In summary
California ranks among the top states suffering economic damage from climate-related disasters. The report describes food shortages, floods, droughts, wildfires, pollution, disease — all linked to climate change.
The federal report, released today, ranked California among the top five states suffering economic effects from climate-related natural disasters. A chapter about the risks and effects in the Southwest contains a long and alarming list of projections, particularly the impact of drought on water supplies, agriculture, diseases and ecosystems.
“Droughts are projected to increase in intensity, duration, and frequency, especially in the Southwest….Human and natural systems are threatened by rapid shifts between wet and dry periods that make water resources difficult to predict and manage,” the report reads.
The Fifth National Climate Assessment, which the U.S. government describes as its preeminent report on climate change, noted the compounding impacts of climate change: A wildfire in one part of a state can migrate across its regions or into other states, and will worsen air quality far from the source. The report also warns of “sudden failures” when the impacts of climate change combine with other factors, like food insecurity and changing migration patterns.
UCLA climate scientist Aradhna Tripati, one of the authors, said the new assessment “documents the state of the science on the physical and human experiences. It shows absolutely that what is happening is not normal.”
“We’re actively experiencing severe climate change impacts It’s no longer theoretical or a distant threat, an abstract one. It is not something that happens in the future here. It is not something only happening in places far away from where we live. All weather is now being affected. And this is human caused,” she said.
Unless greenhouse gas emissions are slashed, even more dire impacts on people, the economy and the environment will be coming, the report warns.
“The effects of human-caused climate change are already far-reaching and worsening across every region of the United States,” the report says. “Without deeper cuts in global net greenhouse gas emissions and accelerated adaptation efforts, severe climate risks to the United States will continue to grow.”
“Despite an increase in adaptation actions across the country, current adaptation efforts and investments are insufficient to reduce today’s climate-related risks and keep pace with future changes in the climate,” the report says.
“It is not something that happens in the future here. It is not something only happening in places far away from where we live. All weather is now being affected. And this is human caused.”
Ariadna tripati, UCLA climate scientist and co-author of the report
Nationwide, annual greenhouse gas emissions fell 12% between 2005 and 2019, driven largely by changes in how electricity is produced. Emissions from power plants dropped 40% due to declining use of coal and more reliance on natural gas and solar power.
Transportation is now the largest emitter nationwide. California has led the way in addressing this, adapting a mandate that will ban the sale of new gasoline-powered cars by 2035.
The report highlighted states’ efforts to combat climate change, such as commitments by California and other states to reduce greenhouse gas emissions in line with the Paris Agreement, and California’s commitment to reach net-zero carbon emissions by 2045.
The economy and public infrastructure
During the 1980s, the U.S. experienced a billion-dollar disaster every four months when adjusted for inflation, according to the report. But now the average is once every three weeks. Between 2018 and 2022, the U.S. experienced 89 events with costs that exceeded a billion dollars.
Billion-dollar weather and climate disasters are events where damages/costs reach or exceed $1 billion, including adjustments for inflation. Graphic via Fifth National Climate Assessment
In coastal areas, people’s homes and properties, as well as public infrastructure, are increasingly exposed to rising seas.
“In coastal areas, sea level rise threatens permanent inundation of infrastructure, including roadways, railways, ports, tunnels, and bridges; water treatment facilities and power plants; and hospitals, schools, and military bases,” the report says.
Florida led the pack, exceeding $90 billion in economic damages from billion-dollar disasters between 2018 and 2022, with California, Texas, North Carolina and Louisiana closely behind, with total damages between $30 billion and $90 billion.
Droughts and floods
The Southwest, which includes California, naturally has intense periods of drought and rainfall that are now exacerbated by changing climate patterns. The report predicts reduced flows in major river basins, including the Colorado River, a major source of water in Southern California.
The Southwest is experiencing a megadrought, the driest period in 1,200 years. What’s more, snowpack is decreasing, which could have implications for “surface water and groundwater supplies.”
“The effects of human-caused climate change are already far-reaching and worsening across every region of the United States.”
fifth national climate assessment report
Even as California and surrounding states feel the impacts of drought, California and the rest of the Southwest are vulnerable to flooding from extreme storms and rapid snowmelts. The report warns that sea level rise may threaten critical water supplies in the Sacramento–San Joaquin Bay Delta region.
“In coastal environments, dry conditions, sea level rise, and saltwater intrusion endanger groundwater aquifers and stress aquatic ecosystems,” the report warns. “Inland, decreasing snowpack alters the volume and timing of streamflow and increases wildfire risk. Small rural water providers that often depend on a single water source or have limited capacity are especially vulnerable.”
Drought in California’s San Joaquin Valley has disrupted farm workers’ employment, reduced food and water security, and affected health with more extreme heatwaves and smog.
The report predicts that the Southwest will experience more extreme heat and smoggy days, contributing to more illness and premature death. Drier air could lead to more dust storms, doubling the deaths attributed to fine dust during the final two decades of this century. The incidence of Valley fever also is expected to increase.
Coasts and sea level rise
The report notes that California’s coastal sea surface temperature has seen an average increase of 0.4° to 0.6°F per decade since the 1970s. This causes marine heatwaves that jeopardize marine mammals, seabirds and fisheries.
The state’s coastal habitats and homes are threatened by rising seas — and California has more people living below 3.3 feet (one meter) of elevation than any state other than Louisiana. The state’s transportation fuel network is also at risk of flooding. The report noted that under one sea level rise scenario, the Toxic Tides Project found that some 400 industrial facilities and toxic sites could be at risk of flooding.
Higher sea levels also could increase coastal groundwater levels, “exposing communities to flooding from water that emerges from underground,” with communities in “low-lying areas” such as San Francisco Bay most at risk, the report says.
Wildfires
The report foresees wildfires, exacerbated by climate change, as continuing to have a major impact in California. Of the 50 largest U.S. wildfires in 2020, 22 occurred in California, and the 7 largest wildfires recorded in California have occurred since 2018, the report noted.
Three of the five deadliest fires on record in California have occurred since 2017, costing 122 lives. In 2021, 3,363 structures burned due to wildfires in California, the highest number lost in any state. During harvest seasons these conflagrations increase risks for workers.
With warmer and drier conditions, wildfires are moving higher in elevation and creating hotter and more severe fires. These trends are expected through the middle of this century. More fires and larger areas burned will lead to loss of biodiversity of species and “result in a significant health burden, especially for at-risk populations.”
Food and agriculture
Climate change is expected to disrupt global and U.S. food production, and California is particularly susceptible to these disruptions. California is the leading state in agricultural cash crops, with substantial income from fruits, nuts and vegetables.
The report says food shortages and higher food costs are expected because of the impact of the changing conditions. Many growers already are trying to adapt to the new rainfall patterns and temperatures.
Drought cost the industry an estimated $1.28 billion in 2021 alone. Warming temperatures are expected to reduce yields of valuable crops, including almonds and wine grapes.
In California, rising temperatures will alter crop timing and locations, potentially harming orchard crops with warmer winters. Fewer cold snaps may reduce frost exposure, but “false springs” could increase vulnerability. Summers will likely see more heatwaves. Meanwhile periodic floods from atmospheric river storms are poised to hit California’s Central Valley, also disrupting farming.