What is albedo and why is it important in climate change?

Albedo is the reflectivity of a surface. A surface that has a high albedo reflects a lot of solar radiation from the sun back into the atmosphere, whilst a surface that has a low albedo reflects little solar radiation, absorbing it instead.

White surfaces (such as ice) have high albedos, whilst black, dark surfaces (such as rocks) have low albedos. This is important in terms of climate change because ice has a high albedo, and so reflects most solar radiation back into the atmosphere, meaning the ice remains cold. However, due to increased sea surface temperatures, sea ice in areas such as the Arctic is melting. The removal of the sea ice results in further sea warming due to the fact that the sea has a lower albedo, and so absorbs more solar radiation from the sun, heating it. This positive feedback mechanism results in further sea ice loss, accelerating climate change.