The U.S. Forest Service is bracing for another rough wildfire year throughout the West, with strict fire restrictions already in place in the Tonto, Coconino and Apache-Sitgreaves national forests.
Relatively cool temperatures helped ease the region through a bone-dry May without a major fire, but June remains the hottest, driest, most fire-prone month — with forecasts calling for dangerously delayed monsoons.
The late arrival of the summer monsoon rains could stretch the peak fire danger into July.
U.S. Forest Service Chief Tom Tidwell this week warned that each year wildfires now burn twice as much land as they did 40 years ago.
“Last year fires were massive in size, coinciding with increased temperatures and early snowmelt in the West,” said Tidwell. “The largest issue we now face is how to adapt our management to anticipate climate change impacts and to mitigate their potential effects.”
The Forest Service considers some 400 million acres at high risk of wildfires, including most of the 4-million-acre Tonto National Forest. Although the Forest Service has in the past decade used thinning or controlled burns to treat 28 million acres — an area larger than Virginia — some 70,000 communities remain at grave risk from wildfires.
The communities of Rim Country remain among the most fire-menaced in the nation, despite the Tonto National Forest’s success in creating hand-thinned buffer zones on the outskirts of most communities. However, many unincorporated communities remain surrounded by thick
forest with just one way in and out —thanks in part to a long delay in the Tonto National Forest’s adoption of a travel management plan, which is supposed to potentially provide back door escape routes for many dangerously isolated communities.
Already, the reservoirs on the Salt and Verde rivers have dwindled to about 60 percent of their capacity. In just one day, the amount of water in Roosevelt Lake dropped by 3,000 acre-feet — the amount the Blue Ridge pipeline will deliver to Payson in a year. Tonto Creek has all but dried up before it reaches Roosevelt and the Salt River has about 60 percent of its normal flow. Curiously enough, the flow of the Verde River is a little above normal, according to the Salt River Project’s daily water report this week.
Back in 1991, fighting fires consumed just 13 percent of the Forest Service budget. But in 2012, the Forest Service spent 40 percent of its money on fires — transferring money from other uses to cope with one of the worst wildfire years in history. The amount spent on firefighting has doubled from about $1 billion annually, according to Tidwell.
The rising fire danger reflects the effects of both a decade-long megadrought and a century-long increase in tree densities due to the effects of fire suppression, cattle grazing and logging.
Climate studies and rainfall projects suggest the problem may get even worse, given the slow pace of thinning projects like the Four Forest Restoration Initiative.
Currently, most of Arizona has lapsed back into severe or extreme drought — along with almost all of New Mexico. A portion of Arizona centered on Gila County is currently just “abnormally dry,” but the U.S. Drought Monitor maintained by the National Weather Service predicts a lapse into moderate to severe drought in Gila County in the next month.
The key to the region’s climate remains the onset of the summer monsoons, when storms brewed in the Gulf of Mexico and the Gulf of California head north and deliver about half of Rim Country’s rainfall.
The monsoons may shift by a month in many years thanks to warming temperatures, according to a study published in the Journal of Geophysical Research conducted by researchers from Columbia University and NASA.
Although the total amount of rainfall delivered by the monsoons won’t change much, the peak of the summer rainfall may shift from July and August to September and October, the researchers concluded.
The finding supports other recent research on the timing of monsoons in the Southwest, given a slow, steady rise in average temperatures.
For instance, a study in the Journal of Climate by researchers from the University of Colorado found that average July rainfall has been decreasing since the 1940s in the Southwest, while August and September rainfall averages have increased.
Another study found that the failure of the monsoon rains has played a major role in megadroughts going back for centuries. The University of Arizona Tree Ring Laboratory researchers analyzed roughly 1 million tree ring patterns over a 470-year period, according to the research published in the Geophysical Research Letters, a scientific journal. UA researchers included Daniel Griffin, Connie Woodhouse and others, with help from the National Science Foundation, the National Oceanic and Atmospheric Administration and the Environmental Protect Agency.
Most previous studies of the decades-long megadroughts that can reduce average rainfall to less than half of normal have focused on the tree ring patterns that result mostly from winter rain and snow. This study looked at the faint, narrow spurt of late “latewood” summer growth in Douglas firs and ponderosa pines.
The scientists discovered that many of the most severe winter droughts came linked to the failure of the monsoon storms.
During the late 20th century, most of the dry winters were followed by normal monsoon rains, which greatly reduced the impact of the drought. That pattern actually proved unusual in the tree ring records dating back to 1539.
The researchers linked these twin-season megadroughts to major upheavals. For instance, an extended drought led to extensive vegetation changes and the 1680 Pueblo Revolt, when Native Americans temporarily drove out the Spanish. Then in 1882-1905, another megadrought killed half of the cattle in the state and led to lasting vegetation changes, turning grasslands into desert shrub.
Experts don’t have a clear explanation for these decade-long droughts that have remained a feature of the climate in the Southwest. However, many agree that the buildup of heat-trapping pollutants in the atmosphere will likely make the climate drier and more volatile — perhaps even play a role in triggering major changes that happened periodically.
Moreover, climate scientists continue to find complex feedback loops that affect rainfall and temperature — including the smoke from wildfires themselves.
For instance, projections suggest wildfires in the West will increase by another 50 to 100 percent by 2050. Ironically, the smoke from those fires will likely decrease rainfall further, according to research by the U.S. Forest Service Southern and Northern Research Stations, published in the journal Forest Ecology and Management.
Those billows of smoke also rise up into the troposphere, where most of the planet’s weather is generated. The soot in the smoke can block the sun’s rays, cooling the planet’s surface. However, the particles in the smoke also can inhibit droplet formation in clouds, effectively reducing rainfall. Moreover, the black soot particles settle on snowbanks, absorbing more heat and prompting the snowpack to melt sooner — which has a big impact on plants and forests.
The study concluded that the projected increase in smoke from fires would likely cool the surface, suppress rainfall, increase the number and duration of droughts and lead to earlier snowmelt, which will affect a host of plants and animals and ultimately decrease water available for reservoirs and human beings.