Warming climate chills Sonoran Desert's spring flowers

Mari N. Jensen in the University of Arizona News: Global warming is giving a boost to Sonoran Desert plants that have an edge during cold weather, according to new research from the University of Arizona in Tucson. Although the overall numbers of winter annuals has 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 in UA's department of ecology and evolutionary biology. "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.

"Southern Arizona has been getting hotter and drier for the last 25 or 30 years, and as a result, the desert annuals we've been studying at Tumamoc Hill have been changing," said co-author D. Lawrence Venable, the UA's director of research at Tumamoc Hill.

…"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."

Flower of a Fishhook Barrel Cactus (Ferocactus wislizeni) taken in Tucson, Arizona, shot bySusan Lynn Peterson Sue in az, Wikimedia Commons, under the Creative Commons Attribution 3.0 Unported License