But those burned trees pulled the fire-released carbon from the atmosphere not all that long ago.
...Vs. the carbon in fossil fuels, which has been underground for literally millions of years.
Not sure what your point might be. If you burn the equivalent of thirty years of forest growth and release that carbon it will take, I don't know, a thousand years to get it back. This isn't a 1 to 1 game. Nothing in the real world works with 100% efficiency.
Atmospheric CO2 remain in the atmosphere for a very, very long time. Thinking we can just reach out and retrieve it --at a planetary scale-- is nothing more than a fantasy being sold to make money.
> If you burn the equivalent of thirty years of forest growth and release that carbon it will take, I don't know, a thousand years to get it back.
Something is wrong with your statement and the answer is right there in your sentence.
If you burn thirty years of forest growth it would take thirty years of forest growth to get it back. A carbon cycle is a cycle, plants die AND plants grow. And the best part is we simply leave it alone to grow.
GP's point is that fossil fuels don't grow like this.
It's easy to get a sense of proportion for these things.
Example: One of the latest fires in Southern California burned through 5200 acres in about four days. What was burned easily represents twenty years of growth.
Simple math: 20 years x 365 days = 7,300 days
The CO2 was released in four days, therefore 7,300 / 4 = 1,825
If carbon re-capture was 100% efficient and 100% reversible (not the case), that means you need 1,825 units of time to recapture what you release in one day.
I used "a thousand years" as a figure of speech to communicate that it takes a massively long amount of time to grab CO2 out of the atmosphere, no matter the source. These are not efficient processes. Even if my figure of speech is off by a factor of 100, it means the annual CO2 contribution by forest fires takes ten years to recapture. That is an unwinnable ratio.
Sticking our heads into the ground and ignoring reality isn't going to solve any problems. For example, there are fires around the world that have been burning continuously for hundreds and thousands of years. And these are not small insignificant fires. If all of humanity evaporated from this planet tomorrow, atmospheric CO2 would still require tends of thousands of years to come down. These are planetary scale problems that are impossible for us to solve. The "save the planet" narratives out there are hubris at best, and money-making/power-grabbing scams at worst.
What I find truly remarkable is that we can't even control these fires that burn for a century or more and we are actually buying into the idea of saving the planet. The scale of these fires, when compared to a planetary scale problem is a rounding error, laughably small. One way I think of it is: Put out all of these long-burning fires and they I'll believe we might be able to affect atmospheric CO2 at a planetary scale. Until then, it's a fairy tale. A fantasy.
You seem to obfuscate pretty simple concepts through some pointless math. Yes if we burn a forest that took 20 years to grow, to capture the same amount of carbon you will need to grow the same amount of trees for 20 years (or equivalently double the trees for 10 years ...). The recapture is 100% efficient and 100% reversible or are you suggesting that carbon is somehow transformed into a different element. If a tree contains e.g. 1 tonne of carbon it needed to extract that amount of carbon from the atmosphere. The thing is, growing trees happens much more frequently than forest fires. So we can capture significant carbon from the atmosphere by planting more trees (with the added side effect that it would make places more pleasant to live).
Regarding coal-seam fires, the amount of carbon they release compared to the amount of coal we burn purposefully is negligible (that doesn't mean we should not put them out though)
> The recapture is 100% efficient and 100% reversible
Nothing is 100% efficient. Nothing.
On the question of time. here's an easy read [0]:
Quoting:
"Changes to our atmosphere associated with reactive gases (gases that undergo chemical reactions) like ozone and ozone-forming chemicals like nitrous oxides, are relatively short-lived. Carbon dioxide is a different animal, however. Once it’s added to the atmosphere, it hangs around, for a long time: between 300 to 1,000 years. Thus, as humans change the atmosphere by emitting carbon dioxide, those changes will endure on the timescale of many human lives."
This article is very interesting in that it shows just how some of our assumptions --things we thought we knew-- are wrong. For example:
"We’re seeing that Earth’s tropical regions are a net source of carbon dioxide to the atmosphere, at least since 2009. This changes our understanding of things."
Sadly climate-change has mutated into an area dominated by some of the most incredible fantasies I have seen in pseudo-science. This is one of them. Looking at burning trees or wood as carbon neutral with the benefit of ignoring the most important variable in the equation: Time. Others are claims to be able to reduce CO2 at supernatural rates (save the planet in 20, 50 or 100 years), etc.
If there's on thing I have learned by taking a deep dive into this subject is that most of what is out there in political and popular circles is somewhere between a fantasies and outright lies. The real science is having trouble getting out to the surface because it has no political or financial value.
You can't get votes if you talk about dropping CO2 by 1 ppm in a thousand years. If, on the other hand, you convince people that we are all going to turn into goo in two decades and we can fix the problem --if you give me money, power or both-- well, that's powerful. And so climate change turns into a cult to the benefit of politicians and those able to make money out of the narrative.
If I spend 20 years accumulating baseballs, and then go out and drop them all in a baseball field full of people over the course of about 4 days, and all those people really want baseballs for some reason, will it take 1825 days for them to pick all the baseballs up?
I'm sorry, that has no relationship whatsoever to the subject. I could take it apart piece by piece. Still, it would be an exercise in futility.
Here's one that might highlight the nature of the problem:
Imagine you burn a cubic meter of wood at the base of a building with twenty floor. All internal doors and stairs are open, so the smoke and gasses can go everywhere. Particles can travel into cracks, air ducts, all kinds of places and land.
A few hours later the fire is out.
Now go and remove all gasses dispersed through the building and recover every particle deposited on every surface across twenty floors.
First. It's impossible.
Second. If you really wanted to attempt such a feat, it would require more energy and resources --by orders of magnitude-- than what went into creating the mess in the first place.
Third. It would take exponentially more time than what it took to consume the pile of wood.
Now take that and extrapolate to a planetary scale.
> Is there math behind this? Even back-of-napkin math?
Here. Maybe this qualifies for "back of the napkin" [0].
Quoting:
"Changes to our atmosphere associated with reactive gases (gases that undergo chemical reactions) like ozone and ozone-forming chemicals like nitrous oxides, are relatively short-lived. Carbon dioxide is a different animal, however. Once it’s added to the atmosphere, it hangs around, for a long time: between 300 to 1,000 years. Thus, as humans change the atmosphere by emitting carbon dioxide, those changes will endure on the timescale of many human lives."
It isn't a matter of just looking at a tree. You have to consider the entire process. This includes energy and time. The time scale for CO2 in the atmosphere isn't measured in days or years, it's measured in centuries or thousands of years.
You can't recapture the CO2 produced by burning a thousand trees in a few days on the same time scale. The real recapture, when all things are considered, is orders of magnitude greater in time. And, of course, because everything in real life is a complex multivariate problem, there are a million other factors that make the process far less from the idealized image a lot of people have in their minds. A lot of those variables are unknown to us. My guess is a good deal of it isn't even measurable. We are still learning a lot. For example, again, from the article, quoting:
"For as long as we can remember, we’ve talked about Earth’s tropical rainforests as the ‘lungs’ of our planet,” he said. “Most scientists considered them to be the principal absorber and storage place of carbon dioxide in the Earth system, with Earth’s northern boreal forests playing a secondary role. But that’s not what’s being borne out by our data. We’re seeing that Earth’s tropical regions are a net source of carbon dioxide to the atmosphere, at least since 2009. This changes our understanding of things."
Going back to the back of the napkin calculations. A tree absorbs about 25 kg of CO2 per year.
A tree.
Not a seedling.
Not a twig.
A seed just weeks out of germination isn't going to absorb 25 kg of CO2 in a year. It takes years, maybe decades (likely species dependent) for it to become a tree that can capture carbon at that rate. Some trees never reach that rate of capture. They are not large enough.
And so, you don't burn a tree in a day --one that captured thousands of kilograms of CO2-- plant a seed and instantly start capturing 25 kg per year. It doesn't work that way.
This is why including variables such as time, growth rate, species and many more is important. Without them we are constructing a fantasy. It might take twenty years for a tree to reach this 25 kg/year absorption rate. By that time you have twenty years of forest fires that have contributed CO2 to the atmosphere that will "stick" to it at a time scale longer than human life or even human generations.
My guess is that the shape of the rate of CO2 absorption for any plant or tree is roughly a sigmoid function [1]. I tried to look this up but Google isn't being helpful in this regard. All you can find are numbers for mature trees. I want to know the rate of absorption per year from seed to maturity. Beyond that, I want to know how this behaves after a tree reaches maturity. Does it continue at the same rate? I have a sense this might not be the case. This is why I am guessing it must look somewhat like a sigmoid, with the possible exception that, once a certain age is reached, it might not stay flat but it might actually decline to some lower rate of absorption. This, in particular, makes sense to me in the context of a canopy or a forest. Interaction between trees and other factors means sunlight can only penetrate to a certain depth into the canopy. This likely means the rate of absorption has an upper bound or might experience a reduction, maybe even a cyclical reduction.
And then there's NASA's discovery that the tropical rainforests have actually become net CO2 contributors. I don't fully understand that yet. It raises a lot more questions in need for answers.
It is all too easy to fall into what I like to jokingly call the "assume a cow is a uniform sphere of milk, one meter in diameter" syndrome. Anyone who has studied physics to a reasonable depth is familiar with the many "assume..." simplifications we are forced to use while learning. Reality is too complex and it would be very difficult to understand things we we stopped to account for all variables while learning. That does not mean that we can then take the cow assumption and apply it in real life to every problem. Sure, a tree can absorb a lot of CO2...but this isn't some magical process that happens instantly the minute you are done burning it. Not even close. A cow is not a uniform sphere of milk. It just isn't.
