Finally, we have a top administration official telling it like it is. Energy Secretary and Nobelist Steven Chu told a Los Angeles Times reporter:

In a worst case, Chu said, up to 90% of the Sierra snowpack could disappear, all but eliminating a natural storage system for water vital to agriculture.

I don’t think the American public has gripped in its gut what could happen,” he said.

Precisely. [You can listen to an interview with the LAT reporter and me on To the Point here.]

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We face desertification of perhaps a third of the earth that is “largely irreversible for 1,000 years” — if homo sapiens are not sapiens enough to sharply and quickly reverse emissions trends. Part 1 looked at the canary-in-the-coal mine for desertification: “Australia faces collapse as climate change kicks in.”

But the Southwest from Kansas and Oklahoma to California are right behind Australia, according to a 2007 Science ($ub. req’d) paper:

Here we show that there is a broad consensus among climate models that this region will dry in the 21st century and that the transition to a more arid climate should already be under way. If these models are correct, the levels of aridity of the recent multiyear drought or the Dust Bowl and the 1950s droughts will become the new climatology of the American Southwest within a time frame of years to decades.

[Note: That study “only” modeled the A1B emissions scenario, which leads to 720 ppm by 2100. We are currently on track to 1,000 ppm (see here).]

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A December U.S. Geological Survey report also warned that the Southwest faces “permanent drying” by 2050.

Before the permanent drying — aka a desert — sets in, you’d expect to see more and longer record-breaking droughts. In fact, Lester Snow, director of California’s Department of Water Resources said Friday:

We may be at the start of the worst California drought in modern history.

Fundamentally, California and the Southwest face one of the gravest dangers predicted by climate science, the expansion of the subtropics, the dry regions of the planet getting drier and getting bigger. As New Scientist explains:

Southern California is already subtropical in the summer. But with climate change, dry conditions could spread to areas like northern California, Washington and Utah, which now get far more rain and snow.

That means climate change hits the great agricultural state with a double whammy — a shift to a climate with less precipitation coupled with the loss of the mountain snowpack that acts as a reservoir for the state, which the state is experiencing right now:

According to a recent survey by the California Department of Water Resources, the snowpack on California’s mountains is currently carrying only 61% of the water of normal years. The Sierra snowpack alone provides two-thirds of California’s water supply, and these mountains have so far only received one-third of the expected annual snowfall, despite December and January normally being the wettest months.

The snowpack loss was the concern Chu focused on when he said:

We’re looking at a scenario where there’s no more agriculture in California. I don’t actually see how they can keep their cities going

He compared the situation to a family buying an old house and being told by an inspector that it must pay a hefty sum to rewire it or risk an electrical fire that could burn everything down.

I’m hoping that the American people will wake up,” Chu said, and pay the cost of rewiring.

Eight years of disinformation and muzzling U.S. climate scientists has left the public largely unaware of the catastrophes that we face of the business as usual emissions path.

That’s why Chu told the LAT reporter that he felt a key part of his job is a “public awareness campaign,” on climate science, which is precisely what I think the entire Obama energy and climate team needs to do if it wants a serious climate bill next year (see here).

While sea-level rise gets far more scientific research and media coverage, I consider the expansion of the subtropics an equally catastrophic impact. Indeed, the U.N.’s top climate official, Yvo de Boer has warned of the desertification-global warming feedback:

You’ll see a sort of feedback mechanism … quite a lot of carbon is captured in soil, so with more desertification (exposing the soil), you also get more CO2 emissions. They are two halves of the same coin.

Part 3 will be a primer on subtropical expansion, with links to recent studies and useful figures.

This post was created for, a project of the Center for American Progress Action Fund.

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