![]() ![]() ![]() In 1895, San Francisco was affected by haze from fires. Keeley and his colleagues reviewed 100 newspaper reports from the 19th Century and found that “large, high-intensity wildfires predate modern fire suppression policy” and concluded that “the 1889 Santiago Canyon Fire was the largest fire in California history.” While fire suppression has allowed the build-up of wood fuel in California’s mountain forests, such as the Sierra Nevadas, big, hot fires burned in southern California’s chaparral or shrubland forests in 1889, 1919, and 1932, long before fire suppression. “In 1781 the smoke was so dense that many persons thought the day of judgment had come.” Things seemed apocalyptic back then, too. On September 2, 1894, the New York Times published an article headlined, “The Cause of the Hazy Air - All Due to the Unusual Prevalence of Forest Fires.” Said a scientist, “Similar conditions have been noticed in the past, notably on the ‘dark day’ in 1781… probably caused by smoke. “It’s hot – monstrous hot!” wrote the San Francisco correspondent for the New York Times on September 17, 1860. High temperatures, forest fires, and smoky skies also occurred in California in the nineteenth century. He pointed out that the 2013-2014 Rim fire, which burned 250,000 acres, exposed five times more people to unhealthy air conditions from smoke than it would have if the same area had been burned regularly with smaller “prescribed” fires.Īs such, even though the intense heat wave spread fires faster than firefighters could put them out, it’s possible we would have awoken to an orange sky even had the planet’s temperature not risen one-degree Celsius over the last 100 years. So does that mean the smoke in the air is a function not of area burned, but instead, a function of wood fuel density? The cause of that is fire suppression and the existing debt of wood fuel.”įor most of the last 100 years, Californians suppressed fires in forests, resulting in the accumulation of roughly five times more wood fuel debris than existed in forests before Europeans arrived. “Climate dries the fuels out and extends the fire season from 4-6 months to nearly year-round,” explains North, “but it’s not the cause of the intensity of the fires. ![]() Is that due to climate change? In part, say scientists. The real problem, scientists say, is that today’s mountain forest fires are hotter and kill more trees than many forest fires killed in the past. “Our historical fire climate studies show that in California forests some years are cooler and moister and have much less area burned, these fluctuating climates would have occurred in the past.” “I wouldn’t say this happened every year,” said Jon Keeley of the United States Geological Survey. Other scientists were less confident in those annual figures. “You talk to Native American elders and they say they burned oak woodlands every 2-3 years.” “On reflection, anthropogenic burning is higher than what we had for the lower estimate,” said the lead author of that paper, Scott Stevens of UC Berkeley. For the last half of the 20th Century, the annual area burned in California was just 250,000 acres a year, whereas the best-available science suggests 4.4 and 12 million acres burned in California annually before the arrival of Europeans. Many reporters note that more area has burned this year in California than at any other point in “the modern period,” but that period began in 1950.
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