Could a bubble shield at L1 combat global warming?

[swampwiz]

https://bgr.com/science/mit-scientists-think-theyve-discovered-how-to-fully-reverse-climate-change/

 

[Orodruin]

If you read the homepage of the MIT group, it is a bit less sensational than the article you linked - labelling it an ”emergency solution if things have gone too far”.

In general, blocking out sunlight seems counter productive as sunlight is ultimately the source of renewable energy, directly in the case of solar power and indirectly in the case of driving winds and waves. Blocking the Sun would therefore seem to increase reliance on other sources such as fossil fuels. The exception here being fission or fusion power if the fuel can be extracted in an environmentally friendly and efficient way.

 

[Baluncore]

We need the phytoplankton in the Southern Ocean to convert excess CO₂ into biomass and O₂. Blocking sunlight would be counterproductive to recovery, as would harvesting the krill that eat the phytoplankton, or killing the whales that eat the krill.

Whales recycle the limited iron to fertilise the next generation of phytoplankton, and so the wheel turns, powered by sunlight. We need the iron cycle in the Southern Ocean to become a runaway success.

 

[Bandersnatch]

It's not about completely blocking off the sunlight. I'm not sure why the responses above seem to assume so.
You reduce insolation by a small percentage, and that's enough to both cool the planet and keep the sunlight-dependent processes going - albeit at a somewhat slower rate/efficiency than otherwise. But it's talking about a couple percent reduction in insolation. For most purposes other than global temperature balance nothing would change.
It (solar shade) is also not a new idea, other than in details of engineering and placement.

 

[Orodruin]

It's not about completely blocking off the sunlight. I'm not sure why the responses above seem to assume so.

I don’t think either of us assumed that. You seem to be making assumptions.

 

[russ_watters]

In general, blocking out sunlight seems counter productive as sunlight is ultimately the source of renewable energy, directly in the case of solar power and indirectly in the case of driving winds and waves. Blocking the Sun would therefore seem to increase reliance on other sources such as fossil fuels.

I don’t think either of us assumed that. You seem to be making assumptions.

I think the percentage matters here, and the take doesn't necessarily work. How much would insolation need to be reduced in order to stop the temperature rise? 1%? That would have little impact on fossil fuel production and no adverse feedback.

 

[Orodruin]

How much would insolation need to be reduced in order to stop the temperature rise? 1%?

The project homepage mentioned 1.8% iirc.

 

[sophiecentaur]

It's not about completely blocking off the sunlight. I'm not sure why the responses above seem to assume so.

Even if the sunshade is partial, the effect on the environment in places where it's needed would still be pro-rata.
You'd have to accept that the "bubble" would cost an awful lot in resources so why not target the shading to places around the Earth where less sunlight would only be of benefit? Selective (and adjustable) reflective screening could reduce local heating in desert areas. I have suggested, several times, that whitewashing roofs, rocks and bare mountains would have only good effects. Apart from "the cost", there have been no significant objections. But that cost would be a tiny fraction of the Boris Johnson level project of a shade in space. Also, we have the technology here and now for my proposed project.

 

[Ibix]

Selective (and adjustable) reflective screening could reduce local heating in desert areas.

I've been giving some thought to painting my roof white at the moment...

 

[sophiecentaur]

I've been giving some thought to painting my roof white at the moment...

The advantage is that you, personally will benefit most. That sort of thing has universal appeal.

 

[Bandersnatch]

Well, how many square metres of roofing and/or rocks would need to be painted (and regularly repainted) white to have the same effect as the solar shade?

 

[sophiecentaur]

And what would the solar shade cost to put up there? How big would the shade need to be, bearing in mind that it would not remain exactly on L1? All that space engineering would pay for a lot of ‘paint’.
By the time humans could engineer the shield, I reckon they would have solved climate change.

 

[Baluncore]

This white paint lark looks to me like it might be a bit counterintuitive.

Vegetation, crops or forest, increase the cloud, and to some extent increase rainfall. In Western Australia, the rabbit-proof fence marks the boundary between farmland and desert. Clouds tend to evaporate as they cross the fence line and move over the desert. Vegetation keeps the soil cool, which makes for more available water, and more ground cover.

Painting the town or desert white would tend to reduce clouds, so you would need to paint a greater area to compensate. Maybe if drought tolerant trees and shrubs were planted, we would be rewarded with clouds, and so not need all that paint.

 

[sophiecentaur]

So where will those clouds come from?
I suggested covering absorbent surfaces and nothing green. The ice caps are reducing in area so how else to get the net reflection back up.
It’s true that anything major could cause unintended other effects. White paint (or equivalent) would cause minimal disruption.

Of course, the obvious carbon zero behavior with much reduced consumption would not appeal enough to be tried by modern society.

 

[OscarCP]

I recommend, as a compendium of possible solutions to global warming, some more peaceful and, or realistic than others, the latest novel by Kim Stanley Robinson "The Ministry for the Future", the name of an imaginary UN organization set up to collect private groups, governments and UN proposals and test some of them to see if they are workable. Its creation and funding of several tens of billions of dollars is prompted by a disastrous heat wave in India that killed twenty million people.

No solar parasol in outer space is mentioned in this novel.

If we are discussing what might be unlikely solutions, there is the old one of putting large solar power collectors in orbit (I imagine also one could be on top of the sun-facing part of the parasol), this power to be beamed to Earth-side stations as radiowaves -- another idea that has been received with much the same skeptical criticism as the one of the parasol.

 

[swampwiz]

I've been giving some thought to painting my roof white at the moment...

I had looked into this when I was getting a house built; the builder told me that in the heat & humidity of the Gulf Coast, the light roof would quickly become mildewed. In today's era of spray-foam insulation (far better than "cotton candy" insulation), I don't think it matters much.

 

[Vanadium 50]

I'm trying to imagine the liability issues the first time there's a blizzard. Especially if a school bus crashes on the ice. Think of the children!

 

[sophiecentaur]

In today's era of spray-foam insulation

Not without problems there. But a system with suitable ventilation would be best of both worlds. Relying on a hot roof to control condensation is a bad design approach.

 

[sophiecentaur]

Clouds tend to evaporate as they cross the fence line and move over the desert.

I'm not sure what you are getting at. Evidence from the rabbit proof fence is only partial - not the PF way. There is more to it than just plants = clouds so no plants = no clouds. Transpiration of plants lowers the ground temperature. Reducing incoming level of solar energy would reduce equilibrium temperature of the ground. I am not suggesting painting green areas; it's the rocks, roads and roofs that I have in mind. Reflecting a percentage of the direct solar radiation will reduce mean surface temperature without reducing photosynthesis where it's needed.

I know the 'space based' solution appeals to people but this bubble could be a seriously blunt instrument which could cause totally unexpected changes to the environment. Until someone can cost the project it's a total unknown. Furthermore, if the bubble were to be built to withstand general wear and tear, it could be very hard to get rid of or modify in the not impossible situation where it's found to do more harm than good. to be honest, we have not proved to be good about climate management to date.

(Makes me laugh when they talk about terraforming Mars when they have pretty much failed down here)