Climate change in California
Climate change in California has resulted in higher than average temperatures, leading to increased occurrences of droughts and wildfires. Over the next few decades in California, climate change is predicted to further reduce water availability, increase wildfire risk, decrease agricultural productivity, and threaten coastal ecosystems. The state could also be impacted economically due to the rising cost of providing water to its residents along with revenue and job loss in the agricultural sector, which impacts low-income Californians disproportionately.
Health impact is expected from wildfires, heat waves, and dirty air, causing more breathing problems, heart issues, and even deaths, especially in cities with a high level of pollution. Economic impacts also include inflation from rising insurance premiums, energy costs and food prices.
Climate-driven wildfires and rising temperatures in California are drastically reshaping ecosystems, causing habitat loss and threatening the survival of species like the California Spotted Owl, Coho and Chinook Salmon, and Desert Slender Salamander.
People in California are affected in different ways that intersect with their socioeconomic identities and cultural practices. The impacts of increased greenhouse gas emissions and PM2.5 make many Californians susceptible to health effects and is an example of environmental injustice.
California has taken a number of steps to mitigate impacts of climate change in the state.
Paleoclimatological evidence
studies indicate that the last 150 years of California's history have been unusually wet compared to the previous 2000 years. Tree stumps found at the bottom of lakes and rivers in California indicate that many water features dried up during historical dry periods, allowing trees to grow there while the water was absent. These dry periods were associated with warm periods in Earth's history. During the Medieval Warm Period, there were at least two century-long megadroughts with only 60–70% of modern precipitation levels. Paleoclimatologists believe that higher temperatures due to global warming may cause California to enter another dry period, with significantly lower precipitation and snowpack levels than observed over the last 150 years.Extreme weather impacts
A 2011 study projected that the frequency and magnitude of both maximum and minimum temperatures would increase significantly as a result of global warming. According to the Fifth National Climate Assessment published in 2023, coastal states, including California, Florida, Louisiana, and Texas are experiencing "more significant storms and extreme swings in precipitation".Wildfires
Numerous studies have found that climate change is increasing the frequency of large and explosive wildfires in California in particular. The economic and human health damages of recent fire seasons has been estimated to be as high as $148.5 billion, or roughly 1.5% of California's annual GDP. This damage is mostly a result of smoke-related air pollution. As a consequence of further global warming, it is projected that there will be an increase in risk due to climate-driven wildfires in the coming decades. Because of warming, frequent droughts, and the legacy of past land management and expansion of residential areas, both people and the ecology are more vulnerable to wildfires. Wildfire activity is closely tied to temperature and drought over time. Globally, the length of the fire season increased by nearly 19% from 1979 to 2013, with significantly longer seasons in the western states. Since 1985, more than 50% of the wildfire area burned in the western United States can be attributed to anthropogenic climate change. In addition, due to human fire suppression methods, there is a build of fuels in some ecosystems, making them more vulnerable to wildfires. There is greater risk of fires occurring in denser, drier forests, where historically these fires have occurred in low-density areas. Lastly, with increases in human population, communities have expanded into areas that are at higher risk to wildfire threat, making these same populations more vulnerable to structural damage and death due to wildfires. Since 1990, the average annual number of homes lost to wildfires has increased by 300%. Almost 900,000 of western US residences were in high risk wildfire areas as of 2017 with nearly 35% of wildfires in California starting within these high risk areas.In 2019, after "red flag" warning about the possibility of wildfires was declared in some areas of California, the electricity company "Pacific Gas and Electric " begun to shut down power, for preventing inflammation of trees that touch the electricity lines. Millions can be impacted. The climatic conditions that cause this warning became more frequent because of climate change. If the temperatures keep rising, such power outages could become common.
Recent wildfire seasons have broken number of records. The 2018 season became the deadliest and most destructive in the state's history, with 103 people killed and 24,226 buildings damaged or destroyed. The 2020 season became the largest in the state's recorded history in terms of area burned, with more than 4 million acres burned across the state in 9,917 wildfires. Out of six of the biggest fires ever recorded in the state of California, five took place in 2020.
In 2017, a study projected that the single largest threat to Los Angeles County hospitals related to climate change is the direct impact of the expected increase in wildfires. In Los Angeles County, 34% of hospitals are located within one mile of fire hazard severity zones. Additionally, one of these hospitals was also deemed in danger of coastal flooding due to the effects of climate change as concluded by the study. This latter issue was also included and focused on, as the study likewise concluded that this would become a greater hazard as sea level rise due to increase annual temperatures.
In January 2025 Southern California wildfires were deadly and affected millions of people. The two largest fires, the Eaton Fire in Altadena and the Palisades Fire in Pacific Palisades burned over 37,000 acres and killed 31 people. In Altadena, the Eaton Fire killed 19 people. 18 victims lived west of Lake Avenue, a predominately black neighborhood in Altadena. Residents from west Altadena received emergency evacuation orders hours after those in east Altadena, after the fire had already reached those residents' homes.
Altadena has long been a culturally diverse area of Los Angeles with long-term homeowners. According to census data, almost 60% of Altadena's population are people of color, and over 75% of Black Altadena residents own their home. In the Eaton fire, over 9,000 structures burned, with over 6,000 homes lost. Many homes in Altadena have been passed down generationally, and there is fear that there will be climate gentrification as families and elderly move away from the burn scar.
These fires in Los Angeles placed thousands under evacuations, with shelters overwhelmed with families, pets, and wildlife. In both the Palisades and Altadena, vast numbers of wildlife were displaced. Larger animals like bears and mountain lions were forced into neighborhoods; new bird species moved into new nests and areas across Los Angeles, while aquatic wildlife such as fish and newts sheltered-in-place. It is unclear about the effects of Monarch Butterflies in the region, who cluster on trees in the region. Studies show that insects and less mobile invertebrates such as aphids, parasitoid wasps, and springtails are essentially gone from the region as wind speeds and the expansion of the fire moved too quickly for them to fly away or find shelter.
Smoke is more toxic from urban fires due to what is being burned, which includes automobiles, plastics, metals, rubber, pesticides, paint, carpets, and anything else found in homes. Even in areas outside of the burn scar, smoke and ash will travel up to thousands of miles, depending on weather conditions. Wildfire smoke can make anyone sick, but children, elderly, and people with pre-existing medical conditions such as asthma are more likely to have health problems during and following smoke exposure.
During the Los Angeles fires in January 2025, more than 600,000 students had school canceled due to wildfire damage, ash, and smoke. More than 80% of students in Los Angeles Unified School District are in poverty, who were unable to access education, resources, and food due to closures and evacuations. Thousands of students from Altadena and the Pacific Palisades whose schools burned down were not able to be funneled into neighboring districts and schools for many weeks to months, and many entered classrooms that had high student-teacher ratios and were unable to get the academic and emotional support they needed.
Wildfires disproportionately affect many different communities of people. The Eaton Fire in Altadena was ignited from sparks on power lines owned by Southern California Edison Power, who failed to shut off power during 100-mile winds. Data shows that power plants are often placed in neighborhoods occupied by people of color and who are low-income, which is reflected by Altadena's racial populations. Children are also disproportionately affected by wildfires, as they are more susceptible to health effects, often have school canceled due to air quality or evacuations, and cannot vote for legislation that affects them and the climate. Elderly and disabled communities are also dramatically affected by health concerns associated with wildfires, and many are unable to evacuate without assistance. People that are low-income often do not have the financial resources to evacuate, and if losing their home, do not have the resources to find new homes, participate in lawsuits, and find personal essentials like clothing and toiletries.
Wildfires are linked to climate justice because climate change exacerbates wildfires, and different communities disproportionately suffer due to intersectional identities. The winds generated in the January 2025 Los Angeles fires are a result of the orographic effect occurring on the San Gabriel and Santa Monica Mountain ranges, which is amplified by decreased precipitation leeward side and increased wind on the windward side of the mountains.