We're on course for 4+.

1.5 is locked in. Nothing short of a nuclear war will stop 2-3.

If people truly care about the humanitarian elements of climate change, they should be looking into how to relocate somewhere north of a billion people from Bangladesh and the surrounding area to land which isn't doomed to be underwater relatively soon.

Of course, you can't make money selling refugees (yet), so this remains a secondary consideration.

> Relying on carbon dioxide removal and so-called negative emissions technologies to lower greenhouse gases in the atmosphere over several decades is too risky to contemplate.

Author is saying to not even think about all solutions? Unprompted, on a post ostensibly sharing research findings? Sounds a bit dogmatic and politically motivated. I don’t trust their results.

The energy budget needed for CO2 removal makes all our energy consumption done to this point a rounding error.

There are possibilities for removal mechanisms that do not require proportionate input in energy directly. For example, you could perfect growing algae and let the algae extract energy from sunlight on its own. We would just have to ensure good transfer of CO2 from atmosphere to water. Another I have seen is crushing rock -- as silicate is weathering it will naturally extract CO2 and the question is how efficiently you can powder rock.

Another possible solution would be finding a process that will remove CO2 as a byproduct. If you have to put a lot of energy into it, at least get some part of it back.

You're describing small systems being scaled up millions of times. It reminds me of the doomed and misguided Ocean Cleanup Project. Where would you grow all this algae? It would take a great deal of area (easily multiple thousands of square miles) because it relies on photosynthesis. You can't build it at sea, because it would be destroyed be storms.

The crushing rock works very slowly - that part of the carbon cycle takes ages. Any significant speedup of that would also be an environmental disaster - again too much rock crushing, and it would have to be spread over large areas.

Even worse, this will all need to be done in an already deteriorated planet, with almost assuredly worse political stability and real economic output than we have now.

> You're describing small systems being scaled up millions of times.

What you are describing is how technological progress works usually. We first typically learn to do something at small scale, then learn to solve problems that are necessary to scale it up.

The problem isn't really whether we can do it but whether we can get people to be willing to do it.

> The crushing rock works very slowly

Yes, it does. But once you crush the rock the rest happens on its own while you are crushing even more of it. Which means after some time the removal will asymptotically reach the speed at which you are able to crush the rock (and supply the air).

I don't think you are grasping the full, physical scale here. This is a lot of CO2, and you need a lot of crushed rock. This is not like integrated circuits or anything - it would be an enormous heavy industrial operation the likes of which the world has never seen. The main problems aren't really even technological - but economic, physical, and ecological. This isn't an area where Silicon Valley can invent some magic silver hammer that they always think is around the corner.

I did not say crushed rock is the solution. I just used it as an example that solution may not require us to supply the amount energy from the grid that we would normally get from emitting the CO2 in the first place.

Also, I think you are just flat wrong about how unprecedented this operation would be. Digging oil and coal from under the sea or thousands of meters below ground is certainly more difficult than crushing rock that is readily available on the surface basically everywhere.

I think the bigger issue is figuring out what to do with that crushed rock so that it has contact with air so that it can actually perform the reactions we want (this might not be solvable).

We can use crushed rock to some extent. For example, I use powdered basalt in my garden. It improves the soil and provides nutrients over long periods of time. But I think we would quickly run out of agricultural soil to fertilise this way.

Crushing many cubic kilometers of rock, transporting it, and then spreading over large areas takes quite a bit of energy, you'll find. It's not easy as you say, and only specific types of silicate rocks work. You seem to keep thinking that the "tech" is what matters here, and not the necessary enormous industrial and ecological inputs this would take.

Also, no, I'm not wrong about the scale. This solution would require orders of magnitude times more mass than the oil/coal extraction you're describing. Again, you still aren't grasping how big this would be. It would require giant open pit mines to take out literal cubic kilometers of rock, and keep doing this for ages.

> Again, you still aren't grasping how big this would be.

You seem to be very sure about knowing what I can or cannot grasp. You wield this sentence as some kind of weapon against me but the fact is you are not presenting any arguments.

Humanity has shown that it can do a lot if it just wants.

Look at the scale of world wars where large part of world's output was converted to war effort because we just didn't like the idea of being conquered by Nazis.

The great pyramid of Giza is 0.2% of cubic kilometers and it was literally built with sticks and rope, for vanity, with relatively few people.

Your claim that humanity can't crush a bunch of cubic km of rock and spread over vast areas of land when faced with existential crisis is shortsighted.

The existential crisis you are talking about is happening right here, right now - and nothing meaningful is being done about it. The correct course of action is to reduce further damage, and not count on our ability to tech our way out of this in a further degraded environment decades from now.

I keep saying "you don't grasp" the scale here because really you don't. Myself and others have explained how enormous this undertaking would be, but you haven't given any kind of solution to the manifold problems we outlined.

humanity can't crush a bunch of cubic km of rock and spread over vast areas of land in a non-polluting way. It won't be carbon negative after drilling, blasting, digging, crushing, transporting, and spreading it around. If you can do it on your garden as a side-effect of hobby gardening, that is a nice benefit.

BTW, I worked as mechanic on heavy equip, crushers, drills, and haulage at many mines.

You would need 96 gigatons of rock a year to just stop the current CO2 production. By comparison all coal mining in before covid was 8 gigatons. To start removing CO2 in meaningful quantities you'd need to increase that number by 5 or more times.

Your low energy solution isn't.

>For example, you could perfect growing algae and let the algae extract energy from sunlight on its own

Yes, we only need to produce more fertilizer than we ever have and keep doing that year on year forever.

>as silicate is weathering it will naturally extract CO2 and the question is how efficiently you can powder rock.

We only need to mine an Everest worth of stone each year for a millennium or so.

Yes. Such achievable goals.

The only ones that come close to being reasonable is dispersing aerosols in the upper atmosphere and reducing the sunlight that reaches the ground directly. That has the problem that we need sunlight for such pesky things like photosynthesis.

"Negative-emissions" carbon-capture technologies have essentially intractable problems scaling up, including basic thermodynamics; that isn't even talking about the massive resource inputs to build a system capable of meaningfully reducing CO2. It's a lot easier to to not emit as much in the first place.

Even barring these severe problems, the precautionary principle is the right thing to apply here. If "negative emission" tech has even a 90% chance of working, we still should focus on reducing emissions, because that tail risk is bad.

It's like why people have fire insurance even though most people's houses never catch on fire.

the solutions are not technological, they are just about people reducing each drastically their footprint, and creating more natural super efficient carbon sinks, also called forests, permacultures, and more vegetation overall

I expected downvotes in a forum where Elon Musk must be considered as a god / savior against global warming (while cars with 500kg of batteries can't certainly be a good idea)

but that's still the truth that someone highly knowledgable like https://en.wikipedia.org/wiki/Jean-Marc_Jancovici would explain in more details

and what are your qualifications?

If this, hypothetically, isn’t the solution, then what is?

It is literally not possible to get everyone to stop emissions. If reducing emissions by planting trees and building carbon banks isn’t enough, will anything be enough?

Seems kinda fatalist to just say “ah, we’re fucked”

Who cares ? /s

Who cares but without the sarcasm tag. People keep posting these doom-and-gloom and it amounts to nothing more than a barrage of “told you so!” commments and sly holier-than-thou shitposts (maybe this one fits into that category.)

Wake me up when someone comes up with a serious plan worth discussing; until then HN is the toxic landfill of trash articles.

Who acts? Who reduced their footprint under 2 Tonnes equivalent CO2 / year? Not many of us, though that's definitely something with many other benefits than environmental

There are many direct air carbon capture technologies under development. Most should cost between $50-200 per ton of CO2 they capture. That translates to $1 to "undo" a gallon of gasoline.

It's worth trying but it's also essential that people pollute less (and not just with CO2, plastic littering, batteries, ..), also note that those air carbon capture companies has received funds from gas companies (https://www.facebook.com/jeanmarc.jancovici/posts/3539457094...)

Perhaps we should build an arc to help these species survive the anticipated hot period.

And the ark should go where ?

I was thinking either a zoo / reservation of some sort and. / or a dna database for later cloning and repopulation.

Thanks also for the gentle spelling correction.

Hate you break it to you but we’re going to overshoot and probably not temporarily

Obvious to me. Why are there doubts? I hope for a non-political discussion.

because people have an overwhelming tendency to believe what the want to believe.

honest question, is it so bad if we go extinct? why bother going through all this effort and anxiety for someone we'll never even meet?

taking an honest look at my own life, I'm just a sophisticated robot that eats, poops and labors just so I can continue to eat, poop and labor yet another day...

I agree. The title should say "permanent damage to current species"

Plenty of animals, plants, and humans will die. And they will be replaced with different animals, plants, and humans.

Of course, in 70 years, even if we fix climate change, we will be dead anyway.

It would be nice if our kids didn't die of climate change. Or their kids

it's not like you're forced to make them...

As it appears, a whole lot of people prefer not to die.

but what about all this obsession about ensuring that there are still humans in say 200 years, when anyone who might exist is a complete stranger to us?

Because humans like other humans? humans want a legacy? humans want the species to persist and even excel? Not everyone is a nihilist.

and yet most humans continue pursuing a lifestyle that is simple not sustainable at an 8 billion people scale, and don't want to give it up. Doesn't sound like they care much about the consequences of their actions on others.

Haven't made the calculations, but I'm quite sure we could keep the current technological pillars of well-being (food, health, heating) without much issue to the environment if we gave up all the other superfluous crap (private cars, gadgets, plastics toys, 3d videogames, etc). And we'd probably be much less depressed too.

I agree there will probably be a mass die off of humans in the coming century as resources dry up and wars erupt over said resources (exacerbated by climate change) but it doesn't mean we have to give up

Because people care about their grandchildren/future family? I honestly can't understand this question. You can see it around you everywhere. Wealthy families even ensure that generations down the line will have some wealth. People give heaps of money to charity to help other people they will never know. People just care about other people even if they don't necessarily know them directly.

Yes. It'd be a waste of effort.

Feel free to disagree.

All these extrapolation attempts need to be taken with a grain of salt.

One thing we know:

* carbon and methane that we release en masse in the atmosphere causes the temperature to rise globally, it has been known for decades. It has a negative impact on the stability of climate and thus food/safety.

Things we don't know:

* exactly how big is the impact of temperature on the habitibility of earth.

* how many degrees of increase is needed to be a danger to mankind's existence? Or how many people (even give or take) will suffer or die?

* how fast will science find applicable solutions and what speed is necessary to keep the harmful effects limited?

So we can keep on repeating that we are not doing enough to mitigate, or even that it is already too late, but that speculating does not solve anything.

Bottom line, we should keep trying to keep temperature increase as low as possible, on multiple fronts: more efficient usage of resources, less inequality between poor and rich, investing in technology, persuade people not to waste resources, thinking about alternative types of economies,... Only future will tell if it were enough.