[ulrashida]

Sea floor mining is widely ridiculed by both environmental and mining professionals as having more risk than equivalent and better understood efforts on land. At least its close cousin, space mining, has the benefit of taking place off planet. I hope we never see this activity occur commercially in our lifetimes: we barely have gotten a handle on surface and underground mining, why do we run off to scrape the ocean as well?

On 1: The study you have referenced refers to the difficulties of remediating historical abandoned sites, often run under inadequate regulations typically in the 1850's - 1960's. Modern sites are no joke to remediate, but regulators are beginning to pick up on what causes problems to occur and how to ensure these costs are factored into the mining operation. The difficulty of applying effective regulations to international undersea areas is enormous.

On 2: That's great -- lots of things could happen to improve technology in both terrestrial and submarine mining.

On 3: Carbon footprint is not everything when determining the appropriateness of mining. The study cited by the Science article assumes tailings deposition at sea -- mines are not permitted to do this. The article also swans repeatedly over how "high grade" nodules are, but makes no direct reference to their actual grade. The underlying paper suggests a grade of 1.3-1.4 weight percent which is on the bottom end of mid-grade.

On 4: This point can not be concluded without further study. While terrestrial mining has had more historical impacts to humans, this does not allow for comparison on future terrestrial mining vs. a relatively unknown ecosystem impact from aquatic mining. Mining is also not assessed on purely anthropocentric impacts. We've begun to appreciate that systems are interconnected and humans are only one receptor. Enormous caution is required, certainly more than "lower emissions = good".

[elil17]

I'm not sure that sea floor mining is widely ridiculed. I've seen it taken about as seriously by grantmakers as other emerging technologies. That said I’m not in the mining space.

I'm don't disagree with your points - there's a lot of uncertainty around all of this research. But, from what I can see, regulators are doing the right thing and being very cautious to do environmental studies at each step of the way. Maybe I'm way off about that.