Fires prior to 1763 were synchronous with region-wide fire years, which coincided with periods of drought. However, after 1763, fires on the peak became asynchronous to widespread-fire years throughout the region. The authors suggest that when this occurs, bottom-up factors may have become more important in controlling the spread of fire. Specifically, Rincon Peak is isolated and surrounded by talus slopes and rock outcrops. However, they also hypothesized that a variation on ENSO, the late 18th-- early 19th century transition period (LEENT) may have occurred at this time, lengthening the fire-free interval. The LEENT period decreased the ENSO signal and limited the wet/dry oscillations and therefore the cycles of high fuel production followed by drought, hence increased flammability, for an extended period. The author’s findings suggest that isolated sky island ponderosa pine forests may be especially susceptible to climate change and drought because of their separation from the larger landscape and the frequent fire regimes that regulate severity in these ecosystems.