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Spying Global Warming in the Desert?

The Chihuahuan Desert is a perfect outdoor lab for using satellites to spot changes in vegetation due to global warming or other climate change.

There is preliminary evidence that global warming may have sped up the pace at which grasslands are being overtaken by mesquite, creosote and other shrubs at desert sites around the world.

Scientists at the Agricultural Research Service’s Jornada Experimental Range in Las Cruces, N.M., in the heart of the Chihuahuan Desert, have been working with the U.S. National Aeronautics and Space Administration and the Henry A. Wallace Beltsville Agricultural Research Center since 1995, gathering data on global climate change as part of NASA’s “Mission to Planet Earth.” NASA’s program is a long-term environmental health checkup of Earth from space. ARS has a lead role in the hydrology part of the project.

The 100,000-plus-acre Jornada desert site is a good stand-in for similar semiarid areas where desertification has been aggravated by overgrazing and drought. Twice a year, ARS physical scientist Tom Schmugge and others from Beltsville join Kris Havstad, head of the Jornada Experimental Range, and colleagues in an aircraft and satellite flyover campaign to test remote sensors by air, space and land.

The Jornada work helps NASA and USDA evaluate the interaction between desert landscapes and climate change.

Schmugge and colleagues are testing sensors to distinguish bare soil from vegetation by their natural emissions of light or colors. They are also testing thermal infrared sensors to measure surface temperature. Surface temperature variations are key to defining regions of high and low evaporation that generate storms.

More details are available in a feature story in the August 2001 issue of Agricultural Research magazine.

ARS is USDA’s chief scientific research agency.