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Comment by pjc50 | Hacker News Reader

Swapping all the CO2 in the atmosphere for Cl would kill us all within 30 minutes (at 400ppm). It's way more dangerous.

That's not the alternative option; nobody is suggesting swapping. Swapping CO2 for fission waste products would also kills us. Swapping it for H2O would drown us!

I think there's like 3 orders of magnitude more water in our atmosphere by weight than CO2, so a swap wouldn't drown us. But the point you were trying to make is clear.

Yes, but as long as we're having some fun with the concept: The problem with CO2 isn't the absolute CO2 in the atmosphere; most(?) of it was already there. It's the changes caused by the added CO2.

The problem with H2O wouldn't be the absolute amount, but the changes brought on by the added H2O. For one thing, it would rain pretty much 24/7 in Florida. :) (Yes, I know it's not at all that predictable.)

I realise this is a silly thought experiment but the point of comparison should be, at the very most, the human industry generated CO2, not all natural CO2. The CO2 from this particular process is probably more relevant and since this process generated 1 ton of Cl per ton of Steel and the normal process generated 3 tons of CO2, we should give it a 66% discount.

> I realise this is a silly thought experiment but the point of comparison should be, at the very most, the human industry generated CO2, not all natural CO2

The pre-industrial levels of CO2 were around 280ppm, while the current CO2 levels are around 440ppm.

For Cl2, in occupational-health situations the permissible exposure is around 1ppm per hour, or 3ppm for 15 minutes. So the 160ppm we'd throw into the atmosphere in this thought experiment (or even the 52ppm at the suggested discount) is going to cause some pretty big problems pretty rapidly.

It won't necessarily accumulate though - there's a reason it was quickly abandoned as a chemical weapon. I would rather worry about its compounds, as it would quickly react with anything it touches.

Arguably the most deadly part of CO2 is that it kills sooooooo slowly. Vent CO2 and nobody blinks. Vent Cl and everyone is gonna hate you immediately for immediately present negatives.

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