Researchers find the current Western drought is worst in 1,200 years

It is intensified by climate change

low water level drought Lake Powell, Glen Canyon National Recreation Area
The public launch ramp at Antelope Point in late March, 2021 at Lake Powell, Glen Canyon National Recreation Area. NPS photo.

New research published this month shows that the current drought in the Western United States is the worst seen in data going back to the year 800. Scientists developed estimates of precipitation during previous centuries using tree-ring reconstruction and found 2000–2021 was the driest 22-year period in the last 1,200 years.

Precipitation, temperature, and vapor pressure anomaly, 2000 to 2021
Observed climate anomalies. Anomalies in water-year (WY: October–September) (a) precipitation total, (b) temperature, and (c) vapour-pressure deficit (VPD). Maps on left show the average WY anomaly during 2000–2021. Yellow box: Southwestern North America (SWNA) study region. Anomalies are relative to 1950–1999. Time series on right show regionally averaged WY anomalies in SWNA (black) annually and as (red) 22-year running means visualized on the final year in each 22-year period. Geographic boundaries in maps were accessed through Matlab 2020a. From the paper.

Since the year 2000, southwestern North America (SWNA) has been unusually dry due to low precipitation totals and heat, punctuated most recently by exceptional drought in 2021. From 2000 to 2021, mean water-year (October– September) SWNA precipitation was 8.3 percent below the 1950–1999 average and temperature was 0.91 °C above average.

In summer of 2021, water levels at Lakes Mead and Powell, both on the Colorado River, reached their lowest levels on record, triggering unprecedented restrictions on Colorado River usage, in part because the 2-year naturalized flow out of Colorado River’s upper basin in water-years 2020–2021 was likely the lowest since at least 1906. Despite an active North American monsoon in 2021, the United States Drought Monitor classified more than 68 percent of the western United States as under extreme or exceptional drought for nearly all of July–October, 2021.

Soil moisture, 800 to 2021
Extended drought events. Summer soil moisture anomalies, expressed as standard deviations from the 800–2021 mean (σ), during the longest 8 extended drought events during the 800–2021 study period. The pink background bounds the years of each extended drought event. The horizontal dotted black line represents the 800–2021 mean. For the first 7 droughts shown, soil moisture anomalies come from our tree-ring reconstruction. For the final drought (2000–2021), anomalies come from our observation-based record. From the paper.

The researchers concluded that anthropogenic climate change accounts for 42 percent of the SWNA soil moisture anomaly in 2000–2021 and 19 percent in 2021.

Drought can have a very significant effect on wildland fire behavior. It affects vapor pressure deficit (VPD), soil moisture, relative humidity, and moisture in live and dead vegetation, or fuels. VPD is an absolute measure of the moisture deficit of the atmosphere and is more closely related to water stress on vegetation than relative humidity.

Soil moisture is a particularly important integrator of drought. Of all 22-year periods since 800, only two (1130–1151 and 1276–1297) contained more years with negative soil moisture anomalies than the 18 observed during 2000–2021.

The authors wrote that the 22-year long current drought is highly likely to continue through a 23rd year.

Percent of US with extreme or exceptional drought, 2000 to 2022
Extreme and exceptional drought in the western United States (US). Weekly percentage of western continental United States (west of 103°W) classified by the United States Drought Monitor (USDM) as under extreme or exceptional drought from January 1, 2000 to December 28, 2021. Calculations were made form weekly shapefiles of USDM drought classifications, available at as of January 9, 2022. The USDM is developed by the National Drought Mitigation Center (NDMC), the U.S. Department of Agriculture (USDA) and the National Oceanic and Atmospheric Administration (NOAA). From the paper.

The research was conducted by A. Park Williams, Benjamin I. Cook, and Jason E. Smerdon.

Extreme wildfires may increase 14 percent by 2030, United Nations warns

Airport Fire near Bishop, Calif.
Airport Fire near Bishop, California Feb. 16, 2022. CAL FIRE photo.

Climate change and land-use change are projected to make wildfires more frequent and intense, with a global increase of extreme fires of up to 14 percent by 2030, 30 percent by the end of 2050, and 50 percent by the end of the century, according to a new report by the United Nations Environment Program (UNEP) and GRID-Arendal.

The study calls for a radical change in government spending on wildfires, shifting their investments from reaction and response to prevention and preparedness.

In the report, wildfire is defined as “an unusual or extraordinary free-burning vegetation fire which may be started maliciously, accidently, or through natural means, that negatively influences social, economic, or environmental values”.

The study, Spreading like Wildfire: The Rising Threat of Extraordinary Landscape Fires (117 MB), finds an elevated risk even for the Arctic and other regions previously unaffected by wildfires in recent centuries. The publication calls on governments to adopt a new “Fire Ready Formula”, with two-thirds of spending devoted to planning, prevention, preparedness, and recovery, with one third left for response. Currently, direct responses to wildfires typically receive over half of related expenditures, while planning receives less than one per cent.

To prevent fires, the authors call for a combination of data and science-based monitoring systems with indigenous knowledge and for a stronger regional and international cooperation.

“Current government responses to wildfires are often putting money in the wrong place. Those emergency service workers and firefighters on the frontlines who are risking their lives to fight forest wildfires need to be supported”, said Inger Andersen, UNEP Executive Director. “We have to minimize the risk of extreme wildfires by being better prepared: invest more in fire risk reduction, work with local communities, and strengthen global commitment to fight climate change”.

Wildfires disproportionately affect the world’s poorest nations. With an impact that extends for days, weeks and even years after the flames subside:

· People’s health is directly affected by inhaling wildfire smoke, causing respiratory and cardiovascular impacts and increased health effects for the most vulnerable;

· The economic costs of rebuilding after areas are struck by wildfires can be beyond the means of low-income countries;

· Watersheds are degraded by wildfires’ pollutants; they also can lead to soil erosion causing more problems for waterways;

· Wastes left behind are often highly contaminated and require appropriate disposal.

Wildfires and climate change are mutually exacerbating. Wildfires are made worse by climate change through increased drought, high air temperatures, low relative humidity, lightning, and strong winds, which causes hotter, drier, and longer fire seasons. At the same time, climate change is made worse by wildfires, mostly by ravaging sensitive and carbon-rich ecosystems like peatlands and rainforests. This turns landscapes into tinderboxes, making it harder to halt rising temperatures.

Wildlife and its natural habitats are rarely spared from wildfires, pushing some animal and plant species closer to extinction. A recent example is the Australian 2020 bushfires, which are estimated to have wiped out billions of domesticated and wild animals.

The report said the restoration of ecosystems is an important avenue to mitigate the risk of wildfires before they occur and to build back better in their aftermath. Wetlands restoration and the reintroduction of species such as beavers, peatlands restoration, building at a distance from vegetation, and preserving open space buffers are some examples of the essential investments into prevention, preparedness and recovery.

Wildfire factors influencing health
Wildfire smoke contains fine particulate matter and potentially toxic combustion products (the latter can be particularly harmful at the wildlandurban interface where waste and rubbish, materials used in buildings and vehicles are often burnt; Hallema et al. 2019). From the report.

The report concludes with a call for stronger international standards for the safety and health of firefighters and for minimizing the risks that they face before, during and after operations. This includes raising awareness of the risks of smoke inhalation, minimising the potential for life-threatening entrapments, and providing firefighters with access to adequate hydration, nutrition, rest, and recovery between shifts. Women firefighters face various challenges ranging from gender discrimination and sexual harassment to ill-designed equipment and protective clothing that puts them at greater risk of injury.

Human Health Exposure wildfire smoke health effects
Smoke particulate exposure pathways and impacts. Smoke exposure is most commonly measured from land-based air pollutant monitors, followed by satellite-based imagery models, with fewer studies measuring personal exposure to smoke (Liu et al. 2015). From the report.

Smoke associated with deforestation fires in the Brazilian Amazon has been found to be responsible for the premature death of almost 3,000 people annually (95 percent percentile confidence interval: 1,065–4,714), demonstrating the regional scale of fire impacts (Reddington et al. 2015).

Our take

The report predicts a global increase of extreme fires of up to 14 percent by 2030 and 30 percent by the end of 2050. The statistics for the United States from the National Interagency Fire Center since the 1980s indicates that the total acres burned and the average size of wildfires has been far exceeding those rates of increase. The data, which does not include Alaska since those fires are managed far differently from the rest of the US, shows during the forty-year period approximately a 400 percent increase in the average size by decade, and more than a 300 percent growth in the total acres burned each year. The statistics for the US are for all fires, not just those that “negatively influence social, economic, or environmental values.”

Average size of US wildfires by decade

Another factor that may influence the size of fires in the US is that some wildfires are not totally suppressed and can be herded around to attempt to protect private land, structures, and certain resources. They may burn for months, and occasionally grow far beyond what was expected. The use of a limited suppression strategy can be to allow fire to be reintroduced to replicate natural conditions and reduce fuels. Or in recent years it could be due to extreme fire activity in the Western US and a shortage of firefighting resources as a result of difficulties in hiring, retention and recruitment.

Total wildfire acres

Thanks and a tip of the hat go out to Rick and Tom.

Fires around the world “have grown weirder”

Williams Fork Fire southwest of Fraser, CO
Smoke column from the Williams Fork Fire southwest of Fraser, Colorado, Aug. 15, 2020. USFS photo by Lauren Demos.

The Guardian has an excellent long-form article about wildland fires, titled ‘A deranged pyroscape’: how fires across the world have grown weirder. Author Daniel Immerwahr writes that in banishing fire from sight, we have made its dangers stranger and less predictable. He writes about fires around the world, pyrophobia, indigenous fire, and how hundreds of thousands die each year from such smoke-related maladies as strokes, heart failure and asthma.

Toward the end of the article he writes about fires in Indonesia where forests have been drained, burned, or clear cut, then summarizes.

Here is an excerpt:

…No single one of Indonesia’s many fires in recent decades has been especially noteworthy. But altogether they’ve been cataclysmic. In 1997, a dense haze of airborne particulates from Indonesia’s fires was perceptible as far as the Philippines and Thailand. That year, on Sumatra – centre of Indonesia’s fires – a commercial plane crashed due to poor visibility and killed all 234 aboard. The next day, two ships collided off the coast of Malaysia for the same reason, and 29 crew members died.

The economist Maria Lo Bue found that Indonesians who were toddlers during the 1997 haze grew less tall, entered school six months later and completed almost a year less of education than their peers. Another economist, Seema Jayachandran, found that the fires “led to over 15,600 child, infant and fetal deaths”, hitting the poor especially hard.

Picture a dangerous fire and you’re likely to imagine a thicket of tall trees blazing in a drought-stricken climate. But a more accurate image is smoldering peat or scrub burning by a tropical logging road. The real threat isn’t catching fire, but the slow violence of breathing bad air. You’ve got a hacking cough, your father suffers a stroke and you watch your daughter – short for her age – leave school a year early.

Fire is not in itself a bad thing. Many landscapes, built to burn, simply couldn’t exist without regular fires, either natural or intentional. Though foresters once sought to tamp blazes out everywhere, we now recognise that as a grave mistake. A fireproof planet isn’t something we can get, or should even want.

We badly need a healthier relationship to combustion. Rather than erratic, runaway fires, we need regular, restorative ones, like we used to have. Our forebears didn’t shun flame – they were relentless fire-setters. But they adhered to two important limits. First, they fed their fires with living vegetation, which reclaims lost carbon as it regrows. Second, they were guided by long-acquired experience with fire’s complex paths and consequences.

We’ve blasted far past both of those limits. We’re now burning fossilized vegetation, which sends carbon on a one-way trip to the warming atmosphere. And we’re kindling fires that bear little resemblance to the ones we’re used to. There’s no generational wisdom telling us what to do when we drain the peatlands of Central Kalimantan or let dry fuel pile up precariously in the California countryside, all while raising the temperature to hitherto unrecorded heights.

Books about fire typically end with prescriptions: we must invest in science, reclaim lost cultural knowledge, burn intentionally, build resiliently, and power our grids renewably. All that is true, surely. But given how complex fire is, and how unprecedented nearly everything we’re doing with it is, the best advice would seem to be: slow down. We have scrambled our landscape, changed our energy diet, altered the climate and revised our relationship to flame, all in a very short time. It’s not a surprise that fire, once a useful if obstinate companion to our species, has now slipped our grasp.

The world won’t burn up, as we sometimes imagine. But the fires of tomorrow will be different from those of yesterday, and we’re racing headlong into that unsettling future, burning tankfuls of gas as we go.

Thanks and a tip of the hat go out to Tom.

New research links Australia’s forest fires to climate change

Shows climate change has driven a significant increase in Australia’s forest fire activity over the last three decades

Climate change factors, wildfire weather and activity
Climate change factors, wildfire weather and activity. From the research.


A lengthening of the fire season towards Autumn and Winter was identified, along with an increase in fire activity in cooler and warmer regions including alpine forests in Tasmania and tropical rainforests in Queensland.

The research published in Nature Communications is the first of its kind and combines analysis of previous forest fire sites with eight drivers of fire activity including climate, fuel accumulation, ignition, and management (prescribed burning).

Thirty-two years of satellite data and 90 years of ground-based datasets from climate and weather observations, and simulated fuel loads for Australian forests, formed the basis of the research, which allowed researchers to identify climate change driven increases versus natural variability.

CSIRO scientist, Dr. Pep Canadell, said the research was one of the most extensive studies of its kind performed to date, and was important for understanding how continued changes to the climate might impact future fire activity.

“While all eight drivers of fire-activity played varying roles in influencing forest fires, climate was the overwhelming factor driving fire-activity,” Dr Canadell said.

“The results also suggest the frequency of forest megafires are likely to continue under future projected climate change.”

Over the last 90 years, three of the four mega fire years occurred after the year 2000. A mega fire year is defined as the cumulative burned area of forest over one year of more than 1 million hectares.

Australia’s mean temperature has increased by 1.4 degrees Celsius since 1910, with a rapid increase in extreme heat events, while rainfall has declined in the southern and eastern regions of the continent. Globally fire activity is decreasing, however, the extent of forest fires in Australia is increasing.

Whole of continental Australia including Tasmania
Burned area, whole of continental Australia including Tasmania, linear fit. From the research.

When comparing the first half (1988 – 2001) with the second half (2002-2018) of the record studied, the research showed that the average annual forest burned area in Australia increased 350 per cent, and 800 per cent when including 2019.

Comparing the same time period, the research showed a five-fold increase in annual average burned area in winter and a three-fold increase in Autumn, with Spring and Summer seeing a ten-fold increase.

“In Australia, fire frequency has increased rapidly in some areas and there are now regions in the southeast and south with fire intervals shorter than 20 years. This is significant because it means some types of vegetation won’t reach maturity and this could put ecosystems at risk,” Dr Canadell said.

“Understanding these trends will help to inform emergency management, health, infrastructure, natural resource management and conservation.”

Bushfire. Courtesy of CSIRO.

The research was conducted by J. G. Canadell, C. P. Meyer, G. D. Cook, et al.

Acres burned in lower 49 states in 2021 was more than average

Eight percent higher than the average of the previous 10 years

Updated Feb. 2, 2022

Total wildfire acres

The number of acres that burned in the United States in 2021 according to the annual report from the National Interagency Fire Center, was more than the average of the previous 10 years. The 6,872,286 acres in the lower 49 states is 8 percent higher than the average of the previous 10 years, and 33 percent above the average in the decade before that, 2001 – 2010.

This is contrary to statements from some fire officials in December who said fewer than average acres had burned. That is only correct if Alaska is counted. When it is, the numbers can be misleading. Alaska is a huge state with a very low population for its size. Many fires there burn far from any structures or private property and are not suppressed. On some fires the only action taken is “point protection,” just keeping a small village or single cabin from burning. A fire can burn hundreds of thousands of acres over a period of months with few if any firefighters assigned.

Alaska acres burned

The burned area in Alaska varies wildly from year to year, for example, about 62,000 acres in 2008 and more than 5,000,000 in 2015. In 2015 more acres burned there than in the other 9 geographic areas combined. (Alaska is it’s own geographic area. Map.) However, so far this year, Alaska has ranked only third in number of acres burned in geographic areas, outranking only the Rocky Mountain and Eastern Areas. Including the Alaska numbers in a calculation of fire activity in the 50 states is misleading and can radically skew statistics.

Fires continue to grow larger

The average size of fires 2021 was the fifth largest in the last 36 years. Since 1984 the six years with the highest average size have all occurred in the last 11 years, according to the available reliable data from the National Interagency Fire Center after 1984.

Average Wildfire Size

The total number of fires is on a downward trend

The number of fires in 2021 was the sixth lowest in the last 36 years.

Number of wildfires

All of the statistics for 2021 are from the annual report for 2021 published by the National Interagency Fire Center. Data from previous years also came from NIFC.

Scientists confirm that nighttime wildfire activity is increasing

Firefighting agencies need to make changes to deal with the the new normal

Day-night proportion of fire activity
Fig. 9 from the study below showing the proportions of heat detected on wildfires at night, vs. during the day. The MODIS (black) time series spans 2003–2020 and the VIIRS (red) time series spans 2012–2020. The horizontal dotted line at 28% indicates the CONUS-wide value detected by MODIS from 2003–2020.

In a study of wildfires in the conterminous United States from 2003 to 2020 researchers found that while fire activity increased during the day in the 18-year period, it increased even more at night.

Heat sensing data from satellites showed significant increasing trends in nighttime wildfire fire activity, with a +54%, +42% and +21% increase in the annual nighttime sum of Fire Radiative Power (FRP), annual nighttime active fire pixel counts, and annual mean nighttime per-pixel values of FRP, respectively, in the latter half of the study period. Activity during the day increased also, with rates of +36%, +31%, and +7% respectively.

Analysis of coincident 1000-hour fuel moistures indicated that as fuels dried out, satellites detected increasingly larger and more intense wildfires with higher probabilities of nighttime persistence.

The information above is from the study “Large wildfire driven increases in nighttime fire activity observed across CONUS from 2003–2020,” by Patrick H. Freeborn, W. Matt Jolly, Mark A. Cochrane, and Gareth Roberts.

Average wildfire size, US, 1985-2000 (except Alaska)

The reason wildfires typically exhibit less activity at night is due to diurnal changes in weather. Nighttime generally brings lower temperatures, higher relative humidity, decreasing winds, and higher fuel moistures in light fuels.

But a warming climate with occasional multi-year droughts and higher temperatures can lead to nighttime higher temperatures and lower humidities. Drought will lower the fuel moistures in live and dead vegetation. These changes can result in fuels at night remaining available for significant and continuous fire spread. This is causing wildfires to burn with more intensity, spread more quickly, and have more resistance to control 24 hours a day.

Annual temperature change

About 15 to 20 years ago firefighters could usually count on wildfire activity slowing significantly at night as long as the wind was not extreme. Night shift crews could make good progress constructing direct fireline near the edge of fires. In the last few years weather and fuel conditions that permit direct attack by ground personnel, day or night, are less common. Fires are getting larger. Megafires that blacken 100,000 acres are no longer rare.

So now what?

As fires show increasing resistance to control we need to ramp up our fuel treatments, including prescribed fires, by a factor of 10. Less than full suppression of carefully selected fires when the season-ending weather event is on the horizon can have a place also, if they are very carefully planned and actively tracked and managed using all of the predictive tools available run by very smart, experienced personnel.

We also need to realize that we will never be able to prevent all wildfires from burning into populated areas, so property owners must realize they have to live with fire, using FireWise principles. Here are six things that need to be done to protect fire-prone communities.

And, community destruction during extreme wildfires is a home ignition problem. Here is an excerpt from the article written by Jack Cohen and Dave Strohmaier:

Uncontrollable extreme wildfires are inevitable; however, by reducing home ignition potential within the Home Ignition Zone we can create ignition resistant homes and communities. Thus, community wildfire risk should be defined as a home ignition problem, not a wildfire control problem. Unfortunately, protecting communities from wildfire by reducing home ignition potential runs counter to established orthodoxy.

We also have to realize that the fire suppression manpower staffing model that was created 50 years ago is obsolete. The agencies that fight wildfires, especially the federal agencies, need to increase the numbers of Interagency Hotshot Crews and engine crews. The crews must be configured and managed to allow personnel to have a reasonable amount of down time at the home unit even during the busiest times of the fire year. They can’t be away from home 90 percent of the time and expect to have a decent work/life balance. One National Forest will begin a pilot program in 2022 increasing the sizes of Hotshot and Engine crews to 30 and 10 people, respectively. This is intended to improve work/life balance and increase the availability of resources.

The reforms in the just-passed infrastructure bill to improve the pay and working conditions of firefighters must be implemented immediately. Slow-walking those improvements, a tactic too often used by the Federal agencies, should not be tolerated.

Technology needs to be adopted to make firefighting more safe and efficient. Firefighters down to the crew supervisor level should have access to real time data about the location of the fire and other firefighting resources 24 hours a day. Communications capabilities need to be robust and bomb proof.

On the afternoon of November 16, 2021 we initiated a 24-hour online poll on Twitter, asking for firefighters’ observations about nighttime wildfire activity.