By Victoria Cavaliere
SEATTLE, July 23 (Reuters) - Firefighters were holding the line on Wednesday against the largest wildfire in Washington state's history, as scientists warned that such blazes across the Western United States were becoming hotter, larger and more dangerous.
The Carlton Complex fire burning east of the Cascade Mountains remained at 16 percent containment as crews cited progress installing lines around its 380 square mile (980 square km) perimeter, said Joni Quarnstrom, a spokeswoman for firefighting efforts.
President Barack Obama has signed an emergency disaster declaration for areas ravaged by the fire, which was triggered by lightning July 14 and spread rapidly through the Methow Valley, 120 miles northeast of Seattle.
"The good news is that all sides have had success building containment lines," Quarnstrom said. "The not-so-good news is that there's a flash-flood warning in effect and wind gusts today could reach 30 miles per hour."
Crews were worried that wind and lightning on Wednesday could fan flames or trigger more fires while floods could force the removal of emergency personnel.
Between 150 and 200 homes and dwellings have been destroyed by the fire, and two tiny communities of about a dozen homes in the Methow Valley, home to about 10,000 people, remained under highest-level evacuation orders.
The blaze was one of about 20 fires currently raging across northern California, Oregon, Washington and Idaho, and scientists warned that such wildfires were becoming more frequent.
"Climate change is producing hotter, drier conditions in the American West, which contribute to more large wildfires and longer wildfire seasons," according to a report released by the Union of Concerned Scientists, a non-profit science advocacy group.
"The risk to people and their homes is rising as a result, a growing danger made worse by the increasing number of homes and businesses being built in and near wildfire-prone areas," the group said.
The Carlton Complex blaze has been especially worrisome for emergency crews because of its spread through a well-populated region. At the height of evacuations, some 1,200 people were displaced, officials said.
The fire also contributed to one fatality, a 67-year-old man who died while trying to protect his home, according to the Okanogan County Sheriff's Office.
Battling the blazes has also gotten more expensive, and the U.S. Department of the Interior has had to divert funds from other programs to pay firefighting costs in seven of the last 10 years, said Jim Douglas, a director of the Department of the Interior's Office and Wildland Fire.
The cost of fighting wildfires has exceeded $1 billion every year since 2000 and the Western U.S. wildfire season has grown from five months on average in the 1970s to seven months today, the report found.
Meanwhile on Wednesday, federal officials banned the use of exploding targets and other explosives in forests in parts of Idaho, Utah, Wyoming and Nevada to try to prevent wildfires amid drought-like conditions. (Reporting by Victoria Cavaliere; Editing by Cynthia Johnston, G Crosse)