As available metals become scarcer, some are looking to deep-sea mining to feed the ever-hungry economies of the world. While terrestrial mining typically involves cutting into the earth, deep-see mining is more akin to vacuuming. The basic idea is that mining ships will deploy devices to scour the seabed for nodules of valuable metals, such as nickel, copper, manganese and cobalt. As would be expected, this new form of mining raises ethical concerns about its potential environmental impact.
Since terrestrial mining has generally been incredibly destructive to the environment and has contributed greatly to political corruption, it is important to consider the potential harms of deep-sea mining before it becomes a significant reality. As with terrestrial mining, the harms must be weighed against the benefits, so the usual utilitarian approach will be taken.
On the plus side, the seabed seems to have an abundance of metal resources that would probably be economically viable to mine. The metals are necessary for the modern economies of the world—they are essential for a large range of products that are taken to enhance the quality of life of millions. As such, the most compelling moral argument for mining the seabed is the economic one. But, of course, this mining would not be without consequences.
One concern is that the mining process will damage the seabed. About 30 years ago researchers used a sledge to simulate one effect of such mining—the marks remain, looking exactly as they did when they were cut. There are also organisms that live on the nodules that would presumably be killed in the process of mining and refining. The mining process also siphons up 10-15 centimeters of the seafloor, which would clearly not be ideal for the organisms living there. There is also the fact that the undesirable sediments will be pumped overboard, and they can drift considerable distances, impacting ecosystems far from the mining sites.
One obvious reply to the concern about damage is that it seems minor—siphoning up some mud and then having some silt drift away from the mining site. This, one might argue, is not even worth considering. While the apparent damage seems less than that of terrestrial mining (which can involve removing mountains), a key part of the problem is that the impacts of such mining are not known. The available evidence does indicate that recovery time from the mining would be very long—so even if the damage is relatively small, this could be offset by its duration. Beyond that, the impact of such mining is not known—it might turn out to have little impact or it might have serious consequences for the oceans and the creatures affected by the oceans. This, of course, includes humans. What is better known is the impact of processing the mined nodules—this will be done on land using the usual sort of processes. As would be expected, this can have significant environmental impact.
While it is almost certain that there will be a significant environmental cost for deep-sea mining, it is probably possible to mitigate the damage. The challenge, as always, is to get those doing the mining to engage in this mitigation. This will no doubt vary greatly between countries, which will be especially problematic because such damage will obviously not respect national boundaries. But, given that the impacts are unknown, the right thing to do would be to continue the scientific investigation into the impact of such mining, that way the true cost of the mining will be known ahead of time and possible means of mitigation can be developed. These metals are, as noted above, critical to the consumer economy that we have created and as such, there seems to be no likely alternative to deep-sea mining. Except, of course, asteroid mining.