[zekrioca]

In the article mentioned by parent comment, they suggest extracting CO2 from atmosphere and storing it somewhere safe. There is (at time of article's writing) no technology capable of doing so. I guess it is would be "safer" than creating a "solar shade"? I am not a climate scientist either..

[robomartin]

The questions nobody answers when it comes to all of these so-called solutions are:

    How much energy will this require?
    How will we generate it?
    Will generating that energy produce CO2 or other problems?
    What resources are we going to need (chemicals, etc.)?
    How are we going to extract or produce them?
    How much energy is that going to require?
    How are we going to produce that energy?
    Will generating that energy produce CO2 or other problems?

Conservation of Energy is an ass. It does not care one bit. Which means we can't solve a problem with less energy than what went into creating it in the first place.

A common misconception is that humanity added a bunch of CO2 in a couple of hundred years. That's not true. It took millions, if not billions of years. Sure, in therms of use using petroleum, yeah, we did it in a couple of centuries. However, the reality of this fuel is that it took billions of years to create. THAT is what we burned; billions of years of stored energy.

That was the other revelation I had during my research. We are looking at this with the wrong time scale. In a couple of hundred years we burned millions or billions of years worth of stored energy. And to clean-up that mess you need far more energy than what it took to produce the mess in the first place.

Imagine how many trees, plants, animals and solar energy went into creating the petroleum we burned. That's the start of the scale of the problem we are trying to fix. In other words, we can't fix it. Not without making a much larger mess.

[philipkglass]

In a couple of hundred years we burned millions or billions of years worth of stored energy. And to clean-up that mess you need far more energy than what it took to produce the mess in the first place.

That would be true if the only way to remove CO2 from the atmosphere were to run "combustion in reverse" to turn carbon dioxide back into hydrocarbons.

That is not the only way, though. Enhanced silicate weathering is attractive because it turns atmospheric CO2 into chemically stable condensed phase compounds, without the huge thermodynamic cost of reversing combustion. The energy cost of enhanced silicate weathering (though still large in absolute terms) is greatly reduced compared to combustion-reversal because it's just accelerating the kinetics of a thermodynamically favorable natural process.

MgSiO3 + CO2 => MgCO3 + SiO2

This is a sketch of the geological carbon cycle [1], the same thing that eventually (100,000 years from now) would remove the excess CO2 from the atmosphere. The idea is to accelerate the drawdown by pulverizing silicates so the above surface-area-limited reaction goes faster.

See e.g. "Enhanced weathering strategies for stabilizingclimate and averting ocean acidification"

https://csas.earth.columbia.edu/sites/default/files/content/...

[1] "The Global Carbon Cycle: Geological Processes" Section 3.6

http://geosci.uchicago.edu/~kite/doc/Wallman.pdf

[robomartin]

In my research of the domain I did come across this. It is one of the scariest proposals out there. These people risk causing irreversible damage to the oceans and all life within them. It's hubris to think we can do something like that and actually control it at a planetary scale. Also, refer back to my questions about the energy and resources required to do this, to do anything.

While you are right in that the process is not combustion in reverse, the reality of the matter is that it much worse than that. Massively worse.

We haven't even gone to the other elephant in the room: Australia. I hope someone eventually publishes an honest accounting of the CO2 that was released into the atmosphere through these fires. My guess is it easily negates decades of clean energy and other mitigation technologies.

I didn't get into it in my original comments. There are two questions everyone should ask when looking at the 800,000 year CO2 concentration chart:

1) How/why did CO2 levels rise?

2) How/why did CO2 levels drop?

These are fundamental questions anyone with a science background should ask almost immediately. The answers, at a basic level, are simple:

1) Massive continental scale fires burning for thousands of years. Remember, no fire dropping helicopters.

2) Storms, rain, water, hurricanes and, yes, trees and vegetation growing over thousands of years.

So, stuff burned for approximately 25,000 years for a 100 ppm increase and stuff grew and rain fell for about 50,000 years to capture the CO2 that was created.

The bottom line is that anyone claiming that we can do 1000x better than if humanity left the planet they are going to have to explain, in great detail, how it is that they know Zeus so intimately that he will grant them magical powers. And I don't think this is an understatement at all.

BTW, the only intelligent proposal I've seen is to plan trees like our lives depend on it. Seriously. Simple tech. We know how it works. We know what it does. And, if we have the water, we know how to grow them. This won't solve the problem any faster but it is likely to make things better. All we have to do is figure out how to prevent our massive new forests from burning, because, in that cases, once again, we will have made the problem een worse. Here's an article on that one:

https://www.livescience.com/65880-planting-trees-fights-clim...

[philipkglass]

Originally you said "Conservation of Energy is an ass. It does not care one bit. Which means we can't solve a problem with less energy than what went into creating it in the first place."

Enhanced silicate weathering is a way to draw down atmospheric CO2 with less energy than went into creating the problem. Still, perhaps it will never be deployed on a large scale if people find the proposal too scary.

That's one of the most depressing things about curbing climate change. There are a number of changes that we could have implemented to prevent the problem from getting as bad as it is now. But all of them scared enough people that they didn't go forward on a scale that was large enough, fast enough. That could be fear of physical safety (opposition to nuclear power), fear of unemployment (coal miners against cleaner power sources), fear of lost profits (businesses against carbon taxes)...

Since the scale of the problem is vast, the scope and scale of any actual solutions will be vast as well.

[robomartin]

My point is that you can't just look at chemical reactions. How much will it take in energy and resources to make it happen? That's where Conservation of Energy becomes an ass.

In other words, it's easy to talk about a solution, any solution, in isolation of what it would really take to deploy it at a scale massive enough to affect planetary level changes. Think about all of the equipment, transportation, processing, people, energy, etc. We literally can't think about things at these scales.

To go back to my super-simple argument about how the planet behaved without us polluting it further. It typically took absolutely massive storms for tens of thousands of years to reduce CO2 by 100 ppm. I use 50,000 years as an average of sorts, but the reality is that the range extends all the way out to 100,000 years for 100 ppm.

Now imagine taking all of that and proposing that we are going to do the same in 50 or 100 years, without leaving the planet, without shutting down every form of transportation, without killing every industry on the planet and without reducing population to medieval levels. That is a tall order. It's one thing to run a little microscopic test (when compared to planetary scale everything is microscopic), quite another to have the audacity to claim we know what will happen if we take it global. We could create quite an ecological mess.

The things you mention we could have done. I don't think they would have made any difference. I mean, not in terms of atmospheric CO2 concentration. Human life, definitely. One of the things I learned --and I can't remember it accurately-- is that CO2 in the atmosphere "sticks" and is hard to mitigate. The idea is that anything we do at ground level will have zero impact past a certain altitude. We can certainly burn stuff and have the CO2 go up and circle the globe but we can't easily pull it down from 10, 20 or 30 km of altitude.

That's what a lot of these simplistic conversations miss. When I say it will take an astronomical amount of energy and resources I am thinking about a process that has to reach out and grab CO2 going up tens of kilometers into the atmosphere all around the globe. We just can't do this by installing solar panels, sprinkling the beaches with chemicals, banning coal and gasoline powered vehicles and devolving into the middle ages. This is a very tough problem and one that likely has no human-scale solution, both in terms of time and resources.

That said, I don't think this is reason for depression. Imagine for a moment if we agreed on this idea that we just can't fix it. What would our conversations turn to then? Improving human life? Developing technologies to help us live with the coming changes? Cleaning-up our act to improve life locally? That and more.

I would imagine the narrative would change radically. For one thing, we would stop hearing from ignorant politicians, celebrities, deniers and zealots. Researchers would be able to work on real research rather than having to get on the bandwagon for fear of never having access to research grants and opportunities. There is no telling what advances we might make if we just stopped the insanity this has become and allowed facts, reason and real unencumbered science and engineering to float to the top. Utopia, I know.

[philipkglass]

One of the things I learned --and I can't remember it accurately-- is that CO2 in the atmosphere "sticks" and is hard to mitigate. The idea is that anything we do at ground level will have zero impact past a certain altitude. We can certainly burn stuff and have the CO2 go up and circle the globe but we can't easily pull it down from 10, 20 or 30 km of altitude.

I'm not sure what you are trying to recall, but this is incorrect as written. The atmosphere stays well-mixed up to about 100 kilometers:

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

Any silicate weathering process that binds CO2 at the Earth's surface will also remove atmospheric CO2 that exists at 30 km from the surface.

The atmospheric CO2 excess was created by generations of humans all over the world. Barring breakthroughs like self-replicating machinery, fixing it will also require global scale efforts over multiple generations. I am not optimistic about people even starting serious efforts toward that end in my lifetime. My pessimism is more because of the misaligned incentives than the huge numbers involved.

If you told an engineer 150 years ago that the world would burn over 4 billion tons of coal in 2013, and asked them to plan how that would happen, it would seem impossible too. Nobody could really plan an endeavor of such scale. And in fact it didn't come from one globally coordinated plan, just a set of incentives that diffused globally. Sadly for the climate, the incentives to stop burning fossils do not spread as easily as the incentives to start.