Climate change in California
Climate change and the effects of global warming with regard to the climate in California primarily revolve around issues such as drought and the subsequent risk of wildfire and related occurrences. A 2011 study projected that the frequency and magnitude of both maximum and minimum temperatures would increase significantly as a result of global warming. The same study further projected that the frequency and magnitude of both maximum and minimum temperatures would likely increase as a result of global warming.
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.Wildfires
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.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, dryer 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 this 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.
Drought
According to the NOAA Drought Task Force report of 2014, the drought is not part of a long-term change in precipitation and was a symptom of the natural variability, although the record-high temperature that accompanied the recent drought may have been amplified due to human-induced global warming. This was confirmed by a 2015 scientific study which estimated that global warming "accounted for 8–27% of the observed drought anomaly in 2012–2014... Although natural variability dominates, anthropogenic warming has substantially increased the overall likelihood of extreme California droughts."In February 2014, the Californian drought effects caused the California Department of Water Resources to develop plans for a temporary reduction of water allocations to farmland by up to 50% at the time. During that period California's 38 million residents experienced 13 consecutive months of drought. This is particularly an issue for the state's 44.7 billion dollar agricultural industry, which produces nearly half of all American-grown fruits, nuts, and vegetables. According to NASA, tests published in January 2014 have shown that the twelve months prior to January 2014 were the driest on record, since record-keeping began in 1885. Lack of water due to low snowpack prompted Californian governor Jerry Brown to order a series of stringent mandatory water restrictions on April 1, 2015.
Forest management
Drought-surviving sugar pines around Lake Tahoe have found among 129 million trees in California killed between 2012 and 2016 by drought and bark beetles. Thousands of seedlings descended from these trees are being planted south-facing slopes on the lake basin's north side with the hope that they carry genes that make them more resilient to drought, waning snowpack and other effects of global warming in the forests of Sierra Nevada.Sea Level rise
A 2017 study published in the Journal of Geophysical Research projected that a sea level rise of between 1 and 2 m will swallow between one-third and two-thirds of Southern California beaches.Health impacts
Expected increases in extreme weather could lead to increased risk of illnesses and death.Heat waves
From May to September 1999 – 2003, a study was conducted in nine Californian counties that found that for every 10 °F increase intemperature, there is a 2.6 percent increase in cardiovascular deaths.
2006 heat wave
A study of the 2006 Californian heat wave showed an increase of 16,166 emergency room visits, and 1,182 hospitalizations. There was also a dramatic increase in heat related illnesses; a six-fold increase in heat-related emergency room visits, and 10-fold increase in hospitalizations.A study of seven counties impacted by the 2006 heat wave found a 9 percent increase in daily mortality per 10 degrees Fahrenheit change in apparent temperature for all counties combined. This estimate is 3 times greater than the effect estimated for the rest of the warm season. The estimates indicate that actual mortality during the 2006 heat wave was two or three times greater than the initial coroner estimate of 147 deaths.
Air pollution
Research suggests that the majority of air pollution related health effects are caused by ozone and particulate matter. Many other pollutants that are associated with climate change, such as nitrogen dioxide, sulfur dioxide, and carbon monoxide, also have health consequences.Five of the ten most ozone-polluted metropolitan areas in the United States are in California. Californians suffer from a variety of health consequences due to air pollution – including 18,000 premature deaths attributed to various causes such as respiratory diseases as well as a number of other illnesses.
Climate change may lead to exacerbated air pollution problems. Higher temperatures catalyze chemical interactions between nitrogen
oxide, volatile organic gases and sunlight that lead to increases in ambient ozone concentrations in urban areas. A study found that for each 1 degree Celsius rise in temperature in the United States, there are an estimated 20–30 excess cancer cases, as well as approximately 1000 excess air-pollution-associated deaths. About 40 percent of the additional deaths may be due to ozone and the rest to particulate matter annually. Three hundred of these annual deaths are thought to occur in California.