Stress In The Sky Islands

Interesting article regarding Mt. Lemmon, just outside Tucson, AZ. The fires there in 2003 were just devastating:

SUMMERHAVEN, Ariz. — High above the desert floor, this little alpine town has long served as a natural air-conditioned retreat for people in Tucson, one of the so-called sky islands of southern Arizona. When it is 105 degrees in the city, it is at least 20 degrees cooler up here near the 9,157-foot summit of Mount Lemmon.

But for the past 10 years or so, things have been unraveling. Winter snows melt away earlier, longtime residents say, making for an erratic season at the nearby ski resort, the most southern in the nation.

Legions of predatory insects have taken to the forest that mantles the upper mountain, killing trees weakened by record heat. And in 2003, a fire burned for a month, destroying much of the town and scarring more than 87,000 acres. The next year, another fire swept over 32,000 acres.

“Nature is confused,” said Debbie Fagan, who moved here 25 years ago after crossing the country in pursuit of the perfect place to live. “We used to have four seasons. Now we have two. I love this place dearly, and this is very hard for me to watch.”

The American Southwest has been warming for nearly 30 years, according to records that date to the late 19th century. And the region is in the midst of an eight-year drought. Both developments could be within the range of natural events.

But what has convinced many scientists that the current spate of higher temperatures is not just another swing in the weather has been the near collapse of the sky islands and other high, formerly green havens that poke above the desert.

Fire has always been a part of Western ecology, particularly when the land is parched. But since the late 1980s, the size and reach of the fires have far exceeded times of earlier droughts. And the culprit, according to several recent studies, is higher temperatures tearing at a fabric of life that dates to the last ice age.

“A lot of people think climate change and the ecological repercussions are 50 years away,” said Thomas W. Swetnam, director of the Laboratory of Tree-Ring Research at the University of Arizona in Tucson. “But it’s happening now in the West. The data is telling us that we are in the middle of one of the first big indicators of climate change impacts in the continental United States.”