Dimming Sun's rays could ease climate impacts in Africa

[Jim__]

From phys.org

"It's not a pleasant thought, but we may have to decide whether it is riskier to reflect away sunlight, or risker to go over the 2C threshold."
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Dialling down the Sun's heat a notch by injecting billions of shiny sulphur dioxide particles into the stratosphere could curtail devastating drought across parts of Africa, new peer-reviewed research has reported.

This form of solar radiation management would slash the risk of another "Day Zero" drought in Cape Town, South Africa—a city of 3.7 million which ran out of water in 2017—by as much as 90 percent, according to a study published last week in Environmental Research Letters.

Global warming to date—just over one degree Celsius since the mid-19th century—enhances the likelihood of such droughts by a factor of three, earlier research has shown.

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[AllaN01Bear]

1. where i used to live , it has been manditory to paint roofs white to reflect sun for 20 30 years .

southern ca area .

[Phoenix61]

3. I'm in Florida and I've never understood why

anyone would choose to have a dark colored roof here.

[exboyfil]

4. Is that because of urban heat sink problem?

It does seem like using a teaspoon to empty a lake. Something that should be done but is not a solution to global warming.

[Bernardo de La Paz]

6. The heat absorbed by a dark roof radiates at night. Nights are warming faster than days

I don't know, but there may be a relationship.

[exboyfil]

2. I saw an estimate for a space based solar shield/collector

The numbers were not pretty given current costs to lift objects into orbit. Moving an asteroid of appropriate size and processing it into solar shielding is probably 100 years away given current progress on technology.

Screwing with our environment by injecting reflective particles in the atmosphere seems to also be very concerning.

[Phoenix61]

5. In 2006 NOVA aired a documentary called

Dimming the Sun. It discusses the impact reducing particulate air pollution without addressing green house gas emissions. Basically, the particulates had mitigated the impact of the green house gasses and when we got rid of them it allowed the full effect of the green house gases to be felt. It makes sense if you think about it. When there is a forest fire green house gases are released but so are particulates. There is a balancing effect. Mother Nature is so smart.

[Bernardo de La Paz]

7. Dark particles absorb heat. White particles reflect heat. Hence cooling after giant volcano eruption

The heat absorbed by dark particulates stays on the planet.

Heat reflected by white particulates has a fair chance to escape by radiation into space.

Volcanoes typically eject sulphate particles into the atmosphere which have a cooling effect on the planet.

[Phoenix61]

8. Interestingly it wasn't about the color of the particulates

as much as it was about how they impacted clouds.

[PoindexterOglethorpe]

9. Maybe we can hope for some massive volcanic eruptions.

Some of those have reduced world wide temperatures for several years.

[Boomer]

10. Some interesting counter arguments

I can't remember the source, but somewhere I read a critique of this proposed technique to block the sun.

As best I can remember, the caution was that this ploy should only be used if we had an aggressive plan already in place to reduce CO2, with the particles serving only as a temporary bridge until that reduction plan had reversed global warming.

Why? Because particle suspension is not a true fix; it's just masking the global warming that is taking place. Without some method of sequestration, the CO2 causing global warming will be with us for tens of thousands of years. Masking that climate forcing just keeps kicking the can down the road. We would be committed to continuing this high tech injection process for effectively forever, and there's no guarantee that an industrial human civilization would last long enough to support that long-term task. The minute we stopped the injection process, ripping off the mask, the full force of the escalated global warming would be revealed all at once. Instead of adapting along the way, we'd be plunged into a new hell.

There were other factors at play, too, but this was the one I remember most clearly.