The arctic is warming up much faster than farther south as greenhouse gases heat the planet. Why would warming affect the arctic more strongly than our temperate and tropical regions? Albedo! That's right, albedo! The Far North has a high albedo, which is merely a fancy way of saying that it reflects a lot of light back into space. This is because much of the surface is covered by ice and snow over much of the year. Absorbed rays of the sun are mostly released as heat that is easily trapped by atmospheric gases. Reflected rays mostly escape through the atmosphere. As the air temperature increases, snow and ice remain on the ground for a shorter time and thus reflect less light back into space.
In the temperate regions, warming air doesn't change the albedo
much, and so there is little feedback enhancing warming. Our desert has a relatively
high albedo because of its scanty vegetation; warming temperatures, unless accompanied
by more moisture, merely means fewer plants and higher albedo—the opposite of the
arctic.
Listen to the Audio (mp3 format) as recorded by KTEP, Public Radio for the Southwest.
Contributor: Arthur H. Harris, Laboratory for Environmental Biology, Centennial Museum, University of Texas at El Paso.
Desert Diary is a joint production of the Centennial Museum and KTEP National Public Radio at the University of Texas at El Paso.