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Comment by melling | Hacker News Reader

Yes, and there’s a lag effect so the temperature will still increase for years after that.

However, to be clear, it’s unlikely we get to net zero in 27 years. We haven’t reached any of our goals so far and the goals only get more difficult

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I seem to recall that the first and second IPCC reports (I haven't read the newer ones) indicated that increases would continue for about 200 years, even if emissions went to zero.

The earth is indeed not in thermal equilibrium due to the speed of the recent CO2 increase, so warming would continue if atmospheric CO2 concentration would be held constant.

However, atmospheric CO2 concentration would not stay constant after emissions stop. It would go down slowly, mainly because it would continue to dissolve into the oceans. This effect cancels out the above point. Which is why the IPCC says that "The global temperature will stabilise when carbon dioxide emissions reach net zero."[1]

Unfortunately, stabilizing temperature does not mean that nothing else changes. The stable higher temperature will still mean that glaciers will continue to melt. Sea levels will continue to rise. Oceans will still acidify further.

[1] https://www.ipcc.ch/2022/04/04/ipcc-ar6-wgiii-pressrelease/

Methane tipping points are already met, especially from tropical wetlands and the polar regions. Add to that the conversion of past carbon sinks to carbon emitters, such as the boreal forests and the Amazon and we are looking at a continued rise of both emissions and temps for a long time.

I know about the "flipped s-curve" that is methane emissions (inflection point in 2007) is it really considered a tipping point though? Do you have some good papers on that?

Here's a paper from July https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2023GB00...

Key Points

    >The rapid growth in the atmospheric methane burden that began in late 2006 is very different from methane's past observational record

    >Recent studies point to strongly increased emissions from wetlands, especially in the tropics

    >This increase is comparable in scale and speed to glacial/interglacial terminations when the global climate system suddenly reorganized

Overall, there is a growing research output although much is still unknown. See for example:

https://www.nature.com/articles/d41586-023-00616-x

https://www.nature.com/articles/s41558-023-01629-0#Sec1

https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/201...

> Rising methane could be a sign that Earth’s climate is part-way through a ‘termination-level transition’

https://theconversation.com/rising-methane-could-be-a-sign-t...

>‘Exceptional’ surge in methane emissions from wetlands worries scientists

https://www.carbonbrief.org/exceptional-surge-in-methane-emi...

Dr Peter Carter has a good run down of the rapid rise in methane emissions:

https://www.youtube.com/watch?v=2oQNrO0fqOA

Thank you so much, I think I might have seen the first paper, will plow through the rest later, it will take me some time!

Thank you for the details, I have read similar reports about temperatures not changing that much later on.

One thing to keep in mind though are aerosols, which can bump the temperature up by a 0.5-1 C (afaik) if we stop emitting them.

Yes. IPCC AR6 estimates about 0.4-0.5C of warming is masked due to anthropogenic aerosol emissions. Given the conservative nature of IPCC estimates, it is probably more.

Yes. Humanity we are not in good shape.

Maybe Greenland will finally get populated and maybe people will stop living in hurricane zones

Yes yes the solution here is to physically move hundreds or thousands of years of capital investment, especially forms of capital investment that cannot be moved and are just abandoned/destroyed.

That way we can emit a bunch more to rebuild that already-built infrastructure in a different locale!

You're forgetting that the rebuild is only for survivors so it's a smaller scale.

There's a lot of time though. It's more a matter of the kids or grandkids moving somewhere colder rather than anything sudden. And the biggest problem with building a new house up north is getting planning permission. The actual construction can be relatively trivial.

It's somewhat ironic all the billionaires are about space and mars and shit - like, ok, super in-hospitable, go for it. While we should be building our space fortresses and geo domes on earth to keep the elements out, and survive on some kind of lab food.

To be honest, we could use a hard reset like that every once in a while.

Maybe the new cities could be built to be walkable.

Unfortunately, humanity repeats itself.

This time it won’t because there aint any fuel left.

That would be a cool story plot: starting civilization again with all the knowledge but none of the fossil fuel power. Solarpunk?

I think you overestimate how much knowledge there will be left.

Of course not all the knowledge will be left but enough to easily build basic engines using Stirling or Carnot cycles or even pressurized steam. Solar panels don't have to be 25% efficient, 5% amorphous silicon cells would also be very useful.

the little domed areas we will call cities will be walkable. so there's that!

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