What do Wildfires, Massive Rainstorms, and Debris Flows have in Common?
The Cascading Effects of the Climate Crisis in California
With the potential to fundamentally alter the physical, chemical, and biological composition of the Earth, the climate crisis is an all-encompassing phenomenon. As a result, a lot of the rhetoric surrounding the climate crisis focuses on its large-scale impacts. Big-ticket issues like sea level rise, water shortages, and global warming dominate global forums.
While beneficial in many ways, this zoomed-out focus creates a disconnect between phenomena and the people that they affect. In order to bridge this gap, we chose to look at the implications of climate change on the prevalence of extreme weather events in California.
Here’s some background:
California is in the midst of one of the most expansive droughts in state history. The past two years have been the driest in the last half of a century and over 80% of the state is experiencing conditions associated with ‘extreme drought.’
As one might expect, periods of extended drought have a number of detrimental effects. They result in a year-round fire season, water shortages for agriculture and residential users, an increase in wildlife diseases, and a reduction in hydropower.
Dr. Amy Champ (@AMYCHAMP on Twitter)
In 2020, wildfires burned 4,257,863 acres of forest, damaged 10,488 structures, and claimed 33 lives. This is not an anomaly. In 2018, damages from wildfires totaled ~148.5 billion USD, close to 1.5% of California’s annual gross domestic product (GDP).
PA Images
The current drought is driven almost entirely by a reduction in ‘atmospheric rivers,’ a weather event in which a column of condensed water moves inland, releasing large quantities of water. California relies on a specific atmospheric river, the Pineapple Express, in order to maintain adequate water supply. In a given year, Pineapple Express storms can produce between 25% to 50% of the state’s annual rainfall.
On October 23rd, an atmospheric river deposited over 7.6 trillion gallons of rain onto Northern California, prompting flash flood warnings from the Northern Bay Area down to Big Sur. Surrounding communities were cautioned about debris flows -- large quantities of rapidly-moving water, rocks, and vegetation.
Debris flows are especially dangerous because of the speed with which they occur. Often striking without warning, flows can exceed 35mph.
The most deadly debris flow in recent years occurred in Montecito, California in January of 2018. Heavy rainfall led to a number of flows from a series of steep catchments in the Santa Ynez Mountains. These catchments had been burned less than three weeks earlier by the Thomas fire.
After exiting the mountain, the flow collided with a residential area, killing 23 people, injuring at least 167 others, and damaging 408 homes.
An aerial view shows destruction in Montecito from the massive mud and debris flows on Jan. 9, 2018, that destroyed or damaged hundreds of surrounding homes and buildings. MATT UDKOW SANTA BARBARA COUNTY FIRE DEPARTMENT
There are a few important takeaways from this event.
Atmospheric rivers are an undoubtedly beneficial component of the climate in the Western US. However, in addition to providing a valuable source of water, they also elevate the risk associated with flash flooding and debris flows.
While these risks are typically negligible, the increased occurrence of wildfires across the Western US leaves affected communities more vulnerable to the negative effects of atmospheric rivers. In this case, climate change has turned an event that provides life into one that destroys it.
Individuals often justify inaction on the basis that climate change will not affect them directly. In addition to being incorrect, this is a myopic and egocentric view. It also fails to account for the fact that the climate crisis is an aggregate phenomena. While changes in climate may appear to only affect one system, the interconnected and dynamic nature of ecological systems will lead to further impacts, creating a cascading effect of damages. As a result, climate change will touch all walks of life, yet humans, and Americans specifically, are still not unified in fighting against climate change. In order to reverse this narrative, it is important that stories like the debris flows in Montecito are spread.