Our focus, however, is on those fires that made 2020 particularly noteworthy so we define large fires as those in the top 1–2% of all fires, which is approximated by fires > 10,000 ha. ( 2018) considered it to be 1000 ha or more. “Large” fires is an arbitrary designation, e.g., Nagy et al. To put these recent fires in a historical context, we have investigated the history of large wildfires in California. However, factors such as management impacts on forest structure and fuel accumulation, made worse by the recent drought, are critically important in some ecosystems (Stephens et al. Historically, drought has often been invoked as a driver of large fires (Keeley and Zedler 2009 Diaz and Swetnam 2013), and California has experienced an unprecedented drought in the last decade (Robeson 2015). The largest fires on record were recorded in 2018 and then were replaced with even larger fires in 2020, although some of these were the result of multiple fires that coalesced into fire complexes of massive size.Ĭauses for these fires are multiple, but climate change has been implicated as a critical factor (Williams et al. In the last decade, the state has experienced a substantial number of fires ranging from 10,000 ha to more than 100,000 ha, and these have caused massive losses of lives and property. While large fires are known in the historical record, in the first few decades of the twenty-first century, the pace of these events has greatly accelerated (Keeley and Syphard 2019). California in particular has had a history of massive wildfires such as the 100,000 ha 1889 Santiago Canyon Fire in Orange County or the similarly large 1932 Matilija Fire or 1970 Laguna Fire (Keeley and Zedler 2009). One of the biggest historical events was the 1910 “Big Blowup,” which reached epic proportions and was an important impetus for fire suppression policy (Diaz and Swetnam 2013). The western US has a long history of large wildfires, and there is evidence that these were not uncommon on pre-EuroAmerican landscapes (Keane et al. Sequías prolongadas, medidas mediante el Índice de Sequías Severas de Palmer (PDSI), fueron asociadas con los picos de grandes incendios tanto en el siglo 20 como en el 21. Antiguos registros muestran incendios de tamaño similar tanto en el siglo 19 como en el siglo 20. ConclusionesĮn la última década ha habido muchos años con incendios excepcionalmente grandes. De hecho, la década de 1920, fue una de las que presentó mayor número de grandes incendios. en 1929 hubo mayor número de incendios que en cualquier otro año del registro). Sin embargo, ha habido otros períodos con aún mayores números de incendios (i.e. ResultadosĮste estudio mostró que eventos extremos como el visto en 2020 no son históricamente desconocidos, y lo que se muestra como distintivamente nuevo es el incremento en el número de grandes incendios (definidos aquí como > 10.000 ha) en el último par de años, y más prominentemente en 2020. Dado que la sequía es frecuentemente asociada a grandes eventos de incendios, investigamos la relación entre grandes incendios y sequías en este período de 160 años. Aquí situamos a éste y otros años en un contexto histórico mediante el examen de registros de incendios en el estado desde 1860. Lengthy droughts, as measured by the Palmer Drought Severity Index (PDSI), were associated with the peaks in large fires in both the 1920s and the early twenty-first century.Įn el año 2020, California experimentó un récord al quebrar el número de grandes incendios. Earlier records show fires of similar size in the nineteenth and early twentieth century. In the last decade, there have been several years with exceptionally large fires. In fact, the 1920’s decade stands out as one with many large fires. Nevertheless, there have been other periods with even greater numbers of large fires, e.g., 1929 had the second greatest number of large fires. This study shows that extreme fire events such as seen in 2020 are not unknown historically, and what stands out as distinctly new is the increased number of large fires (defined here as > 10,000 ha) in the last couple years, most prominently in 2020. Since drought is commonly associated with large fire events, we investigated the relationship of large fire events to droughts over this 160 years period. Here, we place this and other recent years in a historical context by examining records of large fire events in the state back to 1860. California in the year 2020 experienced a record breaking number of large fires.
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