Economist: The thawing Arctic threatens an environmental catastrophe
"One possibility for cooling the pole is geoengineering, the deliberate modification of the climate to reduce warming. Pumping sulphate aerosols into the Arctic stratosphere from high-flying aircraft could be one way to blot out a bit of the sun. Such an approach would cool Arctic summers but have little effect in winter because there would be no sunlight to reflect. Injecting salt crystals into clouds over the Arctic ocean, to enhance their reflectivity, might also encourage some cooling, though the helpfulness of this type of intervention is highly speculative."