The question of whether desalination can be expected to contribute significantly to California’s water supply in the future (it doesn’t at present) is significantly dependent on the prices of desalinated and non-desalinated water at present and in the future.

According to the figure on this website, the price of desalinated water declined from approximately $1800 per acre-foot in 1991, to approximately $600 per acre-foot in 2003. That’s a factor of approximately 3 in 12 years. According to text with figure, the price of desalinated water has dropped by a factor of 4 in the last 20 years.

hbfreshwater.com/index.php?p=7 (add http and www)

Suppose the price of desalinated water continued to drop by a factor of 4 every 20 years for the rest of the century. That would put the price of desalinated water circa 2030 at $150 per acre-foot, and approximately $38 per acre-foot by 2050.

Here is a website with water prices in California:

waterplan.water.ca.gov/docs/cwpu2005/vol4/vol4-background-selectedwaterprices.pdf (add http and www)

Obviously, the prices vary tremendously, with the lowest values being below $10 per acre-foot, particularly for the North Coast, Sacramento River, and Colorado River.

However, even the prices to farmers (table titled “Costs Paid by Farmers for Delivery of Surface Water for Irrigation…”) are as high as $400-600 per acre-foot.

And the prices paid by households in urban areas are typically in the range of $300-900 per acre-foot.

So Stephen Chu’s comment about “I don’t see how they can keep their cities going” was simply completely unscientific.

Also, his comment about “no agriculture” is not supported. Even though desalination might never get down to the ridiculously low prices of less than $10 per acre-foot, if desalination was able to get down even from it’s present value of $600 per acre-foot to $150 per acre-foot–which would happen by 2030, just following price trends for the previous 20 years–significant amounts of agriculture would exist in California. (Because they’re already paying approximately double that price for irrigation water in the South Coast and Central Coast.)

It seems that Chu believes that a “90% reduction in Sierra snowpack” would lead to comparable reductions in water available to California’s supply system. If this were true, such an eventuality could easily be catastrophic for both agriculture and urban areas.

The projections of 90% reduction in snowpack are cited in sources like this:

http://www.calclim.dri.edu/climatewatch.html

ultimately deriving from the IPCC AR4 report using the upper limit of their projected 21st-century warming (~5C).

A couple of interesting things to note in these projections: First, the quoted reduction is for April snowpack — the snowpack essentially disappears entirely every year as there are very few glaciers in California. Second, the above link that shows these reductions states, “No significant change in precipitation is projected for California by any of the emission scenarios.”

So really what we are talking about is more precipitation falling as rain rather than snow and snow melting earlier in the year. What are the implications of this for California’s water system? Potentially, the increased earlier runoff could not all be captured. How bad a problem would this be?

Here’s an interesting analysis of the problem out of UC Davis (actually cited to me by an alarmist):

http://cee.engr.ucdavis.edu/faculty/lund/papers/Zhu2005.pdf

They look at a dozen different scenarios of temperature and precipitation for their impacts on the California water supply system. I looked in particular at the +5C temperature increase with 0% precipitation change case, which corresponds to the 90% reduction in April snowpack projection. For this scenario, they project a 16% decrease in water available to the supply system (see Table 3 in the link). This would certainly be problematic, but catastrophic?

Let’s look at the assumptions they used. First, of course, they are looking at the present supply system of dams and aqueducts — fair enough. Second, though, they assume that NONE of the additional runoff occurring before April 1 will be capturable by the water system, as it would all have to be released for flood-control purposes.

They then admit that “since there is likely to be more wet season storage flexibility than is assumed here, the resulting estimates are likely to be more dire than more realistic results from operations modeling.” So the likely reduction in available water will be significantly less.

So a reasonable conclusion is that a 90% reduction in April Sierra snowpack would lead to about a 10% reduction in available water to the present supply system. And we only have 100 years to improve the supply system…

I should have written: “And not only have the improvements in desalination *not* stopped, if anything, they’re accelerating.”

Unfortunately, I have a bunch of other stuff I should be doing, so won’t be able to participate in these interesting discussions (here and about Daniel Sarewitz’ comments in another post) as much as I’d like.

You write, “Agreed – I don’t think Chu hedged like he should have on agriculture.”

Actually, the comment about the *cities* is even more ridiculous than the comment about agriculture. Most of California’s biggest cities are located on the *coast,* for goodness sake! Even if agriculture did completely stop in California, there’d be no reason why they couldn’t import enough food to feed their coastal cities.

Also, cities require very little water compared to agriculture. There’s absolutely no reason that the coastal cities of California couldn’t desalinate enough water to supply themselves.

“But I can see where Chu is coming from (I think), with books like Cadillac Desert explaining how California’s population is well beyond sustainable levels with their own state resources.”

Well, I haven’t read Cadillac Desert yet. (I ordered it through Bookfinder on Friday night for about $8, including shipping. Is this a great world, or what?)

But if your summary is correct, i.e., “…explaining how California’s population is well beyond sustainable levels with their own state resources…” then I’d be very skeptical. (At least in its applicability to the 21st century.)

I see Cadillac Desert was published in 1986. Well, the progress in reverse osmosis desalination in the last 23 years has been stunning. And not only have the improvements in desalination stopped, if anything, they’re accelerating.

Here is a Powerpoint presentation that indicates that reverse osmosis membrane costs decreased by almost 86% (almost 90%!) just in the 12 years from 1990 to 2002. And water produced per unit of surface area increased by over 90%:

http://www.owue.water.ca.gov/recycle/desal/Docs/UnitCostDesalination.pdf

“Declining Membrane Costs: 86% Cost Reduction from 1990 to 2002

Increase in Productivity due to Increased Surface Area: 94% Productivity Increase from 1990 to 2002

New Pretreatment Approaches: Such as Using Micro- & Ultrafiltration”

It is not at all unreasonable to look 20+ years into the future and think that the costs for Los Angeles and San Diego to desalinate seawater for their water supply will be competitive with, or even less expensive than sources such as the Colorado River or the State Water Project (through 444 mile aqueduct):

http://www.water-ed.org/watersources/community.asp?rid=9&cid=562

“I think I remember reading somewhere that the actual LA river basin could only support some 100K people.”

And I *do* remember an exchange in a book that I read a LONG time ago (almost 40 years ago) that signficantly influenced my life. In fact, it wouldn’t be totally ridiculous to say that I’m an environmental engineer partly due to that book and that exchange.

The book is Farmer in the Sky, by Robert Heinlein. The premise is that there are colonists “terraforming” Jupiter’s moon, Ganymede.

The teenage son tells his dad that another father had commented that Ganymede was a “precarious situation, artificially maintained.” And the father replied, “What do you think would happen to California without the nuclear desalination plants all along the coast?”

It’s probably true that, with 19th century technology, the LA River Basin might only support 100,000 people. But that’s not a relevant observation in the 21st century. And it’s likely to be less and less relevant–not more and more relevant–as the 21st century progresses.

Better get back to work!

Mark

Yes, it seems we do agree.

They are different in a political sense, but much the same in terms of misjustifying the preferred action. Here again is another good example of the distinction between evaluating a justification for an action and evaluating the action.

I don’t think that the quality or appropriateness of the former should be judged by the worth of the latter (ends justify means) and it seems that you would agree.

Thanks.

But I did no such thing; I simply pointed out that, for public policy purposes, emphasizing worst-case scenarios is not “the same thing” as do one`s best to deny any problem. The latter, if effective, blunts both possible mitigation AND individual efforts to adapt.

(In fact, you might not that in discussing Mark B`s comments I disagreed with Mark because I feel that Chu deserves criticism: “I think it would be fair to criticisize him for not providing more balance in his remarks.”)

Looking deeper at those reports, those same two models dramatically disagreed on the precipitation forecasts (even on the sign of the change) for most other areas. This leads us to the bigger issue of whether the climate models have any reasonable predictive powers on the regional level. A lot of knowledgeable scientists (Pielke Sr. included) think not.

And, of course, this leads us to the even bigger issue of whether the climate models have any predictive power on global-geographic and centennial-time scales. Lack of predictive power on smaller geographic and time scales is certainly not proof of lack of predictive power on the larger scales (most of the [non-climate] models I deal with in my professional work do have better predictive value on larger scales), but I have yet to see any convincing demonstration that climate models have the larger-scale predictive power when the lack in in the smaller scales.

And the prediction has been based solely on a few numbers calculated by use of EWAG-based what-ifs that have been run through process-model based computer software in which physical phenomena and processes that are critical to high-fidelity representation of the system of interest are known to be much less than robust ( they are EWAGs themselves ). ( EWAG-based what-if scenarios are not science, and especially they are not Science. )

A more reasoned approach in my opinion would be as follows. Dr. Chu, “In a worst case, up to 90% of the Sierra snowpack could disappear, all but eliminating a natural storage system for water vital to agriculture. Let me first emphasize that these are preliminary results and as such they require especially close study because of the many uncertainties associated with these numbers. We have not yet processed these results through additional analyses in which zeroth-order cuts at the many potential responses are investigated. When all this additional work has been completed, I’ll have some suggested approaches to possible paths of action, should we decide that any response is necessary at this time. With respect to agriculture, not just in California but everywhere in the world, consider the incredible evolution of all aspects of these processes over the past 100 years. One hundred years ago no one could have imagined the truly advanced state and productive efficiency of agriculture around the world.”

Chu now holds an extremely important position from which he will be a major force relative to public policy. As such it seems to me that he should always be very careful about what he says when in a public setting. Too many examples of less-than-sensible utterances will always lead to major problems. That is if we lived in an objective universe. As we are basically in a political universe into which some have attempted to introduce pseudo-science, maybe this will not be a problem for him.

And, not be caviler, but under what conditions are we to take seriously statements like those that Dr. Chu has made. I think that waiting around for a peer-reviewed paper published in an approved Climate Science Journal will not be the standard to which The New Admin will be held.

Mark B. is absolutely right (#18) in my view and I could not say it better.

Tokyo Tom-

Calling me a climatologist is not a “promotion”

I strongly disagree with your “ends justify the means” reasoning. See my chapter in The Honest Broker on the decision to go to war in Iraq. Over stating or misrepresenting knowledge is pretty much a bad idea no matter how noble the cause.

The previous administration’s cherry-picking was designed to say, hey, there’s no problem; Obama’s seems to be to say, hey, we have a big problem that we need to do something about! The difference? The cherry-picking of “skeptics” shifts attention away from ongoing changes that should be cause for concern and from possible risks; that of Chu and “alarmists” at least clue us in to a potential problem and leave us aware of a possible need to adapt, even if we reject any policy prescription calling for mitigation.

(I suspect that the reason why many “skeptics” prefer to discount clikate change altogether is that they fear that if Americans realize that there IS a need to adapt, that Americans will want those who generated the risks to bear some of the costs.)

BTW, I see that energy blogger Robert Bradley Jr. has promoted you to “climatologist” – congratulations! But has he correctly read you as concluding that “there’s absolutely no scientific basis” for Chu’s remarks? http://sciencepolicy.colorado.edu/prometheus/can-someone-point-to-the-science-4930#comment-11830

Mark: “If Steven Chu had said something like: “In a worst case, up to 90% of the Sierra snowpack could disappear, all but eliminating a natural storage system for water vital to agriculture. I can’t even imagine what that would do to agriculture in California, or even to the cities!” (Add a breathless sigh at the end, for effect.) …then I would have no real problem with that.”

Even if Chu had been careful, he’d probably be misquoted! But even if not, unlike you I think it would be fair to criticisize him for not providing more balance in his remarks.