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Comment by soreal | Hacker News Reader

Permanently*

*Until we act to start removing CO2 from the atmosphere through various carbon capture methods

If I didn't make a mistake, we are looking at removing two trillion metric tons of carbon dioxide per ppm. That is probably not a small feat.

EDIT: Of course I made a mistake, it is probably more like three trillion metric tons, I mixed up fractions of volume and mass.

Don't forget that you'd have to do that in an entirely carbon free way and cease all current carbon emissions. That's not happening in our lifetimes.

I would use caution throwing around ultimatums. I'm sure pocket-sized digital supercomputers or a global near-instant communications network didn't seem likely within the lifetime of people born in the Great Depression, but here we are.

These exponential advances in technology are difficult to predict with human brains. I try to stay cautiously optimistic.

Today's computers were perfectly obvious to Gordon Moore in his 1965 paper. By contrast nobody today is writing papers about the inevitable expansion of carbon-free energy production.

Various forms of next generation nuclear would meet that requirement right? People are certainly writing papers on building better nuclear power plants. Doesn't even have to be something exotic like fusion.

If there is some kind of nuclear power that is millions of times cheaper per unit output than it was in 1965, I am unaware of it.

Some folks are certainly hinting at it. http://rameznaam.com/2015/08/10/how-cheap-can-solar-get-very...

This of course depends on the time frame one wants to achieve, but assuming we want to remove carbon dioxide as quickly as we added it, that means we would need some operation comparable in size to the global coal, oil and gas industry extracting carbon dioxide from the atmosphere around the clock. And while I agree with you, exponential growth is in some sense hard to predict, I don't really see us starting such a gigantic endeavor unless we are absolutely forced to by the consequences of climate change.

You make solar power cheaper than coal, and atmospheric carbon useful for something, and you'll soon have to regulate it extraction, not emission.

> Don't forget that you'd have to do that in an entirely carbon free way and cease all current carbon emissions

Plenty of carbon is naturally removed from the environment, at least partly by photosynthesis; that's how an equilibrium was maintained before we humans in wealthy countries started releasing so much more carbon into the atmosphere. We don't need zero emissions.

Carbon is generally not removed from the environment by photosynthesis.

In photosynthesis, CO2 is converted into sugar [0], storing the solar energy in the chemical bonds of the sugar molecule. Later, the energy is released through the reverse reaction where the sugar is converted back into CO2 [1].

Carbon is also used in biology for things other than sugar production, but in general the carbon that gets consumed by an organism eventually gets released when that organism (and the organism that ate it, and so on up the food chain) decays. This is refered to as the carbon cycle.

Under some circumstances, the carbon cycle is broken, and dead organisms end up sequestering their carbon in a place that does not allow it to return to the general environment (eg. fossil fuels).

TL;RD when we burn fossil fuels we are adding carbon to the environment. When plants consume carbon, they are moving it from the atmosphere to another part of the environment, and it almost always ends up back in the atmosphere.

[0] The full reaction is CO2 + Water -> Sugar + Oxygen, or 6(CO2) + 6(H2O) -> C6H12O6 + 6(O2)

Yes, good point. I knew that but somehow it escaped me when I wrote the post. My point was, the global ecosystem can handle the release of some carbon by human activity without a problem; we don't need to go to zero.

However, the sooner and farther we reduce carbon output, the faster we reduce excess carbon in the atmosphere. There's nothing magic about zero; negative output would help too.

until Elon Musk does something about it. Right ?

Plants are able to remove about 10ppm per year. If we stopped emitting, and starting burying plants in the ground it could be done without a huge problem.

i.e. the hard part is not removing the CO2, the hard part is not adding to it.

Trying to bury a significant portion of the global plant mass gain every year in a way that it does not emit greenhouse gases while decomposing seems like a major undertaking to me.

A quick calculation - one ppm reduction means extracting three trillion metric tons of carbon dioxide which contains about 800 billion tons of pure carbon which takes up about 400 cubic kilometers. That is a huge hole to dig even if we would just have to deal with the carbon. And that is for one ppm.

Don't we have plenty of old coal mines? They seem like a natural place to sequester carbon in, given that that's where a lot of it came from in the first place...

> three trillion metric tons of carbon dioxide

Billion not trillion (10^9). All the rest of your numbers are off by a similar factor.

> That is a huge hole to dig

Actually, using the correct numbers (.4 cubic km), if you made a 50 foot deep hole it would be about 3 miles by 3 miles. Not that big - a couple of city blocks.

A typical landfill is larger than that, and we have tons of those.

Nope, trillions. The mass of the atmosphere is about 5.15 × 10¹⁸ kg [1], 400 ppm of that are 2.06 x 10¹⁵ kg or 2.06 x 10¹² t which are about two trillion (short scale) or two billion (long scale) metric tons. I used the short scale [2]. And because the 400 pm are by volume and not by mass you end up with about three trillion metric tons if you take that into account, too. Of course only unless I messed things up.

[1] https://en.wikipedia.org/wiki/Atmosphere_of_Earth

[2] https://en.wikipedia.org/wiki/Long_and_short_scales

Your figure is for 400ppm. But we are talking about 1ppm.

Of course, sometimes you are just blind for the error.

The third sentence:

> That all but ensures that 2016 will be the year that carbon dioxide officially passed the symbolic 400 ppm mark, never to return below it in our lifetimes, according to scientists.

So permanently as in our lifetime which is really the only type of permanence that matters.

and so people suddenly lose interest, those projects wont have much effect until after i'm dead and gone. If we can vastly expand the lifespan of an individual, suddenly they have a vested interest in the next 100, 1000, or whatever years. Suddenly it will make sense to spend a lot today to avoid pain later.

There's a very good chance that all this CO2 will remain in the atmosphere for longer than your permanent backups, permanent government/business records, and even some permanently owned land...

That's permanent enough for me.

> and even some permanently owned land

... especially coastal properties ;)

I don't see anyone doing this currently on a large enough scale, but I'm hopeful that the crashing costs of renewables, which will push the price of electricity down, will be a catalyst for implementing energy-intensive carbon capture and sequestration methods (currently being experimented with in Iceland).

It could be a good way of dumping extra load in a renewable national grid.

Spec the grid so that in low supply situations (low wind, low sun) there is enough power to cover actual demand 90% of the time. Then whenever there is extra power, (windy and/or sunny days) you redirect that extra power into carbon capture/sequestration.

I wish for something like a closed loop cycle: Solar energy into electrolysis to fuel a sabatier process and feed the resulting methane into a syngas-to-gasoline process should be the standard for fuel production in the future. It's energetically expensive, but we'll never run out of water and carbon dioxide.

Not exactly a closed loop - about 30-50% of the carbon dioxide we release is absorbed into the ocean[1]. So this process might actually decrease atmospheric CO2 levels, but ocean acidification will continue to increase.

[1] http://www.gdrc.org/oceans/fsheet-02.html

Carbonic acid in the ocean is in equilibrium with the atmosphere, so if you knock down the ppm in the atmosphere it'll eventually affect the oceans.

is carbon capture actually viable? a completely carbon-free capturing method sounds like perpetual motion or free energy.

Like trees?

trees sound plenty viable. maybe it should be called tree planting instead.

I don't know why this is not on the agenda.

People are instead wasting money on crazy stuff like compressing CO2 into projectile like cans and dumping them into the ocean. Or my favourite, stopping the sheep from NZ from farting!!

The terrestrial biosphere makes a terrible place to store carbon, as you really can't store that much of it, and eventually it has a tendency to burn and release it all back. If you wanted to grow a bunch of forests/crops, and then bury them and grow new stuff I guess that might work. But not as well as pumping new CO₂ underground or into the deep ocean (below the carbon compensation depth, where it will dissolve existing carbonates and buffer the ocean).

Also forests make the Earth's surface darker, thus decreasing albedo and potentially increasing global warming.

"Also forests make the Earth's surface darker, thus decreasing albedo and potentially increasing global warming."

Obligatory:

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

Or just use the wood to build things! Has the added benefit of reducing the use of carbon intensive materials like concrete and steel.

Good idea. Now tell me how you plan to offset the carbon emissions from land use change... You weren't planning on building dense housing with wood, were you?

There's a group doing that.

They can make some pretty impressive engineered beams these days. The fire intensity required to destroy them, they claim, also structurally damages concrete, so it's not the issue most of us take it to be.

The presumotion is that the land would have changed anyway, just in a more carbon intesnive way. Of course "burying it" would seem to require some carbon outputs, and a temporary land use change. What do you think that would be sustainable?

Any carbon you can put below the surface tends to stay put. So it's not 'grow trees' it's 're-establish healthy forest ecosystems'.

A bunch of Doug firs growing on compacted clay isn't going to sequester much of anything.

I'm not saying that healthy forest ecosystems don't have a lot of benefits, it's just that "grow moar trees" as a carbon sink is a trigger for me. Planting trees is the perfect feel-good solution that solves, at most, 0.1% of the problem. It's a "send food to Africa" or "build the wall" analogue solution that doesn't address any of the root causes.

Things one can actually do to help solve this: Plant trees as part of restoring ecoystems; recycle metals (esp. Al); join the diplomatic corps and negotiate climate and trade agreements; buy locally grown food and locally obtained materials; start a massive battery/solar/car company to obsolete the fossil fuel industry; research atmospheric alchemy; eat less meat. Not necessarily in that order.

no reason why it should sound like that.

why shouldn't it? the phrase itself, in my mind, conjures up images of impossible patents and theoretical technology.

maybe I just have a good imagination, but when someone says "carbon capture" I imagine some sort of artillery sized vacuum we can point at the sky and turn on to start sucking carbon out of the atmosphere.

Ignoring costs, it's "trivial" to do with nuclear energy providing the carbon capturing power. But doing so requires a tremendous amount of power (proportional to how much hydrocarbon-based power we're using now, as noted elsewhere in the comments) and a tremendous amount of resource investment (building the power plants, building the carbon capture mechanisms, etc.). So: doable, but insanely expensive.

That said, if the alternative is the death of most ocean life, the depletion of most of the planet's food resources, and therefore the death of a large chunk of the planet, we may end up reevaluating our willingness to spend that kind of change.

Only the solar powered ones.

There is carbon cogeneration though. Diverting point-source CO2, scrubbing it and using it in industrial applications that require carbon dioxide.

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