In the natural world one environmental event or disturbance can initiate or be part of a series of cascading events that intensify the impacts of natural hazards, possibly turning them into disasters.
An article at The Conversation explores how these effects can be enhanced by a warming climate. Below is an excerpt from an article written by Amir AghaKouchak (UC Irvine) and Farshid Vahedifard (Mississippi State University).
“Multiple hazardous events are considered cascading when they act as a series of toppling dominoes, such as flooding and landslides that occur after rain over wildfires. Cascading events may begin in small areas but can intensify and spread to influence larger areas.
[…]
“Also, the severity of these cascading weather events worsens in a warming world. Drought-stricken areas become more vulnerable to wildfires. And snow and ice are melting earlier, altering the timing of runoff. This has a direct relationship with the fact that the fire season across the globe has extended by 20 percent since the 1980s. Earlier snowmelt increases the chance of low flows in the dry season and can make forests and vegetation more vulnerable to fires.
“These links spread further as wildfires occur at elevations never imagined before. As fires destroy the forest canopy on high mountain ranges, the way snow accumulates is altered. Snow melts faster because soot deposited on the snow absorbs heat. Similarly, as drought dust is released, snow melts at a higher rate, as has been seen in the Upper Colorado River Basin.
[…]
“When landscapes are charred during wildfires, they become more vulnerable to landslides and flooding. In January, a debris flow event in Montecito, California killed 21 people and injured more than 160. Just one month before the landslide, the soil on the town’s steep slopes were destabilized in [the Thomas Fire]. After a storm brought torrential downpours, a 5-meter high wave of mud, tree branches and boulders swept down the slopes and into people’s homes.”
Wildfire south of Porto, Portugal, September 2, 2012. Photo by Bill Gabbert.
The climate warming that we have been seeing is expected to continue along with the increased risk of larger, more suppression-resistant wildfires. Scientists have examined how this will affect fires in Europe up to a 1.5°C rise, which is the not-to-exceed target in the Paris climate agreement. Now a study is complete that examines increases of 1.5, 2, and 3°C warming scenarios. Not surprisingly, it found that the higher the warming level, the larger is the increase of burned area, ranging from ~40% to ~100% across the scenarios. Their results indicate that significant benefits would be obtained if warming were limited to well below 2 °C.
Ensemble mean burned area changes. Burned area changes (%) for a the +1.5 °C case with the stationary model SM (i.e., using Eq. 3), (b) the +1.5 °C case with non-stationary model NSM (i.e., NSM). using Eq. (4), (c) the +2 °C case with SM, (d) the +2 °C case with NSM, (e) the +3 °C case with SM, and f the +3 °C case with NSM. Dots indicate areas where at least 50% of the simulations (1000 bootstrap replications × the ensemble of RCMs) show a statistically significant change and more than 66% agree on the direction of the change. Coloured areas (without dots) indicate that changes are small compared to natural variations, and white regions (if any) indicate that no agreement between the simulations is found. Click to enlarge.
The paper, published in Nature, was written by Marco Turco, Juan José Rosa-Cánovas, Joaquín Bedia, Sonia Jerez, Juan Pedro Montávez, Maria Carmen Llasat, and Antonello Provenzale.
In a tweet Sunday afternoon President Trump said the wildfires in California are “magnified & made worse by the bad environmental laws which aren’t allowing massive amount of readily available water to be properly utilized. It is being diverted into the Pacific Ocean. Must also tree clear to stop fire spreading?”
It is nonsensical to think that water projects, whether or not the water is diverted into the ocean, would have any significant effect on the spread of, for instance, the Mendocino Complex of Fires currently growing east of Ukiah that at 273,664 acres has just become the second largest wildfire in the recorded history of California.
Most scientists agree that the increase in acres burned and the average size of wildfires in the United States is due to a number of factors, including climate change (high temperatures, lower relative humidity, drought), fuel buildup due to fire suppression for 100 years, and people moving into areas with continuous vegetation. This migration can increase the number of fire ignitions, and can divert the limited number of firefighters from actually suppressing a fire to protecting structures, allowing fires to grow unhindered at times.
Even the Washington Examiner, a very reliable and strong supporter of Mr. Trump, had some mild criticism about this statement by the President.
And yes, “tree clear”, can help, if by that he means reducing fuels around inhabited areas through prescribed fires and other fuel management techniques. But we will never be able to conduct enough prescribed fires to prevent blazes from becoming megafires. And increasing logging is not the answer. Large, very wide fuel breaks around subdivisions be beneficial, but it is more important for residents in the wildland-urban interface to accept the responsibility to use FireWise principles. Burning embers can cause buildings to ignite at a great distance from the main fire. Homes should be constructed with fire resistant designs and materials. Residents need to thin and/or remove flammable vegetation within 100 feet of structures.
There are many ways that a warmer climate can influence wildfires, causing them to burn more intensely. Higher temperatures can lower the relative humidity, lower the amount of moisture in the vegetation (fuel), raise the temperature of the fuel itself, and cause more powerful thunderstorms with lightning. But one factor that we don’t think about very often is that the heat can persist through the night, influencing fire behavior.
When today’s senior firefighters began their careers, they could usually count on fires “laying down” at night. The intensity and rate of spread would decline to the point where night shift personnel could more easily and safely “go direct”, constructing fireline very close to the edge of the fire…
Research projects substantial increases in area burned across western North America, with implications for land managers and policy makers.
Above: Projected change in annual area burned for the period 2010–2039, with red colors indicating areas with the greatest increase in area burned annually in wildfires, and dark blue the least.
By Susan McGinley, University of Arizona
The massive wildfires that burned in California, Oregon, Montana, Idaho, British Columbia and other parts of North America in 2017 in many cases exhibited a disturbing trend: a marked increase in the amount of area burned.
The Thomas Fire, which consumed 281,893 acres in California’s Santa Barbara and Ventura counties in December, was the largest in the state’s history. The Nazko Complex Fire in British Columbia burned more than 1 million acres, the largest ever recorded for the province.
Thomas Fire, Ventura, CA, Los Padres National Forest, 2017. USFS photo.
That trend will continue in coming decades across the western U.S. and northwestern Canada, though not uniformly, according to a recent study. UA professor Don Falk and Thomas Kitzberger from the Universidad Nacional del Comahue in Argentina, who started working on the research as a visiting scholar at the UA, were co-investigators on the study that also included Thomas Swetnam from the UA and Leroy Westerling of the University of California, Merced.
While it may have been an exceptional year in some respects, Falk’s and Kitzberger’s predictions suggest that years like 2017 are likely to become more common over time. States in the interior Western U.S., in particular, may be faced with large increases in total wildfire area burned, potentially beyond anything that has been experienced in the past.
Their research paper, “Direct and indirect climate controls predict heterogeneous early-mid 21st century wildfire burned area across western and boreal North America,” was published in the journal PLOS ONE in December as the 2017 fire season was ending. The results project where the greatest increases in area burned are likely to occur across the Western U.S. and Canada in coming decades. It suggests that large fires years such as the recent ones in southern and northern California may become more common.
A Model to Measure and Project Fire Activity
“We used 34 years of climate data to calibrate area burned in 1,500 grid cells across western North America, so we could capture the different ways that seasonal climate regulates fire in different regions,” said Falk, a professor in the School of Natural Resources and the Environment in the UA College of Agriculture and Life Sciences.
The key measurement, annual area burned, is a combination of fire size, frequency and variability from year to year. Area burned does not necessarily indicate fire severity, the ecological effects in a burned area.
Taking into account geographic variation, the study data focused on fire occurrence, seasonal temperatures and snowpack. The seasonal climate variables that turned out to be driving the amount of area burned were summer temperatures during fire season, spring temperatures and rainfall, and winter temperatures. Winter and spring conditions regulate snowpack, which can delay the onset of the fire season.
The team built a statistical model for wildfire area burned in each of the grid cells studied, and then tested it with data for actual area burned since 2010 to validate their predictions. It did not project the extent of area burned beyond the mid-21st century, as climate and vegetation changes become more uncertain later in the century.
Findings for western and northern North America show that about half the states and provinces are projected to have a large increase — five or more times the current levels — in total wildfire area burned. Others may see smaller increases, indicating there is no “one-size-fits-all” model. Increases in area burned are unevenly distributed across the study area, with the strongest increases projected in the interior western region.
Heads-Up for Land Management
“Ultimately, this means that the large fire seasons of recent years, such as the one just ending, are likely to occur more frequently, affecting ecosystems, communities and public safety,” Falk said. “These will be billion-dollar fire years. We’re just not ready for fire impacts of this kind, including post-fire effects from flooding after fire.”
The total cost of the 2017 fires in California alone is projected to exceed $180 billion. This includes not only the immediate costs of firefighting, but also the much larger costs, including:
Landscape rehabilitation;
Medical and hospital costs;
Insurance losses and the costs of replacing thousands of homes and other buildings;
Lost economic productivity from the destruction of businesses;
Repair and replacement of key infrastructure such as roads, power lines and dams; and
Weeks of lost income by employees.
Across the U.S., public land managing agencies are being stretched to their limits by the current scale of wildfire. The U.S. Forest Service spends more than half of its entire budget on wildfire response, leaving little for other key elements of its mission such as recreation, ecosystem restoration, research and public education.
Knowing about future regional variation in the projected annual area burned can help land managers and policy makers prepare for the possibility of extremely large fire years. Falk pointed out that seasonal climate changes also are having the effect of making the fire season longer, so there is additional time for more acreage to burn. In years when seasonal climate drives lengthy fire seasons, fire management resources may be stretched to the limit.
“Wildfires act as a multiplier of other forces such as climate change, exposing more and more areas not only to the immediate effects of fire, but also to the resulting cascade of ecological, hydrological, economic and social consequences,” Falk said. “We hope that this research will be a wake-up call to public agencies and legislatures at all levels of government that the fire problem is not going to get any smaller in coming decades.
“If anything, we need a serious, fact-based national dialogue about how to sustain our forests and woodlands through smart management and policy.”
In Western Arizona and Southern California plants are greening up weeks earlier than usual
Spring has started to arrive in the southwest and southeast states. In southern Florida, spring is right on time compared to a long-term average (1981-2010), but parts of Texas, Louisiana, and northern Florida are one week late. In southern California and southwestern Arizona, spring is arriving 1-2 weeks early.
The timing of leaf-out, migration, flowering and other seasonal phenomena in many species is closely tied to local weather conditions and broad climatic patterns.
An early greenup, depending on weather later in the season, could mean herbaceous plants will become dormant and cure out earlier, which may result in a wildfire season in the lower elevations that begins sooner than average.
Pollution from fossil burel-burning sources is decreasing but the air is getting dirtier during the wildland fire season.
As a long and brutal fire season in California starts to wind down, Climate Central issued a report that lays out links between climate change, wildfire, and health effects. The report, titled Western Wildfires Undermining Progress on Air Pollution, analyzes air quality trends from 2000 through 2016 in two large California air basins — the Sacramento Valley and the San Joaquin Valley — that are heavily affected by pollution.
The report finds that while the air quality continues to improve as pollution from power plants, trucks and other fossil fuel-burning sources declines, it is getting dirtier during the fire season. Studies have shown that fire seasons in the West are getting longer and that more large wildfires are breaking out as temperatures rise.
“We focused on an especially bad actor called “fine particulate matter”, or PM2.5 — particles that can reach deep into the lungs and exacerbate a wide array of health problems such as asthma, heart disease, and premature birth. A lot of hard work has been done to decrease PM2.5 from other sources, so it’s troubling to see progress getting undercut by wildfires — and to know that a warming climate will likely have wildfires becoming more frequent and burning more area in California and the West,” said Todd Sanford, Ph.D. scientist with Climate Central.
