California’s Climate Makes It Especially Vulnerable to Global Warming

The skyline of San Francisco appears above the evening fog as the sun sets on the Marin Headlands in Sausalito.Credit…Robert Galbraith/Reuters

The allure of California has long been its almost unbelievably good weather: predictably dry summers and pleasant, if occasionally rainy, winters. Who wouldn’t want to escape swampy heat for this temperate paradise?

Our typically agreeable weather (current heat wave notwithstanding) is officially called a Mediterranean-type climate, defined as having cool, wet winters and dry, warm summers. Only five places in the world share this climate: California, Central Chile, southwestern Australia, South Africa and, of course, the Mediterranean Basin.

“The California climate of having this several-month period of no rain that coincides with the hottest time of the year is globally really weird,” said Anna Jacobsen, plant ecology professor at California State University, Bakersfield. “It’s a really special and kind of unique climate cycle.”

The location of these five ecosystems is no accident. All are on the western edge of continents, between 30 and 45 degrees latitude, with a cold polar current running along the coast. Prevailing wind patterns and the cold current effectively prevent precipitation in the summer, the season when rainfall is most likely in the rest of the world.

The desirable weather that results is not only a draw for humans, but also tends to foster a wide variety of plant and animal species. All five regions are recognized as global biodiversity hot spots, accounting for roughly 2 percent of the world’s land area but nearly 20 percent of its plant species, said Dick Cameron, director of science for land and climate programs at the Nature Conservancy in California.

California in particular, with its varied topography and microclimates, is home to more than 5,000 species of plants, roughly a quarter of which exist only within the state. “Plants far and away are our contribution to global biodiversity,” Cameron told me.

But the unique characteristics of Mediterranean-type climates also make them more susceptible to the impacts of global warming. Because California, for example, gets so much of its annual rainfall from a handful of storms in the winter, even small shifts in weather conditions can produce large effects.

In other words, the very characteristics that make these climates famous (the rain-free summers) “predispose those regions to water scarcity,” said Daniel Swain, a climate scientist at the University of California, Los Angeles. “If the storms don’t occur during the wet season, you’re screwed.”

Plus, increasingly warm weather exacerbates drought conditions by melting snowpacks and quickly evaporating water that’s stored in lakes and the soil. California is currently in the midst of a historic drought, and South Africa, southwestern Australia and the Mediterranean Basin have all grappled with severe droughts in recent years too.

These Mediterranean-type climate ecosystems were already dry places that global warming is making even drier, said Brandon Pratt, professor of biology at California State University, Bakersfield. He put it this way: “You’re already on the margin and now you leave the margin and you jump off the cliff.”

That’s adding up to worse fire seasons too, experts say. These regions have long experienced fires, and their landscapes are in many ways adapted to burn, Swain said.

But the exceptionally parched land and warmer temperatures are fueling fires that become far more destructive than what’s normal. “All of those places are places that have big issues with wildfire.”

For more:

  • One of Europe’s worst droughts in decades has left the water level of parts of the Rhine and the Danube Rivers too low for ships to pass, paralyzing commerce and canceling river cruises.

  • The Western drought is the worst in 12 centuries.

  • At Yosemite, a preservation plan calls for chain saws.

Victor Tejada and his dog cooled off with water from a hydrant in the Skid Row area of Los Angeles on Wednesday.Credit…Jae C. Hong/Associated Press

The rest of the news

  • Heat wave: Operators of California’s power grid called for statewide voluntary conservation of electricity in response to a heat wave that they warned could cause energy shortages, The Associated Press reports.

  • Fires: Wildfires erupted in rural areas of the state on Wednesday, racing through bone-dry brush and prompting evacuations during a brutal heat wave, The Associated Press reports.

  • Tesla law: A bill targeting Tesla’s marketing claims of a “full self-driving” option has passed the California Legislature, The Los Angeles Times reports.

  • Teenage vaccination bill: California will not allow teens age 15 and up to be vaccinated against Covid-19 without their parents’ consent, The Associated Press reports.

  • Help paying for water: A bill that creates a state program to help low-income Californians pay their water and sewage bills is headed to Gov. Gavin Newsom, CalMatters reports.

  • Vasectomies: California lawmakers voted to make vasectomies cheaper, The Associated Press reports.

  • Wine bottle recycling: California would add wine and distilled spirits containers to its struggling recycling program under a measure that advanced Wednesday, The Associated Press reports.


  • Housing and evictions: Los Angeles could end many of its Covid-19 protections against evictions and rent increases by January, The Los Angeles Times reports.

  • Removal: Three Mission Viejo City Council members remained in office beyond the two-year term to which voters elected them and will be removed from their seats, The Orange County Register reports.


  • Death Valley heat: A blast of hot weather expected to stretch through the weekend in Death Valley could tie the record for the hottest temperature ever recorded on Earth in the month of September, The San Francisco Chronicle reports.


  • Toxic algae: A harmful algal bloom known as a red tide is killing off “uncountable” numbers of fish in the Bay Area, with residents reporting rust-colored waters, and piles of stinking fish corpses washing ashore.

  • Humpback whale: Scientists mourned the loss of California’s best known whale, SFGate reports.

Credit…John Kernick for The New York Times.

What we’re eating

Our best Labor Day recipes.

Swimmers at a beach in Santa Cruz.Credit…Peter Prato for The New York Times

Where we’re traveling

Today’s tip comes from Christina Arrostuto, who recommends San Francisco’s backyard:

Tell us about your favorite places to visit in California. Email your suggestions to [email protected] We’ll be sharing more in upcoming editions of the newsletter.

Tell us

Californians: Have growing concerns about climate change affected how you live your life? Have you made any changes? If so, we want to hear about them. (Have you adjusted any daily routines, changed your job or made new financial decisions?)

Email us at [email protected] Please include your name and the city you live in.

This is part of a live event that The Times is hosting in San Francisco on Oct. 12 examining our collective response to the climate challenge. Learn more.

Jamil Jan KochaiCredit…Jalil Kochai

And before you go, some good news

Jamil Jan Kochai knew only 10 letters in the English alphabet when his parents immigrated to West Sacramento from Pakistan when he was 7.

His second-grade teacher, Susan Lung, spent nearly every day after school with him, teaching him how to read and write in English.

The lessons clearly stuck. Two decades later, Kochai is now a published author, The Washington Post reports.

And he was able to thank his former teacher in person last month, when both Lung and her husband attended one of Kochai’s book events.

“When I saw Ms. Lung there, my heart dropped,” Kochai said. “It wasn’t like seeing someone from my past, it was like seeing someone that I’ve known and cared for and loved all my life.”

“I gave her a big hug; a hug I had been waiting 20 years to give her.”

Thanks for reading. I’ll be back tomorrow. — Soumya

P.S. Here’s today’s Mini Crossword, and a clue: Italian response to thanks (5 letters).

Isabella Grullón Paz, Francis Mateo and Briana Scalia contributed to California Today. You can reach the team at [email protected].


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