Minimum Atmospheric CO2 percentage for plant life!

[deema]

It’s something I hadn’t thought about, but it’s a question provoked by being asked what is the present concentration of CO2 in the atmosphere and what was it 150 million years ago, in the middle of the period when the dinosaurs roamed the Earth. The answers are for me very interesting.

What percentage of the atmosphere is CO2? Well I thought it must be something like 5 or 10%! No, it’s actually 400ppm or, 0.4%!

Plants actually die if the level of CO2 in the atmosphere drops too much, it it gets down to around 250ppm or 0.25% they stop photosynthesis and start to die! Plants thrive in much higher CO2 concentration, their ideal is around 3000ppm or 3%. They also become more drought hardy!!

Finally, in the middle of the era when the largest animals to ever exist were plodding around, in a lush green environment the level of CO2 was over 3000ppm or 3%, the ideal levels for plants! and 750% higher than today.

So, when I hear about thermal runaway of the atmosphere, we are all doomed, it seems rather strange when the world not only survived but thrived with massively higher CO2 levels. Why doesn’t this ever feature when we talk about climate change?

 

[Inspector]

deema I'm pretty sure the world's temperatures were higher then too. None or almost no polar icecaps. It took a few billion years for the earth to lock up the carbon in the rock (limestone & chalk etc), coal, oil and dinosaur farts (NG) to bring the temperatures down to where it is. Mankind burning fossil fuels and deforesting the planet is adding a lot of it back into the air again in only a couple hundred years. I think it is foolhardy to believe everything is going to stay the same and we can do as we like. There will always be life but how we do in the new climate is another story.

My feelings on the subject and having expressed them I'll get on with other things.

Pete

 

[mwinfrance]

@deema
Dinosaurs,( giant reptiles ) , giant plants and giant insects did just fine back then with that atmosphere and those temperatures and other conditions, we would not. 3 million years BC was not a documentary, Jesus did not have a pet dinosaur. Nor did / do he or "his dad" exist either.

As for the thinking behind your post, after reading your "restores" and so on, seriously, I thought you had more sense.

 

[Ozi]

It's an interesting point, I don't think you are advocating the do nothing it's all fine approach. I think there is evidence that some plants are benefiting from global warming. As a very insignificant example on the Falkland islands a few years ago I saw pine trees near the accommodation at the airfield. When planted they had grown to building height then been stopped by winter wind as if cut. Now they have grown passed the buildings and look like small trees on top of older. CO2 levels have also had some benefits measurable in human time scales. The point is the whole system is very sensitive to small changes and change is happening very fast. Without the current 0.4% CO2 the world would be 30°C colder meaning ice to the equator as it has been in the past (no idea how that's known). The thing that most worries me is that we are in the middle of a mass extinction and that's never been good news for animals at the top of the food chain. Everyone hears about bees but we are also loosing moths, beetles and many other pollinators at alarming rates, even earthworms are in decline. I think the next few generations could be in for a rough ride, when the 20th / 21st centuries are taught as history we will not be looked on as the sharpest tools in the shed.

 

[deema]

I like to understand the whole picture, I prefer not to be driven by sound bite headlines. What is clear is that CO2 levels are being driven by China, the USA and soon Africa. The rest of the world plays little affect on what happens. So, with that, and appreciating good old Blighty has virtually zero influence I prefer to look at the worst case scenario to determine what the actual effect of higher CO2 levels are.

CO2 levels have risen from around 0.3% to 0.4 in the last 200 years. Arguably, our most polluting era. The would population is close to its maximum forecast, and will soon start to decline. With everyone at least trying to cut CO2 emissions we are unlikely to move to say 0.5% CO2 in the atmosphere. However, if that did occur, what’s the effect on the planet, the answer appears to be plants will thrive better. The level of heating of the earth will be far lower than it’s endured before and life will adapt again. Yes there will be mass extinctions, civilisation will be affected, people will be adversely affected, but the planets ability to continue to support life will not be terminally affected.

I take great comfort that mankind’s efforts are not going to cause the earth to become another Red planet whose oceans have boiled away.

 

[Jacob]

I like to understand the whole picture, I prefer not to be driven by sound bite headlines. What is clear is that CO2 levels are being driven by China,

Not true. China still per capita lower than USA but greater total. But they are also rapidly developing green energy technology and generate more green power than any other nation and also are becoming the worlds largest suppliers of green tech. The future is looking a bit Chinese!

the USA

USA and the developed world are worst, including ourselves.

and soon Africa.

Long way behind

The rest of the world plays little affect on what happens. So, with that, and appreciating good old Blighty has virtually zero influence

Not true.

I prefer to look at the worst case scenario to determine what the actual effect of higher CO2 levels are.

Why not look at the science instead of trying to work it out for yourself?
https://podtail.com/en/podcast/climate-change-for-beginners/
You might be right about life on the planet surviving, but most likely without us. OTOH you could be wrong - there are "tipping points" beyond which things are irreversible.

Odd that there are still climate change sceptics about, you'd expect them to be extinct by now, as change can be seen to be happening all around the globe!

 

[deema]

@Jacob every single fact I’ve presented is the accepted baseline of data all parties agree upon. I’ve just joined up the dots. For the world to remain as we know it now, we have to act. Again all parties agree. What I hadn’t considered fully was what happened if CO2 rise further. The evidence which no party disputes is that the world can and will survive abd be abke to support life. It will be different. Extinction Rebellion are IMO a very inflammatory and politically driven group.

 

[Jacob]

..........

So, when I hear about thermal runaway of the atmosphere, we are all doomed, it seems rather strange when the world not only survived but thrived with massively higher CO2 levels. Why doesn’t this ever feature when we talk about climate change?

It does feature. You just haven't read about it yourself. Google "holocene" and "anthropocene" if you want to catch up. Could say "it's never too late" but in fact it probably is.

 

[Jacob]

.......... What I hadn’t considered fully was what happened if CO2 rise further.

That is the main issue under consideration - you just seem to have missed it!

The evidence which no party disputes is that the world can and will survive abd be abke to support life. It will be different.

Could be true - it's arguable but nobody knows.

Extinction Rebellion are IMO a very inflammatory and politically driven group.

They are concerned about human life as we know it now becoming impossible, as is already happening in many places.
Is that too political and we should just grin and bear it? Maybe they are not inflammatory enough?

 

[sawtooth-9]

We do need a good level of CO2 - probably a bit more than we have now if you want to support lush plant growth.
Climate may well be changing, but it always has - Antartica used to be a green continent.
There may well be a correlation between "warming" and CO2 levels - but there is no substantive proof as to whether this is cause or effect.
And just how do you measure the temperature of a planet with sufficient accuracy to "worry" about a rise of 1.5 Deg and how did they measure it a few thousand years ago ? If they are not using the same methods then the comparison is invalid. We have also covered so much of the earth's surface with concrete and buildings which capture and hold heat energy - these were not here at this level a few hundred years ago. Again a false comparison.
I expect a load of "carp" over these comments but someone should present an alternative view

 

[Jacob]

......
There may well be a correlation between "warming" and CO2 levels - but there is no substantive proof as to whether this is cause or effect.

There is proof and it has been known since 1859 Meet the woman who first identified the greenhouse effect.

And just how do you measure the temperature of a planet with sufficient accuracy to "worry" about a rise of 1.5 Deg and how did they measure it a few thousand years ago ? .....

Good question:
https://www.ncei.noaa.gov/news/how-...buried in sediments at,in the rings of trees.

 

[Fitzroy]

The planet will be absolutely fine, but likely utterly different, just like it was 300 million years ago. Different flora, fauna, and weather. The transition will also be disruptive as some plants fail, sea levels rise and flood large areas of land.

It’s not a problem for the planet, but how humans would cope during the transition and under the new conditions is the problem for us. There would likely be large scale crop failures and significant human migrations to cope with. The human supply chain is very finely balanced for the planet to support 8billion of us, upset the balance wipe out half of humanity, planet would be happier. This is a problem for humanity, caused by humanity.

Animal species would also have to evolve with many failing to do so and going extinct, but new ones would appear.

Interesting times, but not fun for millions.

 

[Spectric]

Plants actually die if the level of CO2 in the atmosphere drops too much,

Humans will die if the oxygen levels drop to much so if we start worrying about everything beyond our control we will never have time to enjoy our woodworking and given time is on natures side and not ours then lets not worry about the next few hundred years ahead but the next 24 hours and leave the bigger problems to the people who falsely believe they have any control to waste their time thinking about them.

 

[Richard_C]

I wrote an essay, The Cyanophytae will inherit the Earth, back in 1973. At the time my argument was based on their remarkable speed of adaptation, they were turning up in nuclear reactor cooling water. But the argument still holds - the rate of change in our environment is too fast for complex organisms to adapt, simple ones will thrive. "It's life, Jim, but not as we know it".

 

[Fitzroy]

We do need a good level of CO2 - probably a bit more than we have now if you want to support lush plant growth.
Climate may well be changing, but it always has - Antartica used to be a green continent.
There may well be a correlation between "warming" and CO2 levels - but there is no substantive proof as to whether this is cause or effect.
And just how do you measure the temperature of a planet with sufficient accuracy to "worry" about a rise of 1.5 Deg and how did they measure it a few thousand years ago ? If they are not using the same methods then the comparison is invalid. We have also covered so much of the earth's surface with concrete and buildings which capture and hold heat energy - these were not here at this level a few hundred years ago. Again a false comparison.
I expect a load of "carp" over these comments but someone should present an alternative view

Ok you got me. My assertion would be that this is an area of scientific research in which many people are working. Being an engineer and having a science based education I have witnessed the lengths which researchers go to to disprove the current thinking. Science thrives on the phrase, 'oh, that's interesting', it creates new avenues for research and study. The scientific method has to consider the inaccuracies and uncertainties in the data, statistics is utilised to understand if the data with these uncertainties supports an assertion/hypothesis, if it does not then a researcher has to stop and understand if these uncertainties can be reduced.

Your statement "And just how do you measure the temperature of a planet with sufficient accuracy to "worry" about a rise of 1.5 Deg and how did they measure it a few thousand years ago?" is an excellent one and one that any researcher will have had to work through. A simple Google search for "how do you measure the temperature of the earth?" returns a plethora of links, in the first one there is the statement "While global temperature is a simple enough idea, measuring it is harder than you might think. We take a look at how scientists measure global temperature." It is an understood problem for which methods have been developed. We are all free to research them and challenge them, and scientists themselves will have challenged them and will continue to challenge them, it's what science does. You have spotted the complexity of the issue, but then rather than explored how the issue has been addressed you've rather lazily jumped to the conclusion that it is unsolvable and therefore everything climate scientists publish is flawed.

I expect with some google research I could understand what has been studied regards the impact of urban concrete coverage on global warming, and is there is or is not substantive evidence (proof is not possible in science) regards cause an effect of warming and CO2 concentration. Although the burden of proof is on you for the statement "there is no substantive proof as to whether this is cause or effect."

We should all learn to think critically about what we are told/shown, and we have the best ever tools at our disposal to test/check/challenge. But to claim an alternative position or 'poo-poo' something we don't like without spending the time to research it is bad form. We all need to learn to argue through fact not emotion or opinion.

There is my carp,

Fitz

 

[Gant]

Looking back at previous geological epochs does indeed show periods of incredibly vigorous life with CO2 (and O2) levels much higher than now. Of course the species alive now are not evolved or adapted to those conditions. But there’s also periods where life was rather more precarious; in the early Triassic for example most of the land was desert, and terrestrial life clung on round the coasts. In many cases the junction between the geological periods was a mass extinction event. That is very scary; we may well be heading that way now.

The most famous mass extinction event was the most recent; it happened at the end of the Cretaceous period when all the dinosaurs were wiped out (except birds). It wasn't the worst such event; about 67% of all species went extinct. But that’s not the full story, presumably over 99% of life was extinguished, but small numbers of 33% of species managed to hang on while the environment stabilised again.

So, if we are headed for an anthropogenic mass extinction, as current extinction rates suggest, it isn’t a question of whether we can live without badgers, it’s a question of whether we are one of the species that manage to scrape through. If we are, it’ll be a few thousand people here and there, and not 8 billion.

 

[Richard_C]

I'm not too worried about the state of being extinct, its the act of extincting that worries me.

 

[Jacob]

I'm not too worried about the state of being extinct, its the act of extincting that worries me.

Me too. I just don't want to be here when it happens.
Apparently coastal environments are most likely to permit survival, due to littoral ecosystems and temperature moderation by the sea.
We are wondering about Blackpool.

 

[bushwhaker]

Lush plant growth mean a more forest fires. Or new opportunities

 

[mwinfrance]

Lush plant growth mean a more forest fires. Or new opportunities

pdf saved for later reading..cheers