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The Climate Context Behind the Deadly Arizona Wildfire

The deadly Yarnell Hill Fire continued to rage out of control on Monday, a day after the flames fanned by erratic winds and temperatures topping 100°F overwhelmed a team of elite firefighters, killing 19 of the 20-member crew. The fire has burned about 200 homes and has burned through at least 8,400 acres — more than quadrupling in size since it began on June 28, according to news reports.

The deaths of the Prescott, Ariz.-based “Granite Mountain Hotshots” was the worst wildland firefighting disaster since a 1933 wildfire killed 25 firefighters in Los Angeles. It was the largest loss of firefighters in the U.S. since the September 11 terrorist attacks. Until Sunday, Arizona had suffered 22 wildland firefighting deaths since 1955, according to the National Interagency Fire Center.

Yarnell Hill Fire from Congress, Ariz., from Matt Oss on Vimeo.

A lightning strike is the suspected cause of the blaze, and a brutal heat wave in the West, combined with bone-dry conditions, likely aided its spread. The high temperature at Prescott on Sunday was in the triple digits. The forecast for Monday called for high temperatures to hover near the century mark, with continued low humidity.

Thunderstorms near the fire are a suspected cause of the erratic behavior of the flames on Sunday, when the firefighting crew was forced to deploy their last-resort fire shelters to try to deflect the flames.

The Yarnell Hill fire, like other wildfires in the West right now, is taking place in the context of one of the most extreme heat waves on record in the region, as well as a long-running drought. While the contributors to specific fires are varied and include natural weather and climate variability as well as human factors, such as arson, a draft federal climate report released in January found that manmade climate change, along with other factors, has already increased the overall risk of wildfires in the Southwest.

And projections show that the West may be in for more large wildfires in the future. Climate models show an alarming increase in large wildfires in the West in coming years, as spring snowpack melts earlier, summer temperatures increase, and droughts occur more frequently or with greater severity.

Statewide temperature trends in Arizona since 1920, with the post 1970 trend line drawn as well.
Click image to enlarge. Credit: Climate Central.

In Arizona, the current drought, combined with the regional heat wave, has created extremely dangerous wildfire conditions. Three quarters of the state of Arizona is experiencing “severe” to “exceptional” drought conditions, according to the latest U.S. Drought Monitor. In neighboring New Mexico, conditions are even more dire, with about 45 percent of the state experiencing “exceptional” drought, the worst-possible category.

Long-running precipitation deficits, including a below-average winter snowpack, have led to extremely dry soil moisture conditions in Arizona and New Mexico, in particular, and in other states across the West.

In recent years, the Southwest has trended toward drier and warmer conditions, which is consistent with climate-model projections that show that the region may become more arid in the coming decades, due in large part to manmade global warming. In fact, Arizona was the fastest warming state in the contiguous U.S. since the mid-1970s, with average surface temperatures increasing by 0.72°F per decade since 1970.

Other contributors to wildfire trends include the consequences of decades of fire-suppression policies, which have left many forests with large amounts of vegetation to serve as fuel for wildfires. Another factor is population growth, and more specifically, development that has taken place at the edge of areas that have a history of wildfires, known as the “wildland-urban interface.” 

Compared to an average year in the 1970s, during the past decade there were seven times more fires greater than 10,000 acres each year in 11 Western states, and nearly five times more fires larger than 25,000 acres each year, according to Climate Central research.

Trends in large wildfires (greater than 1,000 acres) in Arizona, between 1970-2011.
Click image to enlarge. Credit: Climate Central.

Due to a combination of drought and record heat, 2012 saw one of the most destructive wildfire seasons on record, with 9.3 million acres going up in flames, the third-highest since 1960.

Over the shorter-term, firefighters battling the blaze may face more extreme heat through midweek, when temperatures may moderate slightly. Monthly and all-time temperature records have already been set across the West, including a high temperature of a scorching 129°F at Death Valley, Calif., on Sunday. That tied the all-time U.S. record for the highest temperature on record for the month of June, and came close to tying the record for the world’s hottest temperature, which is 134°F, set in Death Valley in 1913.

In Phoenix, even the overnight lows have been toasty, with an overnight low temperature of 91°F on June 30, for example, which tied the record-high minimum temperature for the date.

While individual heat waves have ties to short-term natural weather variability, increasingly common and intense heat waves are one of the most well-understood consequences of manmade global warming, since as global average surface temperatures increase, the probability of extreme heat events increases by a greater amount.

The heat this week poses a formidable obstacle for firefighters, since it affects wildfire behavior as well as human health. Heat is the No.1 weather-related killer in the U.S., according to the National Weather Service.

Editor's Note: This story has been updated to incorporate one more year's worth of temperature data in the U.S.

Related Content
Deadly Heat Wave Continues in West; Wildfire Danger High
The Age of Western Wildfires
Heat Wave May Threaten World's Hottest Temp. Record
Global Warming Behind Australia's 'Angry Summer': Study
Hansen Study: Extreme Weather Tied to Climate Change
8 Images to Understand the Drought in the Southwest

Comments

By Eric Peterson (Front Royal, VA 22630)
on July 1st, 2013

Some broader context can be found scientific papers such as this: http://www.fs.fed.us/rm/pubs/rmrs_gtr292/1990_swetnam.pdf They basically point out that the area burned (total in New Mexico and Arizona) varies considerably but tends to follow ENSO (El Nino means less fire and La Nina more).  In this context with orders of magnitude variation in fire (e.g. in figure 4), the “Arizona Fires on the Rise” chart above can be seen as a minor blip.

Reply to this comment

By Andrew
on July 1st, 2013

Eric - The bottom line is that the climate is a significant control knob governing Western wildfires. As a driver of climate variability in the West, ENSO is a factor, but assigning all of the variability to ENSO, or assuming that ENSO is the major driver and human influences are minor, are both problematic when you examine wildfire data.

Reply to this comment

By Len Conly (Berkeley/CA/94706)
on July 2nd, 2013

What do people expect?  The Arctic ice will be gone in a few years.  If you leave the door of your refrigerator open all day, do you expect the food to stay cold?  The melting of the Arctic ice is bound to have serious consequences.

This is going to get grimmer and grimmer every day.  In an ideal world we would have done a time out on fossil fuel use 20 years ago.

Reply to this comment

By Leslie Graham
on July 2nd, 2013

The figure 4 graph you cite only goes to 1985.
The highest figure on the “Arizona Fires on the Rise”  chart is in 2010 - an El Nino year.
Now that climate change is simply obvious the denial has become hysterical.
Get over it Eric. Global warming is here now. We don’t have time to debate with the Flat Earth Society any longer.

Reply to this comment

By Mike Abbott (Phoenix, AZ)
on July 2nd, 2013

Andrew writes: “In Phoenix, even the overnight lows have been toasty, with an overnight low temperature of 91°F on June 30, for example, which tied the record-high minimum temperature for the date.”

This is a perfect example of the Urban Heat Island effect; the official Phoenix temperature readings are taken at Sky Harbor Airport. What this has to do with rural wildfires I don’t know.

Secondly, I don’t know where you got the data for your “Arizona Fires on the Rise” chart, but according to the National Interagency Fire Center, the years with the lowest number of AZ wildfires since 2002 were 2012, 2011, 2010 and 2008 at under 2,000 fires each year. From 2002 through 2006, the annual number of fires ranged from 2,602 to 4,027. See http://www.nifc.gov/fireInfo/fireInfo_statistics.html.

Thirdly, I don’t know how you can detect a global warming fingerprint in wildfire statistics when, according to the same source mentioned above, 75%-80% of all wildfires are caused by humans (arson, campfires, cigarette butts, etc.)

Reply to this comment

By Jim Daly (St.Paul, MN 55104) (St Paul,MN 55104)
on July 2nd, 2013

There is an oscillation about a mean that affects weather events as well as short term trends. Control knobs are multiple, significant, and chaotic. Ignoring the past provides an incomplete understanding of the present. Temperature is not energy. Low humidity is a factor in high temperatures, yet this high temperature air energy content is low.

Reply to this comment

By Jack Wolf (Pittsburgh/Pa/15142)
on July 2nd, 2013

...we can not dedicate, we can not consecrate, we can not hallow this ground. The brave men, living and dead, who struggled here, have consecrated it, far above our poor power to add or detract. The world will little note, nor long remember what we say here, but it can never forget what they did here. It is for us the living, rather, to be dedicated here to the unfinished work which they who fought here have thus far so nobly advanced. It is rather for us to be here dedicated to the great task remaining before us—that from these honored dead we take increased devotion to that cause for which they gave the last full measure of devotion—that we here highly resolve that these dead shall not have died in vain—that this nation, under God, shall have a new birth of freedom—and that government of the people, by the people, for the people, shall not perish from the earth.

Nero is fiddling as the west burns.

Reply to this comment

By Dave
on July 2nd, 2013

Spring 2013 had one of the lowest wildfire totals in a decade.  According to the National Interagency Fire Center, there were 13,115 fires between January 1st and May 3rd of this year, which burnt a total of 153,277 acres — about half as much as burned last year. This is lowest spring for wildfires since 2004, according to NIFC.

So your theory is that climate change had a negative effect this spring and is having a positive effect this summer?

Here’s a much more scientific statement. Climate change has had no effect on wildfires in 2013.

 

Reply to this comment

By Camburn (North Dakota)
on July 2nd, 2013

Historical context in ref to wildfires shows that the suppression of fire because of proximity to dwellings has resulted in a tinder box that will burn with great intensity.

When one looks at the great droughts that have been common in the SW, the one during the 1400-1650 time frame comes to mind.  Temps, according to proxy data, were higher than present over extended periods of time.  The droughts were so severe that they displaced the Native Americans living in the area.

Climate change is a catch all as the climate has never been static in the world we live in.  We are still well within the variations of the Holocene period, the response to the solar maximum from the mid 1850’s to the late 1900’s is very evident in the temperature record. 

The meandering jet streams are a result of the UV and EUV variation within the TSI.  This has been well documented as of late because of satellite measurements allowing scientists to make a reliable proxy base for extended periods of sun activity and changing climate patterns.

Just as the eastern 2/3 of the USA is experiencing temps of 2-4C below normal, the west is experiencing temps above normal as a result of the meandering jet stream.

Herschel wrote a paper in the early 19th century about the ties to wheat prices and sun activity.  He did not know the cause, but he very clearly demonstrated the result.

Climate change is with us as it has always been.  It is up to man to actually mitigate the change to himself using proper methods of letting fires burn and not allowing building near known fire zones.

To do otherwise is foolish.

Reply to this comment

By Bob Berwyn (Frisco CO 80443)
on July 2nd, 2013

As a climate, forest and wildfire reporter, I’m not comfortable with putting these firefighter deaths into a global warming context. Just sayin ...

Reply to this comment

By PETER D CAPEN (Tacoma, WA 98406)
on July 2nd, 2013

Despite a lengthy two-page article in today’s New York Times, there was no mention whatsoever in the piece of any link between climate change, the ferocity of the Yarnell Hills Fire, and the growing heat and drought conditions in the Southwest.  Once again the American mainstream media has failed to “connect the dots” for the reader, so it is little wonder that the public remains confused about global warming, its implications for the future, and what can be done to begin to address it.  The article points up how distant the gap has become from science and the press.  Global warming is like a victim being tortured on the rack, one click at a time.  He prays for release from his agony, but knows he is probably going to die.

Reply to this comment

By Andrew
on July 2nd, 2013

Bob - I tried to put the wildfire itself, and the spate of fires amid this highly unusual heat wave, into a global warming context, not the tragic deaths per se. I’m curious to know your thoughts/feelings in more detail though, as someone who does great reporting on the mix of forces at work in the West these days.

Reply to this comment

By Bob Berwyn (Frisco CO 80443)
on July 2nd, 2013

Andrew, I don’t know exactly, and I’m not faulting you for writing the story the way you did. When I break the story down, I think every theme and graph stands on its own as being accurate. I’ve frequently reported on many of the same topics. I don’t think there’s any question that we’re going to see more frequent, larger and more intense fires. I think I’m just squeamish about placing these deaths in this context. I think the bigger questions in this case are related to land-use planning and wildfire-fighting policy. Keep up the good work!

Reply to this comment

By Camburn (North Dakota)
on July 2nd, 2013

To put the actual current climate in perspective, one has to examine the paleo data.

The current drought is an extremely mild drought in this area.

http://www.ncdc.noaa.gov/paleo/drought/images/grissno.jpg

Reply to this comment

By Fire Climate (Washington, DC 20035)
on July 3rd, 2013

Andrew,

You and others at Climate Central (and the 2013 Draft National Climate Assessment) have previous covered one important criteria that frequently gets lost in the discussion: the largest or most severe fires do not necessarily occur with the most prolonged or intense droughts. 

In most vegetation types other than dense forests, a period of above normal precipitation that is followed by drought, can lead to larger and more severe wildfires. Precipitation stimulates the growth of grasses and shrubs, which then dry out to carry fire even in some of the driest ecosystems (yes, even in Death Valley).  While “forest fires” are implicated in the worst wildland fires, a good many deadly fires do not actually occur in forested lands, and more lands in the West are shrublands or woodlands than forests.  Thus, fuel other than forest or forest residue carry the fire and enable the fire to spread.

In a worst case scenario, drought (or other conditions e.g., snow damage, frost kill, insects or disease) may have caused mortality of trees and shrubs, a short period of herbaceous growth that subsequently dies back builds a continuous fuel bed, and then a more intense drought follows, capped by a extreme fire weather event, e.g., “dry thunderstorms” that are accompanied by strong downdrafts or the passage of a dry cold front. 

This scenario has been repeated in a number of the more deadly fires since the late 1970s and especially since the mid 1990s.  So, alternating wet and dry periods, rather than simply a long series of dry years, might be more worrisome for much of the West.

In my opinion, climate variability and vegetation shifts that might accompany climate change should be of most concern to land managers and folks who live in the West.  Once vegetation has adapted to a new climate, wildland fire conditions will be more stable or at least more predictable. But, change doesn’t happen all at once or uniformly.

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