What might be the effect of sprinkling black soot over the ice in the Arctic and Antarctica?

Answer 1

This would alter the snow-albedo feedback. Darkening the surface of snow/ice greatly lowers the albedo (reflectivity) of the surface. This would cause the snow/ice surface to absorb more solar radiation by virtue of its lower albedo, which would allow it to heat up more.

Normally most solar radiation is simply reflected by snow back into the atmosphere and mostly out to space, so by causing it to absorb more you are heating up the lower atmosphere. By doing this, you are more likely to melt the snow/ice, whereby the albedo will be even lower, which would then absorb more radiation, etc.. This is called a positive feedback loop.

Answer 2

Sprinkling black soot over ice in the Arctic and Antarctica would decrease the ice's albedo, causing it to absorb more sunlight and melt faster. This would contribute to the already accelerating trend of ice loss in these regions, leading to further impacts such as rising sea levels and disruptions to local ecosystems.