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Comment by londons_explore | Hacker News Reader

> plants are pegged to (IIRC) 10-15% theoretical max efficiency

I suspect this is soon to change.... With CO2 levels around 280 ppm, the biggest challenge for many plants is finding a carbon atom - in fact, many plants grow just as fast under just 10% brightness sunlight.

Now that CO2 is up at 420 ppm, it's far easier to find carbon, so now the evolutionary race will be on to collect more sunlight and grow faster. And plants have done this before, ~20 million years ago, so somewhere there are probably some recessive genes just waiting for their moment to shine again, and natural selection will make them spread like wildfire.

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If it was just CO2 levels going up then maybe. The problem is that temperatures are going up too, so gas solubility is going down. This means that C4 or CAM photosynthesis plants might get an edge over C3 on a larger area.

We’d have to assume that due to the greenhouse effect , the earth was also hotter then ?

20mln years ago the sun was around 0,2% colder, which isn't a lot, but still more than variability from solar cycles.

Do you have a source on that? We have been in an ice age for roughly the past million years. Pretty sure it was warmer in almost every other era prior.

> > 20mln years ago the sun was around 0,2% colder

> Do you have a source on that?

It's not solar radiation forcing that has made things relatively cooler, but it is cooler than 20M years ago. Of course, we could actually reach those temperatures again soon.

https://environmental-geology-dev.pressbooks.tru.ca/chapter/...

See fig 3.1.2.

"The present rate of solar warming is about 8% every billion years. That’s 0.008% every million years or 0.0000008% every century."

"Soon" on an evolutionary scale could still mean hundreds if not thousands of years.

For example, wood is a great food resource for fungi, but it took millions of years for wood-eating fungi to evolve after wood.

Many of the photosynthesizing algae can complete a lifecycle in 8 hours. They should be able to evolve pretty quick to new conditions, especially across the huge volume of ocean water.

Trees and stuff will be far slower, yes.

It's complicated! My bet would be less on individual species slowly adapting, and more on mass extinction and re-specialization.

When there's a big shock, specialists have a harder time, and generalist species have an edge. So, when an ecosystem is destabilized or totally transformed, generalists tend to take over. The thing about generalists is that they adapt to new environments quickly. Once they live stably in a new environment long enough, they begin to adapt to it more stably, and specialize, leading to new speciation.

Songbirds are a great example of this; they exploded out of Australia some 40 million years ago, spread everywhere, and then specialized like crazy into their new environments. They likely out-competed a lot of pre-existing local species as they spread out. Humans are also a great example - we spread everywhere as successful generalists, and started the process of biologically specializing in our new environments without fully speciating. In the case of humans, we know pretty precisely about the wave of megafauna extinctions that accompanied our spread.

The Younger Dryas megafauna extinctions cannot necessarily be attributed to humans. Humans spread tens of thousands of years ago. And numerous megafauna still exist in Africa, the likely birth place of humanity.

What are the alternative hypothesis?

There aren't any unless you're an incredibly fringe academic or using dumb terminology to avoid admitting that strong multiregionalism is entirely dead. Human evolution didn't stop there and there are unresolved questions about where within Africa different phases of the process occurred, of course, but the continent as a whole is undoubtedly where anatomically modern humans emerged.

There's an impact meteor hypothesis, disease, super volcano, and the rapid seesaw climate change itself.

https://blogs.scientificamerican.com/history-of-geology/http...

Well... lots more here. My impression was that African mammals survived in part because they co-evolved with humanity, and didn't get quite the shock as other places where humans showed up fully formed.

https://en.wikipedia.org/wiki/Holocene_extinction#Historic_e...

Wild mammal biomass is estimated to be about 83% lower due to humans. Reduction in biomass isn't exactly synonymous with extinction, but they aren't totally unrelated either.

https://www.theguardian.com/environment/2018/may/21/human-ra...

Yep. I remember being blown away when I learned that most early trees fossilized because there was nothing yet to break them down. Not fungi, not bacteria, not insects.

Pretty crazy to imagine. large swaths of land with layers and layers of fallen trees

Most of them would have broken down, it's not like giant piles of logs. Think more "heavily wooded bog"

The weather still breaks down dead plant matter, even without fungi or insects, I think?

Yes, it turned to mud, then oil.

If there was oxygen, it still burned. One lightning strike would be enough to wipe the ground clean.

There was much less oxygen back then.

This was the Carboniferous age when oxygen levels are thought to have been up to 35% as opposed to 21% now.

Most trees probably grew in swampy areas and the water they fell into would have been lower in oxygen. The material would have built up in the water and mud.

The evolutionary lag hypothesis is trivially false. Simple calculations show you’d quickly run out of atmospheric carbon.

So, can you provide the calculations?

I mean, we did?

Atmospheric CO2 levels in the pre-tree era 400 Myears ago was something like above 6000ppm, compared to 280ppm in the pre-industrial era. Even burning coal formed during this time like mad, 90% of the atmospheric CO2 is still just gone.

Could mean a long time, or could not. There have been new bacteria/fungi discovered around chernobyl which subsist on gamma radiation. It's not like evolution of new processes are guaranteed to happen slowly, it just seems unlikely to happen quickly.

https://en.wikipedia.org/wiki/Radiotrophic_fungus

10% is the theoretical quantum efficiency of the chlorophyll complex. Ps I/II use all sorts of tricks to squeeze electrons out of light, it's hard to imagine it getting better.

Remember that photosynthesis is a two stroke process. Fixing carbon tends to happen at night, so both sides are subject to optimization, and the day side has way more variation (seasonal etc) so you can't just say "RuBisCo sucks so PSI/II must be very suboptimal".

I predict 1000 years from now, CO2 will be up near 700 ppm and biomass will grow ~15% faster on average, but some plants will grow at 100% faster.

I bet you $1000 USD you're wrong.

Not a smart bet to take when the experiment has already been conducted thousands of times:

https://bmcplantbiol.biomedcentral.com/articles/10.1186/s128...

https://extension.okstate.edu/fact-sheets/greenhouse-carbon-...

This isn't new knowledge. We've known this for over 100 years.

"An increase in ambient CO2 to 800-1000 ppm can increase yield of C3 plants up to 40 to 100 percent and C4 plants by 10 to 25 percent while keeping other inputs at an optimum level."

Since neither of them will be alive in 1000 years to collect, it is rather moot, no?

It's mostly a joke on that basis, but I am a little skeptical that the well-known CO2 experiments will apply on average across the globe without being counteracted in part or whole by the temperature & growing season impacts.

In our current breadbaskets plants are going to be losing a chunk of the day in the middle of the growing season when it is too hot to photosynthesize on a regular basis, and the tradeoffs of what land is desertified and what land is defrosted is unlikely to be a net gain. The gains from increased CO2 are starting from in a hole and I'm not expecting to break even, let alone see faster or greater biomass on average, let alone at the rate we see in experiments using our current climate and future CO2 levels.

We have two main types of human corn here (Quebec). Yellow corn, and bi-colour corn.

Yellow corn literally does not come to full harvest if there are too many cloudy days. This happens once a decade maybe. It needs a growing season longer, and with more light than we have here.

Just 300km further south, in Ontario, this is not a problem.

(Bear in mind that the days shorten fast as fall approaches here)

Bi-colour corn can get two crops.

My point is, we already... without genetic engineering, just by selective breeding, get wild variations in growth rate, and yields, and harvest times... with just a decade or two of selective breeding work!

And my second point is, the most fertile land is going to become usable, if temps continue to rise. All that bog in Northern Canada.

We just need crops suited to shorter growing seasons, and very long days at equinox.

Canada is already mostly farmland. It will be interesting to see where this goes.

Re: selective breeding and genetic engineering, that's going to happen regardless of the atmospheric carbon levels.

Also, while I did bring up agriculture and it's fair to point out that it's going to get better over the next thousand years, agriculture is only about 2% of the Earth's plant biomass. While the rest of the biomass will be affected by the heat and benefit from the CO2, unless we start engineering the phytoplankton and the forests and all the other plants around us, it's not going to benefit from it.

Re: Canada's gain, there is a lot of land between 50 and 70 degrees north. The questions are (a) how much land in the north are we trading for how much land in the south? and (b) how does the productivity of the northern land compare to the productivity lost in the southern land?

Re: selective breeding and genetic engineering, that's going to happen regardless of the atmospheric carbon levels

But not to tailor crops, for areas that are currently permafrost.

There are billions of acres of permafrost bogs/peat in Northern Canada. They are even a concern, for as they thaw, they offgas.

Think of these areas as you would think of coal, in terms of CO2 being released.

But! That peat and bog is immensely fertile. If, outside of the growing season length issues, warmer temperatures come, then that is very, very rich, fertile farmland.

But we need specially tailored crops, which would never be created otherwise.

No need to predict this. Greenhouse experiments are conducted regularly with these conditions. There's plenty of data on it.

This Friday there was severe thunder and rain around here while the forecast said no rain at all. The reason was, they had 3 different models running and all of them gave the whole week different results (basically no overlap), so they just took the most probable, which was totally wrong.

I know these models are not that mich related, but when we can't look at the wheather of tomorrow, I question the precision of a model looking 1000 years into the future a bit. It will get warmer, for sure. But _how much_ is IMHO subject to interpretation.

It’s very hard to predict a single coin flip accurately, it’s extremely easy to predict the averages over a thousand coin flips.

> I know these models are not that mich related, but when we can't look at the wheather of tomorrow, I question the precision of a model looking 1000 years into the future a bit. It will get warmer, for sure. But _how much_ is IMHO subject to interpretation.

You say you know these models aren't that much related, but you still question the precision based on weather models. So do you, or do you not think they are much related?

If you throw a marble into a pit I can't easily predict which path it will take, but I can tell you where it will end up with which likelihood.

You can test individual plants, but it's hard to test the effect of evolution in a greenhouse unless you want to wait 1000 years...

Evolution takes a lot longer than 1000 years to affect fundamental processes like photosynthesis, which is an ancient biological chemical reaction. Plants experienced thousands of ppm of CO2 and warmer temperatures for most of Earth's 1 billion plus year history. The fossil fuels that are being burned, the carbon that is being burned, is dead plant matter from millions of years ago, when CO2 was thousands of ppm.

Even without any genetic adaptations (probably?) the world is "greening" due to increased CO2: https://www.nasa.gov/feature/goddard/2016/carbon-dioxide-fer...

Lands with soil that support it are greening. Desertification is a continuing issue and typically do not green without human assistance.

That's not what the data says. The total leaf area has increased by 25 to 30%. And there has been no drop in global precipitation.

Err, "the data" [1] doesn't talk about increases | decreases in total land area with vegetation, the data talks about increases in green leaf area within already established areas of vegetation.

ie. Your data and the prior comment aren't necc. in conflict.

[1] https://www.nature.com/articles/nclimate3004

    We show a persistent and widespread increase of growing season integrated LAI (greening) over 25% to 50% of the global vegetated area, whereas less than 4% of the globe shows decreasing LAI (browning).

The global vegetated area is [2]:

    About 85 percent of Earth’s ice-free lands is covered by vegetation. The area covered by all the green leaves on Earth is equal to, on average, 32 percent of Earth’s total surface area - oceans, lands and permanent ice sheets combined.

[2] https://www.nasa.gov/feature/goddard/2016/carbon-dioxide-fer...

It's good news for maize. That's a very carbon hungry crop.

And the way we use it also creating a bunch of carbon.

In the sense that animals and human beings are big blobs of carbon, yes. Ethanol isn't the primary output of maize.

The growing and processing of it uses large quantities of carbon inputs. Diesel and fertilizer.

The use of those inputs isn't creating carbon, just transforming it. Carbon fueled fertilizer is also used for all other cereal crops under the sun.

>The use of those inputs isn't creating carbon, just transforming it

It is though. Or if you like, it's transforming carbon from "in the ground" to "not in the ground", which is fundamentally the only thing that matters, since you're adding to a closed system.

If you're trying to tell me about the existence of the law of conservation of mass, I'm not sure what to tell you other than 'duh'

The point I was making is that cash crop farming is not a self-contained system even if the earth as a whole mostly is. (Much) more carbon goes into its production than comes out in the crop. Most of that takes the form of operating machinery, but there's also the production of fertilizers, and also the incremental loss of carbon in topsoil through tillage and erosion.

I am singling out maize (and, well, soy) because the scale of it is absolutely crazy; also on the whole most of the product isn't for direct human consumption (animal feed and ethanol). (Also BTW I work on software for running machinery which operates in those fields.)

Anyways, this is intrinsic to farming, which is an extractive process. The question is how to more smartly manage it in the long run.

Ethanol will soon be the primary output of corn (it arguably already is). The current breakdown in the United States as of 2022 is:

- 40% goes to ethanol production

- 40% goes to livestock feed

- rest is human consumption and misc industrial uses

Source: https://www.ers.usda.gov/topics/crops/corn-and-other-feed-gr...

"somewhere there are probably some recessive genes just waiting for their moment to shine again"

That ... Is pseudoscience. And elsewhere is the big greening earth lie big oil was peddling circa year 2000.

The level of idiocy and denialism is incredibly depressing

I can't tell if your comment is a false flag operation. I actually tried to find it any oil executives, lobbyists, or republican said something about big greening but couldn't.

There were a lot of advertisements about " they call it pollution, we call it life" about 15-20 years ago, and I still see some billboards to that extent in PA, funded by groups like CEI:

https://www.npr.org/templates/story/story.php?storyId=542535...

Shouldn't that be "spread like weeds"

And then comes the actual wild fires

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