In point of fact, all we need to do to refreeze the Arctic is to go back to pre-Clean-Air-Act levels of sulphur in jet fuel on all flights passing over the region north of 50 degrees north latitude. Back when we had that the climate hysteria was about a new ice age, rather than "global warming". Sulphur dioxide promote cloud formation, so in a way it is blocking the sun, but simply in the way it would be blocked it we weren't taking extra measures to purify our fuels.