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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 emi

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.

wcoenen 3y ago
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/ https://www.ipcc.ch/2022/04/04/ipcc-ar6-wgiii-pressrelease/
- badtension 3y ago
  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.
  - jules-jules 3y ago
    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.
- jules-jules 3y ago
  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.
  - badtension 3y ago
    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?
    - jules-jules 3y ago
      Here's a paper from July https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2023GB007875 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/d41586-023-00616-x https://www.nature.com/articles/s41558-023-01629-0#Sec1 https://www.nature.com/articles/s41558-023-01629-0#Sec1 https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2018GB006009 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-that-earths-climate-is-part-way-through-a-termination-level-transition-211211 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-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 https://www.youtube.com/watch?v=2oQNrO0fqOA
      - badtension 3y ago
        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!

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.

wcoenen 3y ago

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

badtension 3y ago
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.
- jules-jules 3y ago
  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.
jules-jules 3y ago
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.
- badtension 3y ago
  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?
  - jules-jules 3y ago
    Here's a paper from July https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2023GB007875 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/d41586-023-00616-x https://www.nature.com/articles/s41558-023-01629-0#Sec1 https://www.nature.com/articles/s41558-023-01629-0#Sec1 https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2018GB006009 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-that-earths-climate-is-part-way-through-a-termination-level-transition-211211 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-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 https://www.youtube.com/watch?v=2oQNrO0fqOA
    - badtension 3y ago
      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!