Wild claim: America colonisation ‘cooled Earth’s climate’

O……K…..

Earth system impacts of the European arrival and Great Dying in the Americas after 1492

Here’s a link to the full paper.

Highlights

  • Combines multiple methods estimating pre-Columbian population numbers.
  • Estimates European arrival in 1492 lead to 56 million deaths by 1600.
  • Large population reduction led to reforestation of 55.8 Mha and 7.4 Pg C uptake.
  • 1610 atmospheric CO2 drop partly caused by indigenous depopulation of the Americas.
  • Humans contributed to Earth System changes before the Industrial Revolution.

Abstract

 

Human impacts prior to the Industrial Revolution are not well constrained. We investigate whether the decline in global atmospheric CO2 concentration by 7–10 ppm in the late 1500s and early 1600s which globally lowered surface air temperatures by 0.15C, were generated by natural forcing or were a result of the large-scale depopulation of the Americas after European arrival, subsequent land use change and secondary succession.

We quantitatively review the evidence for (i) the pre-Columbian population size, (ii) their per capita land use, (iii) the post-1492 population loss, (iv) the resulting carbon uptake of the abandoned anthropogenic landscapes, and then compare these to potential natural drivers of global carbon declines of 7–10 ppm. From 119 published regional population estimates we calculate a pre-1492 CE population of 60.5 million (interquartile range, IQR 44.8–78.2 million), utilizing 1.04 ha land per capita (IQR 0.98–1.11).

European epidemics removed 90% (IQR 87–92%) of the indigenous population over the next century. This resulted in secondary succession of 55.8 Mha (IQR 39.0–78.4 Mha) of abandoned land, sequestering 7.4 Pg C (IQR 4.9–10.8 Pg C), equivalent to a decline in atmospheric CO2 of 3.5 ppm (IQR 2.3–5.1 ppm CO2). Accounting for carbon cycle feedbacks plus LUC outside the Americas gives a total 5 ppm CO2 additional uptake into the land surface in the 1500s compared to the 1400s, 47–67% of the atmospheric CO2 decline.

Furthermore, we show that the global carbon budget of the 1500s cannot be balanced until large-scale vegetation regeneration in the Americas is included. The Great Dying of the Indigenous Peoples of the Americas resulted in a human-driven global impact on the Earth System in the two centuries prior to the Industrial Revolution.

1. Introduction

 

The arrival of Europeans in the Americas in 1492 CE marks the onset of disease epidemics resulting in the loss of the majority of indigenous people living in the Americas over the subsequent century (Berlinguer, 1993; Cook, 1998; Crosby, 1972, 1976; Nunn and Qian, 2010). Indigenous land use was widespread before European arrival, particularly in Mexico, Central America, Bolivia and the Andes where terraced fields and irrigated agriculture was practised (e.g. Abrams and Nowacki, 2008; Chepstow-Lusty and Jonsson, 2000; Heckenberger et al., 2003; Hunter and Sluyter, 2015; Whitmore and Turner, 1992), and across Amazonia where diverse pre-Columbian land uses left its traces in the composition of contemporary Amazon forests (Clement et al., 2015; Levis et al., 2017; Maezumi et al., 2018a; Watling et al., 2018). Thus the Great Dying of the Indigenous Peoples of the Americas (Wolf, 1982) after 1492 CE likely led to a reduction in land use. Fields and fallow areas then underwent secondary succession and in many cases increased carbon stocks as they reverted towards similar prior states – with local, regional and potentially global consequences for the Earth System.

The uptake of carbon on the abandoned anthropogenic lands after European contact may have been large enough to impact the atmospheric CO2 record (Dull et al., 2010; Faust et al., 2006; Lewis and Maslin, 2015; Nevle and Bird, 2008; Nevle et al., 2011; Ruddiman, 2005). Furthermore, at the same time high-resolution Antarctic ice-core records of atmospheric CO2 concentration show an anomalously large decline of ∼7–10 ppm (Ahn et al., 2012; MacFarling Meure et al., 2006) beginning in the 1500s with a minimum in the early 1600s (Fig. 1). Isotope analysis shows that the anomaly was driven by an increase in the terrestrial carbon sink (Fig. 1B, Bauska et al., 2015; Francey et al., 1999; Trudinger et al., 1999). Hence, the carbon uptake that is thought to have occurred following the arrival of epidemics in the Americas may have reduced atmospheric CO2 levels and led to a decline in radiative forcing that may then have contributed to the coldest part of the Little Ice Age (Faust et al., 2006; Neukom et al., 2014).

Fig. 1

Fig. 1. Global atmospheric CO2 time series. (A) The CO2 concentrations recorded in two Antarctic ice cores: Law Dome (grey, MacFarling Meure et al., 2006) and West Antarctic Ice Sheet (WAIS) Divide (blue, Ahn et al., 2012). (B) Carbon isotopic ratios recorded in CO2 from the WAIS Divide ice core (black, Bauska et al., 2015) showing an increased terrestrial carbon uptake over the 16th century (B). Yellow box is the span of the major indigenous depopulation event (1520–1700 CE). Loess smoothed lines for visual aid. Error bars are the 1-σ standard deviation. (For interpretation of the references to colour in this figure legend, the reader is referred to the Web version of this article.)

8. Conclusion

 

We estimate that 55 million indigenous people died following the European conquest of the Americas beginning in 1492. This led to the abandonment and secondary succession of 56 million hectares of land. We calculate that this led to an additional 7.4 Pg C being removed from the atmosphere and stored on the land surface in the 1500s. This was a change from the 1400s of 9.9 Pg C (5 ppm CO2).

Including feedback processes this contributed between 47% and 67% of the 15–22 Pg C (7–10 ppm CO2) decline in atmospheric CO2 between 1520 CE and 1610 CE seen in Antarctic ice core records. These changes show that the Great Dying of the Indigenous Peoples of the Americas is necessary for a parsimonious explanation of the anomalous decrease in atmospheric CO2 at that time and the resulting decline in global surface air temperatures.

These changes show that human actions had global impacts on the Earth system in the centuries prior to the Industrial Revolution. Our results also show that this aspect of the Columbian Exchange – the globalisation of diseases – had global impacts on the Earth system, key evidence in the calls for the drop in atmospheric CO2 at 1610 CE to mark the onset of the Anthropocene epoch (Lewis and Maslin, 2015, 2018).

We conclude that the Great Dying of the Indigenous Peoples of the Americas led to the abandonment of enough cleared land in the Americas that the resulting terrestrial carbon uptake had a detectable impact on both atmospheric CO2 and global surface air temperatures in the two centuries prior to the Industrial Revolution.

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171 thoughts on “Wild claim: America colonisation ‘cooled Earth’s climate’

  1. Europeans came to the Americas in 1492. 350 years later Europeans discovered germ theory.

    Those bastards.

    • The Indian population gave the Europeans a few diseases the Europeans didn’t have before arriving in the New World. It was a two-way street.

      • Not many.

        Especially since syphilis was proven to be one of the STDs common to romans, many centuries before Columbus.

        Leaving what? Yellow Fever?

        • Syphilis was endemic in South America and the arriving Europeans contracted their version of it. It was a febrile, fatal disease in Europe. Brothels were erected to help pay for the building of St Peter’s Basilica. When the returning explorers reported to the Vatican they spent time visiting them. Masons from all over Europe spent two years each assisting in the construction, carried it home with them and it spread rapidly in the population.

          As the former head of the HIV/AIDS initiative in the Scandinavian countries explained it to me over coffee in Zurich, the first location from where the South American syphilis was spread was Gandolfo Castle, as was the first international AIDS conference. He felt that was an interesting coincidence.

          • Speaking of wild claims – the use of indulgences to pay for St Peters was a big scandal then and motivated Martin Luther’s criticism and then the reformation. This prostitution claim starts after a a very recent scandal of leaks of Vatican properties used for brothels designed to damage the previous Pope. Pretty obvious that you need to take it with a pinch if salt.

    • The thrust of this seems to be humans caused the LIA and thus the last 300y of warming is also AGW and NOT natural variability. The next step will be “prove” that Roman Warm Period was caused by Romans cutting down trees to crucify people, thus neatly proving what we “knew” already: that any change to climate is and always has been caused by human activity.

      This paper is written by a group of pseudo academic climate change deniers.

    • Attracting grant money with the usual AGW encantations is well known but political activism and supporting “the cause” is a major play too.

      Intro:

      Hence, the carbon uptake that is thought to have occurred following the arrival of epidemics in the Americas may have reduced atmospheric CO2 levels and led to a decline in radiative forcing that may then have contributed to the coldest part of the Little Ice Age

      maybe , could be , kinda ….

      which then morphs into a scientific certitude:

      Conclusion:

      These changes show that human actions had global impacts on the Earth system in the centuries prior to the Industrial Revolution.

      Oh, and don’t forget to add an explicit claim as non geologists to push redefining the geological record.

      to mark the onset of the Anthropocene epoch (Lewis and Maslin, 2015, 2018).

      Activist-crusaders not scientists.

      • Sometimes they “forget” to include the may haves, maybes, the error bars and other crutches in their conclusions.

    • I was thinking parody, or a fake by that group that floats fake papers to show how corrupt the peer review process is.

  2. Classic proof that common sense doesn’t go with education. The US population in 1895 was 65 million. Well into the industrial revolution. Wheels, engines, metal. There is no way there were 56 million people available to die in a a Stone Age culture, without the wheel, advanced agriculture, metal, or even draft animals. Realistically the population of all of North America in the 15 to 16 century was around 20 million.

    • Or the claim that they cultivated ~1ha per person, or 5-10ha per adult, 10-20ha per male. And had enough time to hunt.

    • They are including both north and south America. The Inca empire was estimated at 8 – 14 million at its height plus all those living in the Amazon. The total number is the top of the estimates but not ridiculously out of line.

    • 87 million people died in the years 1914-1919, 37 million during WWI, and 50 million from the Spanish flu. The rate of loss was fantastic compared to post-Columbian Native American dying (even if the original numbers were as high as quoted). Why did we not experience a Little Ice Age?

      • Indeed. In fact just after all that death of the 1914-1919 was a period of warming (1920s-1940s) just the opposite of what you’d expect based on the theory on post-Columbian Native American dying leading to cooler temps.

  3. “The Black Death, also known as the Great Plague, the Black Plague, or simply the Plague, 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 from 1347 to 1351…The Black Death is estimated to have killed 30–60% of Europe’s total population. In total, the plague may have reduced the world population from an estimated 450 million down to 350–375 million in the 14th century.”

    Using the theories and methodologies of these researchers, it would seem that the plague happening first, by over 100 years and causing far more sudden deaths, would have been a significantly greater disruptive force. These researchers should take a look back and see if they can find another coincidence to tie to atmospheric CO2.

    • You are obviously a warmist intent on using logic and common sense. Off to the reeducation camps for you.

    • Michael Combs February 2, 2019 at 8:28 pm
      good pick.
      Sets one to thinking, can we say “The destruction of the Kievan State” was another good example? Now that was a die off.

      There is to much guess world and not enough research.
      For example what areas became so depopulated that farming stopped. Mexico was a very profitable part of the Spanish Kingdom. Seems there was no shortage of people to fill Spanish coffers.

      michael

    • Ludicrous
      58 million dead in 60 years
      70 million buffalo dead in 15 years in the western plains and no ice age
      Stupid. It’s easy to come up with this junk if you know the agenda before starting.

      Check out thi link.

      MASS DEATHS OF NATIVE AMERICANS CAUSED THE LITTLE ICE AGE? FACT CHECK!
      Posted by Richard Thornton | Feb 2, 2019 | Humor, Mysteries, Native American Community, Nature

      https://peopleofonefire.com/mass-deaths-of-native-americans-caused-the-little-ice-age-fact-check.html

    • Well the thing is, the LIA started far earlier than they state in their paper, and the Black Death preceded the European exploration of the Americas. The LIA seems to have started before the Black Death years however, so while perhaps vast amounts of human death could have slightly affected temperatures, the cooling effect was already happening.

  4. “likely led to a reduction” and “may have been large enough” and “uptake that is thought to have occurred” and “may have reduced atmospheric” and “that may then have contributed”

    Gotta love certainty.

    • I’d have been even less likely to believe it if they claimed certainty. There’s nothing wrong with saying “likely” and the like.

      • I fully agree with you Jeff. I am in no way defending this study, but I will defend the use of uncertain words such as “appear”, “seems”, “probable”, etc. in research. I read lots of times on this forum that people want certainty in the results. I would say that most areas of scientific research cannot provide certainty and no competent researcher will suggest they can. In atmospheric research what we try to do is find correlations which could suggest a cause and effect. Then maybe someone else can do further investigation and add more, or even disprove what we may have thought. In my research on tornadoes there is never a certainty. We try to find physical processes that appear be related to the formation of tornadoes. Its not perfect, but we do the best we can with the data and physics we have. And I think it is better than not providing any information unless we are certain of the causes.

        • 100% agreement, with the proviso that it is understood that evidence to the contrary may also emerge, and that such evidence receives the same amount of publicity and consideration. That is the scientific principle, not the burying of facts that do not support our pet theory….

          • “Gotta love certainty.”

            You will find the certainty in the Conclusion section, where they seems to have forgotten that the whole thing was a speculative: may be , could be , kinda likely speculation 😉

    • Jeff, Max, and Tony – All your points are good ones, and I agree with them; however, I was highlighting the nature of the authors’ particulars compared to the certainty of his conclusions.

      Also, just running some numbers off the top of my head, the authors’ remarks concerning the 7 – 9 ppm decline of CO2 effect per the global temperature drop amounts to quite the climate sensitivity to CO2.

  5. “Estimates European arrival in 1492 lead to 56 million deaths by 1600.”

    Its funny most scholars writing at the end of the 19th century estimated that the pre-Columbian population to be 10 million; now some estimates are 100 million or more.
    It seems to me to now be politically correct to exaggerate the number and how peaceful they were,
    before europeans came and destroyed everything.

    • Agreed!

      All of those peaceful tribes had war chiefs, because they were so peaceful…

      Apparently these researchers fantasize epidemic casualties, without investigating said epidemics.
      A) Fantasize huge populations.
      B) Fantasize massive epidemics.
      C) Conclude disease casualties by models or fantasy spreadsheets.
      D) Blame CO₂
      E) QED for gullible CAGW alarmists.

      1) Ignores the massive forest cutting of invading colonists.
      2) Ignores that regrowth forests simply replaced agriculture and city landscaping.
      3) Ignores that introduced disease epidemics affected Native Americans differently depending on contact with Europeans; e.g. conquered Incas versus isolated attempts at fort construction along North America’s East Coast.
      4) Totally, as jeff notes, ignores population estimates by the Spanish, French, English and Dutch who physically encountered Native Americans.

      Just more finagled fudged estimates by models/spreadsheets, producing numbers pre-selected by the researchers. i.e. Confirmation Bias.

    • Scholars at the end of the 19th century weren’t aware how extensive the terracing was in the Andes. Mistakenly thought the Amazon basin was virtually uninhabitable. Thought Mesoamerica was always thick jungle. Were unaware of the large cities across North America.

  6. Nah…The LIA started more like 1350 AD. What these people think, everyone stupid? I sure hope this isn’t indicative of the average college graduate. Even worse, if this is the average intellect of the newly graduated climate scientist, then we gonna need re-education camps. Mainstream science should be jumping all over this pointing out how bizarre this premise is. Of course, if everything predicated upon the sensitivity of CO2 to this level, then the ocean’s indeed will soon be boiling.

    • Again read the paper and the quotes. It does not state that it caused the little ice age but rather
      may have contributed to “the coldest part” of it.

      • First off, prove that CO2 actually dropped 10-11 ppmv from contributing reductions in New World agriculture and by the demise of the peak of New World civilizations during that time period 1492-1750.

        Second, prove that CO2 is the central culprit in causing such climate sensitivity. I doubt you or anyone can, and this ‘paper’ is based upon the principle that CO2 is the magic molecule responsible for everything that happens or happened with the long term climate trends. This of course is the wanted central rationale to make CO2 the demon molecule and now labeled as pollution by ignorant power brokers and politicians hoping to utilize it as source of near unlimited taxation and power/control over the citizenry. If this isn’t reigned in soon, it is sort of the end of the world as we have known it the last 150 years. But not from global warming or climate change, but loss of fundemantal control of our national state(s) to an unelected authority via a gross misuse/abuse of the scientific method. In other words, an outright scam of hideous proportions that benefits the agent provocateurs of this caustic swindle. This will end badly for humanity if allowed to fester but the climate in the near to mid term will continue to be as beneficial and near perfect as it has ever been the last 2.6 million years.

        • “First off, prove that CO2 actually dropped 10-11 ppmv”

          Yeah, really!

          Or prove that reduction in CO2 reduces the Earth’s temperature by 0.15C as they claim in the quote below:

          “Human impacts prior to the Industrial Revolution are not well constrained. We investigate whether the decline in global atmospheric CO2 concentration by 7–10 ppm in the late 1500s and early 1600s which globally lowered surface air temperatures by 0.15∘C,”

          Don’t you love how precise they are. They have it nailed down, don’t they.

      • Looks like Percy hasn’t read many climate papers. They all talk about may be, might have and so on.
        Yet the activists take all of these papers as absolute proof that the worst case scenarios have been proven.

      • Okay, since I have not had the pleasure to sit down and read the full paper, if decrease of 10ppm CO2 ‘may’ have ‘contributed’ to it, what caused the rest?

        The paper seems to be working with the base assumption that the LIA was real and occurred. Does it offer any suggestion as to what caused it? By claiming that a 10ppm reduction ‘may’ have contributed the extension of this logic is that global CO2 levels DIDN’T have anything to do with the rest of it. Either there was a massive decrease of CO2 at the start of LIA or the only conclusion to be made is that CO2 does not drive global temps… OR there was an even bigger decrease in CO2 prior to European/American social interaction that no one seems willing to explain.

        Also, while we are on the topic, if it is accepted that LIA is part of the historical record AND that ‘Pre Industrial Temperatures’ are the baseline for the perfect planet, then how did we climb out of LIA to Pre Industrial? What drove this global change?

        This paper seems… interesting…

    • Having been in academia I can assure you it is less that people are stupid and more that it is incredibly easy to get a paper published if it is politically popular and impossible to get it published if the political climate goes against it.

    • Earthling2 – February 2, 2019 at 8:34 pm

      indicative of the average college graduate.

      if this is the average intellect of the newly graduated climate scientist, then we gonna need re-education camps.

      Mainstream science should be jumping all over this pointing out how bizarre this premise is.

      “YES”, …. and ”YES”, ….. and ”CORRECT”.

      And I also think that Mainstream science should be jumping all over the “textbook publishers”, law suits included, for both the public school textbooks and college textbooks, because said textbooks are what the teachers/instructors are teaching from and what the students are mandated to be learning from.

      The root problem is, “textbook publishers” literally hate old textbooks because they want to sell “new revised editions” each succeeding year or two, NOT reprints of old textbooks, but new and/or newly revised information. And to do that the publishers must include the everchanging Politically Correct social science and the Politically Correct junk science ….. while excluding the “fact based” social and natural sciences. And the lefty liberal Socialists Educators give their 100% approval of the revised contents

  7. “This led to the abandonment and secondary succession of 56 million hectares of land.” There were not that many Indians and they were not big farmers. Even so that is only 138,379,012 acres. The contiguous land area of the US is 7,653,004 km^2 or 1.89 billion acres . So that represents .00732 or 7/10 ths of 1 % of the land.

    The climate scientists are trying to say that 7/10ths of 1% of the land would absorb so much CO2 that it affected climate. If it was suddenly not farmed the soil would give off CO2 to the atmosphere . If grass started to grow on it, this land area is so inconsequential that it is laughable.

    i haven.t bothered to address the rest of the study because I am in a fit of rage after I stopped laughing about this garbage study wasting taxpayer money.

    • I made 2 mistakes. It was 7 % not 7/10ths of 1%. and I misrepresented the geography. They weren’t talking about the US. Only Mexico, Bolivia, Central America and the Andes. The Spanish conquered these lands. Even so, the idea that changing 56 million hectares from farmland to grassland would have any effect on the climate is hilarious. The land are of the world is 149 million km^2. 56 million hectares = 560000 km^2 or 0.003758 of the world land area. So 3/10ths of 1 % of the world land area turned from crops to grass. So what? I am sure that happens every decade where new grassland is formed from deserts and the like. Even so if the land was abandoned for the 1st couple of years it would have given off CO2 NOT absorbed it.

      • Human land use has gone from 4% to 40% worldwide over the past 150 years. If the authors are correct it is midern land use, not fossil fuels, that is driving global warming.

        If a small change in global population from 1500 to 1600 could cool the planet then surely a large change from 1850 to 2019 could swarm the planet.

        If so, then we cannot solve global warming unless we reduce land use. Which would require reducing Hunan population.

        • Following on this trend, human land use increase usually means deforestation. Does it follow from this that deforestation is the cause? I am of the opinion that deforestation affects rainfall (see the article elsewhere about the Amazon creating it’s own rainfall as an extreme example), but I would not claim it is a major driver of climate change without lots of evidence. Interesting though to note the catastrophic implosion of the bronze and ice age civilisations, where deforestation was likely extreme due to the fuel requirements of smelting ore……

        • Perhaps you discovered the real point of the study ferd, but why pick on just one rural province in China (HuNan)? Only about 67m people there.
          🙂

      • Thank you for a simple arithmetical sanity check. Why couldn’t the authors of this travesty of a scientific paper have done the same? Where were the peer reviewers?

  8. While the exposure to the Afro-Eurasian disease environment may have caused a mass die-off among Native Americans after 1492, the LIA had started in the 1300’s, so something happening several hundred years later could have no effect.
    If one reads Charles Mann’s “1491”, estimates of the plagues effect killed off large numbers of farmers in the Mississippi Valley, as well as Mexico and Amazonia.

      • Yes, that’s well established climastrology.

        On that point, isn’t it far more likely that the dip in CO2 was the result of LIA cooling, rather than the cause of cooling?

  9. Once again the reach false conclusions because they start with erroneous assumptions!!! I may have to read their linked reports but I greatly question the Great Dying is related to the Europeans arrival. I don’t think they have sufficient temporal resolution to even say whether the population decline (if there was one? I’d like to examine their proxies) began before or after the arrival of the Europeans. I am certain they are wrong to declare a decline in CO₂ caused a decline in temperature, it’s more likely the other way around. And did they consider a decline in temperature could easily have caused increased mortality, even to the point of a decline in population? Researchers are now indicating the various plagues caused population declines in Europe so I believe the introduction of all those diseases at once likely had an affect on New World populations. But that was on top of, added to, something else (probably climate related) that was already going on.

    Second error:

    Furthermore, we show that the global carbon budget of the 1500s cannot be balanced until large-scale vegetation regeneration in the Americas is included.

    There is absolutely NO WAY to prove a negative like this. No matter how many things they considered to come up with “…the only thing it could have been…” it would likely take me only 30 seconds of thought to come up with something they never considered that could also balance the global carbon budget.

    • So if they admit that ECS is really 1.5 instead of 4.5 they will have to triple the death toll? My crystal ball showed me this headline:

      Genocide Worse Than We Thought

      Latest estimates of ECS prove that 170 million peace-loving, highly-civilized farmers were killed by barbarian European invaders.

      From EurekAlert!

  10. The authors apparently didn’t consider that a principle of physical chemistry is that CO2 is more soluble in cold water than in warm water. If the world cooled off, then some of the CO2 in the atmosphere would have gone into solution. They also apparently aren’t familiar with Occam’s Razor.

    • surely this fulfils Occam Razor, after all we know that Columbus invaded America and that the
      overwhelming majority of the population died as a result. This one simple fact explains 50% of
      the temperature decline during the later stages of the little ice age. They also consider the changes in
      fluxes in oceans as well during that period (see Fig 6).

      • Read Alan Tomalty’s post above, in which he calculates the proportion of land which became grassland, and get back to us.

        • Heck, it would be nice if Percy would read his own post above and explain why he’s directly contradicting himself.

      • Looks like Percy is as big a hypocrite as he accuses others of being.
        Just a few minutes ago he was chastising someone for not noticing that the paper was full of may be’s and might haves.
        And now he’s going full alarmist on us and proclaiming that the papers premise is fully proven.

        This paper explains nothing. It’s a huge accumulations of assumptions and unproven assertions.
        Their claims regarding Indian population. Unproven and widely disputed.
        Their claims that the Indian population was heavily into agriculture. Not supported by the facts.
        Their claims that land abandoned by the Indians would become forested. Depends on where that land is.
        They also ignore changes in forestation in the rest of the world, as well as even bigger changes in forestation that occurred both before and after, yet had no impact on climate.

        Like the rest of the trolls, Percy will use any argument that advances his peculiar religion.

      • “…Columbus invaded America… ”

        May I suggest you are wearing your White Guilt a little too tightly today, Percy. Columbus didn’t even reach continental America until his fourth voyage and if turning up, having a look around and then sailing home again is an invasion then those D-Day planers were certainly doing things wrong.

        I also suggest that you do not fully understand what Occam’s Razor actually is.

        Let me put it this way, here are two possible solutions to why the ‘coldest parts of the LIA occurred’ :
        A – The sun decreased in output
        B – Columbus invaded America (without being smart enough to claim naming rights, tisk tisk) allowing hordes of other Europeans to cross the Atlantic, cause the deaths of a significant percentage of the existing population which in extension lead to farmland (which apparently doesn’t absorb CO2) being replaced by regrowth (which apparently absorbs CO2 in a much greater manner) which reduced CO2 levels by 10ppm globally which helped to make the coldest part of the LIA (not all the LIA mind, just the coldest part) colder.

        Now, using Occam, A or B is simpler?

        Also, applying Occam, correctly or not, does not prove your theory. It is simply a tool to assist people in cutting through the bumf and suggesting where their time and effort could best be applied for further research.

      • surely this fulfils Occam Razor

        “You keep using that word, I do not think it means what you think it means” – Inigo Montoya

        Occam’s Razor is the principle stating that among competing hypotheses, the one with the fewest assumptions should be selected.

        This paper is riddled with assumptions. It’s about as far away from an Occam’s Razor candidate as one can get.

  11. This paper is a Leftist dream-come-true by linking Climate change to agricultural change and then linking them both to a severe racist slaughter of indigenous peoples by evil White Colonists. If it was not so funny to read, one could become quite annoyed by it, but it is just a comic paper, so why bother.

    • Wait till the Marxists get hold of this in Australia. They push the line of white invasion and slaughter and if they can link that to climate change we can close our few remaining coal power stations and follow Spain down the road to disaster.

      • The tragic part of Australian ‘Invasion Day’ Marxists is that if they ever managed to prove Australia was ‘invaded’ it would cancel out the Native Title laws basically overnight.

        Native Title in Australia works on the agreement that Australia was COLONISED. If Australia was invaded then all the land would belong to the invader under the right of conquest laws. Right of Conquest was recognised by the UN back in the day in an attempt to formally define exactly where countries began and ended. Your ethics may vary on if it is a good or bad thing, but it is part of the UN.

    • It’s being reported as unquestionable truth by all the usual left wing suspects, but this is no surprise.

  12. Well, we’ve had normal science, post-normal science … why not surreal “science”? This must be worth a few marks just for the bizarre artistic inventiveness behind it. 😐

  13. We are all meant to feel ‘guilty’ !

    That’s the real purpose, raison d’etre, of this piece of greenist fluff.

    But unfortunately the authors made the basic mistake of confusing causes and effects.

    The LIA started around 1350 CE. That’s well before the Spanish arrived in the ‘Indies’ in 1492. Also there was a huge population drop due to plague and other diseases after 1340 in Europe. This lead to the abandonment of fields and to re-afforstation in Europe.

    BTW, the big dying started in Mexico in 1530’s after a new viral disease was introduced, probably small pox. But Mexico is not big on forests apart from the tropical areas which were not highly populated.

    And BTW, the Mayans civilisation collapsed around 950 CE because of drought. Their city based civilisation disappeared and the land reverted to jungle..

    But I don’t see these authors discussing if this caused global cooling as well..

    All in all : dopey stuff !

  14. The Little Ice age started before Columbus. The climate had changed so much in the 15th century that the Vikings had to abandon their Greenland settlements. This was before Columbus arrived elsewhere in the Americas.

    • They are like the excess deaths that models show occurring due to partial government shutdowns. Percy can explain it to you.

    • Many of them were buried, research has been taking place on the skeletons to learn the cause of death.
      E.g. Nature Ecology & Evolution, volume 2, pages 520–528 (2018)
      They were able to show the presence of pathogens after the arrival of the europeans but not before.
      The huge die-off of the native populations is well documented, in one battle between the conquistadors and the Aztecs the Aztec army was too sick to fight. Some diseases in N America travelled along the trade routes in the continent before the europeans so that often early explorers came across deserted settlements when they moved inland. The native populations became aware that the diseases came with the europeans which is one reason why they tried to destroy the early coastal settlements.

    • where are the bodies?

      OMG no body.. must be easter.

      the logic of no body found is kinda religious

  15. So now we have “science” which “proves” that the “Anthropocene Epoch” actually began in 1492! Who’ed of thunk it? I mean I haven’t had anyone explain to me what caused the weather to be so variable in the early and mid 1930’s despite having many more measurements of the vital statistics of the weather during that time compared to 14 to 1600’s and yet these geniuses have figured out we humans were a significant factor in causing the LIA? I guess we should now see headlines which declare “Scientists Say the Only Way to Save the Earth From Climate Change and Prevent CAGW Will Be An Extensive Genocide Campaign. ” Oh wait! Haven’t I heard that before?

  16. There is nothing TheMagicMolecule™️ cannot do.

    Mr Carbon-Dioxide sez:
    Raze civilizations… I’m there.
    Devour the Medieval Warm Period.. yep! Been there, done that.
    Maunder Minimum… sun control, no problemo.
    A Little Ice Age… yep, cold – my specia-li-ty.
    Modern Warm Period – whoa look out -you’re all gonna fry.

    Why you ask?
    Because some Rentseeking Huckster needs a grant.

  17. 56 million deaths. I am calling this one. The entire human population of that era would have been around 100 million. Agriculture still draws in CO2, as does grass, so the effect on CO2 would be microscopic if even measurable. The effects on global climate due to CO2 bandwidth absorption from the increased forests would be infinitesimal.

    The green lunatics would love to end agriculture, dams, grazing animals for food, use of fossil fuel (for medicines, metals, energy, insulation, wires etc) to go back to the stone age-pre Aztec and Inca technology. What the brainless greenie types are too daft to recognise is that the planet can only support around 7 million humans under these conditions, not 7 billion. Just one in a thousand (pretty tough ones at that- not little green weenie refuse-to-work crybabys that go into rages at the slightest provocation) could survive. The weenie greenies who have no survival skills at all would not have a hope in hell of survival. Those on the brink of starvation eking out an existence would not tolerate these self-centred little parasites-they would eat them.

    Continuing belief in this sort of rubbish “science” could lead to the mass destruction if not actual extinction of the human species.

    • World population in 1500 is estimated at 420-500m. But yeah, they are positing a greater than 10% decline in global population due to pandemic in the Americas. The percentage doesn’t make it implausible, but to claim nearly 6 times as many deaths as earlier estimates of total population is pretty bizarre.

      Also you certainly can’t consider Incan civilization to have been stone age. The conquistadors were quite interested in their metallurgical skills.

      • They could smelt bronze, so technically one could argue they were bronze age. They never got out the very early stages of a bronze age though, even though they had the technology for quite a while. No swords, for example. Perhaps copper was rare there.

      • Mark W
        You asked, “Using the tools available at the time, could the Inca have accessed those mines?” The simple answer is that they were able to extract gold, silver, and platinum from stream gravels, so if native copper was present (which it almost certainly was) then they could have treated it similarly. Whether or not they had the metallurgical skills to reduce copper carbonate or sulfide, I don’t know. But, they only needed small quantities, not a world-class mine.

        There are mine tunnels in the Swiss Alps that were driven for miles 2,000 years ago. They were, apparently, driven entirely by building fires at the tunnel face, then throwing water on the rocks. The shattered rocks were then broken apart using deer antler picks. Mining didn’t require very high technology.

  18. I was lying in bed last night and heard this paper reported by the BBC.
    I groaned, said you gotta be f***n kidding, and went to sleep.

  19. Most of the largest populations in NA had already been greatly reduced hundreds of years before European colonization.

    And what about the fact that Genghis Khan’s invasions killed 5% of the world population around the same times?

  20. The greatest genration must be turning in their graves. We (or Caucasian socialists actually) are destroying all they worked for and died for. History will judge this period very harshly.

  21. The anti-colonial narrative has been part of the green mantra for some time. This is a clear example where science is being twisted to suit the narrative.

  22. The authors estimate that the loss of 55 million people over 100 years reduced co2 by 5ppm.

    Over the past 100 years population has increased by 5.5 billion. This is 100 times greater than the 55 million population loss. By the authors reasoning this should have resulted in an increase in co2 of 500ppm without burning any fossil fuels.

    However the increase in co2 was considerably less than 500ppm. This suggests that burning fossil fuels actually reduced atmospheric co2 by reducing the amount of land required to feed the population.

    That in point of fact, we may not be able to reduce co2 by reducing fossil fuels if in the process we increase land use. This points to a potential problem with increased land use for renewables and biofuels.

  23. The reduction in co2 as a result of fossil fuel use is an idea that has not been explored. Instead the assumption is that fossil fuels increase co2, based on what would appear to be common sense.

    However the co2 flux due to vegetation is very much greater than that due to fossil fuels. The assumption is that the vegetation flux nets out to zero. But the authors of this article provide evidence that this is a false assumption if population is changing.

    By using fossil fuels we have dramatically decreased the amount of land required to support one human being. This should have significantly uncreased the amount if carbon stored in vegetation as compared to what would be required to support 7 billion humans without fossils fuels.

    This us the point that has been overlooked. Fossil fuels increase co2 but they reduce land use which reduces co2.

    Based on the authors numbers it would appear that atmospheric co2 today would be about 700ppm without using fossil fuels to support 7 billion people and about 400ppm to using fossil fuels to support 7 billion people.

      • I’m still waiting on my first check from big oil.

        I actually think the idea has merit. We have dramatically reduced the land required to support 1 human being by the use of fossil fuel which has dramatically changed the natural carbon flux IN COMPARISON to what it would take to support 7 billion otherwise. This has not been accounted for anywhere I have seen.

    • Ferdberple
      I like your line of reasoning. However, something that needs to be taken into account is that only about half of the reasonably well-known anthropogenic CO2 shows up in the atmosphere. There are poorly known sinks that are buffering the increase in concentration.

  24. My thoughts are a reduction of the H20 that the irrigation of crops from the civilizations that high population areas were decimated. The rivers of H20 we use in irrigation reduced the H20 in the air and the greatest warming factor went down. 8,000 years ago we started changing the climate. How? Irrigation.

    • Wasn’t it about then – 7500 years ago [or BC??] – that the Euxine, the Black Sea was formed?
      That increased the area of free water available globally; would that increase be greater than that from irrigation? My guess is yes.
      It also sparked various ‘Flood’ narratives, presumably including the “Noah’s Flood” one in the Old Testament.

      Auto

  25. The indigenous ancestors released a lot of CO2 burning to clear for planting & more open access to hunt animals. Gaia’s microbials then claimed sacrificial indigenous humans to reduce CO2 emissions for Gaia.

    But white privilege exhaling CO2 took over & in doing so they brought about more C3 plant productivity. My inter-sectional university class made me aware how unequal this is &, I hate to tell you, that obviously Gaia is racist.

  26. The unmentioned issue that I see is that there likely was contact between Europe and America prior to Colombus, and I am not using the Dighton stone here as proof, or any supposed anomalous finds; Columbus’ diary of his first voyage mentions seeing a ship hulk of European origin beached on an island, thus europeans had probably reached the American side of the Atlantic before Columbus. This injects a large amount of uncertainty into the equation.

    • Tony Garcia,

      Do you have a reference for:

      ‘Columbus’ diary of his first voyage mentions seeing a ship hulk of European origin beached on an island’?

      A quick Google didn’t come up with anything.

      Ciao
      John

      • I have and read Robert Fuson’s translation of the Log of Christopher Columbus and don’t see any evidence based on a cursory examination. There were rumors that ships had come elsewhere to the west, Columbus attributed them to the “Great Kahn.” Natives had canoes that he said would hold 40-50. Currents could have brought wreckage. Bunch of large trees just appeared on S Padre Island, origin questionable.

        I worked a little with several good historians. Climate people don’t know what they are getting into. History is about as hard as it gets, Chamber of Commerce and other forms of corruption, no replication, only one history. Wait until they get into the expeditions that dealt with floods, hurricanes, etc. No way to compare it statistically.

        I would check Samuel Eliot Morison’s work. He was a skeptic.

        • In the 1400s there was a Chinese treasure fleet commanded by Zheng He which travelled great distances.
          Apparently the Chinese emperor had the fleet destroyed by the 1500s as he was afraid of foreign influences on China.
          Google Zheng He to get details.

      • I picked this up from an article read some time ago, which I did not fact check. When I read your question, I downloaded an abbreviated copy of his journal off this site: https://archive.org/details/cihm_05312/page/n3 and read the journal. On page 219 mention is made of the firing of a lombard at a beached ship. This is the only reference I could find that may be relevant, and there is an article by an historian that claims the ship was the Santa Maria itself
        (https://www.maritime-executive.com/article/Historian-Claims-Shipwreck-is-Not-Columbuss-Santa-Maria-2014-06-09), in which case it will not be another nation’s exploration vessel. Regards, Tony

        • In addition, I believe the island has been identified and the local settlement found, but they are still searching for the location of the spanish fort. Surprisingly, I have not yet read about anyone trying to find that ship’s ballast pile. I have read that in some cases the type of rocks used can help identify the ship’s origin….

  27. So… according to this Columbus prevented global warming and if not for the colonization of the Americas the world would a lot hotter. :-/

  28. If the demise of, for the sake of argument, 50 million and the ensuing ‘reforestation’ can make the global temperature drop by more than a degree, should not the post industrial population explosion to 5000 million have risen the temperature by some, eh, 100 degrees? (Or at least something similarly big?)

    The only positive aspect of the paper is that the authors implicitly acknowledge that the little ice age was a global phenomenon.

  29. They are a few thousand years late for arrival of Europeans. The copper for the bronze age probably came from the Great Lakes region. See America B.C. by Barry Fell.

    • There is a big island in the Mediterranean called Cyprus, which gave its name to the metal found there in abundance, Cuprum, copper.

      • saveenergy
        “Corn?” Please explain. Corn (maize) was introduced to Europe in post-Columbian times, not pre-Roman. Did you mean the mineral resources of Cornwall?

        • Corn in english means grain, prior to the roman invasion of Britain grain (mostly wheat) was major export to the continent along with tin and copper. Corn meaning maize is american usage.

          • “John Barleycorn” is an old song. We’re told men came out of the west “& made a solem vow, John Barleycorn must die ….”

            My impression is that originally the grain refered to as “corn” was barley. Asude from beer suitability in early agriculture barley would likely have been a more reliable crop than wheat.

            Saxon word “barton” is described in an 1857 dictionary as: “… a corn town, or barley village.” England had 30 villages named Barton & some parishes too.

            Barton was the name for a place around a “Bere turn”, which was a barley enclosure. Turn was derived from “tun”, which originally meant an enclosed homestead; & “ton” became an alternate pronunciation of “tun”.

            Thus “Bere” was a name for barley & “Bere tun” –> “Bere ton” –>”Bere turn” –> “Barton.” I surmise the famous beer brewing site of “Burton, Trent” is another intonation of barton.

            Burton’s mineral ratio in it’s water is famous for producing “crisper” tasting local beer with “body”. Now brewing supply companies offer a recreation of that local water by selling “Burton Brewing Salts” (Ca++ 352 ppm, Mg++ 45 ppm, Na+ 44 ppm (contributes to “body”),Cl 16 ppm, SO4– 801 to 820 ppm (contributes crispness & bittering) & -HCO3- 320 ppm).

            I buy “Burton Brewing Salts” to put in my reverse osmosis water & carbonate for drinking; the total dissolved solids produce a tasty mineral water. I add between 1.2 to 1.6 gram per liter & carbonate that from a 20 pound CO2 tank with a regulator (using clever “Fizz Gizz” products for injection). When my rig bleeds CO2 into the air I accept the loss & am content knowing it’s plant food.

  30. ” We investigate whether the decline in global atmospheric CO2 concentration by 7–10 ppm in the late 1500s and early 1600s which globally lowered surface air temperatures by 0.15∘C, were generated by natural forcing or were a result of the large-scale depopulation of the Americas after European arrival, subsequent land use change and secondary succession”

    Okay, assume 10 parts per million, from 280 ppm to 270 ppm.

    According to the IPCC figures, that would result in a wattage drop of
    5.35 ln (270/280)= .195 watts

    resulting in a temperature drop to
    ((240-.195)/240)*0.25 =.999797

    Assume the earth was at a pleasant 14 C = 287 K BEFORE the evil Europeans wiped out the American aborigines.
    Then, temperatures would have dropped to 287 K*.99979= 286.94, a horrendous drop of 0.06 C, aggravating the little ice age.

    And that’s if ALL of the wattage decrease went into temperature, none into latent heat or convection loss.

    • horrendous drop of 0.06 C,
      =========
      And the 100 times greater population increase over the past 100 years would have increased temps 6.0 C except for fossil fuels making it possible to grow 10 times as much food per acre. As a result temps only went up 0.6 C.

  31. This “passes” for “science?”

    Population reduction, that’s the goal.
    And starvation is very effective.

  32. If the reduction in CO2 caused the Little Ice Age, then why do the greenies want to reduce CO2? To put us back into another Little Ice Age?

    • StephenP
      February 3, 2019 at 5:25 am

      “If the reduction in CO2 caused the Little Ice Age, then why do the greenies want to reduce CO2? To put us back into another Little Ice Age?”

      Well, Yes.
      Yes, they do.

      And the necessary reduction of population that that temperature drop would entail [without fossil fuels] – a feature of their plan, not a bug.
      Their aim is a global population under 750 million; current global population about 7,681 million – ref http://www.worldometers.info/world-population/#top20 @ about 2125Z/3rd February 2019.

      Auto

  33. I have an idea. Why don’t we require all renewable energy companies donate their land and profits to Native American tribes in order to provide recompense for all the genocide and land stealing that white Europeans did. /sarc

  34. The timing of these events doesn’t synchronize…

    If one looks at the combined CO2 and δ13C graph, δ13C drops and then increases first and when that stops, CO2 starts to decline. If the CO2 drop was caused by plant growth, both δ13C and CO2 would synchronize in opposite directions. δ13C and CO2 levels are measured in the same gas samples, that is not a sampling error.

    Second, if one looks at the temperature reconstructions (as far as reliable), the cooling was 50-100 years before the 6 ppmv drop in the Law Dome ice core (which has a high resolution of ~20 years).

    Third, there is no explanation for the initial δ13C drop before the δ13C increase. A δ13C drop is only possible by burning a large amount of organics (forests?) with adjacent regrowth and δ13C increase, but there is no increase of CO2 while δ13C drops. The only explanation I can imagine (just speculation) is that the cooling already has started while forests were burning, thus compensating for the CO2 loss, until the forests started to regrow.

    Fourth, the net effect of a change of 6 ppmv in the atmosphere is good for 0.02ºC (Modtran). Not measurable in temperature or climate…

  35. Sounds like just another plug for Soylent Green to save Gaia unless they’re suggesting white guys aren’t generating enough diseases to do the job. Blame modern medicine I suppose.

    I’ve given up trying to work out where these bizarro cult people are coming from so wild speculation it is if that’s the only game in town. The world definitely needs more flippancy.

  36. While we are at it, let’s not forget to blame modern humans for exterminating the Neanderthals.

  37. globally lowered surface air temperatures by 0.15∘C, were generated by natural forcing or were a result of the large-scale depopulation of the Americas after European arrival, subsequent land use change and secondary succession.

    population estimates we calculate a pre-1492 CE population of 60.5 million.
    ___________________________________________________

    Now there’s https://www.google.com/search?q=latin+america+population+2100&oq=Latin+america+populations&aqs=chrome. and we’re brave waiting for doomsday.

  38. Ah… Those evil Europeans destroyed Wakanda in the Americas with their magic CO2 molecule and disease, ‘eh?

    The Socialists revising history again and pretending that the science proves it.

    • No revision of history is needed, the devastating effect of the epidemics is well documented in contemporary sources. One example from a Franciscan friar:
      “Nobody had the health or strength to help the diseased or bury the dead. In the cities and large towns, big ditches were dug, and from morning to sunset the priests did nothing else but carry the dead bodies and throw them into the ditches.”

      • Phil,
        Who dug the “big ditches?” That is probably even harder work than loading bodies onto a wagon. Are we to believe that a couple friars buried 90% of a town?

  39. This might be the CO2 record that has them all in a tizzy:

    https://www1.ncdc.noaa.gov/pub/data/paleo/icecore/antarctica/law/law_co2.txt

    They wrote, “…this contributed between 47% and 67% of the 15–22 Pg C (7–10 ppm CO2) decline in atmospheric CO2 between 1520 CE and 1610 CE seen in Antarctic ice core records.”

    That “75-year smoothed” ice core data does show a 7.6 ppmv decline in CO2 level from 1520 to 1610 AD. Here’s an excerpt:

    1520 283.1
    1525 283.2
    1530 283.2
    1535 283.2
    1540 283.1
    1545 283.0
    1550 282.8
    1555 282.6
    1560 282.2
    1565 281.8
    1570 281.2
    1575 280.5
    1580 279.7
    1585 278.8
    1590 278.0
    1595 277.1
    1600 276.4
    1605 275.8
    1610 275.5

    You can see that the decline started about 1545 AD. That corresponds nicely with the worst of the Aztec epidemics:

    https://en.wikipedia.org/wiki/Population_history_of_indigenous_peoples_of_the_Americas#/media/File:Acuna-Soto_EID-v8n4p360_Fig1.png

    However, it is about two centuries too late to have caused the Little Ice Age. By 1545 the Viking settlers had already been frozen out of Greenland for a century or more. Here’s a graph from the FAR:

    https://sealevel.info/LIA_blamed_on_European_colonization_of_Americas01.png

    What’s more, the truth is that nobody really knows the cause of what these authors call the “European epidemics” that devastated native Aztec and Inca populations. Here’s an article. (Ignore the idiotic headline, which is contradicted by the article; most newspapers add their own headlines, which are frequently inaccurate.)

    https://www.news.com.au/technology/science/archaeology/500-years-later-scientists-think-theyve-solved-germ-mystery-that-nearly-wiped-out-mexican-population/news-story/f35d6baab1f756cf2ae4a8b898bcfa80

    • That 7.6 ppmv drop in CO2 level from 1520 AD (283.1) to 1610 AD (275.5) represents a 2.7% decline (if it is real, and not just an artifact of imprecise ice core measurements).

      If TCR sensitivity is 1°C/doubling (my estimate), then that 2.7% change in CO2 level corresponds to a temperature difference of log2(283.1/275.5) = 0.0393°C.

      if TCR sensitivity is 2°C/doubling (a typical IPCC/alarmist estimate), then that 2.7% change in CO2 level corresponds to a temperature difference of 2×log2(283.1/275.5) = 0.0785°C.

      That includes the effects of all short-term feedbacks.

      Yet the authors attribute a 0.15°C change in temperature to that tiny change in CO2 level, which implies a TCR sensitivity of 3.82°C/doubling. That is much higher than the assumed TCR sensitivity baked into any of the 30 models which AR5 lists in Table 9.5:
      https://sealevel.info/AR5_Table_9.5_p.818.pdf
      Source:
      http://www.ipcc.ch/pdf/assessment-report/ar5/wg1/WG1AR5_Chapter09_FINAL.pdf#page=78

      I wonder is how drek like this makes it through peer-review? It seems that climate science has become one of those fields, like “gender studies” and “critical race theory,” which are dominated by crackpots. Much of the the drek that passes “peer-review,” and gets published in high-profile academic journals, is comparable to this:

      https://youtu.be/kVk9a5Jcd1k

      • Colder water absorbs more CO2, so I’d expect CO2 levels to drop due to the temperature change of the Little Ice Age.

        CO2 levels were around 200 ppm during the last glacial maximum vs. the normal pre-industrial 280ppm, and I believe it was about 8°C colder, so that’s roughly 10ppm per degree.

        If the Little Ice Age temperature drop was around 1°C, that’s in the ballpark of the 7.6 ppm drop you found.

        • I agree, Bart, and that also constitutes evidence that the MWP-to-LIA cooling was global, rather than merely regional.

          There’s a big ongoing debate about that. Defenders of the Mann/Jones/et al “hockey stick” need for the warm MWP and cool LIA to have been merely regional. But if the MWP & LIA were merely regional (Europe & Greenland), rather than global, then they couldn’t have caused much change in CO2 levels in Antarctica (the site of this ice core record).

          • The IPCC in AR5 acknowledges the LIA was global, affecting both the Northern and Southern Hemispheres. They are fuzzy about the MWP, indicating there is debate about it.

            Do the global-MWP-deniers have any explanation for the law dome CO2 increase during the MWP?

        • The oceans are usually in their warm phases during centennial solar minima, because of increased negative NAO/AO.

  40. Those idiotic claims on human caused climate disruptions seem to be endless.

    Here is another climate fool who claims that humans began to modify the climate 5000 years ago, disrupting Milankovitch cycles with methane (breeding) and after, CO2 emission :

  41. A thousand years ago the inca civilisation was wiped out by climate change, wonder what they have marked down for the one.

  42. Someone may have already mentioned this but did not the carbon dioxide levels drop after the temperatures dropped. Would not the oceans have begun to take up more carbon dioxide as a result and could not this have been the cause of the reduced in atmospheric carbon dioxide?

  43. II recommend reading two excellent books by Charles Mann, “1491” and “1493”.

    1491: Summarizes recent studies on what the western hemisphere was like before Columbus.

    1493: What resulted: not just the disastrous effects of European diseases, but things I’d never known about how it impacted the rest of the world. Not just the potato, tomato, etc.

    And Mann doesn’t have an axe to grind: it’s not just “bad imperialists vs innocent native Americans”. While Columbus & his successors did many bad things, they certainly didn’t WANT to exterminate millions of people!

    I recommend you all read both books. I learned a lot from them– and no, I certainly didn’t “learn” that increased CO2 is the leading cause of climate change!

    • The things Columbus et. al. did to the Indians were bad by modern standards, but were comparable to what the Indians were already doing to each other.

      • I think it never does any good to try assigning historical guilt, i.e. “our atrocities are worse than their’s were”, as some people spend all their efforts doing. Every age has had the wonderful mixed with its awful. And very often “they know not what they do” is the case. E.g., who knew about genetics and immunity in past ages? (That’s what wiped out the millions of Amerindians)

        We should just try to improve, based on what we learn from our history.

        And read the Charles Mann books! That was my message; am not qualified to evaluate the “wild claim” paper which started all this.

  44. Ah Ha. I now understand!

    It’s Indignant Indigenous’ Year at the U.N. !

    Splendid.

    Such a cacophony to go along with the UNESCO, UNICEF and 501 (c) (3) & (4) orgs, like “Doctors Without Borders” funded and managed invasion of the U.S. Southern Border! “White Man came, from across the sea … spreading disease, and misery … It’s Now Our Fight, We Have The Right … We Will Ignite … The Climate Bomb … [chorus of drums pounding up a stampede] … Run To The Hills [Evil White Man], Run For Your Life! ”

    Ha ha! 😀

  45. I’ve been waiting to see this ‘wild claim’ come up on WUWT.
    I put it in the ‘Tips and Notes’ section several days ago.
    Did anybody catch that?

    Also, can somebody tell what I did that has caused all of my comments go into moderation before posting?

    Heck, as long as I’m here, is Anthony working on restoring the formatting we had for awhile … when we could edit our comments, and like/unlike comments, etc? I realize things have been hectic, what with the wildfire and all, just wondering if it’s still in the works.

  46. “beginning in the 1500s with a minimum in the early 1600s” – So in only 8 years enough of the population died off AND enough land was reclaimed to wilderness to be detected in Ice Core CO2?

    What do the error bars look like on population estimates, temperature variations, and CO2? We can measure temperature to 0.15C now let alone for 500 years in the past.

    • Yes, and whatever answer they give you, you’ll know that the real facts are the complete opposite. 😉

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