Every spring firefighters throughout the West approach the summer season with a proverbial prediction: If the winter was dry, all those parched trees will burn like torches; if it was a wet winter, all those new grasses will fuel quick fire starts and hot, runaway flames.
After a winter that left record piles of snow in the mountains and drenched most of California’s valleys, it’s no surprise that it is grass fires that are fueling a fast start to the state’s 2017 fire season. More than 16,000 acres had burned by June 3 in 1,229 blazes, most of them in central and southern California.
That is an alarming two-and-a-half-times more acreage than was burned by June 3 last year, said Scott McLean, a spokesman for the state’s Department of Forestry and Fire Protection, known as Cal Fire.
“Everybody’s excited about the drought being over but all that moisture enhances the grass crop. It’s denser and higher, and it catches fire very easily,” he said.
We can look to the hills for relief, federal officials said. The rains that are fueling the green-up in the valleys fell as snow at the higher elevations. The result is a slow start to the fire season in the Sierra Nevada, mostly managed by the United States Forest Service: just 2,576 acres of federal lands had burned by June 3. By June 7 last year, nearly 13,000 acres had burned. The moisture should lead to a delayed and shorter season overall in the Sierra, according to the National Interagency Fire Center (NIFC) in Boise, ID.
The exceptionally wet winter may also offer an opportunity to deal with one of the more problematic legacies of California’s five-year drought: 102 million dead trees. Despite scientific debate, most officials consider them an extreme fire danger. The tool being tested to reduce the potential for future uncontrolled blazes is, ironically, fire.
The precipitation that fell as rain across California’s lower elevations is leading to a “robust green-up,” NIFC officials said. As these grasses and shrubs dry out in early summer heat, the predictions are for above-normal fire activity by July.
The danger areas are not limited to Kern, Riverside and San Diego counties, which have already experienced grass fires this year. They include the low-elevation hills that separate the central and southern California coast from the Central and San Joaquin valleys. Parts of these areas have moved from a pattern of seasonal blazes, occurring between spring and fall, to fire seasons that last all year long, said McLean.
More surprising is the NIFC’s prediction for above-normal fire activity east of the Cascade-Sierra crest in Lassen County and throughout northwestern Nevada. Like the Cascade and Sierra Nevada mountains, this generally arid area experienced an unusually wet winter, which spurred the growth of juniper, sage and other Great Basin shrubs.
That is creating what federal officials call a “robust fine-fuel crop.” As it cures, the threat of wildfire increases. “Once summer temperatures hit, that vegetation will dry out quickly, causing high fire danger,” said Jennifer Smith, an NIFC spokesperson.
By August, the inter-agency maps for fire activity in California show just one other area of concern: the mid-elevation mountains along the coast north and to the east, including Mendocino, Sonoma and Lake counties. In 2015 one of the state’s most destructive fires raced through this area, leaving 76,067 scorched acres (30,780 hectares) in its wake. The Valley blaze claimed four lives and destroyed 1,955 structures. Firefighters experienced some of the most uncharacteristic conditions fighting this outbreak, with flames racing downhill and burning just as hot at night as midday, said McLean.
The topography of this region, combined with increasing population density, makes it one of the state’s expected hot spots for 2017, said McLean.
Race Against Time
With the wet winter leaving much of the Sierra Nevada’s forests damp with no immediate threat of burning, officials and fire scientists are looking ahead to a potentially catastrophic fire hazard still several years in the future. Looming on the horizon throughout the 4,500–6,000 feet (1,370-1,830 meters) elevation in the southern and central Sierra are those millions of dead trees. Weakened by drought, most succumbed to a blitz of pine beetles that ate into their bark and cut off their circulation system.
Left alone, the 102 million dead trees will eventually topple to the ground, creating a tangled mass of fuel. It is only a matter of time until lightning turns these forests into infernos, scientists say.
This summer offers an opportunity to use fire as a tool to reduce the future threat, said Craig Thomas, conservation director for Sierra Forest Legacy, an organization dedicated to protecting Sierra forests and communities. Setting prescribed fires in areas of high tree mortality would consume the fuel in a way that controls both the timing and the extent of the burn, he said. It is a way to return fire to forests, both reducing the potential for catastrophic wildfires and renewing ecosystems dependent on natural fire.
“This is the best year we’re ever going to see for returning fire to the landscape,” Thomas said.
In November, Sierra National Forest officials successfully managed a 700-acre prescribed fire in an area where up to 50 percent of the trees were dead.
Despite this year’s predictions for the Sierra, scientists are all but certain that California and the West can expect an increase in fire activity in both forested and non-forested areas. The early escalation in California grass fires fits the pattern of blazes that by 2050 will double the annual acreage that burned over the last 30 years, forest service officials reported.
Nationwide, the year is off to a punishing start. Twice as many acres had burned by June 7 as the 10-year average. Massive grass fires in Oklahoma and Kansas punched up the acreage early in the year, followed by stubborn fires in Florida and Georgia that burned into May.
Scientists attribute the increases to human-induced warming, which is drying vegetation, raising snow levels and causing snow to melt earlier in the season. The Northern Rocky Mountain forests are particularly sensitive to the changes brought by a warming climate and earlier spring snowmelt, said A. LeRoy Westerling, co-director of the Sierra Nevada Research Institute at the University of California, Merced. He also found that wildfire frequency and burned area in Pacific Northwest forests had increased more rapidly in the last two decades.
It’s all part of a global trend, according to a study published in Nature Communications. Between 1979 and 2013, increases in temperature and wind speeds combined with a greater number of rain-free days to lengthen fire seasons worldwide by nearly 20 percent.
Whether the predictions will play out in reality on the ground in California is hard to determine in June, said McLean, the Cal Fed spokesman: “I’ll tell you in December.”