cafeamericainmag.com
There has been a lot of CW discussion on climate change. This is an article written by someone that used to strongly believe in anthropogenic global warming and then looked at all the evidence before arriving at a different conclusion. The articles goes through what they did.
I thought a top-level submission would be more interesting as climate change is such a hot button topic and it would be good to have a top-level spot to discuss it for now. I have informed the author of this submission; they said they will drop by and engage with the comments here!
Jump in the discussion.
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Notes -
GHG has nothing to do with incoming shortwave; the only crop-relevant effect is temperature. I don't object to longwave geoengineering such as, y'know, air capture or olivine beaches; that's bounded to stuff we're fucking with anyway, as you say.
I object to shortwave geoengineering via aerosols and such, because there are other effects than temperature and some of those could have dire consequences. Almost everything in the Earth system comes back to sunlight in one way or another; you fuck with it at your peril.
We already are fucking with it, so does nature, volcanoes etc.. at least this would be on purpose and controlled.
The amount they're talking about doing, to cool Earth by over a degree, is more than any volcano in recorded history, and the eruptions that even came close caused worldwide famines (most notoriously, the Year Without a Summer). As such, I am not assuaged.
You heat it up by a degree, you cool it down by a degree. I don't see the problem here. We were doing it with bunker fuel on cargo ships for decades, some papers suggest it was keeping the temp down by quite a bit. We just switched over to cleaner fuels and now have the hottest years on record. Again, it doesn't happen all at once, we can fine tune as much as we want. It is literally like pumping water or adding sand, the amount of control is high.
As I've said, I agree with this logic when restricted to longwave. Removing greenhouse gas from the atmosphere with air-capture is indeed fine.
The problem is that reducing shortwave - i.e. blocking sunlight - doesn't just cool the planet. Sunlight is also needed for photosynthesis, which has massive indirect effects through the carbon cycle and, more directly, is how we grow food.
We can bound the harms of global warming pretty well. The harms of global dimming are much harder to bound, particularly at the unprecedented levels needed to do multiple degrees of cooling via dimming. You fuck with sunlight at your peril.
As I previously stated. We have already done this experiment with bunker fuel in tankers and the results are coming in as we stop.
There is a lot of debate over how much warming stopping the dirty fuel burning is going to/has caused because it is a bit difficult to tease out of the overall warming trends, but there is no doubt that it was having a cooling effect and that is now drawing to a close. Same with contrails. Stop global flights and you get warmer days. We don't have to block much sunlight to get great cooling effects, certainly not enough to dramatically effect plant growth. Again we are already doing this stuff, we should do it scientifically instead of by accident.
If your interested in one of the seminal papers on using stratospheric aerosol injection to quickly and cheaply rid us of global warming here it is. It would work. We could ramp it up as slow as we like and just see how it goes.
https://link.springer.com/content/pdf/10.1007/s10584-006-9101-y.pdf
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