Occam’s Razor, the Null Hypothesis, and Anthropogenic Global Warming

For a sophisticated yet understandable introduction to the global warming debate, it is hard to beat this article by Professor Robert Carter at the American Institute for Technology and Science Education site. Dr. Carter notes that there is considerable common ground between the climate alarmists and the climate realists:

Though you wouldn’t know it from the antagonistic nature of public discussions about global warming, a large measure of scientific agreement and shared interpretation exists amongst nearly all scientists who consider the issue. The common ground, much of which was traversed by Dr. Hayhoe in her article, includes:

* that climate has always changed and always will,
* that carbon dioxide is a greenhouse gas and warms the lower atmosphere,
* that human emissions are accumulating in the atmosphere,
* that a global warming of around 0.5OC occurred in the 20th century, but
* that global warming has ceased over the last 15 years.

I would add one more: that the amount of warming attributable to increased CO2 in the atmosphere based on scientific experiment is trivial, and one can argue for a dangerous global warming only by assuming positive feedback effects, e.g. involving clouds, that magnify the otherwise-harmless impact of increased atmospheric CO2. Dr. Carter continues:

The scientific argument over [Dangerous Anthropogenic Global Warming] is therefore about none of these things. Rather, it is almost entirely about three other, albeit related, issues. They are:

* the amount of net warming that is, or will be, produced by human-related emissions,
* whether any actual evidence exists for dangerous warming of human causation over the last 50 years, and
* whether the IPCC’s computer models can provide accurate climate predictions 100 years into the future.

I would add that there is also disagreement over whether the net effect of significant global warming would be good or bad.

In framing these disagreements, Dr. Carter starts with first scientific principles:

Science deals with facts, experiments and numerical representations of the natural world around us. Science does not deal with emotions, beliefs or politics, but rather strives to analyse matters dispassionately and in an objective way, such that in consideration of a given set of facts two different practitioners might come to the same interpretation….

William of Occam

Which brings us to the matter of Occam’s Razor and the null hypothesis. William of Occam (1285-1347) was an English Franciscan monk and philosopher to whom is attributed the saying ‘Pluralitas non est ponenda sine necessitate’, which translates as ‘Plurality should not be posited without necessity.’ This is a succinct statement of the principle of simplicity, or parsimony, that was first developed by Aristotle and which has today come to underlie all scientific endeavour.

The phrase ‘Occam’s Razor’ is now generally used as shorthand to represent the fundamental scientific assumption of simplicity. To explain any given set of observations of the natural world, scientific method proceeds by erecting, first, the simplest possible explanation (hypothesis) that can explain the known facts. This simple explanation, termed the null hypothesis, then becomes the assumed interpretation until additional facts emerge that require modification of the initial hypothesis, or perhaps even invalidate it altogether.

Given the great natural variability exhibited by climate records, and the failure to date to compartmentalize or identify a human signal within them, the proper null hypothesis – because it is the simplest consistent with the known facts – is that global climate changes are presumed to be natural, unless and until specific evidence is forthcoming for human causation.

It is one of the more extraordinary facts about the IPCC that the research studies it favours mostly proceed using an (unjustified) inversion of the null hypothesis – namely that global climate changes are presumed to be due to human-related carbon dioxide emissions, unless and until specific evidence indicates otherwise.

So, what are the tests to which we can subject the anthropogenic global warming theory to determine whether it has more explanatory power than the null hypothesis?

The DAGW hypothesis that I want to test here is precisely and only “that dangerous global warming is being caused, or will be, by human-related carbon dioxide emissions”. To be “dangerous”, at a minimum the change must exceed the magnitude or rate of warmings that are known to be associated with normal weather and climatic variability.

What evidence can we use to test the DAGW hypothesis?

Many different lines of evidence can be used to test the DAGW hypothesis. Here I have space to present just five, all of which are based upon real world empirical data. For more information, please read both Dr. Hayhoe’s and my book.

Consider the following tests:

(i) Over the last 16 years, global average temperature, as measured by both thermometers and satellite sensors, has displayed no statistically significant warming; over the same period, atmospheric carbon dioxide has increased by 10%.

Large increases in carbon dioxide have therefore not only failed to produce dangerous warming, but failed to produce any warming at all. Hypothesis fails.

(ii) During the 20th century, a global warming of between 0.4O C and 0.7O C occurred, at a maximum rate, in the early decades of the century, of about 1.7O C/century. In comparison, our best regional climate records show that over the last 10,000 years natural climate cycling has resulted in temperature highs up to at least 1O C warmer than today, at rates of warming up to 2.5O C/century.

In other words, both the rate and magnitude of 20th century warming falls well within the envelope of natural climate change. Hypothesis fails, twice.

(iii) If global temperature is controlled primarily by atmospheric carbon dioxide levels, then changes in carbon dioxide should precede parallel changes in temperature.

In fact, the opposite relationship applies at all time scales. Temperature change precedes carbon dioxide change by about 5 months during the annual seasonal cycle, and by about 700-1000 years during ice age climatic cycling. Hypothesis fails.

(iv) The IPCC’s computer general circulation models, which factor in the effect of increasing carbon dioxide, project that global warming should be occurring at a rate of +2.0O C/century.

In fact, no warming at all has occurred in either the atmosphere or the ocean for more than the last decade. The models are clearly faulty, and allocate too great a warming effect for the extra carbon dioxide (technically, they are said to overestimate the climate sensitivity). Hypothesis fails.

(v) The same computer models predict that a fingerprint of greenhouse-gas-induced warming will be the creation of an atmospheric hot spot at heights of 8-10 km in equatorial regions, and enhanced warming also near both poles.

Given that we already know that the models are faulty, it shouldn’t surprise us to discover that direct measurements by both weather balloon radiosondes and satellite sensors show the absence of surface warming in Antarctica, and a complete absence of the predicted low latitude atmospheric hot spot. Hypothesis fails, twice.

One of the 20th century’s greatest physicists, Richard Feynman, observed about science that:

In general we look for a new law by the following process. First we guess it. Then we compute the consequences of the guess to see what would be implied if this law that we guessed is right. Then we compare the result of the computation to nature, with experiment or experience; compare it directly with observation, to see if it works.

It’s that simple statement that is the key to science. It does not make any difference how beautiful your guess is. It does not make any difference how smart you are, who made the guess, or what his name is. If it disagrees with experiment it is wrong.”

None of the five tests above supports or agrees with the predictions implicit in the greenhouse hypothesis as stated above. Richard Feynman is correct to advise us that therefore the hypothesis is invalid, and that many times over.

Dr. Carter goes on to talk about why the failure of the AGW theory is so little understood by the general public. Here we enter the realm of politics, and also high finance, as billions of dollars have been spent to enlist scientists in the cause, and to convince naive voters that dangerous anthropogenic global warming is something other than a failed and politically-motivated theory.

Images courtesy of Shutterstock.

  • Lance Orloff · Top Commenter · Partner at Grant, Genovese & Baratta
    Centuries ago, the Aztecs used the human-offering hoax to butcher innocent working-class people to offer their organs to the gods to benefit and empower the governing class. Today, the media, government, and education elites use the man-made global-warming hoax to benefit and empower the government class at the expense of the working class. Even if the government class raised taxes on us to 100% and totally restricted our freedom to drive, fly, boat, heat, and air-condition, global climate would still warm and cool as it always has for the Earth's 4,000,000,000-year history.
    • Paul Graham · Troy High
      And I thought it was because half the baby boomers are women and they now have hot flashes!
    • Dan Culton · Top Commenter
      Paul Graham ... Now the climate alarmist are pointing a finger at earthworms.... really!
    • David Bogut · · Burlingame High
      Think about it though, it's a great way to get people to surrender both their cash and their freedom. Face it, "If you don't do X, Y and Z, you'll kill the planet, and along with it all of us," is a pretty persuasive argument. After all, it's worked for years now. Except there are a few us old enough to remember when the fear being hawked was that our Planet was cooling, and that another age was on the way.
  • Robert McMahon · Top Commenter · Owner/Sole Proprietor at Robert McMahon Gallery
    In the article excerpted in the above post, Dr Carter makes numerous statements of fact and several logical arguments. He offers every opportunity for critics to make substantive counter-arguments.

    Not a single one of his critics has chosen to do so. Instead they choose to obsess about irrelevancies like the religious beliefs of his co-workers and employers, or about Creationism and Intelligent Design - which have nothing whatsoever to do with Anthropogenic Global Warming or his article about it.

    When you choose to argue passionately about asinine and irrelevant things, you tell the world more than you realize.
    • Peter Laux ·
      Perfectly put, you "cut to the chase" Robert, and as you say one of the things they "tell the world" is that by their diversions prove themselves to be "mentally defeated" as they cannot attack Bobs rationale nor logic.
  • Peter Laux ·
    Brandon, what a colossal fail, how embarrassing for you!
    You will be a nomination for "FacePalm 2013"!
    The author of the article is Professor Robert Carter from James Cook University in Townsville Australia. Marine Geology is his game not Biology like the Miami USA Dr Carter you refer to!
    His mate is fellow Australian and Geologist, Dr Ian Plimer, who coincidently likens AGW adherents to Creationists and who should know as he wrote the book attacking Creationism called "Telling lies for God".
    You really have got the "wrong end of the stick!"

    Same goes for you Fammis 3000, your only "exactly wrong" as well!
  • Arnold Townsend · Top Commenter · Fairmont High School
    And there you have it.

    If this was a boxing match, the referee would've stopped the fight after the second "hypothesis fails". I've always thought they overstated the sensitivity of the climate to human activity and simple consideration of order of magnitude should've led them to a more cautious approach. But it appears it was too good as political plum for some. This ends the controversy for me. Until I see further evidence that 1) there is an unusual warming at all; 2) only humans could be causing it, I consider the matter done. But don't expect it to die so easily.

    Does this mean I'm not longer a Holocaust Denier?
    • Angela Kay Harris · · Top Commenter
      Unfortunately, for people who live in an increasingly urban world where everything around them has been altered by human activity, it's so easy to believe that humans are altering everything. I feel sorry for people who live such narrow lives.
  • JV DeLong · VP - Senior Analyst at Convergence Law Institute
    I am not sure what the earlier commenters mean by "creationist". The official position of the AITSE is:

    "What is AITSE’s view on evolution/intelligent design/creation/theistic evolution? AITSE believes that good science allows non-consensus, science-based, views to be considered. Therefore, in our monthly newsletters we provide input from highly qualified scientists and AITSE members who hold a variety of opinions on this subject and support them with science, not the demands of consensus. That way, the reader can make up their own mind. AITSE also openly acknowledges that this question has religious implications and that many people base their opinions on faith as well as science. Since religion and science are both searches for truth, one would expect that ultimately, the same conclusion would be reached. However, since both science and philosophy are works in progress, it may be that such certainty is not possible at the moment—and we can live with that."

    So does "creationist" simply mean anyone who is not an atheist? And where would that leave me, a militant agnostic?
  • Greg Harris · Top Commenter · San Diego, California
    Of the initial 5 points, "human emissions are accumulating in the atmosphere" is not necessarily true. Nature produces so much more CO2 annually than humans. The measured slow increase is easily explained by cold, deep, carbon rich waters welling up and being warmed by the sun, which also explains, after some of the CO2 escapes into the atmosphere due to well understood physical principles, why we also see a slight decrease in pH of the surface waters from the residual CO2. That said, I'm all for reducing human production of CO2 - if and only if the greeniacs will agree to more hydroelectric (requiring more dams) and more nuclear. They can build solar and wind plants too, if they will stop their own from going to court every time one is proposed and are willing to take the environmental hits they cause. What else? Geothermal. We have plenty of that in the Brawley Seismic Zone and we would be tapping it in much greater fashion if not for the greeniacs and NIMBYs who tied up the Sunrise Powerlink in court for longer than I can remember.
    • Ferdinand Engelbeen
      Greg, as Bob Carter says, humans are responsible for the increase of CO2 over the past 160 years. The discussion is about the effect of the increase. Your arguments fail on several points: Nature produces much more CO2 than humans, but nature also absorbs much more CO2 than humans and even more than it produces: nature is a net sink for about halve the human emissions (in quantity, not in original molecules). The physical principles like Henry's Law show that 1°C increase (since the LIA) in average seawater temperature increases the atmosphere with 16 ppmv CO2 (whatever the deep ocean circulation), not the 100+ ppmv we see today. And last but not least: if the oceans were the source, including a lowering of pH, that would give a decrease in total carbon (CO2 + -bi-carbonates) in the surface layers, while we see an increase over time...
      See further:
  • Bobert Bell · · Top Commenter
    This guy starts out of the gate with a Myth, mainly that the "that global warming has ceased over the last 15 years." This is plainly false. I will use Dueling Scientist article over at Skeptical Science to illustrate this:

    "Oregon State climate scientist Andreas Schmittner responded with a letter to the editor, which focused primarily on debunking that particular myth.

    "Fulks claims that global temperatures have not risen during the past 15 years. This is not true. Most heat trapped by carbon dioxide and other gases added to the atmosphere is absorbed by the oceans, as clearly seen in measurements available at the National Oceanic and Atmospheric Administration website... Fulks flunks climate science. He cherry-picks information that supports his conclus...See More
    • Mark Tinder · Top Commenter
      "Hide the decline" Bob.
    • Greg Harris · Top Commenter · San Diego, California
      Oh now that claims the atmosphere would warm catastrophically have been proven definitively wrong, they're trying to claim the oceans are warming. And just like they fiddled with the surface temperature records, and are still fiddling with them, they also fudged some of the ocean data - although there's other ocean data that, thankfully, has not been faked which proves conclusively that the oceans aren't catastrophically heating either.

      Is there warming going on in either the oceans or the atmosphere?

      Yeah, every day, every year, sure there is. It's called SEASONS and the diurnal cycle.

      Remember, way back when, those who refused to be swayed by emotional arguments and actually bothered to STUDY THIS ISSUE FOR THEMSELVES instead of being stampeded where alarmists hoped t hey would go found out that the primary effects of a...See More
    • Greg Harris · Top Commenter · San Diego, California
      Mark Tinder - Great comeback!
  • Steven Litvintchouk · Top Commenter
    Dr. Carter's theories are familiar to the mainstream climate science community.

    What Dr. Carter did NOT say, was that his own theory is that all of the fluctuations in global temperature can be explained by the Southern Oscillation, not by anthropogenic CO2.

    And mainstream scientists took the time to refute his theory:

    Unfortunately, it's behind a paywall so I can't cite the text here.

    If Mr. Hinderaker is really interested in having a real scientific debate on the subject, perhaps he would pay the fee and post here what the reply to Dr. Carter's theory is.

    I don't like ad hominem attacks, the standard tactic used by the Left.

    But scientists are human beings--and I do believe that you're known by the company you keep.
    ...See More
    • Phil Prange · Top Commenter · University of Wisconsin-Madison
      Stop with the ad hominem attacks if you don't like them.
    • Greg Harris · Top Commenter · San Diego, California
      Although I'm not old enough to have actually witnessed it, my sense (from my studies and inquiries) is that there is an oscillation between the northern and southern hemispheres beyond that which is widely discussed. Do you know of the myths of "the Northwest Passage"? There are usually rational reasons for myths like that. In history not directly remembered but passed down in myths and legends the Arctic ice extent was likely well below anything we've seen in our lifetimes. Further, we know from other investigations there was a reason they called Greenland that. Keep in mind, Iceland had more ice than Greenland and Greenland was greener than Iceland until whatever it was that changed it changed. Keep in mind that up to two miles deep ice and snow covered Most of Canada and large parts of the U.S., along with much of Europe and Asia and, naturally, with all that water locked up and trapped in ice, sea levels were much lower. I imagine the atmosphere might have been measurably drier and you want to talk drought? Well we could talk about the Dust Bowl too, back when the REAL "hottest" temperatures were being set, but hopefully everyone who bothered to avoid being manipulated by false emotional arguments already gets it and doesn't need further input from me.

      The rest of you, good luck. We really need you to wake up, but sadly you're not showing any sign or giving us any hope that you will.
    • TJ Buttrick · Top Commenter · Smiths Station, Alabama
      Come now, Steven. Is Dr Carter required to refute creationism in every article he authors? If the piece cited had to do with evolution/creationism, I would expect some sort of disclaimer but why should he state his views on such in an article about DAGW makes no sense. Or do you believe that Dr Carter cannot be correct in his research on anything, simply because "of the company he keeps"?
  • Steve Tibbetts · Top Commenter
    Mr. Qwerty (use your real name, dude) is indeed confusing two "Robert Carters." However, as Mr. Litvintchouk has pointed out below, the American Institute for Technology and Science Education is primarily a Creation Science outfit. Now, that isn't to say that a creation scientist is going to be 100% wrong about global warming, but that's also like saying Ahmadinejad has his history down cold, except for that one little detail about the Holocaust.

    My wife's sister works in molecular biology, and intelligent design tracts from AITSE are reliable fodder for lunchtime hilarity. Please read one of Caroline Crocker's articles and tell me this is a credible scientific outfit (read the second paragraph from the bottom where she decries "...belief in evolution...and disregarding Biblical standards for sexuality.") Great stuff.
  • Brandon Qwerty· Top Commenter (signed in using Hotmail)
    Right. The "American Institute for Technology and Science Education" is run by a creationist idiot named Carolyn Crocker. If that's science, George Bush was a genius.

    The "scientist" Hinderaker quotes above, Professor Robert Carter, "... is currently researching human genetics and other issues related to biblical creation."


    (Oh...we forgot...Bush WAS a genius..)
    • Ken Willis · Top Commenter · University of Denver
      Alas, you are right that the “Institute” Robert Carter hails from is a creationist hideout. “Creationism” is, in my view, just as nonsensical as DAGW. This may be a case where a man who holds weird views in another area has it right in this area. We should look at the scientific argument he makes and judge it alone. I don’t have the knowledge to do that but I don’t need much science to know DAGW is nonsense, on about the same order as so-called “creationism."
    • Ken Willis · Top Commenter · University of Denver
      I’m referring to creationism as science and that does make it nonsense. As religion, however, it is perfectly good.
    • Jon Dewey · Works at, inc.
      Are you saying that scientific forensic evidence of design is an impossible category of evidence for a given physical or biological thing and therefore such evidence and such a science does not exist? Or are you saying that the arguments you hear from creationists are often demonstrably incorrect?
  • Ken Willis · Top Commenter · University of Denver
    I remember hiking in the area of the Matterhorn with my wife in the 1980’s. I would of course remember the trek by itself, but the poignant piece of it was that we argued the whole way about global warming. I argued that it was utter nonsense to believe human activity could have anything to do with it, if it was even happening. She was convinced that it was true, and that I was insane. I didn’t know anything about the science of it, I just knew that a short time earlier the same people were trying to scare us with warnings of global cooling. Besides, it sounded preposterous. As the years went on millions of people fell for DAGW, apparently without the slightest doubt. It’s to the point now that no amount of scientific evidence to the contrary will never change their minds. They believed something that was never supported by science, and now they hold to that believe after it is discredited by science. My wife, thank heavens, has come to her senses.
    • Angela Kay Harris · · Top Commenter
      It'll be fun watching them cling to their ridiculous beliefs as the globe cools, perhaps drastically. The sun is very, very quite these days. I believe they've not observed this low a level of solar activity since the very early 1900s. If the sun doesn't turn up the heat soon, we may be having very long, hungry winters.
    • Mark Tinder · Top Commenter
      Ken-you can't talk a true believer out of his/her religion, and that exactly what AGW is-a religious belief. Of course, you CAN talk people out of their money and freedom, and THAT'S really what the IPCC and its useful idiots are all about.
  • Dave Anderson · Top Commenter · Duluth, Minnesota
    Science refutes the political "solutions" Gore and his ilk are pushing. If we drive our economy back to its state 75 years ago and transfer a large fraction of our wealth to the third world will this stop the hypothetical anthropomorphic warming?

    Science says no.
  • Rob de Vos · Katholieke Leergangen Tilburg
    Ken Willis, you have 4 'twin'brothers on Facebook (same photo), but strangely enough all five of you share the same first name, not the surname. Who is the real Ken?
  • Anthony Paula · Top Commenter
    nice...those that direct( 1.) government and their efforts, (2.) the "news" outlets, and ( 3.) universities seem less interested in facts and truth than their "cause" or religion.
  • Todd Foster · Top Commenter · Eden Prairie, Minnesota
    There's a number 4. Just what has been proposed that would do anything of substance regarding this "problem."

    Extreme economic upheaval to reduce the rise in trace gas by a trace amount. No plan, no matter how extreme, halts the rise in CO2.
  • frammis3000 (signed in using yahoo)
    Here's more of Dr. Carter: A great quote: "I see evolution as the primary stumbling block for people accepting the Gospel." More "science" like that, Powerline. It really polishes your brand.
    • Robert McMahon · Top Commenter · Owner/Sole Proprietor at Robert McMahon Gallery
      Hey Frammis, I've got other quotes from Dr Carter - everything that is in the article linked above. Why not choose a specific quote and address it, if you can. What, not bright enough? Not informed enough? What a surprise.
    • Murray Stewart · University of Wollongong
      Frammis, get your act together.

      You have the wrong Dr Carter.

      Do like Robert suggests and actually read the article.

      Even if you disagree with it you will actually know what you are
      disagreeing with :)
    • Todd Foster · Top Commenter · Eden Prairie, Minnesota
      "You have the wrong Dr Carter."

      He sure does. Robert M. Carter, James Cook University, sport.

      More research like that from anonymous cowards really polishes the Obama voter brand, doesn't it?
  • Gregorio Montejo · · Adjunct Professor at University of St. Thomas
    Very good article on 'global warming.' Unfortunately, the accompanying illustration is not of William of Occam, but rather of Bernard of Clairvaux. Apparently the Powerline guys don't read Latin.
  • PG Farmer· Top Commenter (signed in using Hotmail)
    There is one more theory - just as unprovable as the East Anglia / Pervert State U theory - and that is: mother nature is wanting to head us into another ice age - about time - and my use of ice cold A/C and a 350 HP de-greened V8 is saving us from certain doom in an icy grave.
    • George Murphy · Top Commenter · York Community High School
      Twelve thousand years ago where I live was under a mile thick sheet of ice. Global warming? Yes since the first melted drop of that ice sheet.
    • Steven Litvintchouk · Top Commenter
      PG Farmer:

      No mainstream scientists are pushing any "ice age" theory.

      We conservatives are making a very serious mistake by trying to fight this nonstop guerrilla war against mainstream science. I know from history that those who have tried to do that, ended up losing and discredited.

      My problem with the AGW theory is NOT the theory. My concern is how dealing with AGW will impact the American economy, the American way of life, and America's status in the world.

      I wish we could start discussing that--because that really is what is worrying all of us, isn't it?
    • Harry Taft · Top Commenter
      Steven - Every now and then some one accepts an idea or concept and nothing they see, hear or read afterward, is useful. They have stopped questioning. They have their answer. Ptolemy's theory of the construction of the universe was accepted wisdom for over a thousand years. The idea that anyone has complete knowledge of how our planet's atmosphere warms and cools is ridiculous. The hypotheses of the IPCC "scientists" dictate a constant warming as CO2 becomes ever more abundant in the atmosphere. It isn't happening. What would it take for you to reexamine the subject ?
  • Walt Kozlowski · Top Commenter · Tampa Baptist Academy
    well I believe in the lord but not good to use creationists or inteligent design for science.
  • Neal Evans · Adrian High School
    This just adds to the doubts, many of us have, that man is the cause of global warming.
  • Dan Shapiro · Top Commenter · San Diego State University
    But...but...but the lemmings always need to have something to worry about.

Brophy Saturday 09 February 2013 - 10:29 am | | Global Warming
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Babenchuk, - 16-03-’16 12:21
william kittrell
william kittrell, - 09-07-’17 17:10
uthan hage
uthan hage, (URL) - 14-12-’17 08:53
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