Warming Climate Chills Sonoran Desert's Spring Flowers

http://www.sciencedaily.com/releases/2009/12/091216144145.htm

ScienceDaily (Dec. 20, 2009) — Global warming is giving a boost to Sonoran Desert plants that have an edge during cold weather, according to new research.

Although the overall numbers of winter annuals have declined since 1982, species that germinate and grow better at low temperatures are becoming more common.

"It's an unexpected result -- that global warming has led to an increase in cold-adapted species," said lead author Sarah Kimball, a research associate at the University of Arizona in Tucson. "Because the winter rains are arriving later, they are occurring under colder temperatures."

Climate change is shifting the winter storm track so the Sonoran Desert's winter rains now generally begin in late November or early December, rather than during the balmy days of late October.

Therefore seeds that require winter rains must sprout during the cooler days of December.

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"Even though overall the winter growing season is getting warmer, what's important in this system is that the growing season is initiated at a later date under colder temperatures," Kimball said. "This demonstrates that the response of organisms to climate change can be unexpected."