Comment by Dumblydorr | Hacker News Reader

Comment by Dumblydorr | Hacker News Reader

Isn't it time to block the sun's radiant energy? What is the real disadvantage to trying to lift a giant solar umbrella that blocks light from hitting the Earth? It may be pricy but we spend billions per climate disaster, if we could use a few falcon heavy launches and reduce incoming energy by 1 or 2%, we could buy ourselves the time to fix our emissions and ramp up carbon capture.

The other alternative could be increasing cloud cover by releasing aerosols into the upper atmosphere. This would be like an artificial volcanic eruption, a purposeful but temporary hazing which would buy us a little time and let the planet cool off for 50 years before we're ready to go au natural again.

Can someone give me the critiques of these? They seem much simpler than crying about disasters and reports to GOP foot-draggers and all those who don't care about science. The sad reality is around 10,000 government and business officials have 90% of the power on climate, I don't see convincing all these power brokers to help the biosphere, they want profits not environmental restoration. So, let's have them block the sun's energy until we've transitioned our energy system.

Sure, I'll take a crack at the first one, involving 'a few' Falcon Heavy launches. Falcon Heavy can get (very roughly) 16 tonnes to L1. Ignoring critical station-keeping and rigidity issues entirely for the sake of simplicity, and assuming the sail is a single sheet of aluminized mylar at 10 g/m^2, that's 1.6 square kilometers of coverage. To put the planet in shadow would require about 100 million such shades.

More importantly, people who won't do anything about the problem now while it's getting worse will not do anything if we had a temporary fix in place. This should be obvious from human nature, if it's not obvious, you can observe those temporary fixes permanently installed as infrastructure and business operations all over. We don't need more time to think about it, we just need to get started.

How about the multitude of life on the planet that relies on photosynthesis?

And our own bodies? We get most of our vitamin D from a biosynthesis pathway that requires UVB exposure. Systematically depriving all of humanity of vitamin D could be disastrous.

And our circadian rhythms? The human circadian rhythm is mediated by two processes, denoted "S" and "C", of which C has evolved to rely on daily exposure to sunlight. The circadian rhythm affects almost all parts of our humanity.

Neither of these reduce greenhouse gas concentrations in the atmosphere and I'd be concerned that rather than being used as an extremely short-term fix while we reduce emissions they would just become a band-aid to continue business as usual.

The problem is that once we go down that path we'd have to do it permanently, and if we were ever unable to keep up the release of aerosols or the maintenance of the solar umbrella etc. then the temperature would rapidly soar to wherever it would have been in their absence.

It just seems incredibly high-risk and avoids actually solving the root problem. I saw such geo-engineering described as "a band-aid on a bullet wound" which seemed quite apt.

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