06 June 2007


Los Angeles residents were urged on Wednesday to take shorter showers, reduce lawn sprinklers and stop throwing trash in toilets in a bid to cut water usage by 10 percent in the driest year on record.

OK, first off, who does this? Second of all, there's enough people who do this that they feel compelled to remind people not to do this for conservation purposes? Third of all, what's wrong with you people?

(at least they didn't break out with the mantra I remember way back when from the 70s vintage Southern Californian drought, "if it's yellow let it mellow, if it's brown flush it down")

And before you go off half-cocked with a "global warming" thesis regarding this "worst drought since records began", that may be true on an annual basis, but there's no such thing as an average year for rainfall in Los Angeles. We are either very wet, somewhat dry, or bone dry, rarely in between. This has been the pattern for longer than they've been keeping records, as evidenced by tree rings from the Sierra Nevadas that suggest there have been periods of little rainfall that have lasted centuries in Southern and Central California over the past 3000 years.

A useful chart to see this pattern for yourself is over at LA Almanac which has monthly rainfall totals since they've been keeping records. There are plenty of stretches with three and four year periods under 8 inches of rainfall, and we've survived, and even thrived. The past ten years have actually been fairly wet if you were to average them (we can assume it won't rain again this season, it almost never rains in June, so we'll call 2006-7 as having produced 3.21 inches). The average since they've been keeping records is 14.93 inches, the average the past ten years (assuming no more rain falls this month) is 15.40 inches. So nothing unusual is happening locally, just the usual extremes that we've lived with since well before they've been keeping records.

The real problem lies in the fact that the excess water from wet years runs straight into the ocean and not into an aquifer, so there's no reserve for a year or two period of less precipitation. Over the past ten years we've had two 30+ inch seasons, including a near record 37.96 inches in 2004-5.

If we had a river instead of a concrete ditch, that might help, but then you'd have to allow for flood plains near the river as when it rains here it really rains. The area around the Los Angeles river is heavily industrialized through most of its journey to the Pacific, so I don't see any serious 'rewilding' of the river happening, a more wild river in a desert climate that is a trickle most of the time and a raging river with flows greater than any other river in the word at other times, would present a daunting logistical challenge, so instead we have a concrete ditch that serves as an outdoor movie studio most of the time.

But my main point is that a few bad months shouldn't mean instant drought, the wet years should be managed better, and we've had enough wet years recently that this past few months of 'historic drought' shouldn't be causing the problems it will likely cause.

Also, the reporter for Reuters doesn't know what he's talking about, the reporter states, "Below average rainfall for the past few years has also turned the traditional summer southern California fire season into an all-round event.", if you look at the chart I linked you'll see last season was a close to average 13.19" and the previous year was the near record 37.96", so no matter how you slice it, there has not been "below average rainfall for the past few years".

And the unusual fire season this winter had to due with unusually low humidity coupled with lack of rain from November to February when usually those are our wet months. And almost all the fires were started by humans (either by accident, or on purpose), so if folks would be sensible around brush, we'd do better as well. Little throwaway lines like that one which are either ignorant of the facts or purposefully distort the facts to lead to a conclusion that the data doesn't suggests really riles me, especially in a 'neutral' just the facts wire story.

I just feel it in my bones that the writer of the piece quoted above wanted to launch into a diatribe about advanced human caused global warming and this historic drought was all a sign that we should bow down before the Goracle and do all he asks of us, but pulled back at the last second (it is a short word count wire piece, after all), hoping that the 'facts' as presented would do that job without being too obvious.


bill said...

Do you read Matt Welch? Apparently, the coyotes are eating the cats. scroll down a bit

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