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Rising CO2 won't make trees grow more, study suggests

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Re: Rising CO2 won't make trees grow more, study suggests

#21

Post by philipkglass »

pliny wrote: post #11
abootstrapper wrote: post #5

I’ve heard this argument before from climate change deniers. From a laypersons point of view I wonder why would you assume more CO2 makes trees grow more? More oxygen doesn’t make humans grow more, in fact it becomes toxic.

Trees are made of carbon, humans are not made of oxygen (humans are also made of carbon).

By mass, trees contain more oxygen than carbon. So do humans. Water is 89% oxygen by mass. Cellulose is 49% oxygen by mass. Dry wood contains a bit more carbon than oxygen, but living trees do not.

Re: Rising CO2 won't make trees grow more, study suggests

#22

Post by VBprogrammer »

ocschwar wrote: post #18
abootstrapper wrote: post #5

I’ve heard this argument before from climate change deniers. From a laypersons point of view I wonder why would you assume more CO2 makes trees grow more? More oxygen doesn’t make humans grow more, in fact it becomes toxic.

It's also so trivially easy to refute. If CO2 was a significant stimulant for plant growth, they'd be sucking it out of the air as fast as we were putting it out, and the whole issue would be moot.

I'm not sure that's a good argument. It's entirely plausible that plants need CO2 to exist at a particular partial pressure to absorb it. In the same way people wouldn't drag the O2 level in a sealed room down to 0%.

Re: Rising CO2 won't make trees grow more, study suggests

#23

Post by dragonwriter »

DennisP wrote: post #20
mrfusion wrote: post #6

I’d be curious how they explain the fact that greenhouses typically add co2 for faster growth? ( disclaimer I believe in global warming with all my heart)

Greenhouses are controlled environments where everything else is abundant too. In more natural environments, plants are limited by availability of water and nutrients in the soil. On top of that, plant growth can be reduced by heat stress. They also have to contend with insects and disease, and may not have good defenses when climate change has brought invasive organisms to the area.

Sure, but what that suggests is that the existing established understanding is correct (or at least still plausible): even if the particular trees studied here aren't CO2-limited and don't grow more with more CO2, total plant biomass will or at least might (outside of climate change denial fantasies this doesn't mean increases in CO2 will automatically be neutralized by plant growth, because it doesn't imply that the size of the effect is necessarily sufficient to clear the additional CO2 once long-term equilibrium is reached, doesn't tell you how long it takes plants to reach the new equilibrium when CO2 levels have reached a new plateau, and even if it did all that wouldn't help when CO2 levels are constantly increasing and plant growth can't catch up.)

Re: Rising CO2 won't make trees grow more, study suggests

#24

Post by MASM32_COM »

we have a problem with CO2. The level of CO2 assumed as atmospheric was 275ppm, this assumption was altered to reflect reality, the new reality of atmospheric CO2 accumulation. When gas physiology experiments are conducted it is now proper to assume atmospheric concentrations of 300-350 ppm. these are global average numbers.

en.wikipedia.org/wiki/Carbon_dioxide_in_Earth's_atmosphere

Excessive CO2 concentration in the surrounding atmosphere of a phytostoma -the little pores that plants use to admit CO2 into the mesophyll will close up and occlude further gas translocation, this mechanism is very simple -acidification of the cytoplasm of guard cells about the stoma by way of CO2 reacting with cytoplasmic water and making carbonic acid thus reducing the p[H+].

This is a regulatory mechanism as a plant must regulate CO2 assimilation in check with N~ assimilation in accord with developmental state.

if we expose our plants to excessive CO2 then the stoma close up shop until leaf mesophyll allieviates the p{H+} status which we often do with a circulation of atmosphere. we open a window, or turn on a fan or if we have a LOT of light apx~4000+ Watts/square metre and a signalling frequency of 420nm, the stoma will reopen and we can approach a photosynthetic saturation point - a physiological limit of chloroplasts themselves. there are other particulars such as optimum electrolyte content and composition of root media ; temperature cline and gradient between root and crown, O2 concentration, red, and infrared light intensity , and frequency.

this is a large laundry list so far but when you get used to it its no worse than wiring in for a coding session.

summary is that artificial intervention is required to promote continued uninhibited photosynthesis, and biomass production under a regime of high {> 320ppm} atmospheric CO2 concentration.

Where does all the extra CO2 go to? Our oceans are becoming acidic due to absorbtion of this CO2 and shellfish corals and all other species dependent upon soluted carbonate are having a hard time extracting Ca Carbonate. We are knackering the planet :_{

Re: Rising CO2 won't make trees grow more, study suggests

#25

Post by LinuxBender »

VBprogrammer wrote: post #22
ocschwar wrote: post #18

Earlier quoted context omitted.

It's also so trivially easy to refute. If CO2 was a significant stimulant for plant growth, they'd be sucking it out of the air as fast as we were putting it out, and the whole issue would be moot.

I'm not sure that's a good argument. It's entirely plausible that plants need CO2 to exist at a particular partial pressure to absorb it. In the same way people wouldn't drag the O2 level in a sealed room down to 0%.

Humans can't bring the level near 0% because they would die long before that. Humans need between 19% and 24% O2. Below 19%, humans can't exert much energy without passing out. Above 24% increases damage from free radicals.

Re: Rising CO2 won't make trees grow more, study suggests

#26

Post by nwah1 »

hinkley wrote: post #16
nwah1 wrote: post #10

A number of problems with this method of study, and the headline is misleading. The real question is whether there will be more biomass and more photosynthesis in response to more CO2, not whether individual trees grow more. The climate skeptics don't say tree trunks will get wider, they say there will be more plant biomass. And also this is adding in confounding variables and saying more CO2 could change precipitati…

Several of the reports I've seen have said we will get more biomass, but most of it will be plants we generally refer to as weeds.

Makes sense, considering that most of the plants we have already match that description.

Re: Rising CO2 won't make trees grow more, study suggests

#27

Post by sampleinajar »

mrfusion wrote: post #6

I’d be curious how they explain the fact that greenhouses typically add co2 for faster growth? ( disclaimer I believe in global warming with all my heart)

Based no my limited knowledge in this field, I believe that is because it is an enclosed and controlled system. You can increase all variables (CO2, water, nutrients) together; whereas, a plant in "the wild" cannot. Most things act more conservatively in Nature versus human controlled environments.

Re: Rising CO2 won't make trees grow more, study suggests

#28

Post by nwah1 »

amvalo wrote: post #15
nwah1 wrote: post #10

A number of problems with this method of study, and the headline is misleading. The real question is whether there will be more biomass and more photosynthesis in response to more CO2, not whether individual trees grow more. The climate skeptics don't say tree trunks will get wider, they say there will be more plant biomass. And also this is adding in confounding variables and saying more CO2 could change precipitati…

> The climate skeptics don't say tree trunks will get wider, they say there will be more plant biomass. Speculating that plant biomass might help mitigate global warming doesn't really deserve the label "climate skeptic." It's already confirmed that rising CO2 affects crop growth rates.

What do you mean by mitigate global warming? I think what they argue is that there will be winners and losers, and it isn't some kind of black and white issue.

For instance, the Saharan desert seems to be greening.

Re: Rising CO2 won't make trees grow more, study suggests

#29

Post by porpoisely »

nwah1 wrote: post #10

A number of problems with this method of study, and the headline is misleading. The real question is whether there will be more biomass and more photosynthesis in response to more CO2, not whether individual trees grow more. The climate skeptics don't say tree trunks will get wider, they say there will be more plant biomass. And also this is adding in confounding variables and saying more CO2 could change precipitati…

This is what I dislike about the politically driven climate "science" or any science corrupted by politics. So much of it is intentionally misleading and many times outright false. They manipulate data, cherrypick time frames or simply outright lie.

The problem is exacerbated by the fact that special interest groups fund these misleading studies and are widely propagated by media with a particular interest.

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