Drought Blamed in Deaths of Thousands of Pinyon Pines

New research has found that drought has caused the deaths of thousands of Pinyon pine trees in southern Arizona.

One University of Srizona researcher says he knows the cause of that drought.

"There's clearly a warming trend globally. The scientific community has clearly documented that and of course, humans are partially responsible for that warming trend," says Professor David Brashers.

He says that the drought caused by global warming has also caused problems for Summerhaven, a community on Mount Lemmon near Tucson.

Fires there have charred more than 119,000 acres of forest there since 2003.

Predatory insects have killed other trees weakened by record heat at that ski resort.