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We Could Brighten Clouds to Cool the Earth

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Re: We Could Brighten Clouds to Cool the Earth

#41
post #19
post #12

Earlier quoted context omitted.

Taking care of all of the causes is not enough to fix the problem of climate change. If we hit net zero today, it would still continue to warm for decades, which means more deforestation and desertification through fires. Your proposal is far too conservative to avert disaster.

Source? I think we would avert disaster if we got net zero today. We wouldn't avoid change and things would continue to warm as you say. But it wouldn't be the end of civilization, just very inconvenient. In the other hand if we don't stop making the problem worse we will eventually activate feedback loops that can't be stopped and that do end civilization, kill the majority of humans and other species, and make huge…

Source is I am a meteorologist who has studied climatology. The residence time of GHGs ensure that we will have elevated levels for at least a century, even if we do all the nice things like plant trees. The terrestrial biosphere is too small, and not a long-term solution. Here in California, carbon-credit forests are going up in smoke.

We have already committed to levels that I consider catastrophic. Particularly in the oceans, where CO2 partitioning into the oceans is bleaching coral and the habitats they create. In the terrestrial habitats, desertification widespread and rapid.

The long-term solution offered to us by the Earth system is getting carbon below the carbonate compensation depth to be buried, or at least dissolved into the entire ocean, and not just surface waters. But the ocean overturning time is 500 years, and our timescale is somewhat shorter.

I think how you look at catastrophe solely from a perspective of civilization is wrong, but even from the perspective of a state, things like the drought that caused the famine that caused the civil war in Syria which caused a refugee crisis in Europe are troubling. Imagine how much worse it will be when a massive typhoon hits Bangladesh. But from a human perspective people are already suffering loss of income, home, and lifestyle from climate-exacerbated natural disasters. And the biosphere has been hit hard — adaptation will happen, but the mass extinction means we will lose ecosystem services that will be hard to replace.

Re: We Could Brighten Clouds to Cool the Earth

#42
post #11

Wouldn’t that reduce the available sunlight for photosynthesis? The problem is that we’re trapping more heat per photon. Reducing the amount of photosynthesis might reduce the carbon fixation by plants. Not sure if that’d be a good idea.

Photosynthesis is largely limited by water availability. Plants only uptake CO2 when they can open stomata, which is when they won’t dry out.

Most species experience fertilization effect from CO2 all the way to 1000+ PPM, some to 2000PPM. Higher CO2 concentration reduces the loss of water, since the stomata don't need to be open as long.

https://en.wikipedia.org/wiki/Stomatal_conductance

Re: We Could Brighten Clouds to Cool the Earth

#43
post #28

Earlier quoted context omitted.

The extra carbon in the air has already made plants more productive so there’s some offset already.

Invasive weeds and vines, mainly. Poison ivy, kudzu, and virginia creeper grow faster. Most plants cannot use all the carbon they already get. Instead, they get less able to compete as the weeds choke them.

Not true at all. Most plants can use additional carbon all the way to 1000+ PPM. Some all the way to 2000PPM.

Quotes below, sources below that: - CO2 increased leaf area, water use efficiency, and harvest index (in tomatoes) [1] - Optimal levels for tomatoes may be 2 to 5 times the normal atmospheric levels (1000 to 1500 ppm CO2 versus ambient levels of 350 ppm) [2] - Combining increases in CO2 with fertilization and irrigation could greatly enhance leaf area which when coupled to observed increases in net photosynthesis as a result of elevated CO2 could greatly increase productivity of loblolly pine trees. [3] - demonstrating an optimal CO2 concentration of 889.6, 909.4, and 894.2 ppm for aboveground, belowground, and total biomass, respectively, and 967.8 ppm for leaf photosynthesis (in winter wheat) [4]

[1] https://www.sciencedirect.com/science/article/abs/pii/S03783... [2] https://cals.arizona.edu/hydroponictomatoes/nutritio.htm [3] https://link.springer.com/article/10.1007/s004680050111 [4] https://pubmed.ncbi.nlm.nih.gov/26253981/

Re: We Could Brighten Clouds to Cool the Earth

#44

Earlier quoted context omitted.

The extra carbon in the air has already made plants more productive so there’s some offset already.

This seems plausible, but I'm curious if you have a citation?

https://www.nasa.gov/feature/goddard/2016/carbon-dioxide-fer...

Re: We Could Brighten Clouds to Cool the Earth

#45
post #28

Earlier quoted context omitted.

Invasive weeds and vines, mainly. Poison ivy, kudzu, and virginia creeper grow faster. Most plants cannot use all the carbon they already get. Instead, they get less able to compete as the weeds choke them.

Not true at all. Most plants can use additional carbon all the way to 1000+ PPM. Some all the way to 2000PPM. Quotes below, sources below that: - CO2 increased leaf area, water use efficiency, and harvest index (in tomatoes) [1] - Optimal levels for tomatoes may be 2 to 5 times the normal atmospheric levels (1000 to 1500 ppm CO2 versus ambient levels of 350 ppm) [2] - Combining increases in CO2 with fertilization and…

Elevated CO2 concentration favors plants with C3 pathway, because they appeared when CO2 ppm was much higher, than today. Plants with more recent C4 pathway (evolved around 25 million years ago), do not respond as much to CO2.

https://www.sciencedirect.com/science/article/pii/S197830191...

Re: We Could Brighten Clouds to Cool the Earth

#46

The most damaging hurricanes rely heavily on warm water over their last 2-3 days before landfall. Suppose we focused these bright cloud emitters on the water in front of a tropical storm, as a way to prevent it from strengthening into a hurricane? Imagine the city of Miami deciding that eliminating local hurricanes would benefit its local real estate market. They invest in a fleet of hurricane blockers to be deployed…

The Salter Sink is an interesting idea in hurricane prevention

http://large.stanford.edu/courses/2020/ph240/scott2/

Re: We Could Brighten Clouds to Cool the Earth

#47
post #40

I am counting on there being enough Starlink satellites to block out the Sun. Problem solved.

I know you're joking, but your comment inspires me to imagine a blanket of orbiting solar panels that simultaneously generate a lot of electricity, and also shade the Earth. One can dream!

Re: We Could Brighten Clouds to Cool the Earth

#48
post #2

I think I'm a relative optimist about global warming because there are a number of possible climate engineering interventions which seem fairly cheap and could plausibly buy us another decade or so. I can imagine a future where perhaps India or China decides to act on their own to this effect, risks be damned.

I'm not too worried about warming for the same reason. I am still worried about increased CO2 levels and their health effects. Either we figure out a carbon neutral energy solution(efficiency gains + mass solar and/or fusion) or I think we're screwed(), at least as far as our modern standard of living goes.

- Humans and the earth will survive in any case, just not in our current form.

Re: We Could Brighten Clouds to Cool the Earth

#49
post #40

I am counting on there being enough Starlink satellites to block out the Sun. Problem solved.

I know you're joking, but your comment inspires me to imagine a blanket of orbiting solar panels that simultaneously generate a lot of electricity, and also shade the Earth. One can dream!

You're going to want to put them closer to the sun.

Feasibility of cooling the Earth with a cloud of small spacecraft near the inner Lagrange point (L1) https://www.pnas.org/content/103/46/17184

https://en.m.wikipedia.org/wiki/Space_sunshade

Re: We Could Brighten Clouds to Cool the Earth

#50
post #33

Earlier quoted context omitted.

The IPCC special report on limiting warming to 1.5C is probably the best summary of ways to avoid catastrophe: https://www.ipcc.ch/sr15/ In particular, the figures in chapter 2 are particularly informative. We are going to need to start sequestering carbon in the later part of this century, with as of yet unknown methods, but it's doable. I would caution that climate scientists have been generally too conservative in…

1.5 isn't going to happen. I'll be happy if we manage to keep it under 3. There's no guarantee that doesn't trigger a total disaster, but it's possible it would also just be extremely costly, damaging, and inconvenient. At some level it would be a complete and utter disaster and it's not clear where that is. I think if we could magically reach net zero tomorrow, we'd be mostly fine. Obviously instead we will continue…

> Obviously instead we will continue driving full speed towards the edge of the cliff,

As of now, we're still increasing our speed. Global CO2 emissions go up every year.

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