Can Someone Point to the Science?
February 4th, 2009Posted by: Roger Pielke, Jr.
Energy Secretary Steven Chu, about whom I’ve heard nothing but good things, was quoted as follows in the L.A. Times:
Reporting from Washington — California’s farms and vineyards could vanish by the end of the century, and its major cities could be in jeopardy, if Americans do not act to slow the advance of global warming, Secretary of Energy Steven Chu said Tuesday. . .
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. “We’re looking at a scenario where there’s no more agriculture in California.” And, he added, “I don’t actually see how they can keep their cities going” either.
Can someone point me to a study suggesting that there will be no more agriculture or cities in California by 2100? What does the IPCC say? What is the consensus view?
After 8 years of the Bush Administration’s cherry picking and selective reading of climate science it would be a shame to see the Obama Administration do exactly the same thing.
February 4th, 2009 at 3:11 pm
Somewhat related to this other post on Prometheus: http://sciencepolicy.colorado.edu/prometheus/alls-fair-in-love-war-and-science-4929#more-4929, the article explicitly states, “Chu is not a climate scientist.”
What will we ever do now? We’ve been told an uncountable number of times that only Certified Climate Scientists are qualified to speak on the subject. I’m confused.
And for years, spectacular pronouncements, many appearing as opinion pieces in newspapers, by those who are not Certified Climate Scientists have been routinely discussed in a dismissive manner (and that’s a kindly characterization) by those who are Certified Climate Scientists.
I’m eagerly awaiting the dismissal of Dr. Chu’s remarks.
February 4th, 2009 at 3:21 pm
Quick request – no ad homs or name calling please. Thanks.
February 4th, 2009 at 3:29 pm
“After 8 years of the Bush Administration’s cherry picking and selective reading of climate science it would be a shame to see the Obama Administration do exactly the same thing.”
I don’t see how Chu’s comments that there would “no more agriculture” or “cities” in California in 2100 could constitute “cherry picking.” I can’t imagine even one single peer-reviewed scientific article making such a ridiculous claim.
When I was growing up, my family had a cocker spaniel. She would run at squirrels and cats, barking furiously. Most of the time, the cats and squirrels would run away, and she’d chase after them, barking happily. But occasionally, a cat would simply crouch down and stay put. In that case, our dog would also stop, and her barking would just get higher and higher pitched.
This reminds me of that situation. Except my dog was just a dog…not a Nobel laureate in Physics.
February 4th, 2009 at 4:18 pm
Wait a minute, wait a minute, the situation is very much more confounding than I first realized.
Given the brouhaha / kerfuffle that Professor Pielke’s post here:
http://sciencepolicy.colorado.edu/prometheus/hansen-again-4925
and discussed here:
http://scienceblogs.com/illconsidered/2009/02/pielke_jr_how_low_can_he_go.php
and here:
http://www.inkstain.net/fleck/?p=3347
and here:
http://rabett.blogspot.com/2009/02/gareth-can-eli-have-ethon-back-roger-is.html,
has caused, we have a real problem on our hands.
Given that Dr. Chu’s remarks have not yet appeared in a Proper Peer-Reviewed Climate Science Journal, maybe his comments are merely a first rough draft and we should simply dismiss them paying no attention whatsoever.
On the other hand, as one of Dr. Chu’s focus areas in The New Admin is to be The Great Global Climate Crisis, almost all of his remarks on the subject will very likely appear only in newspapers, some might be strictly Opinion Pieces. Also very likely none, not a single one, will appear in Proper Peer-Reviewed Climate Science Journals for the edification of the general public. I’m sure he will also appear before a very large number of sub- and committees convened by our Congress. Pronouncements in this arena should carry less weight than even newspaper opinion pieces.
Thus everything he decrees on the subject, written and spoken, might be taken to be rough first drafts.
Are we to dismiss everything he says on the subject? Can public policy be built on rough first drafts?
I’m really confused now.
February 4th, 2009 at 5:15 pm
When I read this, my opinion of Chu specifically and Obama’s science team generally took a significant hit. Mark is right. Cherry picking and selective reading are lesser offenses compared to outright fabrication. Aside from the unpleasant comparison with George Bush’s science policy that this should suggest, it is not unlike the former president’s fear-mongering that was used to justify an abusive national security program. Furthermore, exaggeration of this kind only gives fodder to skeptics making accomplishment of environmental objectives less likely.
February 4th, 2009 at 7:16 pm
I’m not sure of blog etiquette in terms of reposting from another thread so I will include something from another discussion that seems to be relevant.
********************
And if we’re going there (to the literature) here’s one of my faves ““The recognition of natural systems as complex and dynamic entails moving to a science based on unpredictability, incomplete control, and a plurality of legitimate perspectives. Uncertainty is not banished but managed, and values are not presupposed but are made explicit. The model for scientific argument is changing form a formalized deduction to an interactive dialogue. The paradigmatic science is no longer one whose explanations are unrelated to space, time and process; the historical dimension, including human reflection on past and future change, is becoming an integral part of a scientific characterization of nature and our place in it.” Funtowicz and Ravetz (1994).
For those not familiar with this paper, what they call “post normal science” requires an extended peer community, participating in quality assurance and the problem-solving process, for its proper functioning. They suggest that a particularly difficult area will be ensuring the quality of post-normal science, which will depend increasingly on trust and integrity of the individual scientists.
*********************
Trust and integrity of individual scientists is where it’s at, if climate science is the ultimate post-normal science. This blog may be serving as an “extended peer community”. Just a thought.
February 4th, 2009 at 7:37 pm
Re: # 2. Is it an ad hom at this site to compare Chu to Hansen? The comparison seems completely correct to me, when I see completely unscientific comments like: “Gripped in its gut,” and: “I don’t actually see how they can keep their cities going” either.” Come on, Roger!
February 4th, 2009 at 8:05 pm
jae- I think we both know what I am referring to … keep it respectable, which you almost always do. I will try to toe a strict line on this … Thanks.
February 4th, 2009 at 8:30 pm
Unpolitical Science:…
The LA Times reports on an interview with Energy Secretary Steven Chu, a Nobel-winning physicist, about the threat climate change pos……
February 5th, 2009 at 8:52 am
Roger, while reading the 23 Jan issue of Science this morning, a book review of “Dead Pool” by Jared Farmer cites “Recent climate modeling–some of it published in Science–predicts that global warming will produce outstandingly large effects on the U.S. Southwest. Increased temperatures will lead to smaller snowpacks in the Rockies, and these will melt sooner and more completely.”
Those cited studies are:
1. E.R. Cook et al., Science 306, 1015-1018 (2004).
2. R. Seager et al., Science 316, 1181-1184 (2007).
3. T.P. Barnett et al., Science 319, 1080-1083 (2008).
So, if computer climate modeling counts as “science”, here are some possibles. I’ll leave it to more qualified commentators to pontificate as to the robustness of these data/studies/models/etc.
Cheers,
Alex
February 5th, 2009 at 9:21 am
[...] course, as climatologist Roger Pielke Jr. points out on his great blog “Prometheus,” there’s absolutely no scientific basis to these [...]
February 5th, 2009 at 9:29 am
In addition to source [3] above:
Cayan, D.,A. Luers, M. Hanemann, G. Franco, and B. Croes. 2006. Climate change scenarios for California: An overview. Sacramento, CA: California Climate Change Center.
http://www.energy.ca.gov/2005publications/CEC-500-2005-186/CEC-500-2005-186-SF.PDF
The Variable Infiltration Capacity (VIC) distributed land surface hydrology model was used to simulate snowpack throughout the century (Cayan et al. 2006a). Projected reductions in snowpack increase with temperature, with the larger losses of spring snowpack in the higher range of projected warming (Figure 6). Each of the simulations shows losses of spring snow accumulation, largely over the Sierra Nevada, become progressively larger over the twenty-first century. In the Sierra Nevada by the 2035–2064 period, snowpack could decrease 12% to 47% from historical levels under the lower range of projected warming, and decrease 26% to 40% in the higher range of projected warming, with precipitation changes playing a partial role in the reductions for the lower temperature cases. By the end of century, snowpack could decrease by as much as 90% in the higher amount of warming—almost double the losses expected under the lower warming cases.
February 5th, 2009 at 11:51 am
First of all, Chu is listed as a “nobel-winning physicist.” That’s nice, but if a Nobel-winning proctologist tells me I need brain surgery, I’m going for a second opinion. This sort of thing abounds in the claims that “most scientists agree” on the AGW alarmist narrative. Most scientists, including most listed on such lists are not climatologists. He demonstrates with this statement that he either doesn’t know or doesn’t care what the science actually says. It’s the narrative that matters.
Second, I think the most aggregious cherry picking going on for the last 8 years and longer was not done by the Bush administration, but by the AGW alarmist cabal that still bases its entire claim on computer models that have repeatedly failed to conform to empirical data, while ignoring things like 11 years of no actual, you know, global warming, record Antarctic ice packs, Arctic ice packs at 1979 levels, the Brookhaven Labs study http://www.ecd.bnl.gov/steve/pubs/HeatCapacity.pdf, showing that most of the minimal CO2-caused warming that will ever occur has already occured and that there is no delay effect (a cornerstone of the alarmist case,) a quadrupling of the polar bear population, two abnormally cold winters in a row that are said to be anecdotal while single warm years are said to be undeniable proof of AGW, to name only a very few. The ignoring of the last 10 years’ data, almost all of which discredits the AGW case, and the ridicule and ad hominem attack against anyone who questions the AGW narrative is at the very least “cherry picking” and goes far beyond whatever the Bush administration did.
February 5th, 2009 at 12:24 pm
I have not read any of the literature cited above. But I’ll make a prediction anyway and claim that none of them say this:
” “We’re looking at a scenario where there’s no more agriculture in California.” And, he added, “I don’t actually see how they can keep their cities going” either. “
February 5th, 2009 at 1:17 pm
Since California’s population tilts heavily towards the coast and plenty of cities in the world survive on desalinization plants, anybody who can’t see how cities can keep going even under 0 precipitation conditions is just ignorant of the state of the relevant art or being dishonest. I suspect that Energy Secretary Chu has heard of desalinization.
Carlsbad, CA’s desalinization plant (all permits issued and due to start construction in 2009 and operation in 2011) will be selling acre feet of water at a price of about $950. Conventional water in CA goes for about $700. This means that even agriculture would likely survive a rainless CA, though the crop mix would change to specialize in high value crops.
In short, it’s dishonest propaganda through and through and any journal that published a study claiming the end of CA agriculture (if such a journal exists) does not deserve the adjective “scientific”.
February 5th, 2009 at 2:22 pm
[...] to “restore science to its rightful place.” But apparently its rightful place involves wildly exaggerating climate threats and/or making them up out of whole [...]
February 5th, 2009 at 3:08 pm
Roger,
There is other science related to this which were used in AB 32, which is likely along the lines of what Chu was referencing. Here’s the abstract from PNAS:
Emissions pathways, climate change, and impacts on California
Hayhoe, et al (2004)
The magnitude of future climate change depends substantially on the greenhouse gas emission pathways we choose. Here we explore the implications of the highest and lowest Intergovernmental Panel on Climate Change emissions pathways for climate change and associated impacts in California. Based on climate projections from two state-of-the-art climate models with low and medium sensitivity (Parallel Climate Model and Hadley Centre Climate Model, version 3, respectively), we find that annual temperature increases nearly double from the lower B1 to the higher A1fi emissions scenario before 2100. Three of four simulations also show greater increases in summer temperatures as compared with winter. Extreme heat and the associated impacts on a range of temperature-sensitive sectors are substantially greater under the higher emissions scenario, with some interscenario differences apparent before midcentury. By the end of the century under the B1 scenario, heatwaves and extreme heat in Los Angeles quadruple in frequency while heat-related mortality increases two to three times; alpine/subalpine forests are reduced by 50–75%; and Sierra snowpack is reduced 30–70%. Under A1fi, heatwaves in Los Angeles are six to eight times more frequent, with heat-related excess mortality increasing five to seven times; alpine/subalpine forests are reduced by 75–90%; and snowpack declines 73–90%, with cascading impacts on runoff and streamflow that, combined with projected modest declines in winter precipitation, could fundamentally disrupt California’s water rights system. Although interscenario differences in climate impacts and costs of adaptation emerge mainly in the second half of the century, they are strongly dependent on emissions from preceding decades.
February 5th, 2009 at 3:15 pm
By the end of century, snowpack could decrease by as much as 90% in the higher amount of warming—almost double the losses expected under the lower warming cases.”
Yes, that’s all fine. 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. (I think the highest rates of warming, and the resultant loss of 90% of the Sierra snowpack by 2100, can already be ruled out, but that’s a relatively fine point.) He would have simply been summarizing the results of a scientific study, and expressing concern about the implications of the study.
But he didn’t do that. He literally claimed that there might be “no more agriculture” in California in the year 2100, and, “I don’t actually see how they can keep their cities going.”
Well, that’s just ridiculous. It’s not even “cherry picking.” It’s not science at all.
Here’s an analysis of the impacts of global warming on California:
http://meteora.ucsd.edu/cap/pdffiles/CA_climate_Scenarios.pdf
That document states, “By the end of the century, if temperatures rise to the medium warming range and precipitation decreases, late spring stream flow could decline by up to 30 percent. Agricultural areas could be hard hit, with California farmers losing as much as 25 percent of the water supply they need.”
February 5th, 2009 at 3:19 pm
Some good stuff on this thread, I’ll be offline for a bit, then will address some of these comments, thanks to all who have commented!!
February 5th, 2009 at 6:57 pm
Mark,
Agreed – I don’t think Chu hedged like he should have on agriculture. 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. LA survives by mooching water from other western states, and was trying to snag water from the Great Lakes! I think I remember reading somewhere that the actual LA river basin could only support some 100K people.
In the quote, I interpret that as Chu referring to what happens to California with the 90% change. I may be wrong, but if Chu is referring to that future world with 90% less snowpack, then he might be right about the cities and agriculture – I have no idea, but he’s a lot smarter than I am.
February 5th, 2009 at 6:57 pm
No sooner had the predictions of smaller future yearly snowpacks become the consensus than Colorado River Basin snowfall and snowpack in 2008 and 2009 exceeded historic average levels. At the same time global temperatures have begun to fall. Both effects are of course not predicted by GCM’s, given constant, continuous increases in CO2 content of the atmosphere. Isn’t nature fun.
February 5th, 2009 at 8:15 pm
RSS
Let’s not forget J.B.S. Haldane, population and evolutionary biologist who said:
“My own suspicion is that the universe is not only queerer than we suppose, but queerer than we can suppose. ”
If it was easy to figure out it wouldn’t be as much funl
February 5th, 2009 at 8:41 pm
Roger, it sounds like Chu is IS guilty of exaggeration, even with support from studies of the kind that others link to, but is it really “exactly the same thing” as what the Bush administration did?
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.
February 6th, 2009 at 12:53 am
All-
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.
February 6th, 2009 at 8:07 am
While Mark at 18 has provided a good summary of one possible approach, I still consider that Dr. Chu has gotten off to a very bad start. He has made an untenable prediction on the state of a specific region of the Earth for times far into the future. Firstly, he did not suggest that the numbers themselves require significant additional study. More importantly he did not indicate that study of the potential impacts of the what-if results had been carried out. These studies, for example, might have been conducted with additional models embedded into computer software. Instead, Dr. Chu simply repeated oft-used clichés that have no bases in science ( or even common sense for that matter).
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.
February 6th, 2009 at 12:21 pm
A few years ago, the big news about California’s climate future was that the “models agreed” that average California precipitation would more than double in the next 100 years. Two of the prominent climate models both showed a 150% increase in precipiation by 2100 (that is, to 250% of present levels). One of the models was Canadian; I think the other was British — I’m not at a location now where I can look up the cite.
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.
February 7th, 2009 at 3:56 am
Roger, I`m very much with you in not liking “ends justify the means” reasoning.
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.”)
February 7th, 2009 at 6:29 am
Tom-
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.
February 8th, 2009 at 1:52 pm
Hi Matt (and everybody),
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
February 8th, 2009 at 2:00 pm
Oops. I see a mistake in my previous comments. (“Awaiting moderation?!” When have my comments ever been “immoderate?”) (No need to answer that!
)
I should have written: “And not only have the improvements in desalination *not* stopped, if anything, they’re accelerating.”
February 11th, 2009 at 12:47 pm
A little late, I know, but I think I have an important contribution to the original question in the post.
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…
March 3rd, 2009 at 10:46 am
These are comments I made today on John Tierney’s blog about the costs of desalination:
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.)