Increased fire susceptibility
Many different factors led to the 2018 California wildfire season becoming so destructive. A combination of an increased amount of natural fuel and compounding atmospheric conditions linked to global warming led to a series of destructive fires. Recent research on wildfires in California, published in August 2018, predicted an increase in the number of wildfires as a consequence of climate change. Humans have been recorded as the main cause of wildfires in California. Various causes, both intentional and accidental, such as arson, unattended campfires, fireworks, cigarettes, cars, and power lines have contributed to this increase in the number of fires. Updating equipment, ensuring forest maintenance is being completed, and having oversight by state and federal governments are some of the mitigating actions that can reduce the risk of wildfires.
Increase in fuel
A direct contributor to the 2018 California wildfires was an increase in dead tree fuel. By December 2017, there was a record 129 million dead trees in California.
Stanford Earth System Science Professor Noah Diffenbaugh stated that atmospheric conditions for California wildfires are expected to worsen in the future because of the effects of climate change in California and that "what we're seeing over the last few years in terms of the wildfire season in California [is] very consistent with the historical trends in terms of increasing temperatures, increasing dryness, and increasing wildfire risk." Other experts agreed, saying that global warming is to blame for these extreme weather conditions. Global warming led to higher temperatures and less rain, creating a drier landscape that gave fires more fuel to burn longer and stronger.
Residential construction in the wildland-urban interface
A wildland–urban interface (or WUI) refers to the zone of transition between unoccupied land and human development. Communities that are within 0.5 miles (0.80 km) of the zone may also be included. These lands and communities adjacent to and surrounded by wildlands are at risk of wildfires. Since the 1990s, over 43% of new residential buildings have been constructed in this area. In some areas, the amount of new residences in those areas is 80%. In the past, when these areas burned, no residences were lost, but now residences are present, which end up being destroyed.