Science and Le Guin Part 2

Following on from Part 1.

Yesterday, I was discussing this post on the blog of the far-right SF publisher Castalia House. I covered some of the confused criticism of Ursula Le Guin’s use of scientific ideas in her books but I singled out one claim for special treatment today.

Here’s the blogger:

“She also claims that it would take the atmosphere “several hundred years to get rid of the CO2”. While I understand Le Guin found math difficult, if humans completely stopped producing CO2, it would take 9-12 days for the atmosphere to rid itself of the amount presently there. Or, if you believe global warm…err “climate change” hysterics, it will take…several years. A few hundred years is baseless ignorance.”

The points I covered yesterday rested primarily on a misreading of the text but in this case, the situation is simpler. The quote from Le Guin is genuine and from The Lathe of Heaven published in 1970. It is also scientifically correct (more or less) whereas the criticism is scientific nonsense – indeed it is error piled on error.

I’ll deal with one minor point first. There is still a misreading/straw man there in that the story does not claim “humans completely stopped producing CO2” (i.e. from industrial/economic activity – people will still breath the stuff out). When the story opens people aren’t using internal combustion engine cars etc but it doesn’t seem to be a zero emission world. However, that is a minor issue compared with the rest.

A diversion

I’ll go off on a bit of a diversion first of all with a thought experiment.

Imagine a toy world with a toy economy [which may not be mathematically sound and is just for the purpose of illustrating an idea]. This world only uses cash and to make it even simpler all the cash is one dollar notes. Each Monday morning Bob gets his pay packet as a wad of notes. During the week he spends his money. Some of his notes go to friends, some to shopkeepers and so on. Now many of those notes find their way back to the bank (there’s only one bank because this is a wholly unrealistic scenario) but some don’t. Sunday night, Bob’s boss Gertrude withdraws money from the bank to pay her employees in the morning. Now Bob’s job is as an economist and he has worked out that on average any given note spends about 5 days out and about before finding its way back to the bank.

Now, as it happens, the previous government of this toy world has been trying to stimulate the economy (perhaps misguidedly) by printing lots of extra money. So there are more notes in circulation than normal. A new government has just been elected and they decide to stop printing extra notes.

Gertrude asks Bob to work out how long it will take for the number of notes in circulation to drop back down to previous levels. I’ve told you already the 5 days figure for notes going back to the bank so it should be easy to work out right!

No. The 5 days is not a useful figure. It tells us the time it takes for a note to get back to the bank but those notes head back out again on Sunday night/Monday morning. The time it will take the toy world’s economy to adjust to fewer notes being printed is a quite different question. For that, we need to know about notes that go missing, are destroyed or put away long-term in vaults or under a mattress. The 5-day figure isn’t wholly irrelevant but from what I’ve said the ADJUSTMENT rate could be 14 days or 20 months or 100 years.

Back to the main feature

Le Guin (back in 1970) is describing an adjustment rate for CO2 given a decline in anthropogenic emissions. The blogger is being scornful of that figure and cites a different figure which appears to be a residence time for molecules of a gas in the atmosphere – akin to the figure for a note in our toy world. The 9-12 days figure is how long a molecule of a given gas is in the atmosphere as part of a cycle before moving to a different part of the cycle.

Also, the gas for that 9-12 figure isn’t CO2.

Best guess, given the context, is the blogger is quoting a figure for WATER VAPOUR (i.e. H2O as a gas). Now water vapour is a major greenhouse gas and plays a big role in global warming but it isn’t CO2 and its role isn’t like that of CO2.

The rate for CO2 that the blogger wants is the one he mentions snidely “Or, if you believe global warm…err “climate change” hysterics, it will take…several years.” Now the mechanics of this are obviously complex but do a quick sanity check. Water vapour has a short time in the atmosphere on average because when it gets cold it falls out of the sky (if you live in Britain you will be very familiar with this phenomenon). There are many processes that lead CO2 to come out of the atmosphere of varying speeds but an obvious one is plants growing which captures carbon (on average) and then being eaten by other living things which releases carbon back into the atmosphere (on average) – which is a process that takes more than a few days. The oceans also play a substantial role in this process at multiple timescales.

So:

1. the figure is for the wrong gas,
2. it is the wrong figure to use.

It is a multiple fail.

The figure needed is the rate at which carbon leaves the shorter term parts of the carbon cycle and gets locked up without returning to the atmosphere. That isn’t simple to work out but 50 years for 50% is a current estimate (https://www.yaleclimateconnections.org/2010/12/common-climate-misconceptions-atmospheric-carbon-dioxide/ ) and 70% in a hundred years. It isn’t a linear relationship so for close to all (say 99%) of the additional carbon from industrialisation to go will take even longer. If Le Guin’s statement is taken to mean all of the carbon then it is an underestimate, if it is taken to mean MOST of it then it is spot on. A reminder: this is a book published in 1970.