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Rainfall clues link climate change to Maya collapse

Ancient Central American rainfall records suggest climate change was linked to the rise and fall of the Maya civilisation…

Caana pyramid in Caracol, Belize. Image courtesy of Douglas Kennett, Penn State

Stucco Frieze in Caracol, Belize. Image courtesy of Douglas Kennett, Penn State
Ancient Central American rainfall records suggest climate change was linked to the rise and fall of the Maya civilisation between AD 300 and 1000, a new study has found.

Giant stone structures throughout the region hint at the strength of the Maya economy and its kings in its heyday, when plentiful rains led to an an abundance of food and a population explosion.

The study, published today in the journal Science, compared rainfall patterns reconstructed from stalagmites inside Yok Balum Cave in Belize with historical clues carved into local monuments.

While rain brought prosperity, the drought that followed brought disaster.

“We propose that anomalously high rainfall favoured unprecedented population expansion and the proliferation of political centres between 440 and 660 C.E,” the authors wrote.

“This was followed by a drying trend between 660 and 1000 C.E. that triggered the balkanisation of polities, increased warfare, and the asynchronous disintegration of polities, followed by population collapse in the context of an extended drought between 1020 and 1100 C.E.”

The droughts were linked to crop failures, death, famine, and migration in Mexico, the study said.

“Over the centuries, the cities suffered a decline in their populations and Maya kings lost their power and influence,” lead author Dr Douglas Kennett, a professor of anthropology at Penn State University, said in a statement.

Dr Andrew Glikson from the Climate Change Institute and the School of Archaeology and Anthropology at the Australian National University said the new paper “builds up on previous studies, confirming a collapse of Maya civilisation due to combined regional warming and deforestation.”

“The ensuing severe droughts and agricultural collapse were caused by aggravation of natural warming trend due to extensive deforestation and thus loss of moisture, droughts and depletion of the ground water the Maya tapped from water holes,” said Dr Glikson, who was not involved in the study.

“The parallel with modern climate change is evident – global warming associated with deforestation, leading to droughts in extensive areas and floods in other regions.”

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  1. Spiro Vlachos

    AL

    At last, an article (the one behind the paywall) cited by The Conversation that explains a historical pattern of changing weather related variables and the correlation with the fall of a civilisation. To parallel this with "modern climate change" may be valid since if such a movement in climate has occurred in the past, why would it not today? Of course, what your article and the one cited fails to mention is that movements in these variables changed direction between then and now. The climate…

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    1. Michael Wilbur-Ham (MWH)

      Writer (ex telecommunications engineer)

      In reply to Spiro Vlachos

      Spiro is one of The Conversation's regular climate change deniers.

      The big difference between the climate changing in the past and what we are doing to the climate today is that this climate change is man made, we know just how catastrophic it will be, we know that we can prevent this climate change from happening without major disruptions to our standard of living, and we know that the economic cost of taking preventive action is less than the cost of adapting to a warmer world.

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    2. Spiro Vlachos

      AL

      In reply to Michael Wilbur-Ham (MWH)

      Unfortunately, you require a minimum level of numeracy to understand my post.

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    3. Account Deleted

      logged in via email @drdrb.net

      In reply to Spiro Vlachos

      I suggest that the difference between the Mayan case and the current case (and the Sunspot theory of the Great Depression) is that one is talking about regional climate changes or phase shifts _within_ the global climate system, where the global energy balance is probably unchanged, and the other is about changes in total global energy levels (caused by greenhouse gases now, and sunspots then if your paper is correct). Note that the Maya region of Central America was getting dryer and possibly cooler at the same time that Europe was having the warmer, wetter Medieval Warm Period. Current climate change, on the other hand, is going to drive warmer, wetter weather _everywhere_ due to the atmospheric energy imbalance.

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    4. Linus Bowden

      management consultant

      In reply to Michael Wilbur-Ham (MWH)

      What? Spiro just posted quite a detailed post that he does believe in climate change, and his knowledge of its many and complex effects in different historical, geographic, and cultural contexts.

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    5. Michael Wilbur-Ham (MWH)

      Writer (ex telecommunications engineer)

      In reply to Linus Bowden

      I base my judgement on a person not just by the one post above, but on what they have said in many other conversations. Google helps me do this quickly.

      All deniers believe in climate change - they all agree that the climate has always changed. But we all know that the term denier is short for someone who 'denies the scientific evidence that human emissions of carbon are causing the climate to change now'.

      So thanks to google I know that your views on climate change are "The tragedy of this issue is that the science has fallen victim to that old truism: 'if you lie down with dogs, you'll catch fleas.' The loudest yappers are unfortunately not scientists, but neomarxist Media Studies luvvies. This is why the public has turned off, as the issue more and more is presented like Maoist propaganda."

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    6. Michael Wilbur-Ham (MWH)

      Writer (ex telecommunications engineer)

      In reply to Spiro Vlachos

      Finding out a little of what someone has said earlier puts their comments into context. It means that my response is appropriate for that person.

      I don't think I hate anyone. But I do believe that some deniers are evil.

      I also believe that some deniers are paid and organised to disrupt some conversations. (A quick analysis also shows that you are probably not part of this organisation.)

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    7. Linus Bowden

      management consultant

      In reply to Michael Wilbur-Ham (MWH)

      Unfortunately, Michael, being able to google is not enough. You still must rely on that primitive technology known as 'reading'. What you cited there was nothing like me denying AGW. I was explaining why so many people out there are indifferent and even hostile to the idea.

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    8. Michael Wilbur-Ham (MWH)

      Writer (ex telecommunications engineer)

      In reply to Spiro Vlachos

      A recent thread had lots of post deleted by the moderator. The posts deleted were personal abuse by the deniers, some of which was against me. Apart from some posts responding to the first deleted post, where the moderator decided the responses were irrelevant once the original post was deleted, none of my post have yet been moderated.

      In the heat of discussion I might have said somethings that I should not of, but I challenge you to find a post of mine which is personal abuse.

      Your post to me saying "Unfortunately, you require a minimum level of numeracy to understand my post." is, in my opinion, personal abuse, because your only defence against my comment is a personal attack.

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    9. Michael Wilbur-Ham (MWH)

      Writer (ex telecommunications engineer)

      In reply to Linus Bowden

      I think that you are pushing the line that the 'alarmists' are so extreme that we should ignore them, climate change is real, but its effects are not so bad, so we don't need to do much to tackle it.

      Readers can make up their own mind.

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    10. Mark Harrigan

      PhD Physicist

      In reply to Spiro Vlachos

      The point of the article, which Spiro either deliberately or foolishly fails to understand, is that sustained climate change (regardless of cause) can have highly damaging effects on a civilisation.

      The article makes no comment about the cause of change in the case of the Mayans (or for that matter about the cause of change today).

      Spiros is on record as denying that the current change is either a problem or man made.

      Unfortunately, you require a minimum level of scientific literacy to understand the current situtation - something Spiro has never demonstrated

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    11. Tim Scanlon

      Debunker

      In reply to Spiro Vlachos

      Spiro, you work at a university, as such the paywall shouldn't be an issue for you.

      In fact, since paywalls shouldn't be an issue, you could spend some time learning about climate science.

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    12. John Coochey

      Mr

      In reply to Mark Harrigan

      Thankyou for making the point that climate change has occurred independantly of industrialisation.

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    13. Philip Dowling

      IT teacher

      In reply to Michael Wilbur-Ham (MWH)

      Michael,
      I was wondering when you will be publishing your own dictionary? You are clearly using words in a way that only the sect of true believers in anthropogenic climate change do.
      "All deniers believe in climate change - they all agree that the climate has always changed. But we all know that the term denier is short for someone who 'denies the scientific evidence that human emissions of carbon are causing the climate to change now."

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    14. Philip Dowling

      IT teacher

      In reply to Spiro Vlachos

      Spiro,
      I found your post remarkably innocuous.
      It is remarkable that some feel the need to criticize every post not for its content but for previous comments that someone may have made, and to adduce a certain profile of beliefs that people must have.
      It is really a pity that such people cannot think of a more constructive approach.

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    15. Mark Harrigan

      PhD Physicist

      In reply to John Coochey

      In the past yes - today no. Which bit (apart apparently from all of it) do you fail to understand?

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    16. Michael Wilbur-Ham (MWH)

      Writer (ex telecommunications engineer)

      In reply to Philip Dowling

      When deniers start playing word games such as the above you know that they are just hear to waste every bodies time.

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    17. John Coochey

      Mr

      In reply to Mark Harrigan

      So all climate change is bad and is now only caused by industrialisation? For goodness sake get real.

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    18. John Coochey

      Mr

      In reply to Gary Murphy

      So everyone wants post separation employment, I was in Defence too. This is so typical of the bed wetters, how many articles can have the required buzz words rather than any development of argument.

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    19. Gary Murphy

      Independent Thinker

      In reply to John Coochey

      Do you have an argument? I thought all you did was criticise and misrepresent what other people have said.

      What is your position?
      Do you accept that the planet is warming?
      Do you accept that it is caused by greenhouse gases?

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    20. John Coochey

      Mr

      In reply to Gary Murphy

      Should that nor read "Are your now or have you ever bee a member of the Communist Party?" ?

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    21. Trevor Ellice

      Geologist

      In reply to Mark Harrigan

      The article makes no comment about the cause of change in the case of the Mayans (or for that matter about the cause of change today).

      yes it does

      “The ensuing severe droughts and agricultural collapse were caused by aggravation of natural warming trend due to extensive deforestation and thus loss of moisture, droughts and depletion of the ground water the Maya tapped from water holes,” said Dr Glikson, who was not involved in the study.

      of course the statement really says nothing and is…

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    22. Spiro Vlachos

      AL

      In reply to Mark Harrigan

      Climate science? I would call it 'undergraduate extrapolations'.

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    23. Mark Harrigan

      PhD Physicist

      In reply to Spiro Vlachos

      That you Spiro for deomonstrating so conculsively just how idiotically arrogant and ill informed climate science deniers can be.

      That you are now on record as labelling the conlcusions of every single national science body of credibility "undergraduate extrapolations" is telling.

      Plese do write to them and tell them how Spiros Vlachos - from his armchair and with no science qualifications whatsoever is right and they are wrong

      http://royalsociety.org/climate-change-summary-of-science/
      "There…

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    24. Mark Harrigan

      PhD Physicist

      In reply to Gary Murphy

      Gary - John has neither an argument nor logic nor evidence. Just obfuscating rhetoric and insult as his previous two posts clearly illustrate.

      He can't even get wind direction right let alone basic physics and science. And you'll never get him to answer your questions - he never does.

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    25. Spiro Vlachos

      AL

      In reply to Mark Harrigan

      I didn't think you all were keeping records of so-called 'deniers'. It shows you as to what lengths you all would go to.

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    26. Spiro Vlachos

      AL

      In reply to Tim Scanlon

      I know enough that assertions made about future levels of climate variables are based on some basic science (statistics) taught to some undergraduates.

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    27. Mark Harrigan

      PhD Physicist

      In reply to Spiro Vlachos

      Your post shows just how arrogant you are in denying the science - something for which you have no answer - only a pathetic whimper of a reply

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    28. Spiro Vlachos

      AL

      In reply to Mark Harrigan

      Another hater. Hatred abounds on this forum.

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    29. Michael Wilbur-Ham (MWH)

      Writer (ex telecommunications engineer)

      In reply to Spiro Vlachos

      There is a useful tool called Google - it quickly enables you to find earlier threads and see what someone said earlier. So no need to keep records.

      It also enables you to quickly look up information and learn. You should try it sometime.

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    30. Spiro Vlachos

      AL

      In reply to Philip Dowling

      I was commenting on the article. And you are doing what?

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    31. Michael Wilbur-Ham (MWH)

      Writer (ex telecommunications engineer)

      In reply to Spiro Vlachos

      And 'assertions' made about relativity and quantum mechanics are based on mathematics, the foundations of which are taught to primary school children.

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    32. Mark Harrigan

      PhD Physicist

      In reply to Spiro Vlachos

      This shows how much Sprio Vlachos does not know.

      Predictions of the possible range of future climate variables are based on basic physics, sophitsicated climate models and comparisons with past paleoclimate records.

      Most of these predictions are proving to be too optimistic. For example Arctic ice loss
      http://www.skepticalscience.com/images/Arctic_models_obs.gif

      But Spiros Vlachos has never been one to let actual data interfere his blinkered belief in denial of the climate science - after all - he's already in effect acknowledged that he claims to know better than the Royal Sociey, the American Physical Society, The American Meteorological society and evey single national science body of choice

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    33. Mark Harrigan

      PhD Physicist

      In reply to Spiro Vlachos

      Spiro - that's reall a sad reply - shows intellectual paucity. I don't hate you, I pity you. Nowhere has the word hatred or anything similar been posted by me.

      I do wonder, though, why you apparently hate the planet and your fellow man so much that you are willing to go to any lengths in your contorted posts to deny the reality of the science and think you know better than the worlds science bodies? Do you think this might say so,mething revealing about your own approach?

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    34. Spiro Vlachos

      AL

      In reply to Mark Harrigan

      Next burn down the Reichstag and have me silenced!

      I made a comment on the article. Get over it.

      I am not interested in your hatred.

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    35. Michael Wilbur-Ham (MWH)

      Writer (ex telecommunications engineer)

      In reply to Spiro Vlachos

      Mark - Do you really think that Spiro is here to debate? Do you really think that he is too stupid to understand any of your points? How can you debate science with him when he plays the same 'teasing' tactics to misinterpretation plain English?

      We all know why he is here - the article concludes with “The parallel with modern climate change is evident – global warming associated with deforestation, leading to droughts in extensive areas and floods in other regions" and Spiro is here to give the impression that climate science is either wrong or still uncertain.

      He is playing with us like you tease a kitten with a piece of string.

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    36. Mark Harrigan

      PhD Physicist

      In reply to Michael Wilbur-Ham (MWH)

      LOL - No Michael - clearly Spiro is not here to debate or engage - just spread his denialism - apparently centred in a deep hatred he has for his fellow man judging by the latest spleen in his comments.

      But as you have been pointing out - the regular tribe of speudo-skeptic denialist posters are on here to disrupt and deny the science - and they should be refuted.

      Fortunately they are part of an ever diminishing cadre since the evidence is plain to most people that such denialism is plain stupid

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  2. Sean Lamb

    Science Denier

    I have in my possession some ancient mayan codexes (bequeathed to me by father Professor I. Jones) that describe the reaction of Mayan society at the time.
    It appears that 97% of Mayan priests thought the cause of this collapse was a refusal to build enough pyramids and cut out enough human hearts to appease the angry sky gods.

    There was a handful of people who remained sceptical as regards the efficacy of human sacrifice towards altering the climate, but they were all reviled as deniers by the priestly elites.

    Plus ca change...

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    1. Michael Wilbur-Ham (MWH)

      Writer (ex telecommunications engineer)

      In reply to Sean Lamb

      The difference between today's climate scientists and the Mayan priests is that the scientific view is built up from evidence.
      The Mayan priests, and the science deniers like Sean, have no rationality behind their views.

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    2. Sean Lamb

      Science Denier

      In reply to Michael Wilbur-Ham (MWH)

      On the other hand, the human sacrifice demanded by the climate tragics is very real.

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    3. Michael Wilbur-Ham (MWH)

      Writer (ex telecommunications engineer)

      In reply to Sean Lamb

      At first I misread your post, and took climate tragics to be those who denied climate change.

      Given we are now pretty certain to get over 2 degrees warming, and more likely is 3 or even 4 degrees, the human sacrifice of dealing with the consequences will be enormous. Millions of deaths seem certain.

      The Garnuat report showed that Australia could reduce its emission and continue with economic growth. So the sacrifice Sean is talking about is not getting to twice as rich as quickly.

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    4. Felix MacNeill

      Environmental Manager

      In reply to Sean Lamb

      Don't give up your day job Sean, you're not going to make it in the world of stand-up.

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    5. Account Deleted

      logged in via email @drdrb.net

      In reply to Sean Lamb

      Sure it is Sean. Why don't you lie down on this pyramid, I've got my sacrificial knife carved from pure science right here.

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    6. Sean Lamb

      Science Denier

      In reply to Felix MacNeill

      I don't have a day job.

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    7. John Coochey

      Mr

      In reply to Sean Lamb

      A good point. The collapse of the old empire was certainly bloody people did not just drift off into the jungle like the missions. A last stand took place at the foot of the major ruins which one historian likened to excavating trenches on the white house lawn. The evidence for a prolong drought - not climate change- people are still there now so presumably the climate changed back again- is very limited lake bed analysis. If it was drought pure and simple it is difficult to see why those settlements near major rivers were the first not the last to go. Other explanations include a parasitic moth arriving from the West Indies for which the maiz had not resistance another is that rather like Easter Island people got tired of laboring building useless edifices. Once again if it was climate change how come the area is fertile now?

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    8. John Coochey

      Mr

      In reply to John Coochey

      PS the article talks about deforestation reducing rainfall. I thought that had been discredited. Do we have a genuine botanist to comment?

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    9. Linus Bowden

      management consultant

      In reply to Michael Wilbur-Ham (MWH)

      Er, you do know that the Mayan priests had empirical astronomy and calendars on their side? It is only because of their precision that the priests could scare the wits of the Mayans by predicting to the hour, minute, and second, when an eclipse would occur, and precisely when it would disappear.

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    10. Michael Wilbur-Ham (MWH)

      Writer (ex telecommunications engineer)

      In reply to Linus Bowden

      I'm talking about the Mayan priests understanding of why the climate was changing and how to fix things.

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    11. Mark Harrigan

      PhD Physicist

      In reply to John Coochey

      Coochey clearly cannot read. Nowhere does the article state that "deforestation reduces rainfall"

      It talks about "combined regional warming and deforestation.” and

      “The ensuing severe droughts and agricultural collapse were caused by aggravation of natural warming trend due to extensive deforestation and thus loss of moisture, droughts and depletion of the ground water the Maya tapped from water holes,”

      Idiot denialism write large

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    12. Trevor Ellice

      logged in via Facebook

      In reply to Sean Lamb

      so the Mayans caused climate change as well - wow they were are powerful culture, up there with the Romulans.

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    13. Mark Harrigan

      PhD Physicist

      In reply to Trevor Ellice

      The moment you think climate change denial idiocy has reached its limit - along comes somone to extend the limits of such stupidity.

      Nowhere does the article state that Mayans caused Climate Change.

      It states that Climate Change, exacerbated by environmental degradation (deforestation) wrought by the Mayans, brought disaster for their civiliation.

      No wonder deniers fail to understand science - they cannot even read plain english.

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    14. John Coochey

      Mr

      In reply to Mark Harrigan

      Thankyou for making my point for me
      "extensive deforestation and thus loss of moisture, droughts " If a drought is not a reduction in rainfall what is it? Can you not read or not reason?

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    15. John Coochey

      Mr

      In reply to Mark Harrigan

      Nowhere does the article state that Mayans caused Climate Change.

      It states that Climate Change, exacerbated by environmental degradation (deforestation) wrought by the Mayans, brought disaster for their civiliation.

      No wonder deniers fail to understand science - they cannot even read plain english.

      Err Err and your point is other than shooting yourself in the foot?

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    16. Mark Harrigan

      PhD Physicist

      In reply to John Coochey

      Which part of exacerbate (= makes worse) as opposed to cause (give rise to) do you not understand?

      Coochey the evidece is clear - you do not even understand the english language - let alone basic science

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    17. Mark Harrigan

      PhD Physicist

      In reply to John Coochey

      Since you seem determined to deny the matter, Google deforestation and rainfall and see how many science papers you find that clearly link the two

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    18. John Coochey

      Mr

      In reply to Mark Harrigan

      Given the Yucatan peninsula is on the Atlantic Coast and the continent suffers from Westerly winds how much evaporation would have resulted in terrestial rains anyway? If the rain falls on the sea it does little for crops.

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    19. Trevor Ellice

      Geologist

      In reply to John Coochey

      yeah there really is a disconnect - thruth is humans are evil they destroy and cause their own downfall even the Mayans with iron axes. What a joke - ever heard of original sin.

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    20. Trevor Ellice

      Geologist

      In reply to Craig Minns

      how many Mayans were there?
      what was the population density ?
      how many trees did they cut down and in what time period, over how big an area?
      how did this effect the climate?
      sure they maight have eaten 'emselves out of house n home - but effecting the climate, really.

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    21. Michael Wilbur-Ham (MWH)

      Writer (ex telecommunications engineer)

      In reply to Trevor Ellice

      There is this useful thing-a-me-jig called the internet.

      Why not do some research and answer your own questions?

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    22. Trevor Ellice

      Geologist

      In reply to Michael Wilbur-Ham (MWH)

      my questions goes to background behind Dr Gliksons extraordinary statement

      to add a few more :

      what is the mechansim by which deforestation affects climate?
      what is amount - how is it measured over how big an area
      is it happening today in the amazon and again how is this measured or demostrated to be occurring
      how can this effect (if demostrated) be reliably projected back into the past

      and finally why don't some journalists ask these questions

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    23. Michael Wilbur-Ham (MWH)

      Writer (ex telecommunications engineer)

      In reply to Trevor Ellice

      Why should any journalist investigate what happened to the Maya civilisation?

      What you are doing is questioning this story.

      In an earlier conversation on this site you said "I am ignorant because I think the whole premise of what is called these days 'climate science' is in error".

      No, you are WRONG because you think it is in error.

      You are IGNORANT because you won't do any research to find out what is true and what is not.

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    24. Mark Harrigan

      PhD Physicist

      In reply to John Coochey

      The predominant winds at Belize where the data was gathered are offshore easterlies. John Coochey doesn't have a clue about anything

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    25. John Coochey

      Mr

      In reply to Mark Harrigan

      Given that the so called Mayan civilization stretched from what is now El Salvador to Tabasco and it now no longer exists I am not sure what you point is.

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    26. Mark Harrigan

      PhD Physicist

      In reply to John Coochey

      "The study, published today in the journal Science, compared rainfall patterns reconstructed from stalagmites inside Yok Balum Cave in Belize with historical clues carved into local monuments."

      First John Coochey wanted to argue that because the record came from the Atlantic Coast the winds would be westerley and so evapotranspiration would not impact on land - he has been proven to be wrong on this statement.

      Now he wants to shift ground to focus on the extent of the Mayan Civiliation - which extended over many hundreds of kilometres in land.

      and thats that to be "not sure what your point is"

      The point John - is that you are completely incapable of understanding what you read - basic geography, climate science or anything vaguely resembling cosnsitency

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    27. John Coochey

      Mr

      In reply to Mark Harrigan

      See my earlier comments above about the affect of agriculture on the overall climate. Also agriculture is increasing in the area with no change in climate today.

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  3. John Coochey

    Mr

    Has anyone actually read the original article? It appears blocked but the analysis is based on stalactite records!!! About as uncertain as you can get and what other similar studies have been cross checked against other data?

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    1. Tim Scanlon

      Debunker

      In reply to John Coochey

      It appears you didn't read this article, let alone the original journal paper. Third paragraph states it measured stalactites and local recordings in the stone ruins. Nothing wrong with this, geological samples are used all of the time for analysis of historical data.

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    2. John Coochey

      Mr

      In reply to Tim Scanlon

      And these records were precisely? I have one advantage that few if any other commentators have on this article. I have spent many months in the mayan areas, my wife has a Mexican god daughter. The area is one of the most fertile areas on earth and is undergoing heavy deforestation for coffee maiz and sugar. At certain times the sky is obscured by smoke from burning of waste in the fields. Should we now expect a decline in rainfall as the forest is removed? This is something which can be checked…

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    3. Mark Harrigan

      PhD Physicist

      In reply to John Coochey

      Ah, the delicious irony of denialism induced blind stupidy!

      "You can rape and pillage your neighbour's crops but only once"

      Now, a circumstance that constributed to that situation woudn't cause a civilisation collapse would it? Would it?

      There are none so blind (and stupid) as those who will not see

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    4. John Coochey

      Mr

      In reply to Mark Harrigan

      The stupidity of bed wetters never fails to amaze me. If you read the article then you will see that the "civilization" took centuries to collapse. That was not a short famine were people fought for available food stocks. Anyone with any knowledge of mezo american history would know that the inhabitants never invented the wheel nor domesticated transport animals. That means that the ability to transport food was very limited so the population necessary to build the edifices which we associate with civilization had to rely on a local self supporting population. In fact the papers destroys much of the logic denialists position an supports the skeptics because any climate change occurred before industrialization and shows what we all know that is that the climate has been constantly changing. Once again why were the communities least affected by drought the first ones to evolve and why are we not seeing a drop in rainfall with current deforestation?

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    5. Michael Wilbur-Ham (MWH)

      Writer (ex telecommunications engineer)

      In reply to John Coochey

      It is not John Coochey's fault that he cannot understand science and the scientific method.

      But John has no excuse when it comes to understanding how people behave.

      For climate change to be 'crap' you need to explain how the vast majority of those trained in climate science in every country for over the last twenty years have got it so wrong. A huge conspiracy or what?

      I don't expect John to understand the science, but for him to have any credibility as an adult I do expect him to be able to provide a reasonable scenario to explain the conspiracy etc.

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    6. Mark Harrigan

      PhD Physicist

      In reply to Michael Wilbur-Ham (MWH)

      Maybe Michael - but given that Coochey consistently demonstrates his lack of understanding of science, it is overweaning arrogance and stupidity to continue to deny its conclusions.

      He has been challenged numerous times to reflect on what might be causing the ice caps to melt, sea levels to rise, ocean heat content to rise, land glacial ice and snow mass to disappear, nights to warm faster than days and winters to warm faster than summers not to mention the continued rise in weather and climate related disasters (over and above other geophysical disasters).

      Apparently all this is to be ignored - which is further evidence of his blind denialism

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    7. John Coochey

      Mr

      In reply to Mark Harrigan

      So when Mark and Wilbur realise they have no argument and this article scores an own goal they change the subject. Pathetic. The subject is supposed to be about drought and the change of culture in meso america. And the next irrelevant comment is? By the way where is the evidence of deforestation raising local temperatures? No flurry of links this time!

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    8. Mark Harrigan

      PhD Physicist

      In reply to John Coochey

      “The parallel with modern climate change is evident – global warming associated with deforestation, leading to droughts in extensive areas and floods in other regions.” isa the concluding statement of the article.

      Mr Coochey is on record as denying the relaity of human induced climate change today. Which bit does he not understand (apart, apparently, from all of it).

      He has not answer, nor the ability, to address the evidence to which I have referred.

      (by the way, nowhere does the article refer to deforestation raising "local" temperatures)

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    9. Michael Wilbur-Ham (MWH)

      Writer (ex telecommunications engineer)

      In reply to John Coochey

      Sorry John, but I'm getting the impression that if I found for you (because you are to lazy to search for it yourself) a scientific paper showing that deforestation does not cause a drop in rainfall, you would believe it.

      Yet you don't accept the IPCC reports which are based on thousands of peer-reviewed scientific papers.

      So on what basis do you decide what is right? Clearly evidence and scientific rigor don't count.

      And once again I point out that for you to have any credibility as an adult you should be able to provide a reasonable scenario to explain why so many scientists are wrong for so long in every country.

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    10. John Coochey

      Mr

      In reply to Mark Harrigan

      That is a lie but only to be expected. Of course climate is changing and humans have some influence on that the question is in general why the bed wetters cannot achieve any credibility nor be consistent, even the 2 per cent tipping point is an political invention with no scientific basis merely to make sure for once all the alarmists are singing from the same hymn sheet. The issue of mayan cultural change is very much open to question and if drought was a major factor (given yet again those communities with access to water were the first to give up building useless temples) there is no evidence that human activity was in any significant way a factor any more than it is now in that area

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    11. Michael Wilbur-Ham (MWH)

      Writer (ex telecommunications engineer)

      In reply to John Coochey

      John Coochey is one of those whom I suspect is part of an organised denial campaign. I suspect that he is paid to write such rubbish, and rather than being stupid he is cleverly using tactics designed to disrupt.

      Have a look at previous conversations on this website and John is notable for being highly active for a time in some conversations, but absent from others. Just as if he has been assigned a shift to disrupt a conversation, as he is doing here now.

      John's conspiracy theory is that all…

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    12. John Coochey

      Mr

      In reply to Michael Wilbur-Ham (MWH)

      Look I will give you my bank entry details and you can send me any money you like but I assure you no one has done so but I would be happy to receive it from anyone. I am reminded of the first time I was in in India where corruption is endemic. There was an article in the mainstream press about a lawyer promoted to the judiciary who received a bribe from a party to a dispute. He then received an offer of a bribe from the other party. He then went back to the first party and asked if they would increase their offer. He was shortly pulled to one side by a senior judge who told him that is not the way it is done. He was free to accept bribes from both sides but should the adjudicate on the merits of the case. But all and any moneys will be accepted.

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    13. Michael Wilbur-Ham (MWH)

      Writer (ex telecommunications engineer)

      In reply to John Coochey

      John, a real person, when challenged to present their views, either answers, admits they were wrong, or goes away.

      For example, look at how Mark Harrigan answers questions sensibly.

      You on the other hand refuse to present your big picture view of how all the scientists got it so wrong for so long in every country, yet you stay. Not just post a few times, but post frequently over a long time.

      And whilst disrupting this conversation, you are notably absent from the other conversations taking place today on this website about climate change.

      And the other deniers who often post frequently and stay a long time are all absent from this post.

      This is strongly suggestive to me that you are doing your shift.

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    14. John Coochey

      Mr

      In reply to Michael Wilbur-Ham (MWH)

      Now answer the current questions instead of citing your religious doctrine.

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    15. Michael Wilbur-Ham (MWH)

      Writer (ex telecommunications engineer)

      In reply to John Coochey

      A genuine person would be willing to explain and defend their views.

      A genuine person wouldn't demand that others answer their question if they are not willing to answer themselves.

      A genuine person would love the opportunity to explain why they think my views are just "religious doctrine".

      What reason could there be for you to be posting so much today if you don't want to present and defend your views other than you are just here to disrupt and are probably paid for doing so?

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    16. Craig Minns

      Self-employed

      In reply to Michael Wilbur-Ham (MWH)

      I have no view on the topic you two are discussing, but I'm amused by the use of the "paid propagandist"slur. It seems that it is increasingly common, when discussing matters which have become polarised, to use such a claim.

      I wonder whether anybody who uses it actually believes it, or if in fact they are reflecting their awareness that a great deal of what passes for discussion is actually fairly scurrilous political maneuvring? Casting one's interlocutor as the political enemy is equivalent to the religious declaration of excommunication/disfellowship - it tells all "right thinking" people that this person is consorting with the devil and should be ignored

      In modern parlance it's a dog-whistle.

      Sorry for the interruption, chaps, as you were.

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    17. Michael Wilbur-Ham (MWH)

      Writer (ex telecommunications engineer)

      In reply to Craig Minns

      Craig,

      I have no issue with genuine people coming here and stating their views.

      But look up astroturfing and you will see that there is a long history of vested interests influencing public discourse. And if you think of the money that those against money are known to be paying for lobbiests in Canberra, setting up groups such as the IPA, TV advertising, etc it would not make sense for them to ignore trying to influence discussions on the internet.

      Out of the 62 comments here as I post this, 32 are either by or responding to John Coochey. If he were a normal person why would he be here so long? Why would his posts be so silly? Why would he ignore questions about what he thinks?

      Whether or not John is actually paid is something that we might never know. But it is very obvious from his posts that he is here to disrupt - not to change people's minds.

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    18. John Coochey

      Mr

      In reply to Michael Wilbur-Ham (MWH)

      Well one thing leftie organizations and religious movements have in common is a dislike of anyone who disagrees with them. I simply ask questions you seem incapable of answering. No one disputes the Mayans stopped building temples and performing human sacrifices and the area, which was and is extensive, because the Mayans still exist, have at least 26 languages apart from Spanish and probably have overall higher literacy than Australia aborigines. The area has changes climate over the centuries…

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    19. Michael Wilbur-Ham (MWH)

      Writer (ex telecommunications engineer)

      In reply to John Coochey

      One thing that the deniers and fundamentalist religious movements have in common is that they ignore any evidence which questions their view.

      This is easy to do if they stay within their group. John would have an easier time if I visited 'skeptics' forums.

      Science is the only philosophy that continually questions itself. If new evidence arises then science change its views.

      John ignores all the evidence of science. He is just here to disrupt this discussion.

      Interestingly he has ignored the other active conversations on climate change on this website.

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    20. Mark Harrigan

      PhD Physicist

      In reply to John Coochey

      John Coochey states "I simply ask questions you seem incapable of answering"

      ROTFLMAO. Coochey never answers questions and always dodegs them. He's been asked many times.

      Tell me John - since you deny the reality of human induced climate change - riddle me this! (you've avoided it on every other post)

      If climate change is not real - what is causing the unprecedented loss of Arctic Sea Ice?

      http://tamino.files.wordpress.com/2012/08/piomas1.gif

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    21. John Coochey

      Mr

      In reply to Mark Harrigan

      Probably the same thing as causing the record Antarctic Sea ice? But I thougth we were supposed to be talking about Mayan cultural change based on unread and probably unreleased data!

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    22. John Coochey

      Mr

      In reply to Michael Wilbur-Ham (MWH)

      Once again the Mayan example shows climate change has been occurring for centuries and much of it was pre industrialization so once again the research supports my position.

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    23. Kim Peart

      Researcher & Writer

      In reply to Mark Harrigan

      I suggest that when the brain-power of the world puts a real plan on the table for our cosmic survival, those denying Earth changes will join the work effort.

      The plan will need to include ~
      Planet defence against asteroids and comets.
      Industrial development beyond Earth.
      An environmentally safe Earth.
      A stellar economy without poverty.
      A sustainable human presence on Earth.

      For now, the banter over who is right and who is not is more like a game of hide'n'seek in the graveyard of human folly.

      We need to bring an end to the denial of the real cost of our cosmic survival, which we have avoided since falling back to Earth from the Moon landings.

      Kim Peart
      http://www.islandearth.com.au/

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    24. Mark Harrigan

      PhD Physicist

      In reply to John Coochey

      Well Done! John Cocchey (almost certainyl without realising it) has just acknowledged the existoing of Anthroprogenic Climate change

      http://esciencenews.com/articles/2012/11/11/why.antarctic.sea.ice.cover.has.increased.under.effects.climate.change

      Correct John - increase (though not a record) in Antarctic Sea Ice is caused by climate change as is the record loss of Arctic Sea ice.

      I've no doubt this is beyond your ability to understand though - just like Wind direction of weather patterns that impact the land mass occupied by the Mayans.

      How do you manage to be so abysmally ignorant about that whoch you regularly post to deny?

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    1. Michael Wilbur-Ham (MWH)

      Writer (ex telecommunications engineer)

      In reply to Michael Brown

      Interesting list, because though the list is clearly meant to make those who accept the science seem 'alarmists', many things on the list will be made much worse due to global warming / climate change.

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    2. Mark Harrigan

      PhD Physicist

      In reply to Michael Brown

      Strawman false list of stupidity created by climate science speudo-sceptics to obfuscate the reality and continue to bury their heads in denial.

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    3. Phil Dolan

      Viticulturist

      In reply to Michael Brown

      Now I'm confused. Denialists constantly say that climate change has been happening for ever so nothing is new. Some evidence comes up of a past climate change and immediately it's ridiculed. What's going on?

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    4. John Coochey

      Mr

      In reply to Phil Dolan

      No it has not been ridiculed but I would question it on a number of grounds including non blinding of observations (Think of James Randi debunking a paper published in Nature that would have us believe that holistic medicine worked. Error was assessors knew which was the active group and which was the control so looked harder for results in the active group and thus found them. LIkewise when the Shroud of Turin was tested each laboratory got three pieces of cloth to carbon date but did not know which…

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    5. Mark Harrigan

      PhD Physicist

      In reply to John Coochey

      John - why must you always invoke religion as a strawman? No one else has.

      There is abundant evidence that climate change is real and a problem - which has been pointed out to you many times but which you refuse to acknowledge and deny.

      The evidence for this linking of the collapse of Mayan civilisation to a combination of climate change exacerbated by their deforrestation is obviously not 100% certain. But it is certainly not implausible.

      Stalactite evidence for rainfall levels, correlated…

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    6. Sean Lamb

      Science Denier

      In reply to Mark Harrigan

      I don't see anything implicitly unbelievable about the concept of the Mayan collapse was brought about by climate change. Personally I believe that the collapse on Easter Island was probably brought about by increasingly dryer conditions, rather than cutting down all their trees to move statues. Although I am in a minority on that one, I can't help noticing that the Chilean government in their modern reforestation efforts seem to concentrate on Eucalyptes that are fairly drought tolerant.

      I am just not sure that the Mayans were really in a position to anything about it, anymore than the people of the Sahara when it dried up 6000 years ago, or the people of Perryland in Northern Greenland when it became unhabitable and so on.

      There is no such thing as a static climate or a golden age, that is what makes modern climate science so monumentally mindless.

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    7. John Coochey

      Mr

      In reply to Mark Harrigan

      I suggest you learn to read or at least exhibit more diligence. I have offered a number of alternatives including the introduction of one or more exotic parasites or a rebellion against the ruling classes which may have been associated with a drought. The area is no longer under continuous drought so that was not climate change. The only reference to religion is that fact that the "Shroudies" could no longer give the shroud as proof of the New Testament because three independent tests put it at…

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    8. John Coochey

      Mr

      In reply to Mark Harrigan

      I am glad I can read the work of someone who knows more than archaeologists who have spent their careers studying the pre columbian mayas. In fact what we need evidence of is a population large enough compared with the uncultivated areas that they could have made any significant difference. I have not seen that evidence, please provide it or shut up.

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    9. John Coochey

      Mr

      In reply to Sean Lamb

      Once again please do some research before committing to paper. It is possible that the statues could have been moved without trees by what we used to call "dog walking" this has been done experimentally and would be in line with the legend of the statues walking to the Ahu where they were erected or left. The issue is that even if we disregard the legend recounted by Thor Heyerdahl of the civil war between the Long Ears and the Short Ears. I have been to Easter Island several times and counted the…

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    10. Kim Peart

      Researcher & Writer

      In reply to Michael Brown

      At one level, thick arguments back and forth end up like mushrooms in the desert sun.

      Mayan civilization collapsed and chit chat will not bring them back.

      Will we avoid collapse, which would put a dead stop to our chit chat?

      Unless we have a sure-fire plan for survival, we may simply talk ourselves to death simply through failing to deal with core survival issues.

      On the basis of the precautionary principle, a potential extinction is the one to prepare for, as its realisation would become our terminal experience.

      A post-extinction argument is as useful as a dead Mayan debating association.

      Apparently, we nearly scored extinction 74,000 years ago, when the Tobo super-volcano sent the planet lurching into the last ice age.

      Kim Peart
      http://www.islandearth.com.au/

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  4. Michael Lardelli

    logged in via Facebook

    It all comes down to energy. Wetter conditions allowed in increase in agricultural production which provided the energy to grow the Mayan population to a size that then exceeded the resource base when climatic conditions changed.

    200 years ago the discovery of fossil fuels - and principally oil - as a source of energy has allowed the stupendous expansion of the human population to beyond seven billion supported by energy-pumped agricultural production and scientific enterprise (itself made possible by an energy-intensive knowledge and research infrastructure including the fact that much of the population has been freed from labouring in agricultural production). Now that oil has peaked and the other fossil fuels are not far away from doing so (see peer-reviewed scientific literature by Aleklett, Rutledge and others) what do you think will happen as we slide down the net energy curve in the coming decades?

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    1. Kim Peart

      Researcher & Writer

      In reply to Michael Lardelli

      Jarad Diamond wrote on the Maya in some detail in his 2005 tome 'Collapse' (p.157).

      If we had only invested our resource bounty and technical prowess in building solar power stations in space and launching industry beyond Earth in the 1970s, we would have opened our options to the stars, instead of burning it all on Earth like there is no tomorrow.

      Do we have time to wake up, get back to the future and begin investing in our cosmic survival insurance policy?

      Sitting around the hearth playing cards may leave us with a fist full of dollars, but no future.

      Kim Peart
      http://www.islandearth.com.au/

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  5. Craig Minns

    Self-employed

    I'm wondering what the purpose of the three frequent commenters here might be. The posts all consist of personal abuse and childish sarcasm, with little of substance.. If any of you are hoping to convince people of the correctness of your view, it seems a strange way to go about it.

    Of course if, as seems likely, you're simply trolling, why bother? Has this sort of thing ever resulted in anyone ackowledging that they have been convinced to change their own viewpoint? You'd have more success in posting about atheism on religious apologetics sites.

    Basically folks, lift your game; at the moment you're looking like grown men trying to play in the under-12s.

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    1. Mitch Dillon

      logged in via Facebook

      In reply to Craig Minns

      I know. It's so disapointing to see little data backing up these broad statements. Very few primary sources referenced between the lot of them. It had the potential to become a fascinating, lively discussion about the corollaries between Mayan civilisation and ours, with contemporary climate change as an extension, but it got hijacked by fundamentalists.
      Good scientific discussion is concise and clear. Make your point quickly, back it up with data, then leave. Innuendo about the other contributors is boring. As a regular reader of these columns, i would really like to see the quality of the arguments maintained.

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    2. Kim Peart

      Researcher & Writer

      In reply to Mitch Dillon

      Mitch ~

      I wonder if Mayan priest-scientists may have said something similar.

      Could the challenge be for folk with vision to demand action ~ even through The Conversation?

      The crisis that we face with the carbon catastrophe is a creation of our whole society.

      Only be checking the foundations of our society ~ how we think and how we communicate ~ might we begin to see our way out of total failure to keep a safe Earth.

      Until such a deep awakening begins, we run the gauntlet of going the way of the Maya, which Jarad Diamond suggests as a prospect (p.409 'Collapse' 2005).

      I hope we will find the humility to face our total failure and engage in the challenge of designing for our cosmic survival.

      We need not join the Maya as a failed society.

      Kim Peart
      http://www.islandearth.com.au/

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    3. Mitch Dillon

      logged in via Facebook

      In reply to Kim Peart

      More of the same...
      Thanks for that, Kim.
      I note the comparison between myself and the Mayan 'priest -scientists'. Depends on the motivations of the protagonists. Mine are simply defined.
      Look, i wont deny Jared Diamond any opportunity to make money from writing about science, but i will protest when he leaves out facts in favour of delivering a good story. As an anthropologist, he's either naive or mercenary:http://www.imediaethics.org/News/149/Jared_diamonds_factual_collapse__.php
      As far as…

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    4. Michael Wilbur-Ham (MWH)

      Writer (ex telecommunications engineer)

      In reply to Craig Minns

      Eddy Schmid - If you did even some minimal research you would find that no-one is claiming that earlier global climate change was due to humans.

      This time is different because humans are causing it, and humans have the ability to stop it.

      Once again there are plenty of places to find out as much as you want as to why the climate scientists know this.

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  6. Eddy Schmid

    Retired

    This supposition has been around for some time, and not a recent finding as intimated in this article.
    However, be that as it may, the FACT is, the scientific community cannot have it BOTH ways, the Mayans did not base their lives and economy on burning fossile fuels, nor can any blame be laid at their feet for deforestation as claimed in the article.
    The Mayan nation was a tiny spec on the earth, and no scientific expert will convince me, their deforestaion was of such a magnitude they altered…

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    1. Mark Harrigan

      PhD Physicist

      In reply to Eddy Schmid

      Eddy - I am afraid all of comment is based on a false understanding of the article and climate science generally

      1) The Article makes no claims the Mayans caused climate change. It states that their deforestation exacerbated the impacts of natural climate change that was occuring.

      2) The Article makes no claim that the actions of the Mayans had a global effect - rather that their actions exacerbated an effect locally.

      3) The main point of the article is that climate change (however caused…

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  7. Eddy Schmid

    Retired

    Mark, thanks for even taking the trouble to respond to my comments.
    However, it would appear you have read far more into my comments then I even intended.
    The FACT is, global warming has been here before, in times when man's presence was minimal and gas guzzling cars or coal fired power stations were still a banker's wet dream. Yet global warming still happened, then.
    I need some serious explanations as to WHY it happened THEN, given the low number of humans in existence then, and their SMALL…

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  8. Eddy Schmid

    Retired

    Michael Wilbur-Ham (MWH)
    Quote; Eddy Schmid - If you did even some minimal research you would find that no-one is claiming that earlier global climate change was due to humans.

    This time is different because humans are causing it, and humans have the ability to stop it.

    Once again there are plenty of places to find out as much as you want as to why the climate scientists know this.
    Unquote.
    That's the whole point, Michael, if it's happened before, we need to know what caused it, to simply…

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    1. Michael Wilbur-Ham (MWH)

      Writer (ex telecommunications engineer)

      In reply to Eddy Schmid

      Eddy, it is very easy. Just do some research.

      Rather than wasting your time (and ours) by asking questions as if you are the first person to think of them, some research will find plenty of work on when climate has changed in the past and on why each change has happened.

      I accept the science. You choose to deny it.

      Because you deny it you reject all the evidence as "alleged data" by "self serving" scientist. How this can include the scientists in Australia under Howard and in the USA under Bush I find hard to comprehend. How it has included the scientists in EVERY other country for over 20 years is even harder to comprehend.

      One of us is very stupid. Readers can make up their own mind.

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    2. Mark Harrigan

      PhD Physicist

      In reply to Eddy Schmid

      Eddy -you appear to either be deliberately trolling - since you repeat points frequently raised by deniers - or you have come very late to the discussion onc limate and seem to have strong views yet be rather ill infromed? Do you really think bodies like the Royal Society or the US meteorological society would not have considered your concerns before they state things like the below?

      http://ametsoc.org/policy/2012climatechange.html
      "There is unequivocal evidence that Earth’s lower atmosphere…

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  9. Phil Dolan

    Viticulturist

    Michael Wilbur-Ham (MWH)
    That's a really good explanation Michael but I really think you're wasting your time. Denialists have a reason to deny. They can't possibly really believe what they write. I'm no scientist but I find it all makes sense when looking at the carbon cycle and listening to what climate scientist say.
    So, either it's their job to deny or they believe that a sky fairy made the world and we can't change it.

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    1. Kim Peart

      Researcher & Writer

      In reply to Phil Dolan

      I would like to offer a prediction,

      that the day will come when climate change deniers may, like holocaust deniers, find themselves in trouble with the law.

      Why?

      Because with ocean acidification up 30% and set to increase ten-fold by 2050, along with growing dead zones in the seas, the stage is set for vast algal blooms in dying seas that release toxic hydrogen sulphide gas that can kill life on land and destroy the ozone layer.

      Taking a contrary position in debating and politics is a…

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    2. John Coochey

      Mr

      In reply to Phil Dolan

      You mean like
      "“The Fourth Assessment Report (AR4) of the Intergovernmental Panel on Climate Change (IPCC) summarized the evidence in the following terms: ‘‘More intense and longer droughts have been observed over wider areas since the 1970s, particularly in the tropics and subtropics. Increased drying linked with higher temperatures and decreased precipitation has contributed to changes in drought’’.

      The most recent research published on The Conversation no less shows there has been no increase in droughts for sixty years. So much for the so called science,

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  10. Mark Harrigan

    PhD Physicist

    @ John Coochey - no John. The recent article on TC about the frequency and extent of drought is a great example of what science is all about. It is about increasing our understanding of how the real world works based on evidence. When evidence is available that leads to a different conclusion the science adjusts - unlike pseudo-sceptics such as yourself who are incapable of altering their views regardless of the evidence and make a virtue out of doubt.

    In relation to the specifics of the conclusions…

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