Calibrating climate scenarios

Submitted by AWL on 3 November, 2020 - 1:57 Author: Zack Muddle
Climate disaster

In the first half of October, Storm Linfa hit Vietnam, followed by Storm Nangka, causing floods and landslides which left almost 100 dead, flooded over 100,000 houses, and forced almost that number to evacuate — while causing serious damage to agriculture and infrastructure. Towards the end of October well over one million people were evacuated in Vietnam as yet another storm, Typhoon Molave, wreaked havoc: destroying over 50,000 houses in total and leaving over six million without power.

Meanwhile, Trump denies climate-change, and the “lesser evil” Biden champions that he will not ban fracking.

The last two years, roughly weekly, I have written a climate column inSolidarity in which I report on such frightening topics. I am alarmed. I want the reader to be alarmed too — and take action.

ForSolidarity 567 I wrote that “David Wallace-Wells’ The Uninhabitable Earth, as reported by Todd Hamer in Solidarity 563, falls into a long tradition of... environmental doom-mongering.”

I’d voiced political questions or concerns about Todd’s review of the Wallace-Wells book, so Solidarity’s editor suggested I write a follow-up comment: I reluctantly agreed.

My key contentions were that 1) cherry-picking and exaggeration can undermine our cause, 2) apocalyptic-seeming narratives are double-edged swords, and 3) more important than them is a sense of agency.

My article turned out far too long, and so some had to be held over for another week, and the rest sub-edited down, which meant omitting qualifications such as “sensationalism, cherry-picking, and exaggeration... can make alarms ring louder. This sells not just books, but ideas.”

“Sounding the alarm is necessary. Climate change is serious and scary, and any complacency in the face of it does need shock treatment, a wake-up call.”

On studying the whole book properly, I find that the qualification “as reported by Todd Hamer”, lost in the sub-editing, was important, and the implied judgement on the book was not really fair.

One example. Todd wrote: “To give one example, the UN predicts between 200 million and one billion climate refugees by 2050 (p.7). One billion people is at the extreme end of their predictions but the fact this figure features at all in a UN document shows the scale of the catastrophe confronting us in the next three decades.”

One issue is that the report cited, predicting 200 million with one billion as a worst case, makes clear that many displacements will be within nation states. Tragic enough, but Wallace-Wells’ assimilation of the total to Syrian refugees in recent years — fuel for European populism — is misleading.

Wallace-Wells does later add important caveats. “Those refugee figures are high-end estimates, produced years ago... the true numbers will almost surely fall short of them, and scientists tend to trust projections in the tens of millions rather than the hundreds of millions.”

This context did not make it into Todd’s article. To make such corrections is not to minimise the scale of the tragedy or encourage complacency. It is to place the struggle to prevent it on surer footing.

Todd summarises the book’s reference to previous mass extinctions which “killed 96% of plants and animals on earth” (Todd) and “began when carbon dioxide warmed the planet by five degrees, accelerated when that warming triggered the release of methane, another greenhouse gas, and ended with all but a sliver of life left on earth. We are currently adding carbon to the atmosphere at a considerably faster rate, by most estimates, at least ten times as fast.” (quoting Todd quoting the book)

In fact, Wallace-Wells’ 96% refers to unspecified species, not individuals — it did not impact plants and animals equally, and marine life was much worse hit — and he recognises, in his end-of-the-book references a range of estimates. The references and notes also recognise “considerable debate about the precise mix of environmental factors” — beyond simply carbon dioxide warming. They also recognise that “The duration of both of those events was much longer than fossil-fuel burning will go on, and so the total amount is lower — but not by a factor of ten. By a factor of two or three.”

Thus the carbon emissions prognosis is actually twenty to thirty times lower, after reading the end notes, than appears at first.

Additionally, the form the carbon takes makes a huge difference. A huge share during the P-T extinction was as methane; the overwhelming majority today is carbon dioxide. Methane is a much more potent greenhouse gas.

Then take the book’s title, “The Uninhabitable Earth”. “It is worse, much worse, than you think”, is Wallace-Wells’ first sentence. Read further, and you find: “it is unlikely that climate change will render the planet truly uninhabitable”. He claims that “some estimates” foresee various (large and enumerated) areas becoming uninhabitable on our current course. The reference is to one person’s article, which Wallace-Wells’ end notes identify as an outlier estimate.

Throughout the book, he raises this spectre of possible uninhabitability or extreme outcomes, while elsewhere bringing in many qualifications (and references to the possibility of human action).

“[A]ll of those paths projected from the present — to two degrees, to three, to four, five, or even eight — will be carved overwhelmingly by what we choose to do now.”

So initial presentation may be sensationalist, and particular claims need taking with a quantity of salt. But for the most part, Wallace-Wells provides that bowl-full of salt himself, giving balance and nuance.

Unbreathable air

The chapter headline “Unbreathable Air” jumped out to me at first, as someone with asthma possibly caused by pollution, as particularly doom-mongering.

“Our lungs need oxygen, but it is only a fraction of what we breathe, and the fraction tends to decline the more carbon is in the atmosphere. That doesn’t mean we are at risk of suffocation — oxygen is far too abundant for that — but we will nevertheless suffer. With CO2 at 930 parts per million (more than double where we are today), cognitive ability declines by 21 percent.

“The effects are more pronounced indoors, where CO2 tends to build up — that’s one reason you probably feel a little more awake when taking a brisk walk outside than you do after spending a long day inside with the windows closed.”

He doesn’t give a source, instead referencing what seems to be a secondary source, a book, which I couldn’t access. The precision in the figures as stated suggests a confidence and level of accuracy that is completely untenable.

There are deeper issues with the claim. The implication that increased carbon dioxide reducing the proportion of oxygen in the air is the cause of any physiological impacts is not, I believe, seriously argued by anyone. At today’s 400 parts per million (ppm) CO2, dry air is approximately 78.09% nitrogen, 20.95% oxygen, 0.93% argon, 0.04% carbon dioxide, with traces of other gasses.

Increasing carbon dioxide to 0.09% would have devastating effects on our planet, but the proportion of oxygen would only change to 20.94%. Slight fluctuations of air moisture and pressure have much greater impacts on the quantity of oxygen going into our lungs. Any physiological impacts would be directly from carbon dioxide proportions. (Carbon dioxide, dissolved in our blood, affects its pH).

Also, 930ppm is not likely anywhere in the near future, and it is likely that people growing up in more carbon-rich atmospheres would be acclimatised to it, just as people growing up in high mountains have larger lung capacities regardless of genetics, and so are acclimatised to breathing an atmosphere so thin it might, with rapid exposure, leave me close to unconscious.

The “brisk walk” reference is also misleading. You feel more awakebecause you are doing exercise (and briskly), not because there is less carbon dioxide on your route.

“But carbon is, more or less, the least of it.” Wallace-Wells redeems himself in this chapter only by not hanging much on such claims.

Elsewhere in the book, I found Wallace-Wells throwing round numbers in a way which wasn’t necessarily over-alarmist, but rather, almost meaningless.

“[I]n 2017, the number of days warmer than what were once the warmest days of the year could grow by a factor of 100 by 2080.”

“There is a 51 percent chance, this research suggests, that climate change will reduce global output by more than 20 percent by 2100, compared with a world without warming... By comparison, the Great Depression dropped global GDP by about 15 percent”.

“If climate change makes conflict only 3 percent more likely in a given country, that does not mean it is a trivial effect: there are almost two hundred countries in the world, which multiplies the likelihood, meaning that rise in temperature could yield three or four or six more wars.”

The first is a reference to actually useful research, but as a statement without context is completely useless to a reader who already knows that the world is warming. The second makes a comparison between a difference between two projections in 80 years’ time and a real world change from one year in the past to another a bit later. The last is entirely hypothetical, and implies a back-of-the-envelope calculation which hasn’t been done, or relies on figures not given to a reader.

Zooming out, taking the book as a whole, stepping back from details like those cited, it is well written, informative, and emotive. It seems clear to me now, from the last pages of section II, that that is how he intends it to be read. But I’ll still take his particular claims with a load of salt.

Add new comment

This website uses cookies, you can find out more and set your preferences here.
By continuing to use this website, you agree to our Privacy Policy and Terms & Conditions.