Climate change is feeding on itself. The warming effects of greenhouse gases are driving processes that heat up the planet yet further. The one which is exciting—and alarming—scientists most is an unexpected reduction in an obscure but fundamental aspect of Earth: its albedo.
The albedo is the fraction of incoming sunlight that a surface or a planet reflects back whence it came. High albedos, whether they are created by white roofs or ice-covered seas, keep things cool; by contrast, when albedos are low, the incoming energy stays here on Earth, raising the planet’s surface temperatures. Robust satellite measurements of Earth’s albedo have now been taken for over two decades. They show it falling with surprising speed. The
oceans, which are responsible for most of the sunshine’s absorption, have been accumulating much more heat as a result.