Atmosphere And Weather

How Forest Fires Change Local Weather Patterns



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Forest fires have a reputation for occurring fairly regularly in some areas of the United States and certain areas around the world. Left behind after the fire is devastation and death. The loss of nature’s beauty, wildlife, natural habitats, homes and even lives of people are just some examples of what is left behind in the aftermath of a forest fire. Another change that can be an effect of forest fires is the changes that can occur in local weather patterns.

Understanding forest fires aids in understanding changes

Forest fires can start naturally under extremely dry conditions. They can also be started accidentally or purposefully. Fires started by humans are considered the means by which most fires get their start. Forest fires that are started by people are the first to be recognized and therefore usually are the easiest and quickest to extinguish, if reported in a timely manner. Fires started by nature, either by lightening, which The Weather Network says can “be a dangerous igniter when it comes to wildfires,” or by extremely dry weather which causes the spontaneous combustion of dried leaves or sawdust may not be detected until quite some time after the fire has started. By the time forest fires started by nature have been discovered, they are usually well on their way to burning extensive areas of land, jeopardizing trees, animals and humans in their path. Such was the case for a vacationing French family of five when a wildfire closed in on them in Spain in 2012. The family became separated from other tourists fleeing the fire and had no where to go. Apparently the decision was made to jump off a steep cliff to evade the fire. The title, ‘Father and Daughter Die Jumping off Cliff to Escape from Wildfire,’ summarizes what happened.

As Boreal Forest explains in ‘Forest Fires - An Overview,’ three elements are necessary for a forest fire to burn. Those three elements are heat, oxygen and fuel, known as the “fire triangle.” Without the presence of any one of the three necessary elements, the fire will burn out. There are several classifications to a forest fire. One set of classification occurs when a forest fire enters the “combustion stage.” The fire may be classified as a smoldering fire, flaming combustion or glowing combustion. Forest fires may also be classified according to which particular part of the forest is on fire. A ground fire occurs on the ground beneath leaves, while a surface fire occurs on the ground surface and can extend up to three meters high. A crown fire, the most dangerous, occurs all the way into the tops of trees, is the fastest spreading and most difficult to extinguish. It is even possible for more than one type of fire to burn at the same time.

Difficulties in putting out forest fires

Forest fires are very dangerous for firefighters. At times, there is little that can be done, without putting the lives of fire fighters in extreme jeopardy. Forest fires may occur deep into a forest, and can be located in rugged terrain. Being able to actually get firefighters transported to the areas where they can successfully fight the fire can be time-consuming and dangerous. Once a fire has spread, it can be even more dangerous for firefighters.

The Big Blowup

Nothing brought the potential of devastation from forest fires to light more than the fires 0f 1910. Still in its infancy, the U.S. Forest Service had little means of fighting massive fires. But the aftermath of the Big Blowup led to new policies on fire prevention and suppression.

On April 29, 1910, a fire broke out in the Blackfeet National Forest in Montana. The U.S. Forest Service chief of the area at the time believed that the undermanned agency would have the upper hand in fighting the fires of that season. But as fires began to spread across several regions, the evidence was clear that danger lurked ahead throughout the coming months. The Forest History Society quotes Clarence Swim of the Forest Service who observed, “The late summer of 1910 approached with ominous, sinister and threatening portents. Dire catastrophe seemed to permeate the very atmosphere…” By August 10, fires had spread and in addition to the Blackfeet fires, were now raging in the Cabinet, Clearwater, Flathead, Kaniksu and Lolo National Forests. More than 4,000 military troops were deployed to help in fighting the fires in Montana, Oregon, Washington and the Idaho Panhandle. Finally believing they had the “upper hand,” authorities began releasing fire fighters on August 19. But a day later, catastrophic devastation would soon be incurred.

On August 20, “hurricane-force winds fanned flames across the Northern Rockies." Fires raged so badly that trains evacuated residents of nearby towns in attempts to beat the flames, which consumed entire towns. But out of the misery emerged heroes like Ranger Ed Pulaski. He ordered the 43 men under his supervision into a nearby mineshaft and threatened to shoot anyone who tried to escape from the tunnel floor where they were lying. He watered down blankets which he hung over the entrance of the mineshaft. Pulaski and all but five of his men survived the inferno of 1,736 fires and the more than 3 million acres of land and more than 3 billion board feet of timber that were engulfed in the Big Blowup. The legend of Ed Pulaski and his daring escape and saving his crew lives on and so do the lessons learned in the aftermath of the Big Blowup. Out of the Fire Suppression Model that was developed, which led to the popular Smokey the Bear campaign, came similar models adopted in many other countries. But what they may not have known in 1910 is how forest fires can change local weather patterns.

How weather is affected by forest fires

While climate changes can affect the health of forests, sometimes the climate changes as a result of forest fires. While drought conditions can increase the likelihood of the occurrence of a forest fire, the after-affects from forest fires are producing climate change. The quick release of large amounts of carbon dioxide into the atmosphere is largely responsible. Research has shown that an upward trend in temperatures in some regions, with earlier spring weather and longer, drier summer weather. With climate change and the cycle of weather patterns affecting the incidence of forest fires and the fires then affecting local weather patterns and pollution, experts are taking a look at how to better manage forest fires. In ‘Feds project climate change will double wildfire risk in forests,’ the Denver Post stated that the U.S. Forest Service scientists estimate that by the year 2050, wildfires will become more severe and the area burned by the fires across the United States will double. Some areas, such as Northwest Colorado may see an increase of more than five times the area burned due to climate changes.

There may be an increase in local pollution in some areas as it becomes increasingly more difficult to move forward with large-scale reforestation due to the need for increased time, money and manpower spent fighting the increase in the number and severity of forest fires. If areas damaged by forest fires cannot be replanted in a more timely manner, the 13% of U.S. carbon pollution currently absorbed by forests may decrease. The Arbor Day Foundation explains that because some forest fires burn very hot, it is difficult for vegetation and trees to re-grow. Not only that, but when forests are severely damaged by wildfires, soil in areas devastated by forest fires becomes water repellant and “no vegetation remains to hold the soil in place and the ground can no longer absorb water.” When it subsequently rains or snows, the soil can erode and runoff may pollute rivers and streams, harming wildlife and fish. Public water supplies may also be adversely affected. When forest areas that are not quickly replanted remain hot and dry, there is the possibility that another fire can occur when the temperature heats up and dry leaves catch fire, lightening strikes or people passing by drop a lighted cigarette or are careless in other ways that could cause the extremely dry forest area to burn again.

Historical data demonstrates occurrence and severity of forest fires

The Arbor Day Foundation presents data dating back to 1988 that shows the number of forest fires in the U.S. and the millions of acres burned each of the years, through most of 2012. The United States Department of Commerce, National Oceanic and Atmospheric Administration presents Fire Weather that explains how forest fire weather is forecast, the role of those instrumental to predicting and fighting wildfires. Also helpful are links to pages such as “Red Flag Warnings.” For example, the Red Flag Warnings for Aberdeen, South Dakota for May 14 included warnings of “Dangerous fire weather expected today.” An increase of winds combined with low relative humidity was expected to result in “extreme fire danger.”

As firefighters and governments struggle with the increasing occurrence of wildfires and the weather patterns affected by wildfires, as well as pollution and other effects of wildfires, there is also a struggle for reforestation of burned-out areas so that further damage will not occur. With a better understanding, consisting of continued on-going research, funding and education and awareness programs targeting the general public, perhaps the local weather patterns will not be so adversely affected in the future.

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