How Guy McPherson gets it wrong

Recently, a few Ars Technica commenters have been posting references to the work of Guy McPherson on climate articles. McPherson is a retired professor of ecology at the University of Arizona, and he runs a blog called Nature Bats Last. In recent years, he has turned his energies to dire warnings of impending climate catastrophe. Those warnings go far beyond what you’ll find anywhere else: McPherson believes humans will go extinct in as little as two decades.

Now, lots of people run blogs that make wild claims, so why am I spending time on this one? McPherson claims to simply be passing along scientific data to the public— data that most scientists are unwilling to talk about and governments are trying to keep secret. As a result, his followers (I mean to use that term more in the Twitter sense than a religious one) seem confident that they have the weight of science behind them. It takes careful examination of McPherson’s references, and a familiarity with the present state of climate science, to uncover that his claims aren’t scientific at all. I also get the feeling that his internet following might not be insignificant (as noted by climate scientist Michael Tobis) and could be growing, yet I couldn’t find any direct challenges with a web search. This makes one.

Bizarro denial

First, I want to go over general problems with McPherson’s claims and talk about what climate science is really telling us. For those wanting specifics, I’ll post a list of point-by-point corrections of McPherson’s main “Climate Change Summary and Update” post in the third section.

In many ways, McPherson is a photo-negative of the self-proclaimed “climate skeptics” who reject the conclusions of climate science. He may be advocating the opposite conclusion, but he argues his case in the same way. The skeptics often quote snippets of science that, on full examination, doesn’t actually support their claims, and this is McPherson’s modus operandi. The skeptics dismiss science they don’t like by saying that climate researchers lie to keep the grant money coming; McPherson dismisses inconvenient science by claiming that scientists are downplaying risks because they’re too cowardly to speak the truth and flout our corporate overlords. Both malign the IPCC as “political” and therefore not objective. And both will cite nearly any claim that supports their views, regardless of source— putting evidence-free opinions on par with scientific research. (In one example I can’t help but highlight, McPherson cites a survivalist blog warning that Earth’s atmosphere is running out of oxygen.)

McPherson bills himself as a scientist simply passing along the science (even as he dismisses climate scientists and their work), but he cites nearly as many blog posts and newspaper columns as published studies. When he does cite a study, it’s often clear that he hasn’t taken the time to actually read it, depending instead on a news story about it. He frequently gets the information from the study completely wrong, which is a difficult thing for most readers to check given that most papers are behind paywalls (not to mention that scientific papers aren’t easy to understand).

McPherson leans heavily on claims from people associated with the “Arctic News” blog about a catastrophic, runaway release of methane that supposedly is already underway in the Arctic. Unfortunately (or, rather, fortunately), the data don’t match their assertions. The latest IPCC and NAS assessment reports, in fact, deemed such a release “very unlikely” this century. One reason for that is that the Arctic has been this warm or warmer a couple times in the last 200,000 years, yet that methane stayed in the ground. Another reason is that scientists actually bother to study and model the processes involved. One thing McPherson and others like to point to is the recent work by Natalia Shakhova’s group observing bubbling plumes of methane coming up from the seafloor on the Siberian Shelf. Since we’ve only been sampling these plumes for a few years, we have no idea whether that release of methane is increasing or if these are long-term features. Similar plumes off Svalbard, for example, appear to be thousands of years old. (More to put this methane in context here.)

That’s exactly the kind of detail and  nuance that’s absent from McPherson’s claims. Instead, he’s content to link to YouTube videos or blog posts (some ludicrously unscientific— see below) and run with the idea that catastrophic warming is guaranteed as a result. He just latches onto anything that sounds scary. McPherson is especially fast and loose with timeframes. He likes to point to the magnitude of past climate changes (which took thousands of years or more) as proof that we are about to undergo similar changes in the next couple decades. That’s quite clearly a fallacious argument, but McPherson never concerns himself with the details. All the casual reader learns it that there was a huge change in the past analogous to the present that shows just how screwed we really are.

And that’s McPherson’s thing— despair. We’re absolutely doomed, he tells us, and there’s nothing we can do about it. Everything is lost. He derides any sort of optimism or action as “hopium”. He notes in one recent post that “With an eye to improving my ‘bedside manner’ when I deliver presentations, I’ve recently become a certified grief-recovery counselor.” With such an extraordinary view, you would expect him to make the scientific case for extinction very clearly. But he does not. His argument fundamentally reduces to “positive feedbacks exist, ergo extinction”. That is, he lists examples of positive feedbacks (things that amplify change, like the added sunlight absorption of ocean water that has lost its sea ice cover) for a while, intending to overwhelm you with the number of processes that could add to global warming. And that’s it. There are no numbers explaining how big an effect each could have, no analysis of likely warming impacts, nothing. The fact is that climate scientists know about all these processes. But instead of throwing their hands up and saying “Oh, shit”, they actually do science.

Again, specific examples of these things are given in the last section of this post. If you take a look at some of his mistakes and demonstrably false claims, you’ll have a hard time thinking of him as a credible source of information.

[Update 3-13-14: Michael Tobis has covered some of the points I skipped over—namely, McPherson’s discussion of feedbacks— in a new post.]

Just the facts

So let’s briefly lay out the central claims of McPherson’s position, and review what the science really says. I think those are 1) positive feedbacks imply runaway global warming, 2) we will experience at least 3 to 4 degrees C warming in the next couple decades, and 3) on a 4C warmer planet, humans are dead.

Numero uno. While the concept of a positive feedback (a little change triggers an addition that makes the change bigger, triggering another addition that…) sounds like snowballing without end, that’s not actually the case here. These positive climate feedbacks (and there are negative feedbacks, by the way) amplify warming, but only to a certain extent. After all, these same processes were in play when the Earth warmed out of the last glaciation (over the last ~18,000 years), which obviously didn’t scorch the planet. Without any of these feedbacks, the glacial/interglacial differences would be much smaller, but they do not cause runaway warming.

There is such a thing as a runaway greenhouse effect– just ask the planet Venus. However, a recent study looking at what it would take to trigger such an event on Earth ballparked the requirements at around 75 times the amount of CO2 currently in the atmosphere, 5.5 times the methane, and some other greenhouse gases. The “business-as-usual” scenario in the latest IPCC report, where we do nothing to curtail greenhouse gas emissions, ends the century at about 2.3 times today’s CO2 and 2 times the methane. We have a lot of things to worry about, but a runaway greenhouse isn’t one of them. (McPherson, by the way, cites this same paper as if it shows that we’re about to trigger a runaway greenhouse.)

So what are we facing if Arctic methane releases increase? Climate scientist David Archer shows some back-of-the-envelope math here. If the release increased by a factor of 100 and lasted for a century, it would be the equivalent of increasing today’s CO2 by 25-90%. Bad? Yes. Extinction? No.

Nummer zwei. The latest IPCC report projects roughly 0.3 to 0.7C of warming by 2035. (The exact numbers are a little complicated, but I explained it here.) Farther into the future, the different emissions scenarios diverge. The “business-as-usual” scenario results in about 2.6 to 4.8C warming by 2100. Rosier scenarios involving moderate efforts to stabilize greenhouse gases yield warming of about 1.1 to 3.1C by 2100. There are precisely zero scientific studies projecting several degrees of warming by 2035, as McPherson predicts. (In fact, he cites one blogger’s childish prediction of a whopping 20C increase by 2050.)

Numéro trois. So what are the impacts of 4C warming? Here’s a handy summary of the many impacts described in the 2007 IPCC report (this section of the newest report isn’t out yet). They include increased droughts, more extreme rainfall, rising sea levels, serious problems for many ocean organisms, real problems for many terrestrial species, lowered agricultural yields… It’s not pretty, and we very much want to avoid it, but it’s not human extinction.

If you think the IPCC reports are lying about the state of the science, feel free to do a Google Scholar search for “climate change projections” in published studies.

[Note 4-7-14: A comment from Paul Beckwith has revealed that I incorrectly attributed some statements and materials to the Arctic Methane Emergency Group, either due to Guy McPherson’s attribution or misunderstandings of my own. I considered preserving these statements for transparency, but don’t want to make the post too hard to read, so I will simply make the appropriate edits. I am grateful to Paul for bringing it to my attention.]


Okay. These corrections and notes apply to this post on McPherson’s blog, which I took to be the most complete explication of his views available for fact-checking. The point of this tedious list is to back up the points I raised above and illustrate the untrustworthy and unscientific nature of McPherson’s claims.

As his post appears to be updated over time, I’ll note that I accessed it on 2-13-2014. I’ll just go top to bottom.

–Guy McPherson (I’ll abbreviate as “GM”) cites the Brysse et al “side of least drama” paper to support his claim that climate scientists are simply unwilling to speak out about the imminent and existential threat of climate change. The paper absolutely does state that “scientists are biased not toward alarmism but rather the reverse: toward cautious estimates”. However, it’s more than a stretch to extend this to the idea that civilization is collapsing and we’re going extinct but climate scientists are saying everything is fine.

–GM writes, “Ever late to the party, the Intergovernmental Panel on Climate Change (IPCC) admits global warming is irreversible without geoengineering in a report released 27 September 2013.” This can only be seen as a new “admission” if you know nothing about the carbon cycle. Warming is irreversible because CO2 remains in the atmosphere for centuries to millennia— this has always been known. Irreversible does not mean unstoppable, however, as GM seems to be implying. Reducing emissions stabilizes greenhouse gas concentrations, limiting warming. In order to lower temperatures, CO2 will have to be removed from the atmosphere— geoengineering. Old news.

–Now we get to “On a planet 4 C hotter than baseline, all we can prepare for is human extinction.” The reference for this pretty important statement? An opinion piece in the Guardian.

–GM references the paper I mentioned above about a runaway greenhouse effect on Earth being easier to trigger than previously thought. Of course, we saw that it requires far, far more warming than any realistic scenario of anthropogenic climate change— a point that is explicitly made in that paper.

–GM notes the discovery of a recent greenhouse gas (perfluorotributylamine) that is 7,100 more potent than CO2, molecule-for-molecule. This seems to be included only for the scary number. How much of it is in the atmosphere? At about 0.18 parts per trillion (in Toronto), it’s completely irrelevant to questions about the climate change we’re currently undergoing.

–GM cites a Geological Society of London release about climate sensitivity— the amount of warming we get from a given increase in CO2. GM describes it by saying that “Earth’s climate could be twice as sensitive  to atmospheric carbon as previously believed.” But that’s not what the release says. The climate sensitivity values that are usually discussed (around 3C for a doubling of CO2) are specific measures over specific timeframes, developed to create a standardized comparison between models. The release describes an analysis of longer-term change, as the climate system comes into equilibrium over millennia. It’s that long-term change that the release says could be double the shorter-term sensitivity . If we’re discussing what we’re facing over the next few decades, that is completely irrelevant.

–Here’s where the Arctic methane stuff gets hot and heavy, as one person is quoted as saying, “The world is probably at the start of a runaway Greenhouse Event which will end most human life on Earth before 2040.” There’s simply no evidence for this. You won’t find any published studies to support it. GM goes a step further, citing an “analysis” on the “Arctic News” blog, predicting a 20C warming by 2050. What is this prediction based on? Curves drawn on a chart. If you fit the right polynomial (a dangerous activity) to the Arctic temperature data that shows roughly 2C warming from 1980 to 2010, you can get it to skyrocket to 20C by 2050. (Well, actually you can’t quite, so a steeper line is simply drawn on.) No climate model. No physics. Just a line. This isn’t science. This is the kind of thing that lazy climate “skeptics” do (the smarter ones won’t).

–GM includes a graph from the same “Arctic News” blog showing methane data. First, it claims that methane is 1,000 times more potent than CO2 (it isn’t) and thus responsible for the vast majority of global warming (it isn’t). Beyond that, it plots a single measurement of atmospheric methane from a single spot in the Arctic (>2,600 parts per billion) on a chart of global average atmospheric methane (currently about 1,800 ppb).  This sudden “increase” is assumed to represent a catastrophic release. Unfortunately, this is simply ignorant. Methane concentration varies quite a bit around the world— highest in the Arctic, lowest in the Antarctic. Absolutely no effort was made to create an apples-to-apples comparison like, at the very least, calculating an average concentration for the Arctic for that week.

–GM reports that the US Navy “predicts an ice-free Arctic by summer 2016”. What does the linked post actually say? The lower bound of the predicted decline in a sea ice model run by Navy researchers was 2016. The researcher calls this “an aggressive interpretation”. What was the central date in the projection? Or the upper bound? We aren’t told. How does this sea ice model compare to others? GM isn’t interested in helping us find out. I would guess this means he hasn’t looked.

–GM quotes climate scientist Jason Box from a newspaper story, saying, “In 2012 Greenland crossed a threshold where for the first time we saw complete surface melting at the highest elevations in what we used to call the dry snow zone.” He uses this to support his contention that the climate system reached a tipping point— a threshold to runaway change—  in 2007. But what Box was actually talking about was a freak event several days long in which melting conditions existed across the entire ice sheet. This was viewed as a weather event, not a significant climate event.

–In a note dismissing biofuels, GM describes them as “the nonsensical notion that industrial civilization can be used to overcome a predicament created by industrial civilization”. This is obviously an axiomatic assertion that makes you worry about GM’s objectivity.

–GM provides a timeline of climate “predictions”, ostensibly showing that they have become more and more alarming over the past few years. (We’ll leave aside, for the moment, that he doesn’t seem to understand the difference between projections— predictions contingent on scenarios of future emissions— and actual predictions.) An updated version of this list can be found here. [Update: I’ve been told that version is actually not the most recent.] The list is flat-out wrong. I dug up the actual numbers on several of them for an Ars commenter. GM claims the IPCC predict 1C of warming by 2100 in their 2007 report. It actually projected roughly 1.8 to 4C, depending on the emissions scenario. These numbers were equivalent to the projections from the previous report in 2001. Next, GM claims the Hadley Centre predicted 2C by 2100 in 2008. The document he links to provides no projections of global temperature of any kind. At the other end of the list, GM claims that the International Energy Agency predicted 3.5C warming by 2035 in 2013. The link goes to a poorly re-written press story from 2010. What did the IEA really say? Their 2010 report described a scenario in which the trajectory of growing emissions by 2035 was such that we would eventually hit 3.5C warming before greenhouse gases were stabilized. [Update: GM had already removed the IEA “prediction” from his post.] So does this list show climate projections becoming rapidly more dire? That’s a big, fat no.

–GM writes, “These assessments fail to account for significant self-reinforcing feedback loops (i.e., positive feedbacks, the term that implies the opposite of its meaning). The IPCC’s vaunted Fifth Assessment will continue the trend as it, too, ignores important feedbacks.” It’s not true that these assessments ignore positive feedbacks. It is true that not all processes are included in climate models, which continue to be developed. The link GM provides is to a story relates to the fact that the generation of models used for the latest IPCC report do not simulate thawing permafrost. For reference, one model that does simulate this process now projects that it would add an additional 0.1 to 0.7C warming by 2100 due to a release of CO2 that would raise the global concentration by 40 to 100 ppm. My guess is that those numbers aren’t scary enough for GM to want to mention them. (To be fair, that’s probably a conservative estimate, but it’s nowhere near the kind of thing GM is talking about.)

–GM cites a paper showing that Earth may have lost its moderate climate to a runaway greenhouse if it were more than 1% closer to the Sun (though it also notes that their analysis doesn’t account for clouds, which might broaden the range). He believes this supports a claim that “A minor change in Earth’s atmosphere removes human habitat. Unfortunately, we’ve invoked major changes.” How does one square this with warmer climates in Earth’s history, none of which triggered that runaway greenhouse? The Cretaceous period, notably, was far warmer than the present day. It wasn’t until an asteroid impact wreaked havoc on the climate system that a mass extinction took place. GM’s definitions of “minor change” and “major change” are fuzzy.

–GM brings up a temperature record from Concord, Massachusetts, in a very interesting parallel to climate “skeptics”. Individual records that show cooling over some period are often cited as proof that all this global warming stuff is hooey. Or the accuracy of a particular record is called into question in some way, as if climate science is a house of cards that can be brought down by the exposure of a single flaw. In this case, GM claims that while the instrumental temperature record indicates about 1C warming there since 1840, an analysis of the flowering dates from Henry David Thoreau’s journals indicates a warming of 2.4C. First off, it’s interesting to note GM implying that instrumental records are woefully inaccurate, when it’s this very information that helped climate science work out the anthropogenic nature of climate change. Second, if GM had bothered to read the paper, he would have discovered that the 2.4C number comes from the local instrumental record, not the flowering dates. The instrumental record was used to study how the flowering dates changed with temperature. I have no idea where he got the 1C number from.

–GM claims that the Next Generation Science Standards (for public schools) “buries the relationship between combustion of fossil fuels and planetary warming”. “The misadventures of the corporate government continue”, he complains. In a post about evolution and climate change in those science standards by the National Center for Science Education, they quote from the standards: “Human activities, such as the release of greenhouse gases from burning fossil fuels, are major factors in the current rise in Earth’s mean surface temperature (global warming).” Why did GM make this up?

–GM cites a briefing from the UN talks in Copenhagen saying that the past shows sea level should be 23 meters higher at today’s CO2 concentration. What does this briefing, from a Jamaican reef biochemist, note about this? “IPCC projections are based on modes for a time period of 20, 50, or 100 years, when the response of the climate system to increased CO2 takes thousands of years, so models miss more than 90% of the long term response…” Again, we’re up against timeframe details. GM equates long-term equilibrium changes with short term, decadal ones. Here’s a study looking at the same thing: they estimate the long term sea level rise at today’s CO2 at 9-31 meters, noting that would take 500 to 2,500 years. The reason for this is that these studies are based on estimating past sea levels and CO2 concentrations (which is complicated). These records are necessarily at long term equilibrium, because that’s what the geologic record preserves for us that far back in time.

–I don’t think I need to comment on this claim: “In other words, near-term extinction of humans was already guaranteed, to the knowledge of Obama and his administration  (i.e., the Central Intelligence Agency, which runs the United States and controls presidential power). Even before the dire feedbacks were reported by the scientific community, the administration abandoned climate change as a significant issue because it knew we were done as early as 2009. Rather than shoulder the unenviable task of truth-teller, Obama did as his imperial higher-ups demanded: He lied about collapse, and he lied about climate change. And he still does.”

–“Arctic News” returns, along with a YouTube video, to claim that “Arctic methane release and rapid global temperature rise are interlinked — including a temperature rise up to about 1 C per year over a decade,according to data from ice cores“. The “analysis” is someone looking at data from a Greenland ice core, deciding that methane looks more important than CO2 (physics need not apply), and noting the abrupt warming at the end of the Younger Dryas, an interesting period about 12,000 years ago and is thought to have been brought about by a disruption of ocean circulation. (Questions remain.) First, temperatures calculated from Greenland ice cores are local temperatures, not the global average, and the change during the remarkable event was less elsewhere. Second, the methane increase in the ice cores they point to as the cause of the warming is from about 450 to 750 ppb— a difference of 300 ppb. Remember that the global average today is about 1,800 ppb. Methane has increased about 150 ppb since 1985. Has that had a similar effect to what they’re proposing? The first link in GM’s statement contains this ludicrous extrapolation: “The atmospheric temperature increase in Australia this year (0.22C) indicates that in 10 years it will exceed 2.2C and in 30 to 40 years, 6.6C to 8.8C.” I’m not sure you can get more unscientific than that. Australia, by the way, has warmed about 1C since 1950.

–For the sake of my sanity, I’m going to skip over the list of positive feedbacks. Suffice to say, some of them are just more “Arctic News” claims and several others are mis-reported. Others are fine. [Michael Tobis took a look at this list in this post.]

–GM finally comes right out and says “the scientists writing official reports on climate change are lying”.

–GM writes “And never mind that warming in the interior of large continents in the northern hemisphere has outstripped model predictions in racing to 6-7 C already, according to a paper that tallies temperature rise in China’s interior in the 15 May 2013 issue of the Proceedings of the National Academy of Sciences.” What does that study really say? “Here, we show central China is a region that experienced a much larger temperature change since the Last Glacial Maximum than typically simulated by climate models… We find a summertime temperature change of 6–7 °C that is reproduced by climate model simulations presented here.” The Last Glacial Maximum, remember, is the peak of the last “ice age” around 20,000 years ago. Why is GM pretending that parts of China have experienced 6-7C of anthropogenic warming, and that this shows projections of future warming to be too conservative?

–GM writes “Through late March 2013, global oceans have risen approximately ten millimeters per year during the last two years. This rate of rise is over three times the rate of sea level rise during the time of satellite-based observations from 1993 to the present.” Sounds like it’s accelerating rapidly, doesn’t it? Even his link is to a post showing why this is not a sign of acceleration. The tremendous La Nina of 2011 dumped tons of rain on Australia and the Amazon, adding so much water to continental storage that sea level fell over 5 mm. As that water drained back to the oceans, sea level rise increased. You can see the most up-to-date data here. This is cherry picking. This is what climate “skeptics” do.

–GM writes “On a particularly dire note for humanity, climate change causes early death of five million people peach year.” This links to a story about an NGO report. The summary from the actual report states, “This report estimates that climate change causes 400,000 deaths on average each year today, mainly due to hunger and communicable diseases that affect above all children in developing countries. Our present carbon-intensive energy system and related activities cause an estimated 4.5 million deaths each year linked to air pollution, hazardous occupations and cancer.”

–GM writes, “The Guardian‘s headline from 13 November 2013 announces, ‘Global warming since 1997 more than twice as fast as previously estimated, new study shows.'” Sounds like global warming is accelerating beyond scientist’s projections! The story refers to a study (which I covered here) showing that one particular global temperature dataset (there are several) was underestimating recent temperatures, primarily due to a lack of measurements in the Arctic. That bias (by which I mean measurement bias, not bias in the political sense) made the recent slowdown in atmospheric warming (related to some action in the Pacific) seem a little larger than it really was. Other datasets had less of this bias. Accounting for this still leaves the last decade of atmospheric warming slower than the previous one. (Again, this is natural variability— warming of the ocean hasn’t slowed.)

–GM writes, “Global loss of sea ice matches the trend in the Arctic. It’s down, down, and down some more, with the five lowest values on record all happening in the last seven years (through 2012).” This may seem like a nit-pick, but this is a pointless statement. The global sea ice trend depends on two places- Antarctica and the Arctic. In Antarctica, there’s been a slight increase recently, while the Arctic has seen a large decrease. Therefore, the reason that global sea ice is down is that Arctic sea ice is down.

–GM writes, “[T]he 13 September 2013 issue of Science contains another surprise for mainstream scientists : The Pine Island Glacier is melting from below as a result of warming seawater.” It’s well known (and bloody obvious) that warming seawater melts marine-terminating glaciers. Calling this “another surprise for mainstream scientists” is just a mindless pot-shot.

–GM writes, “The climate situation is much worse than I’ve led you to believe, and is accelerating far more rapidly than accounted for by models.” The link goes to a YouTube video from David Wasdell of the “Apollo-Gaia Project” telling a parable. He’s not a scientist, but his videos are used as evidence several other times, as well.

–GM cites a Peter Wadhams prediction of ice-free Arctic summers by 2015 or 2016 (more than once, I think). Apart from Wieslaw Maslowski, you won’t find other sea ice researchers making such a dire prediction. As you can see, it would take a truly incredible change in the next couple years for this prediction to come true.

–Back to the pointless pejoratives, we get “In a turn surprising only to mainstream climate scientists, Greenland ice is melting rapidly.” First, this link just refers to the freak surface melting weather from July 2012 I mentioned above. Second, the rate that Greenland ice is melting is no surprise to climate scientists, who have been the ones documenting it year in and year out. GM uses the phrase “mainstream climate scientists” like Sarah Palin says “lamestream media”.

–Here’s a hum-dinger I mentioned way up above. “As one little-discussed example, atmospheric oxygen levels are dropping to levels considered dangerous for humans, particularly in cities.” Yes, that link goes to a survivalist blog. No, we’re not going to suffocate because burning fossil fuels is using up all the oxygen in the atmosphere. It’s true that fossil fuel combustion has sightly lowered the concentration— this is one way we know humans are responsible for rising CO2— but it’s not even remotely close to a significant decrease. Between 1990 and 2005, the proportion of oxygen in the atmosphere decreased about 0.02%.

–GM writes, “An increasing number of scientists agree that warming of 4 to 6 C causes a dead planet. And, they go on to say, we’ll be there by 2060.” The link goes to a blog post by writer David Spratt, who was used as a reference before. Spratt gets the 4-6C comment from a reference to warming in 2100. He invents the “as early as 2060” himself. The “dead planet” part of the statement refers to this World Bank release about the dangerous impacts of 4C warming. Spratt describes this as ending “the world as we know it”, which GM flips into “a dead planet”. You won’t find any such description from World Bank.

–GM cites a video of a PhD student talking about the possibility of 6C warming in a decade and uses this graph to support it, presumably because the spike at the end looks scary. Apart from the fact that the graph doesn’t actually come from the paper he cites, but rather data from two papers (one of which he cites) combined with a business-as-usual projection for the next century (which he does not explain), the scary spike at the end is just the same ~3C warming by 2100 IPCC projection he was discounting earlier. To tidy up the math here, 3C/90yrs =/= 6C/10yrs.

–The end of the post claims that the Pentagon is surveilling us online in case finding out that we’re going extinct turns us into ecoterrorists. Just sayin’…

–Lastly a quote from another post of GM’s, which he explains why he thinks the collapse of human civilization can’t get here quickly enough. “Yet, seemingly contrary to these simple, easy-to-reach conclusions, I work toward collapse. Largely unafflicted by the arrogance of humanism, I work on behalf of non-human species. Industrial civilization is destroying every aspect of the living planet, and I know virtually nobody who wants to stop the runaway train. Yes, collapse will kill us. But our deaths are guaranteed regardless, unless I missed a memo.”

Update: I’ve discovered some interesting comments on GM’s post. A poster named Eric took issue with some of GM’s claims, and pointed out a few of the same errors I’ve outlined above (like reports not saying what GM claims they say). To make sure his criticism came across correctly, Eric noted, “I’m not saying climate change is a non issue- In fact I happen to think that it is humanities BIGGEST issue. However hyperbole and exaggerated threats serve no purpose but too slow down the response and make people lose hope. I appreciate your time and I hope I have contributed to the discussion in a meaningful way.”

After another poster asked if GM was going to respond, he wrote, “I will not take time to deal with Eric the denier. No amount of evidence will convince deniers of anything, so I’ll not waste my time. If you’re interested in evidence, there’s plenty in this post to support all I’ve written and said.” This appears to be a representative exchange.

2,312 thoughts on “How Guy McPherson gets it wrong

  1. Nice work, Scott! I’m an astronomy professor in California and was invited to be on a public panel discussion with Guy McPherson a couple years ago. I’ve also got a PowerPoint debunking GM’s claims, which is worth a look by others as well. One good point which I don’t see mentioned in your debunking (perhaps I missed it because the search term was wrong), was his claim that Earth is on the bare inside edge of the “Habitable Zone”, citing a very colorful and often circulated plot whose original purpose was to narrow the look at exoplanets who might have life. The author of the study explicitly says that the HZ he illustrates is for a simple cloud-free model planet, and that the existence of clouds extends the HZ on both the hot inner edge AND the cold outer edge. So, we’re NOT on the edge of the HZ and 1% ready to tip over to oblivion. I highlight this in my PP, and Archer’s Arctic methane hydrate calculation showing the “methane apocalypse” has been postponed indefinitely, and more.

    Liked by 3 people

    • Indy22, thanks for this post. I’ve wondered about that for years now, and it’s good to have your viewpoint. Would you care to tell us where we are exactly in the Habitable Zone based on your studies and those of the author of that study? I’m curious to know. Thanks! Also, thanks for link to your PPT. Interesting.


      • On slide 29 he talks about a cosmology paper co-authored with Sandra Faber. They envision a sustainable future with a human population of around 50 million. Isn’t that wonderful?
        Whether I believe him or Guy McPherson, I’m dead. The only purpose of these thought experiments (that I can see) is to help me choose how I want to live my life.

        Liked by 1 person

    • Thank you, INDY222. I was almost certain I had seen that idea of Earth being on the edge of the habitable zone discredited a year or two ago. McPherson is probably aware of it, but since he knows his audience is unlikely to be thus aware, he continues to use it.

      He is now just a traveling performer, but his extinction “message” continues to have an appeal, no matter how often it is debunked.


  2. To correct; I was not co-author with Sandy Faber on her Presentation on our long term future, but instead on some purely astronomy papers back in the ’90’s. Faber’s “50 million” isn’t a prediction so much as it’s a calculation of where we would aim if we want to have a representative and unobtrusive presence on our planet amid the other species. Right now, we take more than 1/3 of all the sunlight energy arriving at Earth, just for one species. No, not for solar panels, but for growing forests and crops and pasture which support us and our livestock. Oh, and the fish we cleaned out of the oceans.

    On the habitable zone width, I don’t have a reference for a more realistic one. It depends so intimately on the exact atmospheric composition. I wouldn’t worry about it. We’re not close to the edge and won’t be for hundreds of millions of years of steadily increasing solar luminosity.

    Liked by 1 person

  3. You write:
    “Nummer zwei. The latest IPCC report projects roughly 0.3 to 0.7C of warming by 2035”.
    Are we not up to 0.85 now end of 2016?


    • The link in the next sentence is meant to clarify: “The report says that global temperature averaged over the time period from 2016 to 2035 is likely to be 0.3-0.7°C (that’s about 0.5-1.0 °F) warmer than the average from 1986 to 2005.”

      Basically, just trying to compare the projected near-term warming to McPherson’s claims of much, much faster warming. Sorry if that wasn’t clear!


    • Please kindly note you are nor comparing like with like … Those warming figures are relative to different bases: “the average from 1986 to 2005”, and average temperatures before industrialization !!


    • Becoming vegetarian, vegan, or weekday vegetarian can dramatically solve that problem, starting with you as soon as you finish this sentence. Steps in China are already being taken to reduce meat consumption and improve the choices available. You might also try googling “restorative agriculture”. Cheers!


  4. Pingback: Could abrupt climate change lead to human extinction within 10 years? | Exposing the Big Game

  5. .”..I’m a geoscience educator, hydrogeologist, and freelance science writer contributing at Ars Technica. I am also Science Editor for Climate Feedback. This is my personal blog… ” Excuse me Scott K. Johnson, but where did you study/publish in GeoScience(?) and HydroGeology(?). Sounds like you have just enough qualifications to authoritatively pretend to refute a legitimate biology/climate expert like Guy McPherson. Great looking website though.

    Liked by 1 person

    • Neither my MS in hydrogeology nor Guy’s PhD in ecology tells you anything about his climate science claims.

      I think I showed a number of examples where Guy’s statements about a study didn’t match the contents of that study, or where his source is actually an evidence-free blogger. I recognize that checking every study he references would be a tall (or even impossible, given paywalls) task for a reader, and that still wouldn’t give you the whole picture. All I can do is try to show you the problems with his claims, and hope that helps your assessment.

      But really, I don’t think even that’s necessary to realize that Guy’s claims are radically different from those of climate scientists—Guy says so himself. That’s why he accuses climate scientists of being cowards and liars.

      Liked by 1 person

      • Quite right, SJ. Michael doesn’t need to know your qualifications to assess your critique here. It sounds more like a way out of doing that assessment. Indeed, Guy is also not a climate scientist and maybe that’s why his interpretation of the climate science is so awry (and clearly so, in some cases you and others have shown).

        Michael, check some of Guy’s interpretations yourself. If you do enough, you’ll see that he is wrong or simply speculating in enough cases to throw his whole hypothesis of near term human extinction into question. Guy never seriously engages with his critics, which is another pointer to how much importance you should place on his interpretations of the science.

        Liked by 1 person

    • MichaelZeno:

      Before you continue digging into Scott’s quals, let me ask you humbly, how much of the blog have you actually read? As someone who has read 90% of it, i think it’s of import as I value my time and would prefer doing other things than fact-check those unwilling to do the work.

      As a follow up, if you really think you need greater authority, which is understandable, your efforts to seek out Bill McKibben and Michael E. Mann will reveal very similar outcomes to Scott’s critical review.

      Just trying to save you time.


      Liked by 1 person

    • Yeah, certainly near term human extinction doesn’t appear to be borne out by the science, contrary to McPherson’s claims. But don’t get complacent, there are a lot of scenarios between where we are now and extinction, many of which don’t look rosy at all!

      Liked by 1 person

  6. All of this is very interesting, and at the same time not a bit surprising (though saying that is in no way an attempt to demean it at all). What I find FAR MORE fascinating is the apparent desire, even a yearning, an aching, that so many people have, that they WANT to believe such things. They seem to really be full of a special kind of self-hatred, extended to other humans. The obvious counterpoint is that no one is forcing any of them to be one. And I wonder just how many have indeed chosen the suicide option because of such beliefs. I just wonder what’s behind this kind of psychology, and how many have slipped into it.


  7. Maybe some people want to believe such things, maybe some people are in denial. I tend to think no one really can say with any accuracy what projections will manifest with what time lines. What I hate to see is scientist arguing with each other rather than with the facts alone. Why attack GM? What if he is only half right? We are still in trouble and most models seem to be behind the actual data. An important prediction to watch will be the melting of arctic sea ice by 2016 plus or minus 3 years.

    With the gas & oil industry funding the deniers I think it is helpful to have some extreme voices on the other side to balance the false info saying everything is normal. Does anyone really believe we can have continual growth in a finite system and not suffer any consequences?

    People working to dissuade the public of the current difficulties already faced by populations in low lying and coastal areas and the impending tragedy should be likened to environmental Nazi. They will be responsible for the deaths of 100’s of millions and probably the decline or end of civilization as we know it.

    Time will tell, and a note to those who think GM’s info leads to suicide…When diagnosed with a terminal disease most choose not to end their life but to finally start living in a way that seems self-directed instead of living for cultural expectations. Since coming to the conclusion that “the times they are a changing”, I have found myself acting with more kindness and compassion to my fellow humans.

    “Come gather round people, where every you roam,
    and admit that the waters around you have grown.
    And accept it that soon you’ll be drenched to the bone,
    and if your life to you is worth saving?
    Then you better start swimming or you’ll sink like a stone…”

    Sincerely, Ron


    • What if he is only half right?

      Then he would be half wrong, and highlighting of inappropriate sources and misinterpretation of studies should be helpful in improving that fraction.

      With the gas & oil industry funding the deniers I think it is helpful to have some extreme voices on the other side to balance the false info saying everything is normal.

      False information is not balance, it’s added confusion. I think you counter misinformation with accurate information, not with polar-opposite-misinformation.

      Does anyone really believe we can have continual growth in a finite system and not suffer any consequences?

      No, and I don’t think I or any commenters here have said that.

      Liked by 1 person

    • “Why attack GM? What if he is only half right?”

      You mean, what if we are only “half extinct” by 2026? It’s amazing that so many are willing to give GM a pass on his pseudoscience and his indefensible predictions just because the effects of climate change are becoming more visible, as any rational person expected they would.


    • Good comments Ron. Some will have to wait until their noses are underwater before admitting climate change is having a real, present impact on our civilization. More and more scientists are coming to believe Guy is more than half right. Mother Nature seems to be showing just how right he is after all.


      • Bob (or Ron), could you define “half right”? Also, can you name any scientist who has come to believe that Guy is more than half right?

        If “half right” means “humans are adversely affecting the environment” but not “all life on earth will become extinct within the next 30-odd years”, then, yes, Guy is half right. Otherwise, these seem to be empty words, unless defined more clearly along with evidence that any scientist has shifted his or her view towards Guy’s.

        Liked by 1 person

        • ‘Half-right’ with regard to NTHE would be a 50% reduction in the human population. GM’s scenario involves failure of the world grain crop, followed by starvation. Is it controversial to claim that civilization is dependent on our ability to grow and store grains?


          • “‘Half-right’ with regard to NTHE would be a 50% reduction in the human population.”

            That is not correct. Extinction has a precise meaning. A 50% reduction in a species’ numbers does not mean that the species is “half extinct”, a term that has no meaning. Many scientists think it likely that there will be a substantial fall in the human population within this century.

            “Is it controversial to claim that civilization is dependent on our ability to grow and store grains?

            No, it is not controversial, and “failure of the world grain crop”, or just repeated failures of regional grain crops, would lead to starvation and general upheaval. Again, those are scenarios that are visualized by serious scientists. They are not concepts originating with GM and do not involve human extinction in a matter of years.


      • Who here questions that “climate change is having a real, present impact on our civilization”, and what does that have to do with GM’s specific “message” of extinction within (now) nine years?

        Liked by 1 person

  8. Hi Folks, thanks for replying, good questions.

    What I really mean by “half right” is that I think climate science is, as our president would say, “complicated”.
    With all the variables in the mathematical models I feel all should approach the results with caution. We could be overestimating the effect as conversely we may be under estimating the effect. Why do any of us believe we are so much more qualified to draw conclusions than any other scientist. Again, why attack the messenger, it makes it sound like a personal vendetta instead of arguing for different conclusion based on data.

    That is why watching predictions, such as arctic ice melt, will be important. The question about how current impacts relate to the message of NTHE, is answered by the technique of observation of data following predictions leading to conclusions. I also do not see where GM is using pseudo science, I just see him drawing different conclusions from the sets of data.

    Plus I think we are dealing with 2 issues here. 1 is what will the climate impacts be? 2 How will this affect civilization? 1. I am receptive to the hypothesis GM makes concerning climate impacts, 2. not so sure how it will play out, however GM does provide some scenarios which are worth considering. As a life long rescue professional I find it better to “prepare for the worst and hope nothing happens”. It is sadly comical that there are now debates on how catastrophic the impacts of global warming will be. Is it not already bad enough for the low lying islands of the world, including Tangier in Virginia, where by the way around 80% of the residents do not “believe” global warming is caused by humans.

    I never said I interpreted GM’s conclusions as false, so I stand by my statement that it is helpful to have voices on the other extreme from the paid climate deniers. Plus these voices are growing, Professor V. Ramanathan, Dr. Dahr Jamail, Aaron Thierry, Paul Beckworth, are just some who are adding an increasing urgency to the tone of possible impacts from global warming. Even the more conservative voices (Al Gore, John Kerry) start with dire predictions only to come to a rosy scenario based on things we don’t have and will not have in time to forestall the impacts.

    Thank you for the serious debate.


  9. Thank you for offering serious critique of GM’s analysis. Critique is key to the scientific method, and there has been little so far. GM has attempted what no one else has: analyzing all the major feedback loops and assessing the probable impact on ecosystems and as he says on species we love and our favorite species, Homo sapiens. I’m not given to grieving, although perhaps I should. Perhaps I can’t really grasp the exponential curve and our point on it given planetary and technological limits. No one wants to believe GM is correct in his assessment, and we all including GM want him to be wrong. Every critic I’ve encountered who’s countered some portion of GM’s analysis goes on to elaborate on the seriousness of the predicament, showing me GM’s analysis is essentially on track with what’s already happening: mass extinction.

    Liked by 1 person

    • showing me GM’s analysis is essentially on track with what’s already happening: mass extinction

      But his analysis is not on track. Yes, a mass extinction is probably underway, though it will likely take centuries or millennia to fully play out – GM thinks it will happen within a two or three decades, at most, and be total. So, please, it’s not accurate to say GM is half right or his analysis is on track; he mischaracterises the science and gives out an incorrect message. Don’t mistake the fact of environmental degradation everywhere with GM’s being right with his take on the situation. He isn’t. Because of human behaviour, environmental degradation was always inevitable but total extinction of every life form on this planet within a few decades is not at all likely.

      Liked by 1 person

      • Indeed, how many thousands of people do you suppose are speaking out about environmental issues? Why bother with one who is telling you things that are mostly incorrect just because he also says some thing that are generally acknowledged?

        I have to disagree with this: “GM has attempted what no one else has: analyzing all the major feedback loops and assessing the probable impact on ecosystems“. While it’s certainly true that there are difficulties in combining factors, Guy hasn’t done this analysis. He has simply provided a very poorly supported opinion about it.

        Liked by 2 people

  10. “After all, these same processes were in play when the Earth warmed out of the last glaciation (over the last ~18,000 years), which obviously didn’t scorch the planet. Without any of these feedbacks, the glacial/interglacial differences would be much smaller, but they do not cause runaway warming.”

    Scorch the planet? I don’t think Guy has made that claim (yet). He says the habitat humans survive in will disappear. Scorch not included. Further, runaway global warming Venus style is not possible on Earth. The atmosphere is not dense enough. I haven’t read further. I prefer taking bullshit in small doses.


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