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Comment by GekkePrutser | Hacker News Reader

Hmm... I think we should approach such things very carefully. Doing this at a scale where it actually affects global warming at a meaningful level, we'd have to spray a lot of particles in the air that might hurt us in other ways. Absorption by insects and polluting the food chain, causing local climate effects by remote areas being covered in these etc.

Our ecosystem is very complex and I worry about things being viewed as a "quick fix" possibly digging a deeper hole for us.

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This seems to be the common sentiment, we don't really have an appetite for geo engineering yet. I think it'll take many more climate related catastrophes before we start to accept that engineering our way out of this problem is necessary.

It's not necessary. We can pass robust carbon pricing legislation, convert our grid to clean energy. If the richest countries in the world go this route, the others will be forced to follow (border adjustments will make it impossible for polluters to compete for that rich country $$$). However politically difficult this might seem, it's going to be a lot easier than geo-engineering the entire planet's atmosphere.

CO2 levels already exceed 400ppm. It is too late to adopt 0 emmisions as the entite strategy. We need to either:

A) go carbon negative B) other geo engineering C) adapt to the new climate

By itself, option C is baked in to be a generation defining disaster; so we really want some help from options A and B

> It is too late to adopt 0 emmisions as the entite strategy.

What does "too late" mean here? Certainly it's too late to recover species which have already gone extinct, and it would be too late to avoid some increase in drought, wild fires, floods, etc that we're already seeing, but there's a pretty big delta between the climate that we'll leave our grandchildren if we zero our emissions by 2050 versus the climate we'll leave our grandchildren if we continue polluting.

As for (A), I'm sure we're all ears.

Too late as in we have already started implementing (C).

> but there's a pretty big delta between the climate that we'll leave our grandchildren if we zero our emissions by 2050 versus the climate we'll leave our grandchildren if we continue polluting.

That is not the distinction being discussed. What is being discussed is net-zero vs net-zero plus active countermeasures.

> As for (A), I'm sure we're all ears.

Several ideas are being researched, but at the moment I have not seen any that inspire confidence to become fully viable. Combined with the hardship associated with (C), this is why (B) seems necessary.

Well, I wasn't saying we shouldn't do it. I just mean we should be really careful going about it.

We don't exactly have a great history of messing with ecosystems. Like bringing rabbits to Australia :)

It took us decades to acknowledge global warming while the signs were all there and even now some countries and industry groups are still trying to undermine efforts. Can we really be trusted to do something like this and honestly evaluate the effects?

With marine cloud brightening, which is what this article is about, they spray seawater into the air. They spray it over the ocean. It falls back down pretty quickly, since it's just water, and it doesn't genetically modify anything, because it's just water.

I imagine there would be an extremely large energy cost to spraying such boatloads of water in the air.

Wind and solar power both work well in oceans. You could spray water near wind farms during off peak hours, for example.

Solar might not work well if you're generating clouds.

>You could spray water near wind farms during off peak hours

I think underestimate the carbon cost of this infrastructure and the amount of energy needed to send this water into the air. Chances are it's not going to be doing a whole lot and pales in comparison to the amount of water evaporating and going up due to global warming.

We don’t know what the second and third order effects would be. We can’t even correctly predict what the weather will be 3 days in advance. No chance that we can predict what the consequences of such a significant and never been done change would be.

Seems like a high risk play, only to use as a last resort to me.

I agree, though it seems reasonable to trial it at a small scale as soon as possible so we can gradually scale it up and understand these second and third order effects with minimal risk.

Agree, it’s the only way for us to test our assumptions.

I wonder how well the experimentation approach will work in this case though, as:

1. Effects might be subtle and outside of the expected impact area.

2. Timescale might be really important (effects over a time much longer than we anticipate. Or even a timescale that makes it impossible to run many experiments in reasonable time)

I think this is a general argument that you can make about any risky enterprise (e.g., GMOs, vaccines, etc). There's always the possibility that your testing is inadequate, you can never drive risk to 0, etc. But by starting small and scaling up very gradually (while studying carefully the whole time) you maximize the risk that you will find and mitigate problems early and "cheaply" (i.e., without committing to applying the technique to the entire world).

Anyway, the idea is to have an ace in the hole in case we run out of other options to reduce climate change--at that point, the question is "which is less risky, geo-engineering or runaway climate change?".

As these things go, it's the lowest risk play I'm aware of. You can use it in a fairly specific area, like for example over a melting ice sheet. If you stop actively using it, the droplets precipitate out after a week or two, and everything goes back to the way it was. The biggest drawback, in fact, is that it is not permanent.

Dropping salt on a melting ice sheet does not sound like a great plan.

We'd really need to invest in really detailed computer models to make sure we're not overlooking something and shooting ourselves in the foot, IMO.

Well, if civilization was destroyed by spraying a fine mist of sea water into the air from the back of a boat, I guess I would feel pretty bad. But, that seems highly unlikely, and certainly less likely than that we'll destroy ourselves by continuing to do absolutely nothing to stop the climate from collapsing.

Marine cloud brightening is one of the more reasonable geoengineering approaches because the effect is rather localized and temporary. If the spraying is not sustained, the cloud cover goes away again and that within weeks.

The particles that serve as nuclei for condensation themselves are actually seasalt. It works like this: there are tiny droplets created by spraying seawater into the air. The water then evaporates, leaving salt particles as nuclei for droplet formation again. The salt content of the proposed measures would increase the naturally occuring levels by just 5-10% from what I know.

Do we know that the salt won't leave the sea? I know sand from African deserts can blow all the way across the Atlantic to the Amazon; is there any similar concern to salt building up to toxic levels in other ecosystems?

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