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Reducing sunlight to slow warming seems like the most desperate move with unintended consequences. The planet has evolved for billions of years with a constant

by piyh 4y ago

Reducing sunlight to slow warming seems like the most desperate move with unintended consequences. The planet has evolved for billions of years with a constant amount of sunlight. Greenhouse gas sequestering is the most direct reaction to a Greenhouse gas problem.

javajosh 4y ago
Indeed. The amount of photosynthesis going on is proportional to inbound sunlight. So you might be able to reduce the temperature of the planet in this way but you will also reduce the amount of photosynthesis happening.
- UncleOxidant 4y ago
  And with less photosynthesis happening, less CO2 is being absorbed from the atmosphere.
- Melatonic 4y ago
  Depends where you reduce it though. Theres not a ton of photosynthesis happening in the middle of the REALLY brutal deserts and reducing some sunlight would also reduce the heat and maybe increase plant life and photosynthesis. Thats assuming you can control it that granularly though.
  - guelo 4y ago
    A shield at Langrangian L1 can't be very selective, it would basically shade the whole planet.
- manmal 4y ago
  If the bubbles can be coated, then the filtered spectrum can be influenced. Eg if 20-300Thz is filtered out, then we only lose heat that’s probably not really useful to plants.
  - javajosh 4y ago
    Yes, this would be ideal (although I've rarely seen light measured like that - isn't wavelength almost always used?) If you could have a bandpass filter allowing in ~400-700nm light that would be kind of awesome - definitely a have-your-cake-and-eat-it-too moment. (of course with our luck there will be some process we need that we don't know about that requires the rest of the spectrum too)
- s1artibartfast 4y ago
  Is it? This assumes the the vast majority of plant growth is limited by sunlight, not nutrients, water, or anything else.
daenz 4y ago
Not to mention one of the risks that they mention seems pretty disastrous: >One of the most serious potential risks of solar geoengineering is termination shock. If we were to use solar geoengineering to suppress global temperatures, but we didn't do anything about CO2 emissions, and if for some reason you were to stop suddenly, all of the solar geoengineering, then those temperatures would suddenly spike back up. And that would mean that human and natural systems had less time to adapt to the new conditions. So if it works for awhile, and then for some reason stops working, we end up shocking every system on earth. I appreciate that the scientists are hammering "we need more research" but I don't think we are capable of identifying all of the catastrophic failure modes.
- TSiege 4y ago
  I think this argument really suffers from the fact that aerosols from the burning of fossil fuels is currently suppressing the full amount of warming we should be experiencing given the composition of the atmosphere. In other words, we're already masking some of the warming and as we move globally off coal we're going to see warming spike. Source: https://insideclimatenews.org/news/15092021/global-warming-james-hansen-aerosols https://insideclimatenews.org/news/15092021/global-warming-j...
  - ncmncm 4y ago
    False. Soot increases solar absorption. Cutting coal has multiple desirable effects.
  - daenz 4y ago
    It sounds like you're making an argument for slowly decreasing the aerosols from fossil fuels, so that we avoid the risk of termination shock, rather than an argument for adding more risk to termination shock by adding space bubbles.
    - TSiege 4y ago
      My point is that we will have to do some sort of solar management given the fact that we are currently doing it without even putting any thought into it. Arguably we are currently experiencing a "termination shock" given the move away from coal and other fossil fuels to clean energy. But honestly I don't even understand what "termination shock" really means. Does it matter if removing aerosols happens over the course of a decade or a century when the rise itself is the issue, not the speed of which it happens. 10 years or 100 years is too soon for any ecosystem or species.
ominous_prime 4y ago
Except it hasn't. Solar irradiance has steadily increased over billions of years, and fluctuates regularly with the solar cycle. I'm not saying that this couldn't have unexpected consequences, but you can't start from the premise that solar irradiance has always been constant.
- dkn 4y ago
  From the perspective of users of solar energy on Earth, wouldn't an increase over billions of years appear constant? My intuition tells me that evolution is much faster than that, and any fluctuations due to solar cycle dynamics would already be mitigated as expected by the same process, if it is indeed so regular.
  - ominous_prime 4y ago
    What I was getting as is that you can't start with a false claim to make a convincing argument. I didn't see what the expected reduction is from the MIT research, but if it falls within known effects of the solar cycle, Milankovitch cycles, and recorded volcanic activity it's less risky than stating that it's a change that the earth has never seen.
    - ncmncm 4y ago
      Even attempting it is disastrous, either way. The only winning move is to shut down every attempt at such distraction. We know what we must do. The only thing remaining is to do that.
      - lukeplato 4y ago
        Not my area of expertise, can you please share reasoning as to why reflecting sunlight is disastrous. also please share evidence that attempting multiple strategies is guaranteed to lead to failure or is even probabilistically worse than only relying on current trends of attempting to decrease co2 emissions
TSiege 4y ago
RE "constant amount of sunlight", this is actually untrue. The suns energy output is increasing roughly 10% per billion years. So it's actually never been stronger. It also means that we have much less habitable time on earth than we thought
- zaik 4y ago
  > 10% per billion years So it's about 0.000029% more since humans have evolved?
  - treeman79 4y ago
    Sea has risen 100 meters in last 20,000 year.
- function_seven 4y ago
  An annual sunlight increase of 0.00000001 % is close enough to "constant" to make no difference. And I didn't even bother with compounding, so the real number is even smaller. It's dwarfed by other solar cycles, and those are dwarfed by the near-doubling of CO2 in our atmosphere. I'm not automatically against geo-engineering approaches, but we do need to consider them desperate moves compared to the reduction of the GHGs
pastor_bob 4y ago
Solar luminosity goes up 1% every 100 million years roughly.
Zigurd 4y ago
Geoengineering in general is a high risk. But one aspect of this form of geoengineering, unlike pumping something into the atmosphere, is that it can be reversed quickly.
- rootusrootus 4y ago
  > unlike pumping something into the atmosphere, is that it can be reversed quickly Isn't that a fundamental claim made by those who support pumping sulfur dioxide into the upper atmosphere, however? That if you stop pumping, it quickly degrades and the atmosphere returns to baseline?
  - ncmncm 4y ago
    No, it means that temperature shoots up even faster than before. Meanwhile, the distraction from fixing the root cause brings disaster earlier.
    - AlgorithmicTime 4y ago
shagie 4y ago
We did do that experiment once before. We grounded the entire US air fleet following 9/11. https://globalnews.ca/news/2934513/empty-skies-after-911-set-the-stage-for-an-unlikely-climate-change-experiment/ https://globalnews.ca/news/2934513/empty-skies-after-911-set... https://www.wired.com/2002/05/hot-on-the-contrails-of-weather/ https://www.wired.com/2002/05/hot-on-the-contrails-of-weathe... https://edition.cnn.com/2002/TECH/science/08/07/contrails.climate/index.html https://edition.cnn.com/2002/TECH/science/08/07/contrails.cl... https://www.bbc.co.uk/sn/tvradio/programmes/horizon/dimming_trans.shtml https://www.bbc.co.uk/sn/tvradio/programmes/horizon/dimming_... > NARRATOR: For 15 years Travis had been researching an apparently obscure topic, whether the vapour trails left by aircraft were having a significant effect on the climate. In the aftermath of 9/11 the entire US fleet was grounded, and Travis finally had a chance to find out. > ... > DR DAVID TRAVIS: We found that the change in temperature range during those three days was just over one degrees C. And you have to realise that from a layman's perspective that doesn't sound like much, but from a climate perspective that is huge. > NARRATOR: One degree in just three days no one had ever seen such a big climatic change happen so fast. This was a new kind of climate change. Scientists call it Global Dimming. Two years ago most of them had never even heard of it, yet now they believe it may mean all their predictions about the future of our climate could be wrong. The trail that would lead to the discovery of Global Dimming began 40 years ago, in Israel with the work of a young English immigrant called Gerry Stanhill. A trained biologist, Gerry got a job helping to design irrigation schemes. His task was to measure how strongly the sun shone over Israel. The thing with contrails (and we can turn it up by running rich) is that we have seen that we can turn this on (and off) relatively fast (days). -- Further reading: https://en.wikipedia.org/wiki/Global_dimming https://en.wikipedia.org/wiki/Global_dimming
staticassertion 4y ago
One of the main claimed benefits is that this is easily reversible, if it goes badly.
- ncmncm 4y ago
  If it goes badly, reversing it makes it even worse. And going badly is guaranteed, because CO2 would continue on up, and the ocean ecosystem would collapse. There are quite dramatic fossil records of such events. But civilization would collapse first, so there is that.
shallichange 4y ago

by piyh 4y ago

javajosh 4y ago

Indeed. The amount of photosynthesis going on is proportional to inbound sunlight. So you might be able to reduce the temperature of the planet in this way but you will also reduce the amount of photosynthesis happening.

UncleOxidant 4y ago
And with less photosynthesis happening, less CO2 is being absorbed from the atmosphere.
Melatonic 4y ago
Depends where you reduce it though. Theres not a ton of photosynthesis happening in the middle of the REALLY brutal deserts and reducing some sunlight would also reduce the heat and maybe increase plant life and photosynthesis. Thats assuming you can control it that granularly though.
- guelo 4y ago
  A shield at Langrangian L1 can't be very selective, it would basically shade the whole planet.
manmal 4y ago
If the bubbles can be coated, then the filtered spectrum can be influenced. Eg if 20-300Thz is filtered out, then we only lose heat that’s probably not really useful to plants.
- javajosh 4y ago
  Yes, this would be ideal (although I've rarely seen light measured like that - isn't wavelength almost always used?) If you could have a bandpass filter allowing in ~400-700nm light that would be kind of awesome - definitely a have-your-cake-and-eat-it-too moment. (of course with our luck there will be some process we need that we don't know about that requires the rest of the spectrum too)
s1artibartfast 4y ago
Is it? This assumes the the vast majority of plant growth is limited by sunlight, not nutrients, water, or anything else.

daenz 4y ago

Not to mention one of the risks that they mention seems pretty disastrous: >One of the most serious potential risks of solar geoengineering is termination shock. If we were to use solar geoengineering to suppress global temperatures, but we didn't do anything about CO2 emissions, and if for some reason you were to stop suddenly, all of the solar geoengineering, then those temperatures would suddenly spike back up. And that would mean that human and natural systems had less time to adapt to the new conditions. So if it works for awhile, and then for some reason stops working, we end up shocking every system on earth. I appreciate that the scientists are hammering "we need more research" but I don't think we are capable of identifying all of the catastrophic failure modes.

TSiege 4y ago
I think this argument really suffers from the fact that aerosols from the burning of fossil fuels is currently suppressing the full amount of warming we should be experiencing given the composition of the atmosphere. In other words, we're already masking some of the warming and as we move globally off coal we're going to see warming spike. Source: https://insideclimatenews.org/news/15092021/global-warming-james-hansen-aerosols https://insideclimatenews.org/news/15092021/global-warming-j...
- ncmncm 4y ago
  False. Soot increases solar absorption. Cutting coal has multiple desirable effects.
- daenz 4y ago
  It sounds like you're making an argument for slowly decreasing the aerosols from fossil fuels, so that we avoid the risk of termination shock, rather than an argument for adding more risk to termination shock by adding space bubbles.
  - TSiege 4y ago
    My point is that we will have to do some sort of solar management given the fact that we are currently doing it without even putting any thought into it. Arguably we are currently experiencing a "termination shock" given the move away from coal and other fossil fuels to clean energy. But honestly I don't even understand what "termination shock" really means. Does it matter if removing aerosols happens over the course of a decade or a century when the rise itself is the issue, not the speed of which it happens. 10 years or 100 years is too soon for any ecosystem or species.

ominous_prime 4y ago

Except it hasn't. Solar irradiance has steadily increased over billions of years, and fluctuates regularly with the solar cycle. I'm not saying that this couldn't have unexpected consequences, but you can't start from the premise that solar irradiance has always been constant.

dkn 4y ago
From the perspective of users of solar energy on Earth, wouldn't an increase over billions of years appear constant? My intuition tells me that evolution is much faster than that, and any fluctuations due to solar cycle dynamics would already be mitigated as expected by the same process, if it is indeed so regular.
- ominous_prime 4y ago
  What I was getting as is that you can't start with a false claim to make a convincing argument. I didn't see what the expected reduction is from the MIT research, but if it falls within known effects of the solar cycle, Milankovitch cycles, and recorded volcanic activity it's less risky than stating that it's a change that the earth has never seen.
  - ncmncm 4y ago
    Even attempting it is disastrous, either way. The only winning move is to shut down every attempt at such distraction. We know what we must do. The only thing remaining is to do that.
    - lukeplato 4y ago
      Not my area of expertise, can you please share reasoning as to why reflecting sunlight is disastrous. also please share evidence that attempting multiple strategies is guaranteed to lead to failure or is even probabilistically worse than only relying on current trends of attempting to decrease co2 emissions

TSiege 4y ago

RE "constant amount of sunlight", this is actually untrue. The suns energy output is increasing roughly 10% per billion years. So it's actually never been stronger. It also means that we have much less habitable time on earth than we thought

zaik 4y ago
> 10% per billion years So it's about 0.000029% more since humans have evolved?
- treeman79 4y ago
  Sea has risen 100 meters in last 20,000 year.
function_seven 4y ago
An annual sunlight increase of 0.00000001 % is close enough to "constant" to make no difference. And I didn't even bother with compounding, so the real number is even smaller. It's dwarfed by other solar cycles, and those are dwarfed by the near-doubling of CO2 in our atmosphere. I'm not automatically against geo-engineering approaches, but we do need to consider them desperate moves compared to the reduction of the GHGs

pastor_bob 4y ago

Solar luminosity goes up 1% every 100 million years roughly.

Zigurd 4y ago

Geoengineering in general is a high risk. But one aspect of this form of geoengineering, unlike pumping something into the atmosphere, is that it can be reversed quickly.

rootusrootus 4y ago
> unlike pumping something into the atmosphere, is that it can be reversed quickly Isn't that a fundamental claim made by those who support pumping sulfur dioxide into the upper atmosphere, however? That if you stop pumping, it quickly degrades and the atmosphere returns to baseline?
- ncmncm 4y ago
  No, it means that temperature shoots up even faster than before. Meanwhile, the distraction from fixing the root cause brings disaster earlier.
  - AlgorithmicTime 4y ago

shagie 4y ago

We did do that experiment once before. We grounded the entire US air fleet following 9/11. https://globalnews.ca/news/2934513/empty-skies-after-911-set-the-stage-for-an-unlikely-climate-change-experiment/ https://globalnews.ca/news/2934513/empty-skies-after-911-set... https://www.wired.com/2002/05/hot-on-the-contrails-of-weather/ https://www.wired.com/2002/05/hot-on-the-contrails-of-weathe... https://edition.cnn.com/2002/TECH/science/08/07/contrails.climate/index.html https://edition.cnn.com/2002/TECH/science/08/07/contrails.cl... https://www.bbc.co.uk/sn/tvradio/programmes/horizon/dimming_trans.shtml https://www.bbc.co.uk/sn/tvradio/programmes/horizon/dimming_... > NARRATOR: For 15 years Travis had been researching an apparently obscure topic, whether the vapour trails left by aircraft were having a significant effect on the climate. In the aftermath of 9/11 the entire US fleet was grounded, and Travis finally had a chance to find out. > ... > DR DAVID TRAVIS: We found that the change in temperature range during those three days was just over one degrees C. And you have to realise that from a layman's perspective that doesn't sound like much, but from a climate perspective that is huge. > NARRATOR: One degree in just three days no one had ever seen such a big climatic change happen so fast. This was a new kind of climate change. Scientists call it Global Dimming. Two years ago most of them had never even heard of it, yet now they believe it may mean all their predictions about the future of our climate could be wrong. The trail that would lead to the discovery of Global Dimming began 40 years ago, in Israel with the work of a young English immigrant called Gerry Stanhill. A trained biologist, Gerry got a job helping to design irrigation schemes. His task was to measure how strongly the sun shone over Israel. The thing with contrails (and we can turn it up by running rich) is that we have seen that we can turn this on (and off) relatively fast (days). -- Further reading: https://en.wikipedia.org/wiki/Global_dimming https://en.wikipedia.org/wiki/Global_dimming

staticassertion 4y ago

One of the main claimed benefits is that this is easily reversible, if it goes badly.

ncmncm 4y ago
If it goes badly, reversing it makes it even worse. And going badly is guaranteed, because CO2 would continue on up, and the ocean ecosystem would collapse. There are quite dramatic fossil records of such events. But civilization would collapse first, so there is that.

shallichange 4y ago