Someone asked me to comment on John Michael Greer’s most recent post about the impact of climate change. Some people know him from his spiritual practices, but John Michael Greer mostly became well known among a broader audience for his writing about peak oil and for his prediction of the “gradual collapse” of civilization, as a result of a convergence of multiple problems.
However, John Michael Greer does not believe that climate change is going to lead to any sort of apocalyptic outcome. Instead, he sees it as one more problem that fits into his model of the gradual collapse. For context, Greer is not alone in this among the Peak Oil crowd. Gail Tverberg also seems to think the climate problem is exaggerated.
I don’t bother commenting on every author who insists we’re not faced with an acute emergency, but in general I’ve been quite fond of his writing and have his book on Geomancy on my shelf, so when people ask me to comment on it, I’ll take a look.
I would argue the peak oil crowd found themselves betting on the wrong horse, expecting that humanity would not have to confront the climate crisis because resource scarcity would be such an acute problem that CO2 emissions would naturally come down.
No such thing happened of course, fossil fuel use has merely continued to grow in every year since we stopped hearing about the term “Peak Oil”. In a sense, I think the Peak Oil crowd psychologically anticipated the climate catastrophe before anyone else. Rather than being worried about peak oil, they hoped that increasing extraction costs would force us to halt our march towards oblivion. This did not happen.
John Michael Greer has now moved on to directly downplaying the problem altogether. The core of his argument is as following:
Nor are sudden climate changes anything new. Some of them, in fact, were much more sudden and drastic than the one we’re currently in. The heat spike around 9600 BC is a good example, not least because it’s recent enough that there’s good ice core data, allowing the speed of the change to be measured much more closely than other forms of data will allow. At that time—my source here, in case you want to look it up for yourself, is Steven Mithen’s widely praised book on postglacial times, After the Ice—Earth’s average temperature jolted up 7° C in less than a decade. Nobody’s yet sure how that happened, though there are some plausible theories. The point to notice is that not even the most extreme climate theories right now are predicting a 7° C increase in global temperature over the next decade. Difficult as the current situation promises to be, it’s well within the normal variability of Earth’s climate.
This episode of abrupt global warming refers to the end of the Young Dryas. This is an important point to make, as this episode of abrupt warming reversed a sudden unusual period of cooling during the transition from the Pleistocene into the Holocene. This abrupt warming thus continued the trend of the planet warming up as the ice sheets retreated.
If we look up the book, we’ll find the claim Greer refers to. But it cites no further sources and does not elaborate on its claim. So is it true?
Well, what we can find is this study, which claims there was abrupt warming in Southern Greenland, of 7 degree Celsius during the end of the Younger Dryas. Ice core data from Greenland tends to be used to measure how climate changed in the past.
Important to note however, is that this study does not claim it happened in a decade. It claims it happened in fifty years. This is obviously an important difference. More important however, is to understand that Greenland, is prone to far more rapid temperature fluctuations than the global average, by virtue of being so far from the equator and covered in white snow that reflects sunlight.
In other words, you can’t directly translate what you see in Greenland, into what happens at a global average level. And yet, the book Greer cited, claims that temperatures went up by 7 degree at a global level, over a single decade. Is that claim plausible?
Well, let’s look at some other data we have for the termination of the Younger Dryas:
Proxy records of temperature from the Atlantic clearly show that the Younger Dryas was an abrupt climate change event during the last deglaciation, but records of hydroclimate are underutilized in defining the event. Here we combine a new hydroclimate record from Palawan, Philippines, in the tropical Pacific, with previously published records to highlight a difference between hydroclimate and temperature responses to the Younger Dryas. Although the onset and termination are synchronous across the records, tropical hydroclimate changes are more gradual (>100 years) than the abrupt (10–100 years) temperature changes in the northern Atlantic Ocean. The abrupt recovery of Greenland temperatures likely reflects changes in regional sea ice extent. Proxy data and transient climate model simulations support the hypothesis that freshwater forced a reduction in the Atlantic meridional overturning circulation, thereby causing the Younger Dryas. However, changes in ocean overturning may not produce the same effects globally as in Greenland.
Now we’re looking at a place where biodiversity was actually high and where a lot of land vertebrate biomass would have lived. Here the termination of the Younger Dryas was not as rapid as it was in Greenland.
Inside the study we find a very useful graph:
Now we have data from multiple regions. On the left side we see the onset of the Younger Dryas. In green is the estimate for the beginning of the onset and in red the end of the onset. On the right side, we see the end of the Younger Dryas. In green we see the beginning of its termination. In red we see the completion of the termination.
And look what we see: In Greenland, the Younger Dryas begins rapidly and ends rapidly in an estimated thirty years.
But when you move away from Greenland, towards the equator, where most humans and other lifeforms would have lived, you notice that the whole Younger Dryas event was much more gradual, both in its onset and in its end. In the Philipines, it took about 500 years to end the cooling event. In the East Indian ocean, it took 300 years to end.
While we’re at it, please note something else: The Younger Dryas did not start at the same time everywhere! It did not end at the same time everywhere either! In West Africa it started slowly but early, ahead of anywhere else by centuries. Then we see it starting in the East Indian ocean, almost two centuries later. A few decades later it starts in South China.
Then eventually it starts in Greenland. And yes, just as the event causes very rapid cooling in Greenland, it also comes to a very abrupt end in Greenland. But now look at this pattern of termination of the Younger Dryas, taking place at different time periods decades apart in different parts of the globe, lasting centuries.
Then tell me: How do you plan on reconciling these observations, with a global increase in temperatures of 7 degree Celsius, within a single decade? Good luck.
So now you have three options as a critical reader:
- You can believe the book Greer cited, an archeologist who says global temperatures increased by 7 degree celsius in a decade, while discounting the two studies I linked to.
- You can believe the truth more accurately resembles the two studies I just cited: There was about 7 degree Celsius of warming in Greenland over five decades, but Greenland was an extreme outlier compared to the rest of our planet. The archaeologist must have drawn a wrong conclusion, probably based off a study he read about Greenland.
- You can somehow try to reconcile the two studies I cited, with the book cited by Greer.
Option 1 seems nonsensical to me. Option 3 seems highly implausible to me. This leaves me with option 2.
The conclusion we arrive at is that yes, the termination of the Younger Dryas was rapid. But no, it was not far more rapid than the currently ongoing global warming. The termination took place over multiple centuries and not simultaneously.
More importantly perhaps, the termination would not have involved seven degree Celsius of global warming either! Rather, it involved seven degree of warming, in Greenland. Temperatures always fluctuate far more extremely in the far North during periods of climatic change. Just because Greenland warmed seven degree, does not mean the rest of our planet did!
Take a look at this graph from the study I cited:
You can see my point here: Yes, there was rapid and severe warming in Greenland. But in the Tropics? There was never anything near seven degree of global warming during the termination of the Younger Dryas in the first place! It involved less than two degree of warming in these parts of the world!
So, seven degree Celsius of global warming in a decade, 9600 years ago?
Sorry, that did not happen. The guy who wrote that book made a pretty awful error. There is just no way to reconcile it with the data that we have. His 7 degree Celsius of global warming in a decade estimate is off by at least an order of magnitude.
This is the central claim of John Michael Greer’s post. He argues that we have seen far more rapid warming during the termination of the Younger Dryas, so today’s global warming is not unprecedented. I have now shown you why this is incorrect. I don’t feel like commenting on the rest of the post.
Unfortunately, tens of thousands of people will be reading Greer’s post and making a conclusion that is psychologically convenient for them: The extremely rapid global warming we are experiencing today pales in comparison to what happend 9600 years ago. Then they will happily drive their SUV back to their office and complain about autistic Swedish children and hysterical climate alarmists.
How many people will read my post, in which I point out the error in his argument? A few dozen, if I’m lucky.