The Chihuahuan Desert is a high elevation region, and newcomers sometimes find themselves puffing during activities that wouldn't phase them a bit at sea level. As the air becomes thinner with altitude, it becomes more difficult to obtain oxygen. It's just as well that we desert dwellers didn't live near the end of the Permian Period some 250 million years ago, or even puffing wouldn't have saved us.
Whereas today the atmosphere is about 20% oxygen, it plunged from a
high of about 30% 300 million years ago, to bottom out at around 12% near the end of
the Permian. The Permian Period is best known for the great extinction at its end, when
the vast majority of living things died out. The great drop in oxygen content may well
have played a part, leaving land surfaces above about 1650 feet with too little oxygen
to support vertebrate animals, if we can judge by today's fauna. Crowded into half
the area, it's no wonder that the end-Permian animal community was decimated.
Breathe deep and consider how lucky we are.
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.
Huey, R. B., and P. D. Ward. 2005. Hypoxia, global warming, and terrestrial late Permian extinctions. Science 308:398-401.
Kerr, R. A. 2005. Gasping for air in Permian hard times. Science 308:337.