a large amount of carbon that’s being sucked out of the atmosphere," explained co-author Prof Mark Maslin.

"There is a marked cooling around that time (1500s/1600s) which is called the Little Ice Age, and what’s interesting is that we can see natural processes giving a little bit of cooling, but actually to get the full cooling – double the natural processes – you have to have this genocide-generated drop in CO₂."

Where’s the support for the connection?

The drop in CO₂ at the time of the Great Dying is evident in the ice core records from Antarctica.

Air bubbles trapped in these frozen samples show a fall in their concentration of carbon dioxide.

The atomic composition of the gas also suggests strongly that the decline is being driven by land processes somewhere on Earth.

In addition, the UCL team says the story fits with the records of charcoal and pollen deposits in the Americas.

These show the sort of perturbation expected from a decline in the use of fire to manage land, and a big grow-back of natural vegetation.

Ed Hawkins, professor of climate science at Reading University, was not involved in the study. He commented: "Scientists understand that the so-called Little Ice Age was caused by several factors – a drop in atmospheric carbon dioxide levels, a series of large volcanic eruptions, changes in land use and a temporary decline in solar activity.

"This new study demonstrates that the drop in CO₂ is itself partly due the settlement of the Americas and resulting collapse of the indigenous population, allowing regrowth of natural vegetation. It demonstrates that human activities affected the climate well before the industrial revolution began."


For a start, the Little Ice Age did not start in the late 16thC, as the paper implies.

HH Lamb, along with many other climate historians, is quite clear that temperatures began to decline from the High Middle Ages as early as the 13thC. This cooling trend began in the Arctic, but soon spread elsewhere in the 14thC.

Where you demarcate the end of the MWP and the beginning of the LIA is of course academic. But the decline in global temperatures was an ongoing process from the 13thC to the late 17thC, when temperatures appear to have bottomed out. (Following a small amount of warming, temperatures again dropped to low levels in the mid 19thC).

Whatever caused this long term trend of declining temperatures, it certainly was not colonisation that started 300 years later!


This global cooling would be enough to explain the drop in atmospheric CO2 concentrations, without the need for any man-made involvement.

In any event, the authors reckon that this great dying reduced CO2 by a tiny 7 to 10 ppm. This, even by IPCC standards, would be fat too small to have a measurable effect on global temperatures.

According to the paper, their theory only accounts for a cooling of 0.03 to 0.08C during the 1500s and early 1600s, which would not be enough to account for the climatic changes observed during that time.

Lamb reckoned that English temperatures  were 1.5C less than the early 20thC during the coldest phase in the 1690s. And the abundant evidence of massive glacial expansion throughout the world indicates that this was not just a local phenomenon.


One particular problem for their theory, which the authors don’t seem to address, is what brought about the gradual warming after 1700. Lamb identified that there was a sharp change to warmer conditions between 1700 and the 1730s, in places as varied as England, Greenland, central and northern Europe, China, California and New Zealand.

The authors fail to show how their theory explains this, and there is certainly no evidence that the forest regrowth, which they surmise took place in the 16thC, was somehow magically and suddenly reversed a century later.



The Little Ice Age, of course, poses huge problems for AGW obsessed climate scientists. Until they can explain its causes, and indeed earlier cycles of warming and cooling, they cannot explain 20thC warming.

This latest exercise looks to be just another attempt to marginalise it as a minor, man-made anomaly. This, as we know, is sheer nonsense.

We know, for instance, that ice cores in Greenland indicate that the 19thC was the coldest time since the Ice Age itself. And we also know that glaciers expanded hugely around the world during this era.

This was no mere blip, as the authors imply.

  1. MrGrimNasty permalink
    February 9, 2019 7:23 pm

    Agricultural land use is responsible for the cooling of the USA, cooling that doesn’t exist they say.

    Man-made global warming surged after the pause (with the super El Nino), a pause that doesn’t exist they say.

    Oh what a tangled web…………………..

  2. February 9, 2019 7:27 pm

    People must be really desperate to keep the climate change scam going when they are willing to produce such garbage.

    • Jon Scott permalink
      February 15, 2019 7:19 pm

      Correct! Given there is 2 trillion dollars a year being sucked out of Western economies and into the climate fraud it make it even more obscene that this is the best they can come up with!

  3. February 9, 2019 7:30 pm

    There’s been a discussion about this at ‘The Conversation’ for a week –

    quite a few rip it apart…but amazing how many believe it (despite good data to the contrary) just because its a theory in an academic study.

    • Jon Scott permalink
      February 15, 2019 7:20 pm

      this is the problem. The marxists learned this a long time ago. Take a very small grain of truth and wrap it in a great big lie and a lot of people will believe it.

  4. JohnBillScott permalink
    February 9, 2019 7:34 pm

    The population of North America were essentially nomadic hunter gatherers so the was no expansive agriculture as we know it today. The PC authors seem to be trying to exploit the current fad of colonization and now genocide by the European explorers and settlers who also died in great numbers.

    There is no reference to the Great Plague which wiped out 75 to 200 million people between 1346 and 1353.

  5. February 9, 2019 7:35 pm

    Of course it had nothing to do with the Maunder and Dalton Minimae that occurred at these times? Obviously this is an attempt to deflect ‘blame’ from a phenomena that man cannot change (number of sunspots) to one that mankind can change (concentration of atmospheric CO2), The fact is that lack of sunspots whose magnetic field deflects alpha and beta particles from hitting the upper atmosphere and allows seeding of clouds. These clouds block heat and light from the Sun, therefore the Earth’s average temperature falls, which means less energy is in the system, therefore solar and wind power will become even more negligible than they are now and the fuel for wood burning power stations will decrease due to:
    a) the drop in temperature
    b) the amount of light reaching the Earth’s surface both of which affect the efficiency of photosynthesis.
    The result of this is that we will be cutting down CO2 absorbing trees at a faster rate than they can replenish themselves.

  6. February 9, 2019 7:35 pm

    As usual, alarmists have it backwards. The icy weather caused conflict between natives and settlers, and also between tribes. Records from Virginia history describe this clearly. The genocide followed the cold conditions rather than causing them.

    • RAH permalink
      February 9, 2019 8:31 pm

      Yea, but it’s always mans fault Ron. Everything bad that ever happened is due to human activity you know. Leftist scumbags in academia were revising history long before they started on the weather records and data.

  7. Chris Lynch permalink
    February 9, 2019 7:37 pm

    How very convenient – the highly inconvenient Little Ice Age was “man made” itself! Laughable drivel. Can any intelligent person doubt that this is anything but pernicious political ideology masquerading as science at this point?

    • Jon Scott permalink
      February 15, 2019 7:23 pm

      Our young, well immersed in unacceptable leftist ideology in schools on both sides of the pond are willing believers. Mark my words. McCarthy! Where are you when we need you? You were born just too early.

  8. February 9, 2019 7:54 pm

    Thanks for picking this up, Paul. I find it difficult to believe that a supposedly respectable university should publish such rubbish.

    • Derek Buxton permalink
      February 10, 2019 10:22 am

      Are there any “respectable” Universities left? It appears that standards dropped as soon as the Universties took the Governmment shilling.

    • Jon Scott permalink
      February 15, 2019 7:29 pm

      “Cooling II-XX. It is so clear that there is a concerted effort to get climate change into every respectable and unrespectable science. Worthless research is sexed up with climate change added like flavourings on the top of an icecream. Here we have seen the Lancet contaminated and also some TrickCyclist review…Mark my words these people are serious and they have YOUR tax dollars and Pounds and Euros backing them up!

  9. Immune to propaganda permalink
    February 9, 2019 8:00 pm

    CO2 levels have no bearing on climate. ICE core sample from the Ordovician ice age had CO2 levels fourteen times higher than today’s at 4400 to 4800 parts per million. So 400ppm today means we are victims of the eco socialist Agenda 21 CO2 causation hoax. Which means energy rationing via smart meters in the not too distant future, whilst keeping our homes warm will only be available for the well off at £3,000 to £6,000 annum utility bills. I wish I was joking, but I’m deadly serious.

  10. Calling BS when I see bs permalink
    February 9, 2019 9:04 pm

    Where is Ice age after Nazis and commies killed easy more than that?

  11. February 9, 2019 9:17 pm

    they’re really pushing this into the realms of psyop now. People are falling for it left, right and centre. Saints preserve us!

  12. Chris MD permalink
    February 9, 2019 9:29 pm

    Revenge served cold, The Times 1/2/19

    UCL have just completed a fascinating piece of research, reported in The Times (Revenge served cold, 1/2/19) in which it is described how the Spanish Conquistadors actions, culminating in the execution of Tύpac Amaru in 1572 AD, are thought to have caused the last Mini Ice age.
    The thinking being with most of the population wiped out there was rapid reforestation which in turn sucked CO2 out of the atmosphere and which in turn caused cooling.
    The difficulty with this theory was that the Mini IIce Age had already set in, it was the cause of Viking decolonising of the once green Greenland in 1350 AD. The last Mini Ice age ended in 1850 AD.
    It is however interesting to note that increased CO2 levels, now at 410ppm, has resulted in the present day greening of the Earth.
    Chris Matchette-Downes

    They did not publish like the BBC The Times UCL met office are fixated on this CO2 myth

    • Allan spector permalink
      February 10, 2019 12:29 pm

      Arousing fear or sex tittilation are effective measures in selling newspapers and media attention and MAKING LOTS OF MONEY!

    • February 10, 2019 3:52 pm

      Oh I agree totally. I just would like to point out that NASA says the lady Maximum of the Lia started in1850 . It didn’t end in 1850 It ended closer to 1900 .

  13. February 9, 2019 9:31 pm

    Academia is very busy these days destroying its reputation.

  14. Broadlands permalink
    February 9, 2019 9:43 pm

    “To put that in the modern context – we basically burn (fossil fuels) and produce about 3 ppm per year. So, we’re talking a large amount of carbon that’s being sucked out of the atmosphere,” explained co-author Prof Mark Maslin.”

    And to put THAT in perspective with the Paris Agreement plans, it is ~17 times less ppm of CO2 than will be required to get the climate back to 1987…350 ppm. By weight those 50 ppm is more than 300 billion tons of oxidized fossil fuel carbon to suck into new trees, or bury safely…somewhere? And in about 12 years… A hoax?

  15. markl permalink
    February 9, 2019 9:51 pm

    Doesn’t matter if it’s true or not or even if it’s plausible anything supporting AGW automatically gets published. The people writing this crap and the people publishing it should be ashamed.

    • dave permalink
      February 9, 2019 10:16 pm

      It is almost sweet, the monomania of these people – or it would be if they were indulged as simpletons.

  16. JCalvertN permalink
    February 9, 2019 10:30 pm

    The putative 60 million people didn’t all live in rainforest areas.
    Also, secondary regrowth jungle has a different structure to ancient forest. Can the authors find all the vast regrowth areas they are proposing?

  17. February 9, 2019 11:33 pm

    I am so glad University College is not my alma mater.

  18. Jeff permalink
    February 9, 2019 11:48 pm

    “60 million people were living across the Americas at the end of the 15th Century (about 10% of the world’s total population), and that this was reduced to just five or six million within a hundred years.”

    Rubbish, large areas of Canada, North america, and South america had tribes relatively intact at 1600.
    And to say every man, woman and child had the equivalent of 1 hectare under active cultivation that reverted to forest cannot be correct IMO.
    So many were relying on grazing animals such as bison and hunting and gathering.

  19. alexei permalink
    February 10, 2019 1:56 am

    In an attempt to verify the pre Columbian population in Wiki, I was astonished to find the University College “research findings” were already incorporated as fact in Wiki’s entry. Moreover, it states that Prof. Mark Maslin asserts that the large death toll also boosted the economies of Europe: “the depopulation of the Americas may have inadvertently allowed the Europeans to dominate the world. It also allowed for the Industrial Revolution and for Europeans to continue that domination.”[56]

    One can only wonder how he arrived at this conclusion……..

  20. Daris g permalink
    February 10, 2019 2:39 am

    Hmmm, all this time we thought farming the land was the carbon maker, now it’s not farming it that causes the problem. Gee whiz, who knew!!;)

  21. M E permalink
    February 10, 2019 2:42 am

    see Crabtree’s Bludgeon . It explains the connection between The Thames freezing and a putative sudden removal of agriculture from North America.

  22. Charlie Moncur permalink
    February 10, 2019 3:17 am

    Who pays the salaries of these “pseudo-scientists”. Time to pull the plug on funding?

  23. yonason permalink
    February 10, 2019 3:50 am


    Michael Mann and his hockey team “proved” that neither Medieval Warm Period nor the Little Ice Age occurred.

    Warmist scam artists are so inconsistent.

  24. Steven Anderson permalink
    February 10, 2019 7:49 am

    Once again UCL seem more interested in rewriting history to support its tedious revisionist view than it is in plain scientific fact. If the warming started 300 years earlier, somebody needs to enquire why they are wasting everyone’s time and resources desperately trying to patch together a case blaming Western colonization of the Americas.

  25. February 10, 2019 8:09 am

    How fascinating! I wonder what genocide caused the Thames to freeze over in 1963?!!

  26. dave permalink
    February 10, 2019 8:46 am

    While the population of the Americas was declining, the population of the rest of the world was expanding by much more, with presumably a commensurate increase in human land use.


    World Population

    1500 438 million

    1600 579 million

    1700 682 million

    We have a fairly good estimate for the numbers in the Aztec Empire in 1500, and it is ‘6 million.’ That is really not many, is it? Ming China alone was 125 million at the same time.
    Even if the Spanish Pox killed all the Mexicans, ‘Gaia’ was never going to notice it.

    So, looking at the expansion of human numbers in early modern times, I guess the hypothesis must be that the Little Ice Age was caused by an INCREASE in anthropogenic carbon dioxide. Of course, taking one factor in a complex dynamic web is plain silly. And choosing what is clearly a trivial factor – crops around a village versus woods and pasture – is plain insane.

    A point that seems to have been overlooked is that carbon dioxide is dissolved in the oceans and is in equilibrium with the carbon dioxide in the atmosphere. If an increase in plant biomass should “suck” 100 molecules of carbon dioxide out of the air, the air will “suck” 50 molecules out of the oceans. That halves any effect automatically.

  27. Dave Clough permalink
    February 10, 2019 9:31 am

    Bogus studies blaming man for what happens during a solar minimum. Man is nothing more than a fart in the wind when it comes to climate.

  28. Wellers permalink
    February 10, 2019 11:01 am

    Poor young UCL graduate student Alexander Koch who wrote this thesis spent three years researching it. Funded by us! He and Mark Maslin seem only able to conceive a world where the earth’s climate is influenced by man, despite the overwhelming evidence of natural effects such as from the sun. What a total waste of time and money.
    I studied chemical engineering at UCL in 1980 but I’m afraid that it seems to have gone downhill since.

  29. Clay Smith permalink
    February 10, 2019 12:04 pm

    This is the most stupidity I’ve seen in years.
    It’s like saying, when you see a horse pull a cart you have it all wrong.
    The cart is pushing the horse.
    I don’t believe that this study is anything more the the prelude to fictional movie, or a drug and alcohol induced stupefied condition.
    If this paper is reviewed and accepted by peers, this science-based study opens up the the door to say, we can change the world weather by having everyone stand outside with a lighter for 10 minutes and spring will be a month early.

  30. February 10, 2019 1:00 pm

    Are you certain this is not from the BABYLONBEE or The Onion? The Indians had extensive agriculture around the Great Lakes in NY State and elsewhere.

    When working on my PhD dissertation on vegetation associated with diabase rock in the Gettysburg Basin of Pennsylvania, I read a number of published accounts from records in the 1600’s and later to reconstruct what the land was like.

    One military account from the 1600’s talked about vast areas of Indian orchards and crops. They also talked about the fact that you could travel by horse from PA to North Carolina without being bumped off due to the fact that the Indians burned the heck out of the forests. This was for travel (war parties), edge vegetation for increased wildlife, etc. They talked about miles and miles and miles of smoke.

    Where did these geniuses get this utter nonsense?

  31. Jonah the Whaler permalink
    February 10, 2019 1:31 pm

    This has to be the singular worst piece of tripe ever published in the name of Science! It’s an embarrassment for the entire scientific community!

  32. Jason permalink
    February 10, 2019 1:38 pm

    What a load of total nonsense – it has been known for decades that the Medievel cool period was caused by very low sun activity.

  33. Pat permalink
    February 10, 2019 6:15 pm

    But at least this acknowledges the existence of the little ice age. I saw recently an alarmist series fronted by Tony Robinson that also acknowledged the little ice age as well as many other occasions when changing climate caused hardship or disaster, all before the industrial revolution.
    I wonder if Prof. Mann intends to sue these people as they flatly.contradict.his Magnus opus. Also I wonder how long before it’s generally realised that there is nothing remotely unusual about the recent climate changes such as they are, and hence no specific cause for worry.

    • Chris MD permalink
      February 10, 2019 7:00 pm

      Sadly we wont be allowed the simple luxury of putting the record straight as the “science” has been decided by green grant junkies and the politicians.

  34. Jon Scott permalink
    February 10, 2019 6:42 pm

    Another one! WHO IS PEER REVIEWING THIS GARBAGE before allowing it to be published OR is saying “Climate Change” some kind of magic wand to get your paper rubber stamped for publishing? This is the unsubstantiated twaddle of a scandal rag like the News of The World or the National Enquirer not a sober scientific journal! Money has to be changing hands for supposed scientists to look the other way. No one lets garbage like this through for free! This is truly shocking because this is impinging on my area of work. I am penning a letter to the editor as we speak!

  35. matthew dalby permalink
    February 10, 2019 8:01 pm

    There is so much rubbish in this report that it is easy to overlook some of it. I refer to the statement that the Little Ice Age was partly caused by a series of large volcanic eruptions. This isn’t the first time I have heard this claim, but I have yet to see it subjected to the ridicule it deserves. It is an undisputed fact that large volcanic eruptions can cause a temporary dip in temperatures, however possibly the largest eruption in recorded history, Tamboro in 1815 caused a drop of roughly 1 degree for 1 or 2 years. Therefore to get sustained cooling for several centuries (even if volcanic activity was only responsible for part of it) would require an eruption on that kind of scale every couple of decades at least. Volcanoes tend to leave behind a lot of evidence (lava, ash etc. and sometimes written or oral records) so the simple question is where were all these massive eruptions? Since there doesn’t seem to be much if any, this is just one more desperate attempt by alarmists to downplay the role of solar cycles on the climate.

  36. Raymond Sanders permalink
    February 10, 2019 9:38 pm

    From Richard Horton, editor-in-chief of The Lancet.
    ‘peer review to the public is portrayed as a quasi sacred process that helps to make science our most objective truth teller, but we know that the system of peer review is biased, unjust, unaccountable, incomplete, easily fixed, often insulting, usually ignorant, occasionally foolish, and frequently wrong’
    This paper ticks all the boxes

    • February 11, 2019 2:32 pm

      The ‘Peer Review’ quotation is already a leading contender for ‘Truism of the Year’. And of course we have all noticed that the Climate Change Alarmists always proudly declaim that their papers are peer reviewed!! QED.

  37. Glenn permalink
    February 11, 2019 12:35 am

    What is a grand solar minimum? What happens to our climate when there are multiple large volcanic eruptions? What happened during the oil field fires as result of USA conducting war operations, first middle east war??? Global cooling. People were not a factor. In past Great Die Offs. 2 of three of my examples are not man made. Volcanic eruptions put more CO2 in the air than the totality of man CO2 from time in memorial. CO2 follows earth ambiant temperature. Do Grand Solar Maximum sun cycles influence ambiant earth temperature?? Yes. Look at world history to see what was happening in the west and the east, written records. Our climate is primarily driven by solar cycle.

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