In my opinion, it's not such a good idea, so sorry to dump on the scientist. There's grave concern for the arctic, I track it via the Jaxa arctic sea-ice extent vishop web page on a daily basis. It's scary.
Steven Desch's plan is still a bit like pumping harder on the gas to provide the power to apply some brakes, because the 1 million wind pumps would have to be currently made with fossil fuel industry power. I imagine, that because they're not generating electricity, just pumping cold, salty water up; they won't deplete the rare earth metals used to make electric wind-turbines. So, it's not as bad as it might be.
But, 1 million wind turbines: for electricity turbines that's enough to power 2 billion homes at a cost of £2000bn (though economy of scale would bring that down).
It's disappointing that he says: "“Our only strategy at present seems to be to tell people to stop burning fossil fuels.. It’s a good idea..." What he should be saying is "that is of course essential." Because it's not just a good idea, we have to get our emissions down to zero (and rapidly, and then go negative!), because CO2 will hang in the atmosphere for 100s to 1000s of years. Prioritising CO2 over arctic geoengineering is wiser, because it'll provide centuries of better breathing space (quite literally); whereas this, like all geoengineering projects encourages BAU and creates a maintenance issue: you're going to have to replace 5% of them every year: that's 50,000 wind pumps per year.
In addition, because global warming would get worse, the effort to keep the arctic frozen would increase. That's because of warm waters entering from the Atlantic and Pacific as well as warm air from the rest of the planet, pressures on the jetstream and higher radiative forcing due to greater CO2 in the atmosphere. These things wouldn't change and all of them are a product of burning FF.
The question though is that prioritising this would probably deplete renewable energy efforts, because the companies used to build turbine blades would first be diverted to build these things.
The definitive lay perspective on Geo-engineering, I think is the chapter on it in Naomi Klein's book "This Changes Everything."