Image copyright Getty Images Image caption If the conditions persist, California will see more wildfires
California wildfires are getting hotter and more intense, creating a unique and complex threat to the nation’s second-largest state, researchers say.
Some of the biggest fires in the state’s history are related to the scorching heat and drought, scientists say.
Studies of wildfires in 2017 and so far this year found wildfires increased and the intensity of some of them increased.
California produces more than 75% of the country’s fruits, nuts and vegetables.
So far this year, at least 36 people have died in at least 17 fires in California, Canada and Washington state.
What are the main aspects of the warmer conditions?
Researchers say overall rising temperatures, coupled with weaker spring snowmelt, will make wildland fires in California more intense and more difficult to fight.
What are the implications?
A 2014 study found drought in western and central California increased the risk of such fires by 27%. And a 2017 study estimated that forests and other wildland areas were most vulnerable to wildfires.
Ongoing drought has also increased wildfire intensity in the eastern part of the state.
Firefighters use shelters, thick black soot and other heavy materials, to protect themselves from the heat and smoke of wildfires
What has happened in 2018?
California state officials say weather conditions over the past two months have been especially conducive to wildfires, including the main reason – a lack of rain.
The California Office of Emergency Services defines a fire season as June 1 to November 30. There have been more than 1,800 fires over that period – resulting in the destruction of 2,000 homes.
How much does climate change have to do with the fires?
Comparing fires from 1978 to 2016, researchers at the University of California at Berkeley found that dead and dying trees are a big reason for increasing wildfires in California.
Image copyright Getty Images Image caption The highest temperatures across northern US in June have topped 40 degrees C
The increased use of fire suppression to keep the fires small has also led to an increase in the number of fires that are much more intense.
They estimate that:
Since 1978, California has seen only two years where 1.5 million acres of wildland were burned; that compares to 15 years in the mid-1960s.
Between 1977 and 2016, the percentage of California’s forests in annual burn zones grew from 12% to 28%.
The report says most of the increase can be attributed to climate change.
What is the future?
Most of the fires in 2017 were in the summer, and researchers expect that number to continue to increase due to worsening climate change.
Those fires burned 557,712 acres of land, dwarfing the 55,794 acres that were burned during the statewide average in 1977.
A second study, by the British Geological Survey (BGS), used the same criteria as the Berkeley study, but looked more broadly at wildfires in Western and Central California.
It found that wildfires increased dramatically in temperatures of 40F and above, as well as during months of 100F and above.
Previous research found wildfires in the US Northwest have increased or decreased due to the temperature and drying conditions of the late 19th and early 20th centuries.
The Southwest is expected to get much drier or warmer over the next few decades, the study’s authors concluded.
Image copyright Getty Images Image caption In June, 12 wildfires burned 675,804 acres across New Mexico, Arizona and Colorado
The Northern Rockies and Great Lakes region will also be impacted.
Firefighting organisations have been doing training exercises since the fires in late June to help prepare for the extreme weather they expect in the future.
Dr James Mettler, the lead researcher for BGS and a senior fellow at the University of Washington’s Environmental Earth System Science Center, said in a statement: “Now that we’ve seen what we can expect in the next century, it’s important for firefighting agencies to plan for what we need to do to manage our forests now.”