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150 years and counting: confidence in climate science

In the lead up to the release next month of the Intergovernmental Panel on Climate Change’s (IPCC’s) Fifth Assessment Report we are exploring concepts of confidence and certainty in climate science. The…

Sometimes a piece of the puzzle won’t fit, but overall the picture is coming together. Dave Ginsberg

In the lead up to the release next month of the Intergovernmental Panel on Climate Change’s (IPCC’s) Fifth Assessment Report we are exploring concepts of confidence and certainty in climate science. The first article is here

Building any scientific theory is like putting together pieces of a jigsaw puzzle. Pieces of evidence are assembled in order to resolve the complete picture.

And the picture has never been clearer for the puzzle of human-induced climate change.

The theory that additional carbon dioxide (CO2) in the atmosphere would increase global temperatures, and cause other changes to Earth’s climate, is not new. That puzzle box was opened nearly 200 years ago.

Joseph Fourier, who made the initial hypothesis of a greenhouse effect, identified the very first piece of the climate change puzzle in 1824. In 1859, John Tyndall identified the “greenhouse gases” and their role in the atmosphere.

In 1896, Svante Arrhenius made the first suggestion that humans could influence the climate. Even well over 100 years ago, he postulated that global temperatures would rise by 5-6C if the CO2 concentration of the atmosphere was doubled.

More puzzle pieces were added when Brooks reported increases in temperatures in the 1920s. But it was Guy Callendar who, through meticulous examinations undertaken from the late 1930s to 1960s, identified not only increases in global temperatures, but also suggested that these were caused by human emissions of greenhouse gases.

By the late 1950s and into the 1960s the atmosphere was being studied in increasing detail with the sudden expansion of observations that were associated with the International Geophysical Year. In addition, scientists gathered yet more puzzle pieces with the advent of computers that could accurately model the physics of the atmosphere.

In 1960, Charles Keeling first published what is now known as the “Keeling Curve”, showing consistent rises in observed atmospheric CO2.

By now, the scientific puzzle was well and truly taking shape. There was clear evidence that CO2. was increasing in our atmosphere and that temperatures were increasing concurrently. Many independent lines of evidence were consistent with Arrhenius’ theory from over 60 years prior.

Throughout the latter half of the 20th century, this evidence continued to grow, increasing confidence in the theory that humans were affecting the climate. Scientists used high accuracy instruments to observe changes, reconstructed past climatic changes and also modelled the climate system using the fundamental laws of physics and chemistry.

At the same time, the number of alternative hypotheses about the observed warming declined. While scientists were neatly putting together these puzzle pieces, they were also examining whether any other known process, besides human activities, could be responsible for the observed changes. Solar variations, volcanoes and other natural cycles were all systematically discounted.

From 1991 to 2011 alone, more than 4,000 additional pieces of the climate change puzzle were gathered. An estimated 97% of them fit the puzzle and were consistent with previous evidence. So of these 4,000 pieces, 3,880 pieces demonstrated that humans were having a noticeable and significant influence on our climate.

Trying to construct a puzzle is difficult and time consuming. You might lose a few pieces along the way, and sometimes some pieces just don’t fit. But as with any large puzzle, there comes a point where there are enough pieces, enough consistent evidence, to be able to resolve the picture.

The result of nearly 200 years of scientific endeavour is now a clear and recognisable picture of humans influencing the climate through the emission of greenhouse gases.

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50 Comments sorted by

    1. John Whelan

      logged in via Facebook

      In reply to Wil B

      Thats all very well but, from everything I read, the globe isn't warming and hasn't for 15 years. Yet in that time CO2 concentration has definitely increased to a level where most Climate Scientists and their computer models predict that the Globe should be warming. Now, there will be no point in 'Climate Scientists' climbing all over me and pushing the science when there is clearly a very big disconnect between actual and prediction. Clearly the models and the science is incomplete and therefore, the science is NOT settled.

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    2. Wil B

      B.Sc, GDipAppSci, MEnvSc, Environmental Planner

      In reply to John Whelan

      John, the simple issue is that you're not reading hard enough. You're not qualified or don't have the ability to conduct independent science, so, just like me, you read what the experts are saying. And unsurprisingly, this is not a big issue.

      Science is never settled 100%, it is always advancing. But in terms of general policy and economic restructure implications, yes, it is very much settled.

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    3. David Bentley

      logged in via LinkedIn

      In reply to John Whelan

      Dear John. Please explain to the rest of the class why you think it is preferable to pick average surface temperature records for one single year (1998 presumably) and then compare it to surface records for 2012 and then draw your conclusions from this simplistic approach point to point approach. Then please explain how this technique and your associated conclusions are superior to for instance considering a combination of rolling average surface temperatures and/or total global heat content including oceans and global ice volumes in understanding whether the globe is or is not warming.

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    4. Chris O'Neill

      Retired Way Before 70

      In reply to John Whelan

      "from everything I read, the globe isn't warming and hasn't for 15 years"

      You have been misled by some liars and shameless cherry-pickers. The global surface has indeed warmed over the past 15 years even though that starts with an unusually warm year:

      http://www.woodfortrees.org/plot/hadcrut4gl/from:1998/trend/plot/hadcrut4gl/from:1998

      A lie gets half way round the world before the truth gets its boots on. Just remember that.

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    5. Chris O'Neill

      Retired Way Before 70

      In reply to Chris O'Neill

      "The global surface has indeed"

      most likely

      "warmed over the past 15 years"

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    6. Tony Thomas

      Writer for Quadrant Online and Quadrant print monthly

      In reply to Gary Murphy

      So to explain the pause in atmospheric warming in the past 15-17 years (as acknowledged by IPCC chair Pachauri last February), the alarmists create a new theory, that the 'missing heat' (if any) has slid down somehow into the deep oceans. In other words, their previous models, ("Scientists used high accuracy instruments to observe changes, reconstructed past climatic changes and also modelled the climate system using the fundamental laws of physics and chemistry.") were grossly deficient. Why do I recall the famous emailgate quote from IPCC warmist Kevin Trenberth: "The fact is that we can't account for the lack of warming at the moment and it is a travesty that we can't."

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    7. Alice Kelly
      Alice Kelly is a Friend of The Conversation.

      sole parent

      In reply to Tony Thomas

      I think it's scientists who measure ocean temperature. You may be interested to look at a graph they've made, you could also find it's an interactive graph with other information included e.g. salt content;
      http://www.nodc.noaa.gov/OC5/3M_HEAT_CONTENT/index3.html
      And an explanation;
      http://earthobservatory.nasa.gov/Features/HeatBucket/
      Are you aware of currents in the ocean, both in the upper layers and lower? Perhaps you could explore this fact.
      One last thing, do you think alarmist and warmist are accurate terms to describe those who have noticed that the ocean has warmed?
      If yes, could you show me a graph covering the last 20 years which shows otherwise?

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    8. Ken Fabian

      Mr

      In reply to John Whelan

      John, by repeating the 'no warming for 15 years' claim all you have demonstrated is how ignorant and misinformed you are. Even if ordinary citizens have the right to misunderstand and disbelieve and spruik whatever opinions they like, with a problem of this scale for our MP's and community leaders to do so is unacceptable.

      Temperatures rising, leveling off, rising, leveling off - each time at a higher plateau - is global warming. For it not to be warming it would be rising, falling, rising…

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    9. Chris O'Neill

      Retired Way Before 70

      In reply to Tony Thomas

      "the pause in atmospheric warming in the past 15-17 years (as acknowledged by IPCC chair Pachauri"

      You're not telling the truth about what Pachauri said. The only thing he acknowledged was that the warming (yes warming) over that period was not above the 95% confidence level considering the noise in global surface temperature. Warming has occurred with a lower than 95% statistical significance.

      The real issue is why people like Tony Thomas and Quadrant are pursuing a disinformation campaign.

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    10. Fred Payne

      retired

      In reply to Wil B

      For me it is significant that for more than 30 years that I have been aware of this issue, the predictions of the climate scientists advocating warming seem to have been more accurate than those of its opponents.
      But even if the warming camp is wrong - it would probably be smart to start working on the process of cleaning up the damage that human presence is causing across all sections of the environment.

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    11. Alice Kelly
      Alice Kelly is a Friend of The Conversation.

      sole parent

      In reply to Tony Thomas

      Tony Thomas, I've just had a look at quadrant online and am really shocked at the partisan outlook (rubbish) in this publication. Completely at odds with the reality of the science.
      "In modern times, there are no examples where a comparable degree scientific consensus was achieved and the results were later proven to be wrong. Zero."
      Show me a climate model that fits the data more accurately and passes peer review. That is, explain warming atmosphere and oceans, ocean acidification, change in intensity of storms etc drought, sea level rise, loss of ice, change in polar vortex. If all these changes are due to something other than humans show me the climate model which can explain all of them. Except of course acidification and CO2 levels in the atmosphere as this is caused by human beings emitting green house gases Perhaps you can recall the models which explain another hypothesis?

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    12. Paul Richards

      integral operating system

      In reply to Alice Kelly

      Alice Kelly wrote [Q1]; "Are you aware of currents in the ocean, both in the upper layers and lower? Perhaps you could explore this fact." Most K5-K8 students could demonstrate atmospheric thermodynamic layers from wikipedia.
      Alice Kelly wrote [Q2]; "One last thing, do you think alarmist and warmist are accurate terms to describe those who have noticed that the ocean has warmed?" The term alarmist has been around for many decades, the term warmest surfaced recently. It came from the religious…

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    13. Tony Thomas

      Writer for Quadrant Online and Quadrant print monthly

      In reply to Alice Kelly

      Hi Alice, It takes me about 10 seconds to meet your challenge about the ridiculous and unscientific notion of 'consensus'.
      One of the most famous cases of consensus science gone ridiculous involved the theory of Continental Drift. In 1912, a German scientist named Alfred Wegener introduced the theory that the continents were not stationary, but rather moved.
      Any child can see that the continents fit together like a jigsaw puzzle, yet the scientific community took over 50 years to stop ridiculing…

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    14. Eric Smith

      logged in via Twitter

      In reply to Gary Murphy

      That is truly amazing.

      Human created heat decided all by its little self to go to the oceans instead of the air just when climate 'science' fell on its ass.

      It's as if when Galileo dropped the balls from the leaning tower of Pisa, they arrived on the ground simultaneously for the first time. Millions of scientists around the world thought 'funny, it didn't do that yesterday, the heavy one landed first'.

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    15. Alice Kelly
      Alice Kelly is a Friend of The Conversation.

      sole parent

      In reply to Chris O'Neill

      Yeah, Chris, it still surprises me to read it, it's plastered all over quadrant. I suppose a few want to give the impression there's two sides, (scientific community 97-98%) ,a few uninformed vocal disbelievers, spread as much silliness as fast as possible.
      I suppose us warmists could also be called acidifiers, or ice melters.
      The articles in quadrant online come under a heading titled Doomed Planet, with such titles as Spot the error, the IPPC can't, Scaring kids for a greener world ("Whether or not oceans are turning acidic is a question science has yet to settle"), Alarmism with an Austrian accent, Warmism's whoppers, How to de-program a warmist, Time to de-plug renewable energy. And it goes on all the way down the page. All very mature stuff eh?

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    16. Tony Thomas

      Writer for Quadrant Online and Quadrant print monthly

      In reply to Alice Kelly

      Alice, that 97-98% of scientists/articles/whatever meme is just ludicrous, albeit published in pal-reviewed lit. For heavens sake check the methodologies used, they're always manipulations. Go to Joanne Nova's blog and check this 97% rubbish out properly.

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    17. Alice Kelly
      Alice Kelly is a Friend of The Conversation.

      sole parent

      In reply to Tony Thomas

      An argument 100 years ago is hardly modern. You have not answered my question. Your answer is not adequate, if you want to devote your time to writing on behalf of 2-3 % of scientific opinion fine. Don't expect to be taken seriously. Every major scientific body in the world disagrees with you, as do I. http://climate.nasa.gov/evidence
      Perhaps you can explain rapid warming after 1950?

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    18. Tony Thomas

      Writer for Quadrant Online and Quadrant print monthly

      In reply to Alice Kelly

      In one of the e-mails, East Anglia’s Phil Jones, long a power player in the production of these reports, said this about some scientific articles he did not like: “I can’t see either of these papers being in the next IPCC report. Kevin and I will keep them out somehow — even if we have to redefine what the peer-review literature is!”

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    19. Alice Kelly
      Alice Kelly is a Friend of The Conversation.

      sole parent

      In reply to Tony Thomas

      We've all heard this stuff before here, you can't explain to me in any coherent manner why there has been so many rapid changes to climate on earth for the last 60 years. Changes which used to take thousands of years are now taking decades. These changes are well documented in every credible scientific publication.
      I asked you for credible peer reviewed explanation and modelling which could explain all changes. Not explanations in denier blogs (discredited).
      First you mention a pause (actually…

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    20. Tony Thomas

      Writer for Quadrant Online and Quadrant print monthly

      In reply to Alice Kelly

      I'd reply but life's too short and I've got worthwhile writing to do.
      All the best, Alice.

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    21. Account Deleted

      logged in via email @drdrb.net

      In reply to Tony Thomas

      The fact that Tony considers Quadrant writing = worthwhile writing tells you all you need to know about his ability to answer.

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    22. Account Deleted

      logged in via email @drdrb.net

      In reply to Tony Thomas

      And yet the papers were in fact referred to in the IPCC report. I guess science isn't so corruptible after all.

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    23. Account Deleted

      logged in via email @drdrb.net

      In reply to Eric Smith

      Actually, it's just that we've only measured heat down to the 750 metre level since the mid 90s, and only recently managed to measure heat content down to the 2000 metre level. Climate scientists haven't talked about deep ocean warming before because they didn't have the data. Before that, they worried about holes in the earth's energy budget - something that was seized on by denialists at the time. Now that hole has been filled by new ocean data, denialists seem to think that filling it at this time is somehow proof that climate science is wrong. This is consipratorial reasoning that puts 9/11 troofers to shame.

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    24. Chris O'Neill

      Retired Way Before 70

      In reply to Tony Thomas

      "Phil Jones"

      Not content with spreading disinformation about what Pachauri said, Tony Thomas moves onto the smear campaign of Phil Jones.

      What a troll.

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    25. Jonathan Maddox
      Jonathan Maddox is a Friend of The Conversation.

      Software Engineer

      In reply to Tony Thomas

      "Why do I recall... "

      Because these are the answers Trenberth was casting about for. We are, now, measuring the temperature of the oceans, deep and shallow. We are measuring not only the extent of polar ice but also its thickness, on the ocean and on land. We have the data. The heat is here.

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    26. robert gallacher

      logged in via email @googlemail.com

      In reply to John Whelan

      john your concerns are real and valid.add to the lack of statistically significant warming,no tropospheric hot spot,a resurgence in arctic ice this summer coupled with a long term trend in winter extent,an increase in antarctic ice ,and the quite frankly ridiculous claim the missing heat is in the oceans ,which cannot be measured because argo floats only drop to 2000m.

      the tiny changes in measured ocean temp have to be expressed in joules as hundredths and thousandths of degrees c do not raise eyebrows. all adds up to the massive failure of the models to track observations and the killer blow ,the divergence of temperature from co2 increases.

      IPCC climaste science can only spin this out for so long,it would appear murray salby was correct in stating co2 rises lag temp rises,makes perfect sense considering the planet is still warming from the last ice age.

      and a question to finish on,what will cause the greatest hardship for ALL species on earth,some warming,or some cooling ?

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    27. robert gallacher

      logged in via email @googlemail.com

      In reply to Gary Murphy

      gary ,instead of telling people ocean heat content has increased in the last 15 years,would you like to produce some actual evidence of that.i would be keen to learn of the instrument used to survey depths down to 5000 plus metres,along with the increase in temperature they measured.
      the datum used to show the previous mean temperature of the entire oceans would also be appreciated.
      bear in mind there are only 3500 argos or so,with many out of commision or unreliable (such as the one providing readings of ocean temp from the central african continent a year or so ago) it would be folly to place any significance in what is a relatively unestablished technology.
      even long term,looking at the distribution of bouys ,it will only be localised information they will provide.if you divide the ocean areas with over 2000m by 3500,it is a truly massive area each boy is attempting to represent.

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    28. robert gallacher

      logged in via email @googlemail.com

      In reply to David Bentley

      for the same reason it seems fine for the climate science community to pick a period where the planet is warming after an ice age to tell us all a less than one degree c rise is significant,and that looking at their crystal balls,sorry models it is going to get warmer.

      there is no measurable empirical evidence to suggest any of the catastrophic effects that are predicted for humanity if co2 ppm keep rising will happen.
      the next few decades are just as likely to cool as warm.
      the climate has always changed,and will continue to do so,regardless of co2 levels in the atmosphere.

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    29. Chris O'Neill

      Retired Way Before 70

      In reply to robert gallacher

      "the lack of statistically significant warming,"

      in 17 years. BIG DEAL.

      "no tropospheric hot spot"

      Just a pity it makes no difference to how fast the surface warms.

      "a resurgence in arctic ice this summer"

      A resurgence to the fourth lowest level on record? WOW! What a resurgence!

      "coupled with a long term trend in winter extent"

      i.e. it keeps getting thinner.

      "an increase in antarctic ice"

      Not nearly enough to make up for Arctic ice loss, to put it mildly.

      "and the quite frankly ridiculous claim the missing heat is in the oceans ,which cannot be measured because argo floats only drop to 2000m"

      You're not suggesting the oceans below 2000m deep are cooling are you? Because there is no slowdown in ocean warming above 2000m deep: http://thinkprogress.org/wp-content/uploads/2013/07/ocean-heat.jpg

      Frankly, your claims are quite ridiculous.

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  1. David Thompson

    Marketing Research

    If any of you guys, or your mates, are members of the Geological Society of America/London hassle them to get a vote to officially acknowledge the Anthropocene as a new geological epoch.

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  2. Marc Hendrickx

    Geologist: The Con is a bad Monty Python sketch, for climate sense see: http://www.thegwpf.org/

    Steve McIntyre, doyen of the citizen climate scientists, had a relevant post a little while ago comparing a simple model derived from Guy Calender's work on CO2 from 1938 and recent climate model outputs. Despite 60+ years of development Calender's simple model out performed the CMIP5 GCMs.
    The best performing CMIP5 models ran too hot.

    http://climateaudit.org/2013/07/26/guy-callendar-vs-the-gcms/

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  3. Mark McGuire

    climate consensus rebel

    Quote from this article: "At the same time, the number of alternative hypotheses about the observed warming declined."

    Here is a missing piece.

    Will the AR5 will bring back the "burning embers" diagram which was removed from the AR4?

    Mar. 1, 2009 — A new study by scientists updating some of the findings of the Intergovernmental Panel on Climate Change (IPCC) 2001 Third Assessment Report finds that even a lower level of increase in average global temperatures due to greenhouse gas emissions…

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    1. Felix MacNeill

      Environmental Manager

      In reply to Mark McGuire

      The first is not an 'alternative hypothesis', merely a debate about how to illustrate the science.

      And the reason 'tipping points' are not included in IPCC reports is precisely because the IPCC is profoundly conservative and cautious and, because tipping points are incredibly difficult to model, it's almost impossible to give reliable details. Everybody knows that tipping points exist, although exactly what, when and where, is incredibly difficult to forecast. But, in terms of the take away message it is something like: 'There is an army of about 500 angry vikings about to come over the hill and attack your poorly defended little village...oh and, by the way, we can't see completely clearly through the dust clouds, but there might well be a few thousand mounted mongols following close behind...'

      I have a pretty fair idea of where my breakfast would be heading, either way.

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  4. Eric Smith

    logged in via Twitter

    From the Guardian, following climategate. James Lovelock's excoriating view of the lying, dumb, little oinks who do modern climate science.

    on CRU scientists

    I was utterly disgusted. My second thought was that it was inevitable. It was bound to happen. Science, not so very long ago, pre-1960s, was largely vocational. Back when I was young, I didn't want to do anything else other than be a scientist.

    They're not like that nowadays. They don't give a damn. They go to these massive, mass-produced…

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    1. Chris O'Neill

      Retired Way Before 70

      In reply to Eric Smith

      "just can't say anything, or who are afraid to say anything"

      like Michael Mann.

      Yeah right.

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  5. Ken Fabian

    Mr

    Climate science denial is truly insidious and so entrenched within conservative political thinking that it will prevent the full importance of AR5 from being appreciated. Or acted on.

    With deniers front and centre of what looks like our next Australian government, it's poisonous influence will continue to distort the national conversation - and it will distort the international one as well. Even though I doubt the out and out deniers even outnumber those that accept the science within the LNP…

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    1. Doug Hutcheson

      Poet

      In reply to Ken Fabian

      "It's a profound betrayal of public trust when elected MP's tolerate, endorse or promote those views." Especially when large numbers of the promoters know perfectly well that the science is in and the prognosis is bad. Failing to tell the passengers that a cliff is approaching is an act of unmitigated cowardice.

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  6. robert gallacher

    logged in via email @googlemail.com

    i trust you are both aware of the open letter richard tol has sent to the university of queensland ?
    if not please read the letter below. using the 97% consensus figure in your article somewhat devalues it,and leads me to believe you may be applying the same lack of principle in the creation of the article.

    Dear Professor Høj,

    I was struck by a recent paper published in Environmental Research Letters with John Cook, a University of Queensland employee, as the lead author. The paper purports…

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