California’s fourth Climate Change Assessment was released at the end of August. The assessment is based on a series of 44 technical reports. Besides an overall summary of the consequences of climate change on the California environment — natural and structural — there are separate reports for nine different regions of the state.

The Hill area is included in the Los Angeles Region Report, which spans from the San Jacinto Mountains west to the Pacific Ocean.

“In California, facts and science still matter,” Gov. Edmund G. Brown Jr. said in the press release announcing the assessment’s availability. “These findings are profoundly serious and will continue to guide us as we confront the apocalyptic threat of irreversible climate change.”

Based on current research, the assessment’s authors foresee more frequent and larger wildfires, sea levels rising, higher temperatures and more deaths due to heat.

The state is already experiencing growing wildfire destruction. The report expects this phenomenon to worsen. However, for the Los Angeles region, the report was less specific, “… large uncertainties remain in current wildfire models, and [this] is an area where further research is required.”

“By the year 2100, if greenhouse gas emissions continue to rise, one study found that the average area burned by wildfires would increase 77 percent and the frequency of extreme wildfires burning more than 25,000 acres would increase by nearly 50 percent. In the areas that have the highest fire risk, the cost of wildfire insurance is estimated to rise by 18 percent by 2055,” another section reported.

Within the Los Angeles region, average temperatures, minimum and maximum, have been trending higher for decades. “The top five warmest years in terms of annual average temperature have all occurred since 2012,” the report states. The warmest year in more than a century was 2014, and the next four warmest were (in order) 2015, 2017, 2016 and 2012.

As temperatures rise, the study expects the demand for electrical power also will grow as residents use air conditioning more to remain cool. Thus, one area, which will be significantly affected by the changing climate, is the local electrical-generation systems.

Natural gas is the dominant fuel for Southern California generation facilities today and many are nearing retirement, according to the report. The replacement systems will have an effect in the future. Brown just signed Senate Bill 100 [see accompanying story], which establishes how much of the electricity system should be powered from renewable energy resources. The new objectives are 50 percent by 2025, 60 percent by 2030 and, ultimately, 100 percent by 2045.

“California is committed to doing whatever is necessary to meet the existential threat of climate change,” Brown wrote in his SB 100 signing message. “This bill, and others I will sign this week, help us go in that direction. But have no illusions, California and the rest of the world have miles to go before we achieve zero-carbon emissions.”

Precipitation was more difficult to project because the region lies between the wetter northern portion of the state and the drier areas to the south. What the authors do anticipate are more extreme periods of dryness or wetness.

For example, much of the studies project storms from “atmospheric rivers” will be more intense. But the trend for Santa Ana wind events does not appear to be more or less through the end of the century.

The assessment and its accompanying reports may be found at www.climateassessment.ca.gov.

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