Impact of drought on wildland fires in Greece: implications of climatic change?

Abstract

An increasing trend and a statistically significant positive correlation between wildfire occurrence, area burned and drought (as expressed by the Standardized Precipitation Index, SPI) have been observed all over Greece, during the period 1961–1997. In the more humid and colder regions (Northern and Western Greece) the number of fires and area burned were positively correlated to both summer (SPI6_October) and annual drought (SPI12_September), whereas in the relatively more dry and hot regions (Southern and Central Greece) the number of fires and area burned were correlated only to summer drought. In 1978, Greece entered a period of prolonged drought, possibly as a result of the global climatic change. Data analysis of the period 1978–1997 revealed a statistically significant increase in the mean annual number of fires, the area burned and the summer and annual drought episodes in the relatively more humid and colder regions (Northern and Western) of Greece (which in the past were characterized by less fires and area burned) compared to the more dry and hot regions (Southern and Eastern Greece), which always presented high fire activity. Additionally, analyzing the two sub-periods (1961–1977, 1978–1997) separately, drought was significantly correlated only to fire occurrence during the years 1961–1977, whereas during 1978–1997 drought was significantly correlated mainly to area burned. It became obvious that drought episodes, although they are not solely responsible for fire occurrence and area burned, they exert an increasingly significant impact on wildfire activity in Greece.