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Wildfires Not Caused By Climate Change

December 16, 2013

By Paul Homewood


For anybody still convinced that wildfires are caused, or made worse, by “climate change”, a look at an Environmental Impact Report by the California Department of Forestry and Fire Protection would be enlightening.



Wildfire Trends

Over millennia, fire has played an integral role in regulating the spatial pattern, composition, and structure of California’s natural resources. With its Mediterranean climate, productive soils, and frequent ignitions from lightning and Native American peoples, fire has been an endemic force shaping the landscapes of California. From coastal grasslands to sub-alpine forests to the Mojave Desert, fire has been an active ecological agent in almost all vegetated areas.
Fire provides an essential ecological function by cycling nutrients, changing plant composition and structure through mortality and fire induced regeneration, modifying habitat for wildlife, and increasing forest health by consuming fuels, thereby making forests less susceptible to unnatural fire severity, pests, diseases, drought, and pollutant stresses. Many tree and shrub species depend on fire to expose bare mineral soil and create gaps for seedling establishment and reduce shade-tolerant competition.
Fire helps maintain a mosaic of habitat conditions in the landscape and preserve biodiversity. Within fire adapted ecosystems, many common plants exhibit specific fire-adapted traits such as thick bark and fire-stimulated flowering, sprouting, seed release and/or germination (Chang, 1994). Some understory shrubs and herbs require the direct effects of fire (heat and/or smoke) to stimulate germination. Where fire return intervals were short, such as ponderosa pine forests, surface fires of low intensity removed seedlings and saplings, consumed accumulated tree litter and downed woody material, and accelerated the return of nutrients to the soil. In frequent fire-adapted communities this maintained an open, park-like forest stand with a continuous ground cover of grasses, herbs, and shrubs beneath the forest canopy (Kaufmann and Catamount, [nd]; Parsons and DeBenedetti, 1979). 


For purposes of analysis, the history of wildfire in California can be loosely categorized into pre-European settlement fire regimes and post-European settlement fire regimes, especially the last fifty years where rigorous fire suppression efforts have been undertaken.
Natural fire regimes that existed prior to European settlement in California (pre-1700) involved a wide range of fire frequencies and effects on ecosystems; roughly one-third of the State supported frequent fire regimes of 35 years or less. Some areas likely burned on an almost annual basis. Pre-European settlement fire patterns resulted in many millions of acres burning each year, with fire acting as a major ecological force maintaining ecosystem vigor and ranges in habitat conditions. The pre-settlement period is often viewed as the period under which the “natural” fire regime standard for assessing the ecological role of fire developed.


In the suppression (modern) era, statewide fire frequency is much lower than before the period of European settlement. Between 1950 and 2008, California averaged 320,000 acres burned annually, only a fraction of the several millions of acres that burned under the pre-settlement regimes.


Before the twentieth century, many forests within California were generally open and park like due to the thinning effects of recurrent fire. Decades of fire suppression and other forest management have left a legacy of increased fuel loads and ecosystems dense with an understory of shade-tolerant, late-succession plant species. The widespread level of dangerous fuel conditions is a result of highly productive vegetative systems accumulating fuels and/or reductions in fire frequency from fire suppression. In the absence of fire, these plant communities accrue biomass, and alter the arrangement of it in ways that significantly increase fuel availability and expected fire intensity. As such, many ecosystems are conducive to large, severe fires, especially during hot, dry, windy periods in late summer through fall. Additionally, the spatial continuity of fuels has increased with fewer structural breaks to retard fire spread and intensity. The increased accumulations of live and dead fuels may burn longer and more completely, threatening the integrity and sustainability of the ecosystems.
Species composition within these forests is also rapidly changing. Plant and animal species that require open conditions and/or highly patchy edge ecotones are declining and streams are drying as evapotranspiration increases due to increased stocking. Additionally, streams are being infiltrated by silt and debris following high severity fires, and unnaturally severe wildfires have destroyed vast areas of forest (Bonnicksen, 2003). Some insects and disease have reached epidemic proportions in parts of the State and forest conditions are conducive to more outbreaks. The understory of these once open forests is now dominated by smaller shade tolerant trees that would have previously been thinned and/or consumed by fire.



So :

  • Large and frequent wildfires were the norm before European settlement.
  • Regular wildfires provide an essential ecological function and increase forest health and diversity.
  • Acreage burnt reduced drastically during the 20thC, as fire suppression methods took effect.
  • This fire suppression, though, had the calamitous effect of allowing a dangerous build up of biomass, that now makes fires larger and more intense.



Perhaps somebody might tell Obama.

  1. A C Osborn permalink
    December 16, 2013 7:17 pm

    This has been shown many times before, especially for Australia, if it is mentioned often enough maybe someone will take notice.
    Here is another one

    Is this the most outlandish claim for Climate Change yet.
    Climate change is causing Earth’s poles to DRIFT, claim scientists.
    University of Texas researchers think that the Weather can affect the position of Earth’s Magnetic Field, quote
    Lead researcher Jianli Chen said that ‘ice melting and sea level change can explain 90 per cent of the shift’ and that ‘the driving force for the sudden change is climate change.’

  2. December 17, 2013 1:44 am

    Pre-European regimes were more natural, but human-managed, in great part, by the natives. They used small burns to clear areas for meadowland openings, etc., and to clear underbrush. A far more “sustainable” system.

  3. jfreed27 permalink
    December 17, 2013 8:32 am

    Recently at a joint meeting of Ceres Insurance and the LA County Fire Dept, the Fire Dept. official reported that fire season in Southern California is now almost 70-80 days longer than it used to be.

    Every science report I have read indicated fire damage is many times greater than in pre-1970’s fires. Area is greater, intensity is greater, numbers are greater.

    [All sounds a bit anecdotal – any evidence?
    Nationally, the number of fires was many times greater in the 20thC than now, but they tended to be smaller. The Impact Report explains the reasons for this.]

  4. December 17, 2013 11:31 pm

    Reblogged this on CACA and commented:
    Perhaps somebody might tell Obama, that the US has endured its Second Slowest Fire Season On Record


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