An example of the climate that plays a huge role in the fire regime of "Pinus contorta" is quite complex. There are three different oscillations that play a major role in droughts. These are the Pacific decadal oscillation (PDO), Atlantic multidecadal oscillation (AMO) and El Niño (ENSO). A combination of these oscillations being in effect (+) or not in effect (−) have a global effect on the water available to these forests. So when the AMO +, ENSO − and PDO −, there is going to be a drought and likely a severe subalpine fire.