"Trees like CO2?"

Source:

https://climatediscussionnexus.com/2021/02/24/trees-like-co2/

"A new study finds that plants like plant food (but)  they like it in a slightly different way than people expected, and science likes to test hypotheses in small as well as large ways.

... the issue was whether more CO2 helps them because they lose less water, as had been expected, or because they gain more CO2, as was apparently discovered.

... In case you’re not a plant, one of the reasons that increased CO2 helps those who are to grow in marginal areas is that plants need holes in their leaves to let CO2 in.

Which they call “stomata”.

... those holes also let water out.

... if there’s more CO2 you can get by with fewer smaller holes, which lets you colonize an area that was too dry because it’s cold, at high altitude or both.

According to these researchers, “following an analysis using carbon and oxygen isotopes in tree rings from 1901 to 2015 from 36 tree species at 84 sites around the world, the researchers found that in 83% of cases, the main driver of trees' increased water efficiency was increased photosynthesis - they processed more carbon dioxide.

Meanwhile, the stomatal conductance only drove increased efficiency 17% of the time.

This reflects a major change in how trees' water efficiency has been explained in contrast to previous research.

... it’s just one study, and tree rings aren’t everything, and it’s just one century, and who knows who’s out there doing other studies that might say no, it’s 19%, or you guys are all wrong, it’s the stomatal conductance that dominates.

But there’s one thing they almost certainly won’t say ... more CO2 means more trees.

...  “Human activities emit about 36 billion tonnes of carbon dioxide into the atmosphere each year….

Carbon dioxide is exchanged continually between the atmosphere, plants and animals through growth, death and decay, and also directly between the atmosphere and ocean.

About half of the carbon dioxide ... is soaked up by land and forests (land sink) or by the oceans (ocean sink).

The rest, about 16 billion tonnes each year, accumulates in the atmosphere; there is no convenient hole in the sky for it to escape through.

There are, however, convenient holes in plants’ leaves for it to go in through.

And yes, trees like plant food."