About 300 people are gathering at the Visalia Convention Center today to hear forest scientists talk about how climate change is affecting the southern Sierra.

Prof. Andy Westerling from UC Merced said that the number of large forest fires in the western United States has increased dramatically since about the mid-1980s. He linked the surge to longer summers that are hotter than ever in recorded history, caused by climate change. Forest fires last longer, too, from about 1 week before the mid-1980s to about five weeks today, he noted.

Westerling's research has gotten publicity in the media and in professional circles. The symposium today is being sponsored by the U.S. Forest Service, the National Park Service and the U.S. Geological Survey, and many in attendance are foresters.

Climate scientist Nate Stephenson from the USGS said climate change "is here and there's a high probability it's going to get worse" through the 21st century. The cause is more carbon dioxide in the air, put there by "human influence," he said.

Droughts come and go, but what's different is that average temperatures are hotter by a few degrees Centigrade. Combined, forests have been dying off in places.

"I wake up with a cold sweat," Stephenson said. "I don't want to lose our forests."

To save forests, it might be a good idea to thin forests mechanically because the beetles that kill trees thrive less in thinner stands, he said. And "prescribed burns," or controlled forest fires, can also control growth. The two go together, he said.

That's music to the ear of Tulare County Supervisor Mike Ennis of Porterville,

"I was glad to hear someone say we need to do some tree thinning," Ennis said. "I've been saying that for a long time."