I've thought about doing a kickstarter to charter a boat to try this (kind of a Bizzaro world version of the Rainbow Warrior.) but was told by some experts (took their class) not to do this.
The #1 concern is that this is borrowing from Peter to pay Paul, that is you end up depleting nutrients other than iron so that there is less production somewhere else.
A #2 issue is that it's not as simple as it sounds, you can't just dump iron off the size of a barge and expect it to work, you really need to be monitoring the process and need a whole flotilla to do that.
I agree and I think adding to #2 is that the surface area would have to be at least as large as the polar ice caps. Their melting will have a significant impact on reflected light/heat so adding tiny patches here and there would be a minuscule spec in the bucket, I think.
Another issue I think would be putting this reflector anywhere other than where the polar ice caps exist could potentially change current temperatures and further mess up the global climate long term. Unintended consequences.
The main point of iron fertilization is to make plankton and other organisms grow in the ocean so that some will sink to the bottom and capture carbon that way, not so much promote reflection. Seeding the atmosphere with sulfur is one approach to that, cloud brightening another.
One unintended consequence of iron fertilization could be the promotion of growth of toxic plankton that add neurotoxins to the food chain (e.g. “Red Tide”) but that’s not the only one.
Another interesting aspect of this is that the UN Law of Sea forbids this. Most countries with a coastline are signatories with the notable exception of the US:
Correct choice of site can eliminate the danger of creating toxic blooms. I bet you can do small experiments “under the radar” but in larger efforts you’ll have trouble leaving port. Ask George Russell about that last one.
The effects can be observed from satellite images which one hand gives a "hands off" way to know it worked or didn't work without extra effort on your part but it also means everyone else will know you (or at least somebody) did it.
What a coincidence that in the CarbonDioxideRemoval google group I opened that can of worms just the day before that guest essay opened it in "The Newspaper of Record".
Every time this has been brought up since the 1990s, it has driven scientists over the edge. As I pointed out to the CDR group, this is just one more case where the Algorithmic Information Criterion is ignored as a resolution to scientific controversies (rendered intractable more because of their very importance than the lack of data).
The #1 concern is that this is borrowing from Peter to pay Paul, that is you end up depleting nutrients other than iron so that there is less production somewhere else.
A #2 issue is that it's not as simple as it sounds, you can't just dump iron off the size of a barge and expect it to work, you really need to be monitoring the process and need a whole flotilla to do that.