eli5: If plants and trees thrive on Carbon dioxide, and humans are producing more carbon dioxide, does that mean vegetation is benefiting from greenhouse gases? If not, how come?
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They need it, but more of it isn’t automatically better. Much like us and oxygen, once they have enough to carry out their processes adding more isn’t going to help anything.
On the other hand, changing levels of CO2 can change the environment in a number of ways, and a changing environment is always tough on things adapted to the current one. Plants develop in an area based on a certain soil composition, temperature, water availability, seasonal cycles, a whole host of things impacted by the weather and the animals, fungi and other plants around them. Those can be impacted by greenhouse levels easily and result in wiping out large areas of plants. New ones more adapted to the changes may move in, or the death of the old ones may result in altered soil, lost water, more extreme temperature fluctuation, etc…. That makes it very difficult for new ones to move in, which is where you see desertification. The likelihood of that depends on the area and the rate of change, with faster changes being worse.
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Only to a certain extent. The levels of CO2 are rising faster than existing vegetation can use, and they don’t really benefit from an excess.
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There’s a lot of bad answers in this thread. The short answer is yes. The direct effect of increasing carbon dioxide in the atmosphere is increased plant growth. Now, that’s not true 100% of the time. Plant growth can be limited by other factors- water availability, other macronutrients, etc.
The other big however is the secondary effects of increased CO2 concentration in the atmosphere. Warming beyond a certain point could be quite bad for plant growth. One big thing is it increases evapotranspiration, which can dry plants out and inhibit their growth.
Modeling all these effects out is of course complicated. The most likely outcome is that the optimal CO2 level for plant growth was somewhere between the pre-industrialization baseline, 280 ppm, and our current concentration of 420 PPM.
https://www.scientificamerican.com/article/ask-the-experts-does-rising-co2-benefit-plants1/
It’s a double edged sword. Yes plants are benefitting from it to a degree both in increased supply and more areas are temperate enough to sustain more variety of plant life. One of the major problems is the plants who benefit the most are ocean algae and these having too large a bloom can be toxic to ocean life. We also pollute the ocean waybmore than we should considering 70% or so of the total oxygen is produced by ocean plant life.
So while technically greenhouse could be beneficial to plants it wouldn’t necessarily be good for the environment
In the same way your body couldn’t really make of use of .1% more O2, plants aren’t optimized to make use of more CO2, at least not a meaningful way. They have evolved to use what they have, and no evolution mechanism has existed to have CO2 be a limiting factor.
The other side of this is just recognizing the sheer volume of CO2. Keep in mind that we measure CO2 in parts per million, which you can think of as 1% of 1% of 1%. So VERY small increases in CO2 have a MASSIVE impact on climate because even a very small percentage based in increase is trillions and trillions and trillions of more CO2 molecules.
The degree plants can benefit from higher CO2 is limited because there need other things. Most plants have access to plenty of CO2 already, so there is some, but not much, added potential there. Other things plants need, such as water, phosphorus, and/or fixed nitrogen are generally the more limiting factors. Also, a particular plant species evolved to live in a particular environment or range of environments. If the climate and ecosystem change as a result of more CO2, that can stress or kill the plant.
Taken to the extreme, too much CO2 is also toxic to plants. For example, corn will show symptoms of CO2 toxicity within several days of being in a 1% CO2 (24x current atmospheric levels) at sea level pressure. (Plants just use CO2 to make their food. They need oxygen to use that food like animals and fungi, and can’t hold onto or make enough O2 on their own to live. At even higher CO2 levels, plants will suffocate.)
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