DISCUSSION: There are currently dozens of wildfires burning across the western U.S. The picture above is actually a satellite image of smoke from fires (indicated by red squares) in December 2017 in southern California (photo credit: NBC 4 Los Angeles and NASA). It seems like wildfires and fire seasons have gotten worse (more fires and/or greater acreage burned) in recent years. Part of the reason for this is human-caused climate change. Studies have indicated that an increasing average global temperature due to an increase in greenhouse gases can cause warmer, drier, and windier conditions to intensify and occur more frequency in some regions (e.g., western North America), all conditions that are especially dangerous should a fire be ignited. In addition, studies have indicated that human-caused climate change can cause wetter winter and springs in some locations, fostering more plant growth. When this increased growth dries out over the summer dry season, it can provide additional fuel for fires.
But, climate change doesn't tell the whole story. To get a fire, there must be an ignition source. Lightning and human ignition (e.g., fireworks, camp fires left unattended, cigarette butts, etc.) are the primary ignition sources. More people moving into wilderness areas provides more opportunity for accidents to happen. It is difficult to determine whether global climate change has had any influence on thunderstorm occurrence. Regardless, thunderstorms are going to occur with or without people and their influence on the climate.
Fires are a natural part of many ecosystems. They help thin forests, allowing for more diversity to occur in a forest and for the remaining trees to have more space and nutrients to grow (i.e., healthier trees). In addition, repeated smaller fires can burn up fuel (e.g., twigs, leaves, etc.) before they can accumulate on the forest floor, preventing a future larger fire. With more people living in wilderness areas and the resulting need for more aggressive fire fighting, fuel potentially builds up, increasing the risk of more dangerous fires in the future.
The main takeaway message here is that people indirectly influence fire risk via our influence on climate. They also more directly influence fire risk by moving into wilderness areas and potentially increasing the risk of igniting a fire. Obviously, it is a tragedy when people lose their homes and/or lives in a fire. But, it is important to keep in mind that fires left to burn away from people are not necessarily a bad thing.
Finally, given that it is Independence Day in the U.S., please be cognizant of the fire risk should you decide to shoot off fireworks. If you live in a region that has been especially warm and dry lately, it may be best to leave the fireworks to the professionals.
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©2018 Meteorologist Dr. Ken Leppert II