With urban development where wildfires have raged, conflict seems inevitable. Is there a better way? By Lawrence Herzog, University of California, San Diego Californians probably never realised – perhaps even to this day – how close a 2007 wildfire came to destroying a significant portion of San Diego. Hot, dry ‘Santa Ana’ winds, combined with heightened seasonal drought conditions in the region, led to the outbreak of two powerful conflagrations: one in the suburban hills of northern San Diego county, the other to the south along the US-Mexico border near the town of Tecate. The event was unlike previous wildfires in the region – it was poised to become an ecological catastrophe.The state’s second most populous urban region might have been deeply wounded; powerful winds were thrusting the firestorm directly toward the city centre. Thick smoke and ash made it difficult to breathe; residents across a region with more than 3 million inhabitants were advised to stay indoors. City and county officials evacuated thousands of citizens. Tens of thousands more had their bags packed, valuables in their cars, ready to flee. On the Mexican side of the border, more than 60 square kilometres of land was burning near the cities of Tecate, Tijuana and Ensenada. This wildfire was now both a regional and international emergency, and was spreading south of the border. On the third day, by chance, winds shifted to the south and later toward the east, slowing the wildfire’s path toward the urban centre. Once the wind direction changed, it carried more humidity from the Pacific Ocean, giving firefighters a chance to control the crisis. EMBED START Image { id: "editor_2"} EMBED END Image { id: "editor_2"} In the decade and a half since the 2007 San Diego wildfires, California has seen an alarming spike in wildfire outbreaks, directly tied to global warming. Ten of California’s most destructive wildfires have burned since 2015. These include the Camp Fire of 2018, in central California, which led to 85 deaths; the 2017 Thomas Fire which burned over 1,100 square kilometres of land in Ventura and Santa Barbara counties; and the 2018 Woolsey Fire in Los Angeles, with a total of over 380 square kilometres burned and 1600 structures damaged or destroyed. The year 2020 was a frightening reminder, with a series of large-scale wildfires up and down the state, including the North Complex, August Complex, and LNU Lighting Complex fires in northern and central California; these burned over 4,000 square kilometres of land. Then, in July 2021, the Dixie, KNP Complex, Caldor and Monument fires burned thousands more square kilometres in northern and central California. The 2007 wildfires and the conflagrations since could have been a huge wake-up call about the dangers of San Diego’s emerging suburban settlement pattern, its connection to the natural ecosystem and to the ecology of wildfire. But, to this day, it seems the lessons are yet to be taken seriously. Southern California has continued to be one of the fastest growing metropolitan regions in North America over the last four decades. Indeed, while most counties in the US saw their population shrink, between 2010 and 2020, southern California’s counties all experienced significant growth — as high as 10 percent in Riverside county, or seven percent in San Bernardino.The San Diego metropolitan area has kept pace. Even though land shortages and high housing costs have slowed growth, San Diego’s 2020 population of 3.4 million is expected to increase to 3.8 million by 2035. But for more than three decades, there has been almost no recognition among developers, or even government, of the risks of wildfires and the fragility of inland southern California’s arid ecosystem. Most of the urban growth will occur in the eastern fringes of the region, in an arc of suburban growth of inland cities and towns – what locals used to call the ‘back country’, and what ecologists now term the ‘wildland-urban interface’. The limited supply of land along the coast for development, especially within the city of San Diego, has added pressure to build inland. This trend has been further exacerbated by greater homebuyer interest in larger homes on larger lots. This suburban growth pattern has unfolded without considering the implications of poorly managed, low density sprawl-type growth in a semi-arid region where wildfires are part of the natural ecological cycle. Three out of four homes built in San Diego since 1990 are in the wildland danger zone that lies between coastal foothills and mountains further inland.