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> Our 2019 emissions were ~36 gigatons The plants absorb about 25% of that and the oceans another 25%. If we absorb 10 gigatons yearly by 2050, that might be g

> Our 2019 emissions were ~36 gigatons The plants absorb about 25% of that and the oceans another 25%. If we absorb 10 gigatons yearly by 2050, that might be good enough.

lucb1e 5y ago
Wait, 36 originally × .75 from plants × .75 from oceans - 10 captured = 20¼ Gt. I think you're off by about 10 Gt? And that's assuming the ocean and plants will infinitely capture more and more carbon, which I sincerely doubt as well, but I'll go ahead and assume you mean this as a bridging method to get us another decade or two to finalize real solutions.
- flavius29663 5y ago
  it's actually 36 - (36x0.25) - (36x0.25) - 10 = 8. But yeah, we would have to reduce our emissions by at least 8GT to get to zero. That is totally doable, advanced economies are already reducing CO2 at a faster rate than 25% over 30 years: the US has reduced it's emissions by 1GT in 10 years (16% reduction).
  - lucb1e 5y ago
    If you absorb 25% (you wrote "plants absorb about 25%" and same for trees), then 75% remains, so apply ×0.75 twice instead of applying ×0.25 twice.
    - flavius29663 5y ago
      but that's not how it works...plants absorb a quarter of total emissions and the oceans about a quarter too. So half the emissions are absorbed, and half are not.
      - Mizza 5y ago
        I think you're making a very common mistake, which is misunderstanding the carbon cycle. We could, theoretically, grow enough plants to get down to pre-industrial levels. However, plants decompose when they die, re-releasing their carbon into the atmosphere, and lots of the plants alive to die are grown using petrochemical fertilizer, which was taken from under the ground, not the atmosphere.. So, we'd have to keep all of those new plants alive, forever, or maintain that extreme level of plant growth forever. This seems like an even harder problem.
        flavius29663 5y ago
        You're oversimplifying it. First of all, the ocean is a sink for CO2, it absorbs it and mix it down in the depths, not release it back. Plants don't sequester the carbon, like you said. But on the other hand, the extra CO2 is causing a bigger plant mass growth. So called greening of the deserts (but not just deserts). So basically the living biosphere is growing and absorbing CO2 as it does, because it can. The plants evolved when there was more CO2 around, 200-300 is very close to starvation, they thrive in 1000+ environments. Total Earth biomass is 550 gigatons, much larger than 36 which is what we emit every year. But obviously it cannot keep up...since the year 1750 we emitted 1700 gigatons, so more than 3 times the weight of the biosphere. That being said, I can see how the biosphere can grow by 2% with all the extra CO2 and go from 550 to 560, 570 and so on.
        Mizza 5y ago
        The limiting factor for plant growth isn't carbon, it's nitrogen.
        flavius29663 5y ago
        While that is true for a lot of circumstances, in others the addition of CO2 helps the plants survive droughts and other conditions easier. https://www.nasa.gov/feature/goddard/2016/carbon-dioxide-fertilization-greening-earth https://www.nasa.gov/feature/goddard/2016/carbon-dioxide-fer... https://theconversation.com/yes-more-carbon-dioxide-in-the-atmosphere-helps-plants-grow-but-its-no-excuse-to-downplay-climate-change-130603 https://theconversation.com/yes-more-carbon-dioxide-in-the-a... https://onlinelibrary.wiley.com/doi/full/10.1111/gcb.14950 https://onlinelibrary.wiley.com/doi/full/10.1111/gcb.14950
daddylonglegs 5y ago
Surely dissolving CO2 in the ocean acts as a buffer, not a sink? We will have to stop emitting all of that CO2 as well (and future generations will have to sequester it). The net absorption / emission from the biosphere involves a lot of emission following from our changes to the planet. We can significantly reduce our emissions (and slowly recover some of them) with better stewardship of the environment but there is a risk to the sequestered carbon: eg. where climate change causes forests to die and release most of their stored carbon.
- lutorm 5y ago
  Moreover, higher CO2 content in the oceans leads to acidification. This is bad for coral and organisms that build shells. I don't recall the exact reason but my understanding is that it tends to dissolve carbonates.

> Our 2019 emissions were ~36 gigatons The plants absorb about 25% of that and the oceans another 25%. If we absorb 10 gigatons yearly by 2050, that might be good enough.

lucb1e 5y ago

Wait, 36 originally × .75 from plants × .75 from oceans - 10 captured = 20¼ Gt. I think you're off by about 10 Gt? And that's assuming the ocean and plants will infinitely capture more and more carbon, which I sincerely doubt as well, but I'll go ahead and assume you mean this as a bridging method to get us another decade or two to finalize real solutions.

flavius29663 5y ago
it's actually 36 - (36x0.25) - (36x0.25) - 10 = 8. But yeah, we would have to reduce our emissions by at least 8GT to get to zero. That is totally doable, advanced economies are already reducing CO2 at a faster rate than 25% over 30 years: the US has reduced it's emissions by 1GT in 10 years (16% reduction).
- lucb1e 5y ago
  If you absorb 25% (you wrote "plants absorb about 25%" and same for trees), then 75% remains, so apply ×0.75 twice instead of applying ×0.25 twice.
  - flavius29663 5y ago
    but that's not how it works...plants absorb a quarter of total emissions and the oceans about a quarter too. So half the emissions are absorbed, and half are not.
    - Mizza 5y ago
      I think you're making a very common mistake, which is misunderstanding the carbon cycle. We could, theoretically, grow enough plants to get down to pre-industrial levels. However, plants decompose when they die, re-releasing their carbon into the atmosphere, and lots of the plants alive to die are grown using petrochemical fertilizer, which was taken from under the ground, not the atmosphere.. So, we'd have to keep all of those new plants alive, forever, or maintain that extreme level of plant growth forever. This seems like an even harder problem.
      - flavius29663 5y ago
        You're oversimplifying it. First of all, the ocean is a sink for CO2, it absorbs it and mix it down in the depths, not release it back. Plants don't sequester the carbon, like you said. But on the other hand, the extra CO2 is causing a bigger plant mass growth. So called greening of the deserts (but not just deserts). So basically the living biosphere is growing and absorbing CO2 as it does, because it can. The plants evolved when there was more CO2 around, 200-300 is very close to starvation, they thrive in 1000+ environments. Total Earth biomass is 550 gigatons, much larger than 36 which is what we emit every year. But obviously it cannot keep up...since the year 1750 we emitted 1700 gigatons, so more than 3 times the weight of the biosphere. That being said, I can see how the biosphere can grow by 2% with all the extra CO2 and go from 550 to 560, 570 and so on.
        Mizza 5y ago
        The limiting factor for plant growth isn't carbon, it's nitrogen.
        flavius29663 5y ago
        While that is true for a lot of circumstances, in others the addition of CO2 helps the plants survive droughts and other conditions easier. https://www.nasa.gov/feature/goddard/2016/carbon-dioxide-fertilization-greening-earth https://www.nasa.gov/feature/goddard/2016/carbon-dioxide-fer... https://theconversation.com/yes-more-carbon-dioxide-in-the-atmosphere-helps-plants-grow-but-its-no-excuse-to-downplay-climate-change-130603 https://theconversation.com/yes-more-carbon-dioxide-in-the-a... https://onlinelibrary.wiley.com/doi/full/10.1111/gcb.14950 https://onlinelibrary.wiley.com/doi/full/10.1111/gcb.14950

daddylonglegs 5y ago

Surely dissolving CO2 in the ocean acts as a buffer, not a sink? We will have to stop emitting all of that CO2 as well (and future generations will have to sequester it). The net absorption / emission from the biosphere involves a lot of emission following from our changes to the planet. We can significantly reduce our emissions (and slowly recover some of them) with better stewardship of the environment but there is a risk to the sequestered carbon: eg. where climate change causes forests to die and release most of their stored carbon.

lutorm 5y ago
Moreover, higher CO2 content in the oceans leads to acidification. This is bad for coral and organisms that build shells. I don't recall the exact reason but my understanding is that it tends to dissolve carbonates.