Forest fires got larger 1984-2011

True on ppine.

After a fire history study of the Ishi Wilderness it was noted that before the fire suppression era the wilderness burned about every ten years. After the full suppression policy the fire frequency decreased to once per decade -- meaning nothing changed. The west slope of the Sierra Nevada shows a similar pattern. The increase in human caused fire occurrence basically negated the smaller sizes resulting from aggressive suppression. The same number of acres burned each year on average. We know some very large fires occurred historically. 1827 was a year the west burned. Large fires occurred from northern Mexico to central BC that year, from the Pacific coast inland to the Rockies. 1872 was another big fire year, but not as much as 1827. Agee noted a correlation between large fire years and solar sunspot cycles.

Everyone says they want public lands managed according to the best available science. Up until the early 1960s full aggressive fire suppression was the best available science, which is why I do not assert it was a bad policy. Full suppression was supported by science, the public, and even a relatively young environmental organization called the Sierra Club. 1972 saw the first modified suppression policy in the Bob Marshall Wilderness. Since then about half of all fires have been suppressed, the rest have been allowed to resume their ecological role. Even outside Wilderness areas an assessment is made on how to best manage any fire that starts. As mentioned in my earlier post the default strategy now is defensive containment unless a fire is threatening high values (which also may include watershed, habitat, endangered species, recreation/tourism, or air quality, not just homes).

Changes in fire severity are more difficult to track. Burn severity only began to mapped and recorded in the early 1990s. Before then records are hard to come by.