The wool over our eyes

AI Use Disclosure

The ideas here are my own. I use AI tools in various parts of the writing process, including summarizing my notes and prompts, improving grammar, tightening wording, and checking whether an argument is clear. These posts are as much notes for myself as they are for anyone else who is interested.

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Clothes contain carbon. CO2 contains carbon. So here is a dumb question:

if the extra CO2 carbon in the air became wool,
how thick is the sweater we pulled over the planet?

Answer: about 0.4–2.5 cm thick if it’s fluffy, or about 0.95 mm if you crush the wool down to fibre density.

If your screen is set up correctly, that’s this thick:

crushed flat: 0.95 mm
fluffy low end: 0.4 cm
fluffy high end: 2.5 cm

So take a moment.

Look out the window.

Close your eyes.

Remember your last vacation and all the travelling you did.

sheeps with wool

And imagine: The DisCovering of Heaven.

sheep without wool

At that point, “why is it getting warmer?” is pretty much self-explanatory.

Why?

Last night a heat storm started a long-running disco party at 02:00 and woke me up.

Today I went swimming in a public pond and the water in the top layer felt like a warm bath at home.

Europe is the fastest-warming continent in the world: https://www.reuters.com/graphics/CLIMATE-AUTOMATED/MONITOR/akpeykqqapr/

Biking back from my swim, I had an idea for a question that doesn’t really make sense. I will defend my choice of writing this post on two grounds: it was feverishly hot, and the result gives a terrifying sense of scale.

The world does not need another physically accurate explanation of global warming. This certainly is not that.

The question of how thick a blanket we have pulled over the world is, in a thermodynamic sense, nonsense.

But maybe it is the kind of nonsense that nudges a skeptic into figuring out how heat does work.

For this post, I am only going to work out the nonsense.

The carbon

if the extra CO2 carbon atoms in the air became the carbon in wool,
how thick would Earth's sweater be?

I used NOAA’s March 2026 global CO2 number, 428.60 ppm, and the usual round pre-industrial baseline, 280 ppm.

NOAA reports CO2 as a dry-air mole fraction. So this is basically a counting problem. Out of every million dry-air molecules, about 429 are CO2 now. Before industrialization, call it 280.

Using an atmosphere mass around 5.15e18 kg, that gives:

317 GtC
1,163 GtCO2

That is the excess carbon still in the air. It is not cumulative emissions. It ignores the carbon that went into oceans, trees, soils, concrete, and all the other sinks.

The wool

Clean wool is mostly keratin, and keratin is roughly 50% carbon by mass.

This is cheating, obviously. Wool is not pure carbon. Assume the universe supplies the hydrogen, oxygen, nitrogen, sulphur, and sheep.

317 GtC / 0.50 = 635 Gt wool

If I use wool fibre density, about 1,310 kg/m³, that wool has a fibre-material volume of about 485 km³. Spread over Earth’s whole surface, land and sea, the mass-visualization layer is only:

0.95 mm

That is the crushed-flat answer. Real sweaters are mostly air. If I use a rough, illustrative lofted wool density range of 50–300 kg/m³, the layer becomes:

4.1 mm to 24.9 mm

Or almost 2.5 cm of wool, everywhere you look.

Sources

If you want the actual radiative-transfer explanation, go read the physics or turn on a microwave worth of GPU electricity so ChatGPT can explain it.

First written: 2026-06-28
Last edited: 2026-06-28