Wildfire in the Twenty First Century¶

Wildfire is a natural phenomena that plays a critical factor in numerous ecosystems including but not limited to boreal forests, grasslands, and montane. Wildfire serves to rejuvinate ecosystems by burning and eliminating dead woody material and creating space for younger generations of lifeforms to grow. Many plant species in these habtiats have adapted to wildfire and require these events to spread their seeds. Wildfires can occur in a large diversity of size, intensity, and geographic distribution. Wildfires may be caused by many different natural causes including lightning strikes, rock falls, volcanic eruptions, and severe weather events.

Humans have lived with wildfire for our entire existence and although it may pose a significant threat to our communities and well being, it has also played an important role in our development as a species. Many indiginous peoples used wildfire as a tool to manipulate their environments in beneficial ways by intentially igniting wildfires. These controlled burns allowed early humans to clear land, create habitat for prey species, create zones of safety where desired, and other functions. In the modern era, our co-existence with wildfire has been more fraught. The number of humans living in the Wildland Urban Interface (WUI) has exploded exponentially over the past several centuries. Although naturally caused fires still occur frequently, many wildfires are caused accidentally or intentionally by humans. The United States, partcularly in its western regions, has experienced a stunning increase in large wildfires over the past several decades. Many of these fires have occured within the WUI, leading to massive losses of property and life.

Studies indicate that climate change has had a significant effect on the increase of the occurrence of fire weather in recent decades. Fire weather refers to conditions which influence the risk and behavior of wildfires and include factors such as consistent high temperatures, low humidity, windy conditions, and the duration and intensity of these factors. As our world becomes hotter, drier, and has more variable weather, the conditions that allow wildfires to ignite and thrive are present much more often.

These findings correlate with the increase of size and intensity of wildfire events over the last decade. Previously recorded wildfire records have been smashed repeately in recent years. For instance, the largest combined fire event in California history, the August Complex (1,032,649 acres), occurred in 2020. The record prior to the August Complex was the 2018 Mendocino Complex (459,123 acres). 2021 saw the largest single fire event in the state's history, the Dixie Fire (963,309 acres!), which also has the distinction of being the first documented wildfire to cross the Sierra Crest, a geographic barrier previously thought impassible by wildfire. Another large fire (the Caldor Fire) crossed this dire milestone several weeks later. Of the top 20 largest wildfires recorded in California as of 2021, only three occurred before the year 2000.

Citations¶

"Top 20 Largest California Wildfires" (PDF). California Department of Forestry and Fire Protection. September 20, 2021.

Zhuang, Y., Fu, R., Santer, B. D., Dickinson, R. E., & Hall, A. (2021). Quantifying contributions of natural variability and anthropogenic forcings on increased fire weather risk over the western United States. Proceedings of the National Academy of Sciences, 118(45). https://doi.org/10.1073/pnas.2111875118

Abatzoglou, J. T., & Williams, A. P. (2016). Impact of anthropogenic climate change on wildfire across western US forests. Proceedings of the National Academy of Sciences, 113(42), 11770–11775. https://doi.org/10.1073/pnas.1607171113

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Analysis Description¶

We are examing the occurrences of wildfires in the state of California. We will analyze the number of fires per year and the max size of fire per year. We will plot these out by County and prepare a chloropleth map showing the results.

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Data Description¶

This is spatial data showing wildfire occurrence location and related information from 1992 through 2020. The data includes 2.3 million spatial features representing over 180 million acres burned. It is maintained and stored by the U.S. Forest Service Research Data Archive.

Citation¶

Short, Karen C. 2022. Spatial wildfire occurrence data for the United States, 1992-2020 [FPA_FOD_20221014]. 6th Edition. Fort Collins, CO: Forest Service Research Data Archive. https://doi.org/10.2737/RDS-2013-0009.6

Plots of Max Fire Size and Number of Fires per Year, by County¶

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