American Airlines have recently demonstrated what could be the world's cheapest way to fight global warming. Working with Bill Gates' Breakthrough Energy Group they have shown that avoiding “ice supersaturated regions” of the atmosphere where long-lasting airline contrails can form, they can significantly reduce their warming impact.
Marc Shapiro, the head of contrails at Breakthrough Energy, said this is the “highest-leverage climate opportunity that we
know of,” the equivalent of removing carbon from the atmosphere at a
cost of 10 dollars per ton or less. And it will be standard practice in the very near future.