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We should remember that CO2 is an essential fertilizer for plants and phytoplankton, all of which thrive when there is much more CO2 in the atmosphere. Their ph

We should remember that CO2 is an essential fertilizer for plants and phytoplankton, all of which thrive when there is much more CO2 in the atmosphere. Their photosynthesis processes evolved in and are ideal for an environment with CO2 concentrations at least 5-10x the current levels. At or below 150 ppm of CO2 in the air, all land-based plants would go extinct.

sintaxi 8y ago
Exactly. I wouldn't reduce the CO2 even if it was possible.
roter 8y ago
Perhaps only if we consider CO2 in isolation without attendant water, temperature, and mineral stresses. And perhaps not on longer time scales [0]. And perhaps not everywhere [1]. [0] http://science.sciencemag.org/content/360/6386/317 http://science.sciencemag.org/content/360/6386/317 [1] https://www.nature.com/articles/nclimate2995 https://www.nature.com/articles/nclimate2995
NeedMoreTea 8y ago
They might thrive, if and only if, they can move to an area where they have their needed heat, water and light exposures. If atmospheric CO2 is 5x or 10x everything will need to be migrating an awful lot of miles northwards. To soils and locations that may not be suitable for ph or mineral reasons. Plants almost certainly can't migrate fast enough for current rates of change, let alone more. So there's agriculture screwed. At or above 1,000ppm, or 2.5x current outside levels, human performance starts to decline. People will complain of drowsiness and stuffiness. Those levels can occur in buildings already. I don't look forward to a future where opening a window for fresh air delivers stuffiness, and inside buildings rise commensurately. Who knows how many pollinating species will go extinct, and at what levels, as they can no longer breathe enough to fuel their activities.
tzs 8y ago
> Their photosynthesis processes evolved in and are ideal for an environment with CO2 concentrations at least 5-10x the current levels Wait a second. For the last few million years CO2 levels have been in the 180-300 ppm range (except for recently where they have gone above that). What makes you think that plants that initially evolved hundreds of millions of years ago in very high CO2 environments did not continue evolving as CO2 levels changed, so that the plants we now have find 180-300 ppm to be ideal?
- zerealshadowban 8y ago
  The two photosynthesis paths that evolved in land-based plants (C3 and C4) are very specific, not adaptable. There has been no such thing as further "evolution" of these chemical/physical processes in plants.
gameswithgo 8y ago
This is completely false, misleading information. Disappointing to see it is at the top. Different plants have varying levels of ideal co2 concentrations, and many do worse when they are higher than now. Not to mention since co2 will change temperature and weather, the net effect could be bad for a given plant even if the plant would thrive with more co2 in isolation.
- zerealshadowban 8y ago
  My main point is that if CO2 levels fall below 150 ppm there would be a mass extinction of land-based plants, and of all the animals who depend on this vegetation. If you care about life on the continents, and human life, this is a valid concern when people explore schemes to rapidly remove massive quantities of CO2 from the atmosphere.
  - EamonnMR 8y ago
    It is unlikely that we will accidentally lower CO2 levels too quickly.
    - thebooktocome 8y ago
      Moreover, if we do happen to accomplish such a thing, it's easy to raise C02 levels; just burn more fossil fuels temporarily.
      - EamonnMR 8y ago
        I wonder if we'll ever increase the biomass enough that we'll actually want to increase the total carbon in the system...
  - deleted 8y ago
    [deleted]
thatcat 8y ago
CO2 is one variable of many. Temperature is more important because it determines what enzymes can work efficiently. It's unlikely that current plants would survive the accompanying temperature changes that would occur if CO2 significantly increases.
- zerealshadowban 8y ago
  Maybe we should go by scientific facts? plants thrive in warmer climate and higher CO2 levels, not in colder climate and at starvation levels of CO2. I suggest you look into the operations of commercial greenhouses, then study the temperature and CO2 records matching the origin and evolution of plants going back to hundreds of millions of years ago.
  - thatcat 8y ago
    Yes, I certainly think we should follow basic logic. I worked at a greenhouse. Historical data is obviously not based on current plant genetics. Do you think people use a greenhouse in midsummer? There is clearly a maximum temperature that varies for different plants. I suggest you look up the thermodynamics of CO2.
    - zerealshadowban 8y ago
      Yes, there are many commercial greenhouses that operate year-round, including the summer months. The deliberately increased level of CO2 in a commercial greenhouse has no measurable thermodynamic impact.
scarejunba 8y ago
Sure, but we want it to be in the 200 to 300 area instead of 400 ppm. No one is proposing killing all plants. We know plants do just fine at that concentration.
cbkeller 8y ago
Geologist here. This is misleading. Yes, CO2 is what plants eat, but it doesn't tend to be the limiting nutrient very often on Earth today. For the ocean (where 50-85% of photosynthetic oxygen production, and equivalently carbon burial, happens [1]) there are actually maps of this [2], and you may note that CO2 does not appear. On land, it's usually water, nitrogen, or phosphorus [e.g., 3]. Accordingly, there have been many studies on CO2 fertilization, but since it's not the limiting nutrient it doesn't tend to have much of an effect [e.g. 4]. At best there are benefits for some plant species in areas where water is the limiting nutrient, since higher CO2 means plants can keep their stomata closed more [e.g. 5], but even this is a bit of a mixed bag since dry places tend to get hotter and drier under global warming. [1]https://en.wikipedia.org/wiki/Phytoplankton#Oxygen_production https://en.wikipedia.org/wiki/Phytoplankton#Oxygen_productio... [2] https://media.springernature.com/m685/nature-static/assets/v1/image-assets/nature08101-f1.2.jpg https://media.springernature.com/m685/nature-static/assets/v... [3] https://nph.onlinelibrary.wiley.com/doi/full/10.1111/j.1469-8137.2012.04116.x https://nph.onlinelibrary.wiley.com/doi/full/10.1111/j.1469-... [4] http://www.pnas.org/content/early/2016/12/07/1610156113.short http://www.pnas.org/content/early/2016/12/07/1610156113.shor... [5] https://nph.onlinelibrary.wiley.com/doi/full/10.1111/nph.12459 https://nph.onlinelibrary.wiley.com/doi/full/10.1111/nph.124...
- zerealshadowban 8y ago
  Biologist here. I have a simple question in response to your disinformation: What CO2 level is used in commercial greenhouses? All scientific, controlled experiments with plants demonstrate conclusively that they thrive (faster growth, larger leaves, increased biomass, larger fruits, less need for water, etc.) at higher CO2 levels than what we have today and than we had before the Industrial Revolution. I encourage people who are intellectually curious and honest to look up the scientific papers on the topic and read them for themselves (you don't have to be a biologist or a geologist to understand the experiments, the parameters, or the outcomes).
  - humbledrone 8y ago
    GP said that CO2 was not the _limiting factor_. I took this to mean that something else is often the bottleneck, such as access to nutrient matter. Presumably in a greenhouse, more CO2 can be used because other bottlenecks are reduced.

sintaxi 8y ago

Exactly. I wouldn't reduce the CO2 even if it was possible.

roter 8y ago

Perhaps only if we consider CO2 in isolation without attendant water, temperature, and mineral stresses. And perhaps not on longer time scales [0]. And perhaps not everywhere [1]. [0] http://science.sciencemag.org/content/360/6386/317 http://science.sciencemag.org/content/360/6386/317 [1] https://www.nature.com/articles/nclimate2995 https://www.nature.com/articles/nclimate2995

NeedMoreTea 8y ago

They might thrive, if and only if, they can move to an area where they have their needed heat, water and light exposures. If atmospheric CO2 is 5x or 10x everything will need to be migrating an awful lot of miles northwards. To soils and locations that may not be suitable for ph or mineral reasons. Plants almost certainly can't migrate fast enough for current rates of change, let alone more. So there's agriculture screwed. At or above 1,000ppm, or 2.5x current outside levels, human performance starts to decline. People will complain of drowsiness and stuffiness. Those levels can occur in buildings already. I don't look forward to a future where opening a window for fresh air delivers stuffiness, and inside buildings rise commensurately. Who knows how many pollinating species will go extinct, and at what levels, as they can no longer breathe enough to fuel their activities.

tzs 8y ago

> Their photosynthesis processes evolved in and are ideal for an environment with CO2 concentrations at least 5-10x the current levels Wait a second. For the last few million years CO2 levels have been in the 180-300 ppm range (except for recently where they have gone above that). What makes you think that plants that initially evolved hundreds of millions of years ago in very high CO2 environments did not continue evolving as CO2 levels changed, so that the plants we now have find 180-300 ppm to be ideal?

zerealshadowban 8y ago
The two photosynthesis paths that evolved in land-based plants (C3 and C4) are very specific, not adaptable. There has been no such thing as further "evolution" of these chemical/physical processes in plants.

gameswithgo 8y ago

This is completely false, misleading information. Disappointing to see it is at the top. Different plants have varying levels of ideal co2 concentrations, and many do worse when they are higher than now. Not to mention since co2 will change temperature and weather, the net effect could be bad for a given plant even if the plant would thrive with more co2 in isolation.

zerealshadowban 8y ago
My main point is that if CO2 levels fall below 150 ppm there would be a mass extinction of land-based plants, and of all the animals who depend on this vegetation. If you care about life on the continents, and human life, this is a valid concern when people explore schemes to rapidly remove massive quantities of CO2 from the atmosphere.
- EamonnMR 8y ago
  It is unlikely that we will accidentally lower CO2 levels too quickly.
  - thebooktocome 8y ago
    Moreover, if we do happen to accomplish such a thing, it's easy to raise C02 levels; just burn more fossil fuels temporarily.
    - EamonnMR 8y ago
      I wonder if we'll ever increase the biomass enough that we'll actually want to increase the total carbon in the system...
- deleted 8y ago
  [deleted]

thatcat 8y ago

CO2 is one variable of many. Temperature is more important because it determines what enzymes can work efficiently. It's unlikely that current plants would survive the accompanying temperature changes that would occur if CO2 significantly increases.

zerealshadowban 8y ago
Maybe we should go by scientific facts? plants thrive in warmer climate and higher CO2 levels, not in colder climate and at starvation levels of CO2. I suggest you look into the operations of commercial greenhouses, then study the temperature and CO2 records matching the origin and evolution of plants going back to hundreds of millions of years ago.
- thatcat 8y ago
  Yes, I certainly think we should follow basic logic. I worked at a greenhouse. Historical data is obviously not based on current plant genetics. Do you think people use a greenhouse in midsummer? There is clearly a maximum temperature that varies for different plants. I suggest you look up the thermodynamics of CO2.
  - zerealshadowban 8y ago
    Yes, there are many commercial greenhouses that operate year-round, including the summer months. The deliberately increased level of CO2 in a commercial greenhouse has no measurable thermodynamic impact.

scarejunba 8y ago

Sure, but we want it to be in the 200 to 300 area instead of 400 ppm. No one is proposing killing all plants. We know plants do just fine at that concentration.

cbkeller 8y ago

Geologist here. This is misleading. Yes, CO2 is what plants eat, but it doesn't tend to be the limiting nutrient very often on Earth today. For the ocean (where 50-85% of photosynthetic oxygen production, and equivalently carbon burial, happens [1]) there are actually maps of this [2], and you may note that CO2 does not appear. On land, it's usually water, nitrogen, or phosphorus [e.g., 3]. Accordingly, there have been many studies on CO2 fertilization, but since it's not the limiting nutrient it doesn't tend to have much of an effect [e.g. 4]. At best there are benefits for some plant species in areas where water is the limiting nutrient, since higher CO2 means plants can keep their stomata closed more [e.g. 5], but even this is a bit of a mixed bag since dry places tend to get hotter and drier under global warming. [1]https://en.wikipedia.org/wiki/Phytoplankton#Oxygen_production https://en.wikipedia.org/wiki/Phytoplankton#Oxygen_productio... [2] https://media.springernature.com/m685/nature-static/assets/v1/image-assets/nature08101-f1.2.jpg https://media.springernature.com/m685/nature-static/assets/v... [3] https://nph.onlinelibrary.wiley.com/doi/full/10.1111/j.1469-8137.2012.04116.x https://nph.onlinelibrary.wiley.com/doi/full/10.1111/j.1469-... [4] http://www.pnas.org/content/early/2016/12/07/1610156113.short http://www.pnas.org/content/early/2016/12/07/1610156113.shor... [5] https://nph.onlinelibrary.wiley.com/doi/full/10.1111/nph.12459 https://nph.onlinelibrary.wiley.com/doi/full/10.1111/nph.124...

zerealshadowban 8y ago
Biologist here. I have a simple question in response to your disinformation: What CO2 level is used in commercial greenhouses? All scientific, controlled experiments with plants demonstrate conclusively that they thrive (faster growth, larger leaves, increased biomass, larger fruits, less need for water, etc.) at higher CO2 levels than what we have today and than we had before the Industrial Revolution. I encourage people who are intellectually curious and honest to look up the scientific papers on the topic and read them for themselves (you don't have to be a biologist or a geologist to understand the experiments, the parameters, or the outcomes).
- humbledrone 8y ago
  GP said that CO2 was not the _limiting factor_. I took this to mean that something else is often the bottleneck, such as access to nutrient matter. Presumably in a greenhouse, more CO2 can be used because other bottlenecks are reduced.