> plants love CO2

In artifical conditions in laboratory there is a significant effect, up to 20% when doubling pre-industrial CO2 concentration.

But, in practice for wild plants nitrogen quickly becomes the bottleneck, so the real gains are much smaller.

And even for farming plants (which have fertilizer providing additional nitrogen) the real gains diminish, and are more in 5-10% range. For some crops CO2 has very little effect at all (for example corn).

Additionally - crops grew with raised CO2 levels have less proteins and useful nutrients.

And then you have to factor in the harmful effects from global warming on crops (heat damage, dry soil, less farmland available) and the overall effect is likely negative.

https://www.scientificamerican.com/article/ask-the-experts-d...

Here's where a management that aims for diversity of plants comes in handy. If care is taken to plant the correct proportion of nitrogen-fixing plants, and other plants (such as comfrey) that will grow really deep roots to extract trace minerals, the nutrient density can be increased. There are techniques to increase the soil fertility with the correct selection of plants. There is a design science, permaculture, that takes all these factors into account.

That applies to farming, but not to nature. All current animals evolved with the amount of nutrients in plants on average now. If that changes quickly, they'll have a hard time adapting.

I believe in global warming with all my heart but just to be balanced the heat also gives you a longer growing season and let’s plants thrive in higher latitudes.

Edit funny the downvotes. I’m on your team guys! Just think we can’t ignore counter facts.

The length of the growing season is affected by many things, like rain, days below freezing, days above threshold temperatures, etc. It's not clear at all that warmer global temperatures means a longer growing season.

For crops that tolerate the extra heat. Those which don't will need to be grown further toward the poles, which will reduce the length of growing season.

Reseeding a field with a new crop is technology known since thousands of years.

I don't think there is any risk of areas reaching temperatures too hot for any plants?

> which will reduce the length of growing season

Why?

...because plants that are overheated can't grow. Depending on how overheated they get they may merely become stressed, or they can die. But plants also need temperatures, particularly soil temperatures, that rise above some minimum before they germinate. So you need a period when the soil temperature is high enough, but the air temp is not too high. Figuring out the length of that window is very complicated.

Corn, for instance, can't grow when the temp is over 104 or so (depending on cultivar) and dies when exposed to temps over 110 or so. It maximizes its growth rate at around 86 degrees.

So: if you have a summer month when temps are regularly over 104, that's not really a growing season for corn. Thus you have to try to plant earlier and harvest earlier, and the window when you can do that successfully may be considerable shorter than it would if the temp stayed below 104 during the summer.

So then you try to go closer to the poles. But -- depending on temperatures and a lot of other factors -- that may not be a totally satisfying solution either. Corn needs specific amounts of rain, which may or may not coincide with periods when the temperatures are good. It also needs large amounts of soil nitrogen, which may or may not be present in arctic soils, and if the plant doesn't have it growth is slowed. Corn also needs the soil temperature to be relatively high to germinate (above 50 degrees, again depending somewhat on cultivar). In arctic soils, it may take a while for the soil to warm up that much in the spring, and that may reduce your growing season. So how all the factors play out, and whether those factors result in a longer or shorter growing season, are intimately connected to exactly how the climate changes.

I've used corn as an example, but of course other crops and wild plants all rely on complicated, interconnected conditions to thrive. The specifics are a bit different for every plant.

It all depends. There are a lot of factors that we won't really know until people start trying to do it.

It may become hotter, but solar declination isn't going to change. Move towards the poles and the sun will have lower elevation, fewer hours of light, and the balance of seasons will change.

How much is enough to matter? Will the net effect be more or less than change from CO2 or temperature? You tell me. We seem to have a lot of unknowns.

Plants adapt. The ones that can tolerate the extra heat will survive better and therefore propagate more than plants that don't.

There are no teams. I have to say even the statement "I believe in global warming" is kind of problematic, because your faith isn't required for it to be real. It is a thing that is, not a thing that only exists in your head.

Just because you believe something doesn't make it a fact.

"Global warming" would be better named "wilder temperature swings" (which is why we hear the phrase "global climate change"). Larger temperature swings (colder winters, hotter summers, no real spring or fall seasons) are not good for growing crops.

The north, where a lot of the new greening will occur, also has shorter days as winter comes. How much longer could the growing seasons in the north get?

In the movie Interstellar, mildew was the straw that broke the camel‘s back for agriculture. From what I‘ve read, this can be a possibility if CO2 rises too high.

And it was somehow easier to move people and farms to a giant space station than to build climate controlled greenhouses on earth. But it looked stunning in the movie..

The space station was an arc traveling to the new planet they found.

People also got sick and died from dust particles, I guess the conjecture was that earth would soon become uninhabitable.

If the bottleneck changes from CO2 to Nitrogen, maybe plants will start adapting to get better at fixation, pushing that limit higher than the CO2 limit.

Plants don't really get better at fixing nitrogen. They get better at hosting symbiotic colonies of nitrogen-fixing microbes in their root systems.

It's splitting a hair, to be sure, but developing root nodules for hosting a nitrogen-fixer species is a lot easier than evolving all the biochemical precursors from scratch. Nitrogen fixation symbiosis may have evolved independently in plants at least three times. It would have been a big advantage from 460 to 380 Mya and then again, to a far lesser extent, from 240 to 160 Mya. Teredo shipworms also employ nitrogen-fixing symbionts, in their gill structures, as well as some termites, in their guts, but the latter only derive benefit in an extremely low-nitrogen environment.

Since atmospheric CO2 has dropped after the last peaks, some plant species failed to preserve that symbiosis. They would have an easier time getting it back, now that CO2 partial pressure is rising back to levels experienced in prior geological eras.

The ultimate bottleneck is likely to be iron or magnesium.

That kind of evolution takes a while.

This sounds like something the GMO industry would be working on already.

If you seeded an ecosystem with nitrogen supplements would it allow the plant life to grow at an accelerated rate and capture carbon?

You use ammonia to add nitrogen to crops. Making ammonia is an extremely energy intensive process that already contributes about 2-3% of global carbon emmissions. [1]

So you could spray ammonia everywhere to promote growth, but it's not clear that you'll offset the carbon emissions from making so much ammonia in the first place.

[1] https://m.phys.org/news/2018-07-electrochemically-produced-a...

Ahh that’s what I figured, too bad

nitrogen fixing cover crops is the way in agriculture I guess

we are already doing that aggressively to feed everyone, and we worry it might be hard to keep it up, as is.

Of course. I've seen people using the "when an ice melt in a glass, the glass doesn't overflow" argument. They can't see the ice on the land, the albedo effect, the salt concentration, the sea temperature, the gulf stream... If you make things complicated, the truth lose a lot of people to convenience.

That's something the geeks have still a hard time to understand. They won't convince anybody by being right. That's not how public opinion work.

Clearly increased plant growth due to higher CO2 concentrations are not stopping CO2 concentrations from spiking precipitously right now, because it's still spiking precipitously.

It's very small effect that would take enormous spans of time to make any significant difference. Also in order for those plants to grow faster and make a difference, there needs to be a significant amount of plants. So it's a marginal issue. If plants grow at (made up number) 2% faster due to higher CO2 concentrations, that doesn't help much if we've wiped out 90% of the plant biomass.

but TFA clearly says we haven't wiped out 90% of the plant biomass. It clearly says that there are more plants than there were 20 years ago, not less.

CO2 concentrations are growing at <1% pa (year on year - there are large variations between northern hemisphere summer/winter), so an additional 2% absorbing effect from an increasing number of plants is not insignificant.

As I said I was making up numbers. Given enough plants they will eventually sequester all the CO2 (if we let them). This effect would make that slightly more efficient, that's all. However the actual amount of plant matter sequestering the CO2, and what those plants are and how efficiently they work to do so, are likely to be a much more significant factors. Whatever those factors are though, we're talking about extremely long periods of time.

The fundamental problem is that humans are not plants. In 100 million years all the CO2 might become coal or oil again but humans won't be there to witness it.

No, not again. Coal came from plants in an era where microbes could not yet decompose plants.

Peat is the first step in forming coal. Peat still forms under the correct conditions, so coal can still be formed.

Conditions might be rarer, but the steps aren't solely reliant on the absence of microbes which now exist.

Don't forget to credit fungi too!

No more coal. Right now the only way carbon is permanently lost from the ecosystem is from ocean crustacean shells being lost to the bottom of the ocean. Interestingly enough, before humans started freeing carbon, the ecosystem was in a period of all time low for available carbon.

It's not a slam dunk that more CO2 == good for plants.

As per https://www.politico.com/agenda/story/2017/09/13/food-nutrie...

> As best scientists can tell, this is what happens: Rising CO2 revs up photosynthesis, the process that helps plants transform sunlight to food. This makes plants grow, but it also leads them to pack in more carbohydrates like glucose at the expense of other nutrients that we depend on, like protein, iron and zinc.

The GP is talking about a "greening effect" on the Earth due to CO^2, but the article you've linked to and this quote is talking about how the nutritional content of plants for human consumption might suffer with more CO^2.

Unless you think that the only thing that's "good for plants" is their suitability for being eaten by humans this seems like an unrelated issue.

The vast majority of the Earth's plant biomass isn't going to be eaten by humans. You're not going to nibble on the oak tree in your back yard, but increased CO^2 in the air will make it more efficient at sequestering carbon.

It's not going to be some amazing increase in perceived growth rate. The CO^2 level indoors is often 2-3x what it is outside, and people already grow plants in those conditions.

Green mass of the leafs is the captured carbon dioxide that doesn't contribute to a greenhouse effect. Even if all leafs will be oxidized in a year, it doesn't matter because new leafs will emerge. Though I'm not sure about actual green mass on the Earth and cannot compare it with mass of CO2 in athmosphere, maybe it is too small to have any effect.

An our challenge going forward is the long term sequestration of carbon, this will not help, as it will not capture the excess CO₂ released by humanity. If a significant part of this greening is farmland, there is of course also the CO₂ released through field work and harvesting to consider.

There's a good reason that the effect causing global warming is called the Greenhouse Effect, and CO2 a greenhouse gas. It comes from the use in greenhouses. The effect has been known for well over a century (which makes it all the more odd there's so much political resistance now to accept that this is happening).

And while more plants is certainly a nice thing, there's more to having a healthy planet than just having more plants, especially when it comes at the cost of melting ice caps and changing weather patterns, possibly leading to desertification and less plants in other places.

Although according to the article, this particular increase in greenery is mostly due to projects to plant more trees in Indian and China, and investments into agriculture. All of them good things that don't really need more CO2 in the atmosphere.

> it seems this fact is usually omitted so as not to complicate the intended message

Any time a group starts altering the facts like this, it just shows that they value their 'message' above the truth, and they lose all credibility.

Edit: Downvote = disagree, or people genuinely believe it's OK to lie to further your cause, I'm not sure what's more disturbing.

The fact is often omitted because people use it to erase the problem. Is it worth submerging a large area of Bangladesh for a very slight global increase in plant growth?

In particular there's a faction of people who use "CO2 is plant food" to argue that it cannot be harmful, that reduction efforts would be wrong, etc.

For me, the problem with your remark is that it's proposing some kind of alteration of message (lying, in essence) by "a group" which is not really identified, but might be "climate scientists" - but with no actual evidence.

And also, the whole discussion branch nearby on the greening effect of small increases in CO2 is really missing the point, and is completely ungrounded in any science. There is a whole literature out there on how significant this effect is relative to other effects of rising CO2! (Spoiler: it is not that significant.)

> For me, the problem with your remark is that it's proposing some kind of alteration of message (lying, in essence) by "a group" which is not really identified, but might be "climate scientists" - but with no actual evidence.

So you disagree with the grandparent post's statement that "But it seems this fact is usually omitted so as not to complicate the intended message."?

There are plenty of large, prominent climate activist groups making prominent public statements. I've never heard a single one of them discuss this aspect. (Contrast with scientific papers, many of which do mention it and which are not what we were talking about).

The place to start would be: https://science2017.globalchange.gov/chapter/10/

The key phrase you're looking for is: CO2 fertilization.

Activists often think it's okay to lie to advance their cause.

Well, obviously. Look at how many lies we take as fact in order to get through any modern discussion on politics and public policy.

It's also extra Co2 for parasites.

>this fact is usually omitted so as not to complicate the intended message.

That sounds a lot like intentionally misleading people.