Climate Change and the Future of California’s Fire Seasons
Climate Change and the Future of California’s Fire Seasons
Tom Rolinski Senior Meteorologist
Climate Change and the Future of California’s Fire Seasons
Our Climate is Changing
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Riverside Annual Precipitation 1925-2017
Climate Change and the Future of California’s Fire Seasons
Summer Maximum Temperature Change
Winter Minimum Temperature Change
Our Climate is Changing
Climate Change and the Future of California’s Fire Seasons
A Few Things About Future Climate Projections
There are at least 30 statistically downscaled global circulation climate models which contain a high degree of variability.
For the sake of simplicity, the climate projections shown here use an ensemble approach containing 10 model members.
Change of Mean Projected Annual Total Precipitation for 2016-2075
Drier
Climate Change and the Future of California’s Fire Seasons
Wetter
Overall, much of Southern and Central California is projected to be drier, while the northern half of the state is expected to be wetter in the coming decades.
Change of Mean Projected Precipitation
(April/May/June) for 2016-2075
Climate models suggest the spring months will be drier over Southeast California and wetter over much of Northern and Central California
Climate Change and the Future of California’s Fire Seasons
Drier
Wetter
Change of Mean Projected Precipitation (Sep/Oct/Nov) for 2016-2075
Climate Change and the Future of California’s Fire Seasons
Drier
Wetter
Climate models predict the fall months to be drier over Southern and Central California and wetter over much of Northern California
Change of Mean Projected Annual Max/Min Temperature for 2016-2075
Climate Change and the Future of California’s Fire Seasons
7° F
1° F
Mean Maximum Temperature Mean Minimum Temperature
The North American Monsoon (NAM)
Climate Change and the Future of California’s Fire Seasons
Research suggests that there will be a weaker monsoon signal over the Desert Southwest in the decades ahead.
Climate Change and the Future of California’s Fire Seasons
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1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010 2015
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Acres Burned by Wildfires Statewide 1950-2017
(with 10 Year Moving Average)
California’s Wildfire Activity
Climate Change and the Future of California’s Fire Seasons
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200,000
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Values Forecast Lower Confidence Bound Upper Confidence Bound
California’s Wildfire Activity
Climate Change and the Future of California’s Fire Seasons
How will our changing climate affect future fire seasons in California?
Facts Over the past 60 years: • Maximum and minimum temperatures
have been increasing in many areas of the state.
• It has become drier over parts of Northern and Southern California and slightly wetter across the central portions of the state.
• The number of acres burned due to wildfires has been increasing.
• Most of California’s wildfires are caused by human activity.
Questions to consider Since most wildfire causes are human related, how will the following change over the next 30-60 years? • Population • Demographics • Human behavior • Economy • Transportation infrastructure • Changes in the Wildland Urban
Interface regions
Climate Change and the Future of California’s Fire Seasons
Assumptions (Not Facts) based on anticipated changes in weather conditions During the next 30-60 years: • Maximum and minimum temperatures are projected to increase statewide. • Annual precipitation amounts are expected to decrease over the southern
half of the state and increase over Northern California. • The spring and fall months are expected to be drier over the southern
portions of the state. • The NAM signal may weaken with less lightning activity over California
during the summer. • Drought frequency and intensity may increase. • Tree mortality may become more commonplace. • Fuel loading may increase in the north and decrease in the south.
How will our changing climate affect future fire seasons in California?
Climate Change and the Future of California’s Fire Seasons
Conclusions • The length of fire season may increase in the south. • Potential for more wind related wildfires during the fall
months over Southern California. • The length of fire season may change little in the north. • There may be fewer lightning related fires in the Sierra
and over Northern California. • Potential for more severe fires in the south due to
possible drier fuel conditions. • Fire behavior may become more extreme, especially in
the south.
How will our changing climate affect future fire seasons in California?
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