By Dr. Jeff Masters, Weather Underground

The Exceptional U.S. Wildfire Season of 2012

The 2012 U.S. fire season was the 3rd worst in U.S. history, with 9.2 million acres burned–an area larger than the state of Maryland. Since the National Interagency Fire Center began keeping records in 1960, only two years have seen more area burned–2006, when 9.9 million acres burned, and 2007, when 9.3 million acres burned. Although the 2012 fire season was close to a record for most acreage burned, the total number of fires–55,505–was the lowest on record, going back to 1960, said scientists at a December 2012 press briefing at the American Geophysical Union meeting in San Francisco. The average U.S. fire size in 2012 was the highest on record. A September 18, 2012 report, The Age of Western Wildfires, published by the non-profit research group Climate Central, found that the number of large and very large fires on Forest Service land is increasingly dramatically. Compared to the average year in the 1970s, during the past decade there were seven times as many fires larger than 10,000 acres each year, and nearly five times as many fires larger than 25,000 acres. On average, wildfires burn twice as much land area each year as they did 40 years ago, and the burn season is two and a half months longer than 40 years ago. The increase in large fires is correlated with rising temperatures and earlier snow melt due to climate change, but fire suppression policies which leave more timber to burn may also be a factor.

The Top 5 U.S. Wildfires of 2012

Whitewater-Baldy Complex Fire, New Mexico: Largest fire in New Mexico history

The Whitewater-Baldy Complex Fire started as two fires that merged, both caused by lightning. The Whitewater fire was first detected on May 16th, and the smaller Baldy fire was detected a few days earlier on May 9th. These fires then merged on May 24th and together burned a total of 297,845 acres until it was 100% contained on July 23th. Mid-July rain showers helped fire crew contain this fire. This fire was difficult to contain due to rugged terrain with gusty winds, and relative humidity less than 3%. The fire consumed timber, mixed conifer, poderosa pine, pinon/juniper, and grasses. The suppression costs of the Whitewater-Baldy Complex Fire surpassed $23 million, according to the GACC. This is the largest fire in New Mexico history, which surpassed the previous record of 150,000 acres consumed by the Las Conchas Fire in 2011.

Waldo Canyon Fire, Colorado: most expensive in Colorado history

The Waldo Canyon Fire was the most expensive wildfire in Colorado history, costing $353 million, according to the Rocky Mountain Insurance Information Association. The cause of the fire is still under investigation, but investigators have determined that it was started within 3 miles of the Waldo Canyon trail head, off of U.S. 24, and was human-caused. The burn started on June 23rd and burned through July 10th, burning a total of 18,247 acres of brush, mountain shrub, oak, grass, pinion juniper, ponderosa pine, douglas fir, spruce, and limber pine. This fire was a major threat to neighborhoods and homes, as it started only four miles from Colorado Springs. Approximately 347 homes were burned and 2 people were killed by the Waldo Canyon Fire. Due to the proximity of this fire to nearby neighborhoods, over 32,000 residents were evacuated.

High Park Fire, Colorado: 2nd largest in Colorado history

The High Park Fire was caused by lightning and first detected on June 9th in the mountains west of Fort Collins. The fire burned 87,284 acres of timber, grass, and brush until it was 100% contained on July 1st, making this the second largest fire in Colorado history. The largest Colorado fire remains the Hayman Fire, which burned 137,760 acres in 2002. The High Park Fire killed one person, and was briefly the most destructive fire in Colorado history, after destroying 259 homes. However, this record was quickly surpassed by the Waldo Canyon Fire just a few days later.

Chips Fire, California: $55 million in suppression costs

California’s Chips Fire began on July 29th and burned a total of 75,431 acres in northern California, including 48,297 acres of the Plumas National Forest, 18,374 acres of Lassen National Forest, and 8,762 acres of privately owned land. The cause of the fire is unknown. The fire forced hikers on the Pacific Crest Trail to bypass this section by hiking Hwy 70/89 or by taking a bus and skipping this section all together. The fire was contained Aug. 31st, with a total of $55 million in suppression costs. Mainly timber was consumed in this fire.

Western U.S. wildfires expected to increase due to climate change

Expect a large increase in fires over much of the globe late this century due to climate change, says research published this June in the Journal Ecosphere. Using fire models driven by output from sixteen climate models used in the 2007 IPCC report, the researchers, led by Max Moritz of UC Berkeley, found that 38% of the planet should see increases in fire activity over the next 30 years. This figure increases to 62% by the end of the century. However, in many regions where precipitation is expected to increase–particularly in the tropics–there should be decreased fire activity. The scientists predicted that 8% of Earth will see decreases in fire probability over the next 30 years, and 20% will see decreases by the end of the century. The models do not agree on how fire danger will change for a large portion of the planet–54% for the period 2010 – 2039, and 18% for the period 2070 – 2099. Six key factors were found to control fire probabilities in the models. Most important was how much vegetation there was (NPP, Net Primary Productivity). Three other factors, about half as important, were precipitation of driest month, mean temperature of warmest month, and the difference between summer and winter temperature. Two other minor factors were mean temperature of wettest month, and annual precipitation. The authors found that future fire occurrence appears to primarily be a function of available moisture in many areas, and that the expected global increase in temperature of 3.5°C used in the models will not become the single dominant control on global wildfire. In the U.S., the regions most at risk of increased fires are the tundra regions of northern Alaska, and the West, with Arizona and Colorado at particularly high risk.

Figure 10. Predicted fractional change in fire probability for the period 2010 – 2039 (top) and 2070 – 2099 (bottom) for the average of sixteen climate models used for the 2007 IPCC report. For the 2010 – 2039 period, the models agree that 8% of Earth will see decreases in fire probability, 38% will see increases, and the models are too uncertain to tell for the other 54%. For the 2070 – 2099 period, the models agree that 20% of Earth will see decreases in fire probability, 62% will see increases, and the models are too uncertain to tell for the other 18%. Image credit: Climate change and disruptions to global fire activity, Moritz et al., 2012, from the journal Ecosphere.

Coolest fire video of 2012:

(Go to http://www.youtube.com/watch?v=lsyvOYcWgcg)

A fire tornado in Curtin Springs, Australia, from mid-September, 2012. NOAA comments: “While rare, fire tornadoes (also known as fire whirls) generally form when superheated air near the surface of a large fire zone rises rapidly in an airmass where sufficient horizontal or vertical vorticity (spin in the atmosphere) is also present. Much like a dust devil or whirlwind, the rapidly rising air above a wildfire can accelerate and turn the local vorticity into a tight vertical vortex, now composed of fire instead of dust.”

From Kari Kiefer and Jeff Masters

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