Recent increases in acres burned of forests are mainly due to a changing climate — Scientists have known for sometime that fire activity tracks regional weather patterns, which in turn, are governed by global climatic forces such as the Pacific Decadal Oscillation (PDO — a recurring long-lived El Niño-like pattern of Pacific climate variability– see chart 1). For instance, the very active fire seasons of the 1910–1930s, occurred during prolonged drought cycles determined by the PDO that resulted in much larger areas burning historically than today (Powell et al. 1994; Interagency Federal Wildland Fire Policy Review Working Group 2001; Egan 2010) (chart 1). In fact, compared to the historic warm PDO phase of the early 1900s, most of the West is actually experiencing a fire deficit (Littell et al. 2009, Parks et al. 2012). However, with warming temperatures, early spring snowmelt, and longer fire seasons over the past few decades more acres are burning each year (Westerling et al. 2006; Littell et al. 2009) (chart 1).
So if wildfires are important to forests then why have forests of mammoth trees survived – like Cathedral forest and the giant redwoods? Have they just gotten lucky. Maybe it’s just the pines and other types which are more unlucky. The sad fact is most fires are actually started by human beings, aren’t they? That isn’t natural.