Tuesday, January 28, 2014

Water worries

It almost felt as if it might rain today. I'll believe it when I see it.

Ten days ago when Governor Brown declared a drought emergency, the situation was dire:

The Sierra Nevada snowpack on Thursday was 17 percent of normal. And last year, most cities in the state received the lowest amount of rain in any living Californian's lifetime. The rainfall records go back to 1850.

For the past 13 months, a huge high-pressure ridge in the atmosphere has sat off the West Coast, diverting storms that normally would bring winter rain northward to Canada.

During the dire drought of 1976-7, I remember people holding rain dances on Mt. Tamalpais. But what is happening this year is much worse. Most locations had record low rainfall during 2013.

A month and more of what are summer temperatures in San Francisco (60+F) has been great for someone like me, who lives to spend time outside. But is this the new normal? Probably not. But if the new normal is anything like this, can California really support what will soon be 40 million residents? After all, much of the state was always a desert, only rendered fertile by irrigation. The history of the state is a history of wars over water.

This image shows the snow pack in the Sierra in 2012; and the snow pack today. There's not much white snow this year.

If you live here, you know all this. But talking with faraway friends, I have realized that it is hard for folks to imagine what it has been like in California this winter.


Rain Trueax said...

And at Parker, crossing the Colorado River was amazing as I've never seen it this low. This is the water that Arizona counts on since Jimmy Carter created the canals that have allowed regions without water to grow in numbers previously unimagined. What happens if that water isn't there? There is a lot of reusing water in Arizona but it's not enough given the numbers, the lawns, the swimming pools. Climate change can mean massive population movement. Even Oregon is dry and if this is not just a cycle but a real change, it's hard to say where it will lead ;( We are used to wanting things to be as they have been. Earth doesn't operate that way.

Hunter Cutting said...

FYI/FWIW - here's the science:

- Global warming is helping to intensity the California drought, and may even be contributing to the unusual weather pattern blocking storms from the state.

- Climate change has increased temperatures in the United States, and warmer temperatures in turn increase early snow melt, increase evaporation of snow pack and reservoirs, and dry up soils - all of which intensifies drought conditions and reduces water supply. California has witnessed record high temperatures this summer, and record highs tend to be broken when natural variation and climate change run in the same direction, in this case towards warming.

- Climate models have long predicted that subtropical areas, such as southern California, would become drier (through expansion of Hadley Cell circulation) and precipitation would move northward to higher latitudes. And generally that pattern has been observed on a global scale. However the models are not clear about the direction of precipitation changes due to Hadley Cell expansion in intermediate areas such as Northern California where the state gets the vast majority of its total precipitation.

- The current shortfall in precipitation appears to be driven by a different (but perhaps related) mechanism than Hadley cell expansion, rather it's due to a large, persistent, and unprecedented ridge of high pressure that has set up over the West Coast, shunting winter storms (the main sources of California's annual water supply) well to the north of California into Southeast Alaska, leaving California exceptionally dry.

- Climate change may be at least partly responsible for this unprecedented high pressure system. We know that global warming is already changing global weather patterns, and this particular kind of change was foreseen by at least one pair of intensive computer studies that projected the impact of a melting Arctic and found that it moved California storms northward as currently observed. So, climate change may have increased the odds for the very event we're now experiencing.




For a full discussion of these studies see:


Hunter Cutting said...

Whoops I meant record high temperatures this WINTER.

Classof65 said...

Instead of contemplating oil pipelines through our nation we would do better to build water pipelines from the east to the western half of the nation. At least we wouldn't have to worry that leakage would ruin the aquifers or kill wildlife.

Rain Trueax said...

California wanted PNW water some years back. That was popular-- not. I think we need to come up with better ways to reuse water. Tucson has done it and right now they are taking some of that Colorado River water and pumping it into their aquifers. They may need them. They also reuse sewage water on golf courses... not that golf courses ever make sense in arid regions.

janinsanfran said...

Friends of mine have worked on water issues in Las Vegas for a decade. The city actually does a decent job at reducing water waste. But in the end, it is desert ...

Thanks Hunter!

Hattie said...

Whereas Hilo,Hawaii got 27 inches of rain in two days recently. And a fair amount of rain yesterday. Crazy.
Seattle is dry with a.m. ground fog and it has been beautiful on the coast. My friend who lives in Long Beach reports temperatures in the low 60s.

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