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Comment by textech | Hacker News Reader

This is serious. I'm sure that this will have and is likely already having some serious impact on humans that we don't know much about despite what the studies claim.

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Serious question - will it cause plants to grow faster since they consume CO2?

Maybe slightly but it's very rare that the limiting factor on plant growth is the availability of CO2. Much more commonly plants are limited by access to nutrients and sunlight.

I worked for an algae biotech company and while we did "dope" our ponds with CO2, providing ample mixing to get more sunlight and supplementing the ponds with plentiful nutrients (the "big 3" but also trace elements of a number of more obscure inputs) had dramatically larger impacts on growth rates.

AFAIK, the FACE studies do show faster growth with more CO2, but it's only observable at concentrations ~200ppm over ambient. [https://nph.onlinelibrary.wiley.com/doi/10.1111/j.1469-8137....]

> Much more commonly plants are limited by access to nutrients and sunlight.

In many parts of the world water is also pretty important. We know that global warming will change global air currents, but is pretty difficult to predict how this will affect precipitation.

Yep - very good point - you can easily see my bias here since our "plants" were suspended in water (an algae farm) so it was never a concern for us - but if you look at the basic photosynthetic formula you need as many molecules of water as you do of CO2.

The sorta bigger half here is that it allows plants to grow in more locations than with lower CO2 levels, because plants can photosynthesize while using less water than before (they need to expose themselves to the atmosphere less).

Which is why you more often see stuff like deserts greening when they were dead before. The Amazon rainforest isn't going to 2x in height.

Yes, the increase in CO2 levels has probably caused an increase in plant growth.

NASA Earth Observatory:

https://earthobservatory.nasa.gov/images/146296/global-green...

This is true. It's not universal, though, because some plant growth is not primarily gated by CO2 availability -- e.g., in drier climates.

Yes, in many greenhouses CO2 is added to the atmosphere. But 10% faster plant growth does not compensate for thay fact that we reduced forest cover in uk to like 12%

Yes, but that is not necessarily a good thing in terms of carbon capture. Eg research indicates that in the tropical rainforests, lianas get the largest boost, allowing them to basically smother the tall trees. However, these store the most carbon, so the total carbon stored in the forest goes down.

I wonder if it might slow metabolism and increase obesity levels. There were some strange stories a few years ago about a study that concluded it wasn't just humans that have gotten fatter in recent times, but wild animals too. Even laboratory animals kept under supposedly identical conditions have gotten fatter. I am sure you can look up the reports if you google.

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