Comment by Retric | Hacker News Reader

Comment by Retric | Hacker News Reader

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That’s probably a significantly more difficult problem than stopping pollution as you actually need someone to pay for it directly. And of course we don’t know a good way to only try and cool the Arctic.

<Massive simplifications ahead> You can ballpark this yourself a 288 K black body in equilibrium is radiating as much energy as it receives, at T^4. To drop that by 1C to 287K means blocking 1- ( 287^4 /288^4) or roughly 1.4% of all sunlight. As the earth’s radius 6,371 km ignoring the atmosphere, the classic sunshade at L1 idea needs a surface area of something like 1.7 million km^2. And that’s assuming we didn’t keep dumping any CO2 into the air and ignore the fact the earth isn’t in equilibrium it’s warming etc etc.

A few ideas for getting various things into the upper atmosphere have been considered but reflecting an extra 1.4% or more sunlight would be a true ly Herculean task with any of those ideas and you couldn’t stop as they all decay over time.

Why does every solar geoengineering project seem to pretend that decreasing solar radiation wouldn't impact photosynthesis which also binds CO2, and, uh, supports the entire food web / our civilization?

We already are massively stressing the biosphere: mass extinctions, mass destruction of habitat, mass disruption of migration patterns, warming, plastic pollution, invasive species.

And the suggestion is to reduce incoming photosynthetic energy by percentage points????????

I get that photosynthesis happens in a narrow band of frequencies compared to other solar radiation that would be absorbed then emitted back/trapped as IR radiation... but still, geoengineering should focus on methods that explicitly track the bound/removed CO2.

Note I do not for a second believe that schemes for sequestration by pumping CO2 deep underground won't have huge amounts of ignored/undetected leakage, especially since it is a petroleum industry scheme that already pretends massive methane leaks aren't occurring far more than is accounted for in current petrol extraction.

Photosynthesis is more limited by water than sunlight in many areas. So it may make sense to cool some subtropical areas.

At least they try to solve issues with science/engineering instead of just giving up and throwing hands in air about climate change issues.

Solar engineering is interesting because we've already observed it, for periods of a year or two after major volcanic eruptions. Those have put enough sulfur dioxide in the stratosphere to block about one percent of sunlight, and disaster did not ensue.

Since the sulfur dioxide goes away after a year or two, if it does start to cause a problem then you can simply stop emitting it. However, if you absolutely want to avoid potential impact on crops, another proposed method is to use a fleet of wind-driven ships, seeding low-lying clouds over the oceans.

As for storing CO2 underground, there is one method that might work: pumping it into basalt formations, where it turns into rock in about a year. There are several pilot projects doing this.

"want to avoid potential impact on crops"

I'm not trying to demonize you pointing this out, but the semantics of this is interesting and typical of modern engineering, and it is in the same blind spot that economics has...

No I'm not interested in crops as all. I don't care about farm yields, profitability, market fluctuations, food supply or all.

I am concerned about the stability and long term survival of the biosphere. Yes, so that we don't go extinct, but more that that, so that we aren't living in domes in a no longer life supporting planet.

Of course, engineering (and economics) are disciplines that can only work on the basis of things they can measure. Your statement basically refers to something that is measurable: crops and crop yields.

But do we have economic or engineering measurements of the health of local and global biomes, beyond "wow they are a lot worse than they used to be"? Do we have any way of saying "this engineering project or economic policy will result in this degradation to the almost infinitely complex natures of habitats and biomes? We do not. We don't even really have good approximations.

What is disturbing is that the approximations we DO have, like species extinctions, population declines in top species, qualitative observations of ecosystems, go functionally and absolutely ignored in policy, and by economics. Engineering, which produces the only hopes of technological solutions to our problems, still is riddled with the "make it work, don't worry that much about side effects" (well, since that's all the management and budget economics allow).

I harp on engineers in this case because in my experience they are strangely conservative and republican, and by extension, anti-environment. I believe this is because every large engineering project has this stage:

"The environmental impact review"

Which is a huge blob of uncertainty, and engineers hate uncertainty. And therefore, by human nature, they hate the thing the uncertainty surrounds. And so they hate environmental reviews, and they hate the environment.

This really really really needs to change.

I completely agree that we need to protect the whole biosphere, so please s/crops/biosphere, that was my bad.

At this point, sadly, geoengineering may be a necessary part of protecting it. We're on the verge of positive feedbacks that could take things out of our hands, as the planet starts emitting vast amounts of greenhouse gases with no more help from us. If all we do is stop emissions, there's a good chance that we'll cross that tipping point before we're done. It's possible that we've already crossed it.

And I want to emphasize I wasn't trying to shit on you in particular. You gave great insight in your comment.

How long does it take for the carbon to affix? This I imagine is like the olivine scheme?

From the articles I've seen, about a year, maybe two. Similar chemistry to olivine I think, but the idea is to use more concentrated CO2 from DAC or fossil exhaust, and pump to basalt formations deep underground. The olivine schemes I've seen use it as beach sand, absorbing CO2 from air in a weathering process.

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