Thursday, September 1, 2022

A Reprint of the Mediterranean-Type Climate of California-Pros and Cons

Here's an interesting article on California Mediterranean-type Climate from California Today, September 1, 2022- The Pros and Cons

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By Soumya Karlamangla

California Today, Writer

The Golden State is one of only five regions in the world with a Mediterranean-type climate. 

The skyline of San Francisco appears above the evening fog as the sun sets on the Marin Headlands in Sausalito.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.


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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.


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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:

The New York Times

September 1, 2022


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