[gault8121]

The article fails to mention a really important idea - Sulfur Dioxide is not the only aerosol that can be injected, and there are other options that seem much more promising. For example, using Calcium Carbonate may actually help restore the Ozone layer while also reducing the temperature.

> Source: https://news.harvard.edu/gazette/story/2019/09/harvard-group...

> "The chemists think the solution could be calcium carbonate — the stuff of chalk, limestone, marble, and seashells. It may be less harmful to the ozone, and it’s not a big health concern. The team is studying how the substance affects chlorine and nitrogen oxides, which also exist in the stratosphere — largely due to man-made emissions — and speed ozone destruction. The researchers think the calcium carbonate might help to lower levels of these gases."

[mountaintimefrm]

Too much calcium carbonate is really detrimental to a wide variety of plants, it causes a condition called iron chlorosis. Basically plants will readily absorb calcium instead of iron (they need iron to do their chemistry for photosynthesis), the result of which is yellowing leaves, poor production, plant death, etc. Spraying massive amounts of calcium carbonate in the atmosphere, if it makes it down to the plants on the ground, sounds like a great way to cause massive forest die offs. Much like sulfur creates acid rain, calcium in the atmosphere would create "basic rain" which is just as much of a problem if you're a plant that requires a fairly narrow range of soil pH.

[gault8121]

So I am having trouble finding this source now, but I have perviously read from the main team researching Calcium Carbonate, SCoPEx (https://scopexac.com/), that the intention is to spray the calcium carbonate high enough in the atmosphere so that it does not float down to the ground but rather dissipates into space. There is a specific height in the atmosphere where it needs to be released, and yes, if it fell to earth, this wouldn't be a viable solution. I can't find where I read this, but this is one component of the current hypothesis.

[mountaintimefrm]

Interesting, I will look into that.

[kortex]

I love this idea. I would wager that calcium carbonate dust has a higher ballistic coefficient than SOx (ratio of mass to cross section, a measure of ability to stay aloft), meaning if we overdo it (unlikely but the most common concern), the decay rate would be faster.

Plus would also mitigate acid rain somewhat, and isn't noxious the way SOx is.

[gault8121]

Yes, exactly - it's an interesting idea worth researching. Thanks for adding this idea!