[gpt5]

Genuine question - if CO2 half life in the atmosphere is less than 50 years, why are we so concerned about it? Wouldn’t the problem solve itself given that we are both reaching peak consumption of fossil fuels and that they are expected to deplete with the next century?

In other words, wouldn’t the co2 concentration go down naturally within the next 100 years even if we let thing run naturally?

[pjerem]

Because if it’s somewhat true to say that stopping CO2 emissions would rapidly pause climate change, there is no short term « reverse » (in hundreds of years) of the climate.

We are in such a situation that every +0.01°C increase in global warming is gained more or less indefinitely.

The only thing we can do is stopping net emissions and learn to live with the climate as it is when we achieve this.

We really don’t care a lot about concentrations going down in the next centuries because by the time it happens, the harm would be done already for multiple centuries.

We are really facing today, 50°C in summer and devastating events, for our generation and our kids. This precise battle is already lost but we must fight for it to not be even more dramatic.

[daddylonglegs]

50 years was my (over optimistic) estimate of how long the CO2 would be left in the atmosphere before being sequestered by one of the carbon removal technologies being touted. In reality it's going to take centuries for our descendants to stabilise the climate - and I'm still being optimistic.

[lutorm]

On short time scales, the oceans take up a lot of CO2 because there's an equilibrium with the atmosphere. However, increased acidification of the oceans is bad on its own, and this buffering hurts when you try to take the CO2 out of the atmosphere since then the oceans will turn into a net contributor.

[malloryerik]

It looks as though those numbers are mistaken.

https://blogs.edf.org/climate411/2008/02/26/ghg_lifetimes/

[gpt5]

This article seems to conflate "Time it takes for 50% of the CO2 increase to be removed from the atmosphere" with "time it takes a specific molecule that was released to the atmosphere to be removed".

The former is more relevant to the discussion, and is stated as ~30 years.