Comment by exoverito | Hacker News Reader

Comment by exoverito | Hacker News Reader

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There will always billions in losses from something, especially when global wealth is estimated to be around 450 trillion. The Dust Bowl was a disastrous incident of climate change, yet it didn't occur because of CO2. The damage caused by the California Wildfires are just as much a function of expanding developments into forests, immediately putting out small fires leading to the accumulation of fuel over time, and opposition to controlled burns. Property damage and deaths from flooding are mostly a function of population growth in the developing world, without sufficient corresponding investment in water management infrastructure.

Regarding the solution, stratospheric aerosol injection would be the most immediate and effective solution to rising temperatures. It's been estimated that current increases in CO2 have a radiative forcing effect of about 2 watts per square meter, compared to the total solar irradiance of 1361 W/m2. If CO2 levels doubled to 800 ppm then it's estimated this would have a radiative forcing effect of 6 W/m2. This scenario would require mitigation strategies like stratospheric aerosol injection to reduce solar irradiance by about 0.4%. In the context of plant growth this reduction in sunlight would be negligible given that photosynthesis is only 1 to 2% efficient. If anything we should see significantly accelerated plant growth by about 10 to 50% due to the CO2 fertilization effect at 800ppm.

I'd be curious to see the science on enhanced plant growth; my understanding is that the benefits of increased CO2 fade very quickly. I believe we can already see plant pores evolving to be smaller as they were in previous times when the Earth had greater CO2 levels.

About the only thing that gives me hope is SRM, but it's a half-assed solution at best. A world with 800ppm CO2 and a dimmed sun via aerosols is not the Earth that I was born to; it is probably not possible to fully understand the affects.

The optimal CO2 level for plant growth is between 800 and 1000 ppm, as observed within greenhouses.

https://www.frontiersin.org/journals/plant-science/articles/...

There is no perfect solution. One of the benefits of stratospheric aerosols is that they only stay suspended for 10 years or so, reducing the risk of long term effects. They are also an exceptionally cheap strategy, on the order of a few billion a year to cool the entire Earth. Compare that with the many trillions needed to just get to carbon neutral, while significantly reducing economic growth and living standards.

The world we were born into will not exist in any scenario. As they saying goes, you never step in the same river twice. CO2 emissions show no sign of decreasing, especially as China, India and Africa continue developing. Furthermore, we are on the cusp of AGI within the next decade or so, which will radically change reality far more than the Earth possibly getting a bit warmer in a 100 years or so. The IPCC does not even predict major cataclysm, and expects only sea level rise of a couple feet in the worst case scenario.

> they only stay suspended for 10 years or so

And then what happens? Earnest question.

Back to the ground in rainfall I guess.

Yeah that's kind of what I was getting at: the implications of all these aerosols falling to earth later, and getting into everything.

Calcium carbonate aerosols are proposed as a good alternative to sulfur dioxide since they are basic and do not react with ozone. Calcium carbonate is used an additive to soils to reduce acidity and is used by organisms to construct bone tissues. Furthermore, these aerosols would be extremely diffuse. It's estimated that we'd need 5 million tons of sulfur dioxide per year to reduce temperatures by 1 degree centrigrade. Assuming we need 10 million tons of calcium carbonate that eventually descends to the Earth, that would come out to be 0.0196g per square meter. Effectively negligible, and may even be beneficial for areas that have slightly acidic rains.

And then we have to do it again, and again, and again; once you grab that tiger's tail, there is no letting go. In the meantime, sense of urgency abated, we would most likely keep on burning fossil fuels and putting more CO2 into the atmosphere, locking ourselves further into the loop.

It is a terrible idea which will almost certainly happen.

Entropy is inexorable and must always be resisted. Humans need to drink water and eat food, again, and again, and again. Unimaginable amounts of time, effort, and resources are spent every day maintaining civilization. If we build out solar panels, we will have to replace them in 20 years. There is no free lunch.

We don't know how bad the climate will be at 800 ppm. 300 millions years ago, during the Carboniferous era, there were vast forests and very high CO2 levels, around 1000 to 5000 ppm. If the Earth gets too hot we will simply do stratospheric aerosol injection. If climate change turns out to be overhyped, then we get the CO2 fertilization boost for free, win-win.

Regardless, the real solution is next level energy production from advanced fission, deep geothermal, and ultimately fusion power. With a vast surplus of energy we could do wildly impractical things like filter sea water for gold, and of course extract extremely diffuse gases from the atmosphere. Renewable energies are very low energy density, and more akin to farming from a physics perspective. They make sense in certain situations, but are not reliable for powering an advanced industrial civilization.

I also suspect people's intuitions are out of perspective in terms of time scales. It seems likely AGI will arise within the next 20 years. Climate change is nothing compared to the singularity and rise of superintelligence.

Seems plausible at least, and you are of course correct about the world; the CO2 level of the atmosphere when I was born was well below 400 and we'll not see that again as long as I live. That's what I tell those who respond viscerally to the idea of messing about with the atmosphere purposefully - we are already altering it regardless.

I mean, we can try to un-alter it rather than altering it further and hoping it will cancel out.

> If anything we should see significantly accelerated plant growth by about 10 to 50%

If that’s true, there should be global evidence of this happening already- are you aware of any publications confirming this effect?

You say accelerated growth like it’d be a good thing, but I don’t think we should wish for it or expect that to mitigate any damage… getting to the point of doubled CO2 would probably be extremely bad. If CO2 levels doubled, we’d for sure lose significant amount of our ice sheets, and some coastal cities along with it. Some of that is already happening anyway, but tripling the radiative effect will make it go much faster and much farther. As it stands, any increase in plant growth isn’t in any way making up for the rate we’re cutting down and paving over all the plants, and it’s not clear that 10 to 50% accelerated plant growth would make up for it either… even assuming that accelerated plant growth actually leads to more plants and a greater volume of oxygen cycle, and not just earlier blooms.

https://en.wikipedia.org/wiki/Deforestation#Rates_of_defores...

https://www.antarcticglaciers.org/glaciers-and-climate/what-...

> there should be global evidence of this happening already

There is. https://www.nasa.gov/technology/carbon-dioxide-fertilization... for instance.

"From a quarter to half of Earth’s vegetated lands has shown significant greening over the last 35 years largely due to rising levels of atmospheric carbon dioxide, according to a new study published in the journal Nature Climate Change on April 25."

Interesting observation: Trillions of dollars have been spent to date on emission reduction with many incurring a consequent lowering of quality of life. Some would say this is inevitable but better to survive than the alternative. To date (as far as I can tell) there has been no discernible reduction in the rate of increase in CO2 as measured at Mauna Loa station. When will this paramount metric relate to measures taken? Any guesses?

From your article:

"The beneficial impacts of carbon dioxide on plants may also be limited, said co-author Dr. Philippe Ciais, associate director of the Laboratory of Climate and Environmental Sciences, Gif-suv-Yvette, France. “Studies have shown that plants acclimatize, or adjust, to rising carbon dioxide concentration and the fertilization effect diminishes over time."

The beneficial effects of increased CO2 will also be more than counteracted by other problems as the world temperature rises, such as greater heat stress and lower soil moisture.

> Trillions of dollars have been spent to date on emission reduction with many incurring a consequent lowering of quality of life

It's cheaper to avoid the warming in the first place rather than deal with the consequences, so complaining about the cost is a false economy.

> To date (as far as I can tell) there has been no discernible reduction in the rate of increase in CO2 as measured at Mauna Loa station

It's possible that we've reached peak CO2 emissions:

https://ourworldindata.org/grapher/annual-co2-emissions-per-...

...however we need to cut them significantly.

Are you suggesting that trying to reduce CO2 isn’t worth it? What alternative are you proposing? What lowering of quality of life are you referring to? How do you know what Mauna Loa would have measured without the efforts to date? And what is the expected delay between CO2 reduction and effect?

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