Shared from the 5/9/2018 San Francisco Chronicle eEdition

Climate change’s alarming impact

State enduring multiple calamities, report finds



Average air temperature increases have accelerated since the mid-1970s. The last four years were the hottest on record.

WILDFIRES: The five largest fire years since 1950 occurred after 2006. The Wine Country fires in 2017 were the deadliest and most destructive in state history.

DROUGHT: California is becoming drier. The 2012-16 drought was the most extreme on record.

SPECIES MIGRATION: About 75 percent of small mammal species and 80 percent of bird species surveyed in the Sierra Nevada region have shifted ranges in an effort to find suitable habitat.

Source: Cal EPA

Michael Macor / The Chronicle 2017

The Wine Country fires, which killed 45 people, were the deadliest and most destructive wildfires in state history.

Bigger, more intense forest fires, longer droughts, warmer ocean temperatures and an ever shrinking snowpack in the Sierra Nevada are “unequivocal” evidence of the ruinous domino-effects that climate change is having on California, a new California Environmental Protection Agency report states.

The 350-page report released Wednesday tracks 36 indicators of climate change, including a comprehensive list of human impacts and the effects on wildlife, the ocean, lakes, rivers and the mountains.

The study pulled together research from scientists, academia and research institutions and found that despite a marked downward trend in greenhouse-gas emissions in California, including a 90 percent drop in black carbon from tailpipe emissions over the past 50 years, CO2 levels in the atmosphere and in seawater are increasing at a steady rate.

“To me, it shows how important it is to bring carbon emissions down to zero and to limit the amount of climate change that occurs as much as possible,” said Christopher Field, director of the Stanford Woods Institute and a top climate scientist whose research is reflected in the report. “The risks are coming into sharper focus, the range of impacts are coming into sharper focus. (The report) reinforces and amplifies the messages we’ve already seen.”

The report, called Indicators of Climate Change in California, shows a dramatic increase in temperatures since 1895, especially since the early 1980s. The warmest year in California history was 2014, followed closely by 2015, 2017 and 2016. Most alarming of all, though, are night temperatures, which have increased 2.3 degrees over the past century, the report notes.

Extreme heat waves have also increased since 1950, according to the report. Record heat combined with drought has had a debilitating effect on the ecosystem. The drought from 2012 to 2016 was the most extreme in terms of high temperatures since records began in 1895. Some 129 million trees died during the drought, which deprived the trees of water, dried out their sap and promoted infestations of bark beetles, which thrived in the heat.

The drought coincided with record-low snowpack. Snow-melt has, in fact, been in a continual decline, decreasing by 9 percent since 1906, according to the climate document. The largest glaciers in the Sierra have shrunk by an average of about 70 percent, the report said. Meanwhile, the water temperature in Lake Tahoe — California’s signature high-altitude water basin — has warmed nearly one degree since 1970. The study said the warming has been 10 times faster over the past four years.

Sea levels have also been rising and temperatures have been warming, according to the report. The mean sea level in San Francisco has risen 7 inches since 1924. Oxygen depletion has also been detected in the water off San Diego.

The result of all this change has been an alarming increase in extreme weather-related calamities. The five largest fire years since 1950 have all occurred since 2006, and last year saw the deadliest and most destructive wildfires in state history. These included the Thomas Fire in Southern California and the wind-blown wildfires that killed 45 people and destroyed 8,900 homes in Sonoma, Napa, Lake and Mendocino counties in October.

“The observed changes in wildfire have outpaced all of the models,” said LeRoy Westerling, professor at UC Merced who has created fire models for the California Energy Commission. “Warmer temperatures enhance the droughts, and that drives more wildfire.”

Westerling said there are likely to be more forest fires, as opposed to chaparral fires, in California in future years. That means more wildlife habitat will be destroyed by fire, humans will be breathing more particulate matter, more homes will be in danger, and the cost of homeowners insurance will continue to rise.

“Under any of the scenarios we’ve looked at, we see increased wildfires in the Sierra Nevada, Southern Cascade and North Coast range forests because their elevation makes them more sensitive to temperature increases.” he said. “It means we are going to have big increases in air pollution emissions from these burning forest fires.”

But there are bright spots.

Senate Bill 32, signed by Gov. Jerry Brown in 2016, put California on course to reduce emissions an additional 40 percent below 1990 levels by 2030. The state expects to drop below 1990 levels within two years. Concentrations of black carbon from vehicle exhaust have already dropped 90 percent over the past 50 years even as diesel fuel consumption has increased seven-fold, according to the report.

California’s leadership role in the development of clean fuels and sustainable energy has largely been driving the market in the rest of the country. Experts say that innovative spirit, in defiance of the political winds blowing in Washington, D.C., have put the state at the forefront of a new economic model that could eventually make clean energy the standard throughout the world.

“As California works to both fight climate change and adapt to it, it is critical that we understand the dramatic impacts climate change is already having in our state,” said Matthew Rodriquez, the California secretary for environmental protection. “California’s climate leadership is unquestioned, and this report builds on the essential scientific foundation that informs our efforts to respond to climate change.”

Still, California contributes only a fraction of the world’s carbon emissions.

“If I were going to look across North America, ground zero for climate change is the Arctic. It is just changing really, really rapidly,” said Steven Beissinger, professor of conservation biology at UC Berkeley. “But California is an important laboratory to understand the effects of climate change on biodiversity.”

Peter Fimrite is a San Francisco Chronicle staff writer. Email: Twitter: @pfimrite

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