Thursday, February 22, 2007

Colorado River to Take Hit from Global Warming

Anyone who has paid close attention to water issues in the West will find much that's familiar in a new report from the National Research Council about the Colorado River. The report warns that increasing population growth in the interior West, combined with droughts made worse by global warming, will be putting increasing pressure on the Colorado.

The report notes that the Colorado River Compact, which divied up the flow between the upper and lower basin states, was signed in 1922 — right after a particularly wet period in the interior West. The average flow for the purposes of the compact was pegged at 16.4 million acre feet a year. Today, according to the report, the average flow of the river is 15 million acre feet per year. And tree-ring records show that extended droughts lasting decades or even longer are a recurrent feature of climate in the West, causing the Colorado's flow to fall significantly below average.

Now, based on many climate model simulations, "the preponderance of scientific evidence suggests that warmer future temperatures will reduce future Colorado River streamflow and water supplies," the report concludes. "Reduced streamflow would also contribute to increasing severity, frequency, and duration of future droughts."

This is occurring against the backdrop of a burgeoning population in the West. Arizona alone saw its population rise by 40 percent just since 1990. Here in Colorado, population grew by 30 percent. Although Westerners have made strides in reducing per capita water use, continued conservation will not be enough in the face of rising population and dropping availability of water, the report states.

It offers no simple solutions. Instead, it calls for continued conservation, use of innovative technology, greater cooperation between Colorado River basin states to prepare better for drought, increased communication between water managers and scientists, and, of course, more study:

"The report thus recommends a comprehensive, action-oriented study of Colorado River region urban water practices and changing patterns of demand be conducted. The study should evaluate a range of issues, including demographic projections and water demand forecasts, impacts of urban water demands on riparian ecology, and contemporary urban water policies and practices."

No surprises there, but the issues raised by the report are a reminder of the compelling need for good environmental journalism in the West. Reporters who are knowledgabe about the complexities of water in the West are desperately needed — to avoid common mistakes, such as the one made in NPR's All Things Considered broadcast on the report by Elizabeth Shogren yesterday. It wasn't a huge mistake, but it betrayed a lack of knowledge of how the reservoir system on the Colorado River works. Shogren stated that Lake Mead "keeps taps flowing in Southern California, Nevada, Arizona and Colorado. The problem is that Colorado gets no water from Lake Mead.

Lake Powell, impounded behind Glen Canyon Dam, is a kind of hydrological bank for the upper basin states — Colorado, New Mexico, Utah, and Wyoming. It helps the states meet their obligations under the Colorado River Compact to send a specified amount of water down the river to the lower basin states — Arizona, California and Nevada. When drought prevails, the upper basin states can take water out of the bank and send it downstream, meeting their compact obligations while also satisfying their own water demands. Meanwhile, Lake Mead is used by the lower basin states to store water for their own uses. According to the U.S. Bureau of Reclamation, "Hoover Dam helps ensure a dependable water supply for municipal, industrial and other domestic uses in southern Nevada, Arizona and southern California. More than 16 million people and numerous industries in these three states receive Colorado River water that was stored by Hoover Dam."

No taps in Colorado depend on water from Lake Mead.

-- T.Y.


John said...

Tom -

Your comments here and over on Inkstain about the fact that there's nothing new here raise an interesting question. To what extent is this report "news", and if so in what way?

A report like this is based on the assembly of existing science, so by definition it's not going to have anything "new" in it. But it's very weight, bringing it all together in one spot and stamping it with the NAS voice of authority, gives it some newsy heft worth reporting, I think.

In my story, I chose to emphasize a theme that I think has been underreported - the ag-urban water issue.

Anonymous said...

The problem with this analysis is that warming based on increasing CO2 has never happened before - CO2 changes have always followed temperature changes. So, to say warming *will* dry the sw US is irrational - of course modelers haven't made that link yet...

Tom Yulsman said...

John: I think you are right — putting it all together in one report and giving it the NAS/NRC 'voice of authority' is what made it newsworthy. And the most newsworthy aspect is the ag-urban issue — because transfers of water rights from ag to urban use are already happening and have a profound impact on people in our region. Send us a link to your story.

-- Tom

John Fleck said...

Anonymous -

You're free to assume you're smarter than the scientists who work on this issue. You're also free to ignore the straightforward answers they offer to the argument you raise. Journalists have different obligations. We are obliged to report to our readers what the scientists say, and to listen to their arguments on issues such as the one you raise.

Tom - (gotta watch an ad if you're not a subscriber)

- John

Anonymous said...

JF -

I don't believe I've seen any "straightforward answers" to that question, other than "well, it could have..."

Do you have some references?

HL said...

I think the challenge of global climate change is going to be compounded by the extremely difficult task of adapting the Law of the River to new circumstances.

Change on the river itself, whether to re-allocate the resource among the states of the basin or to address individual states' unique circumstances, is not going to happen easily.

The Colorado River Compact was borne out of strong distrust between the states of the upper basin and the states of the lower basin. And even within those basins problems of perception and fears of being unable to get a fair share persist.

Of course global climate change is not the only problem that is going to assault the stability of the Law of the River. The entire doctrine is built on a faulty assumption. The compact drafters assumed an average annual flow for the Colorado River that is somewhat higher than it has actually turned out to be over the past eighty or so years. That problem is only going to get worse.

And of course population pressures in the basin show no signs of easing. It is all well and good to talk about reducing agricultural use (which will help quite a bit) and conserving the resource, but I am not sure that these things will be enough to accommodate the demands of a region that continues to experience unbelievable demographic change.

I think part of the problem is that governments all too frequently delegate the real work of water policy to people who get paid by the hour. Until the iron triangle is broken, I worry that the interior West's most important river will be at the mercy not only of the climate but of greed, jealousy and inertia.

John Fleck said...

Anonymous -

Colorado River Basin Water Management: Evaluating and Adjusting to Hydroclimatic Variability, by the National Research Council. It just came out this week. :-)

Anonymous said...


First off, you missed the point completely. There is no correlation in the past record between CO2 changes and subsequent temperature changes. That, my friend, is the first point.

Whatever changes we get from increased ghg's will be far different than other past changes, since the mechanism is different than ever before in the record. As you well know, Svensmark et al have shown a quite robust correlation between cosmic muons reaching the troposphere and temperature changes, the causative mechanism being cloud modification. Whatever the cause though, previous changes in temperature were not based on changes in the radiant component of the tropospheric lapse rate. That is the second point.

Then, you might as well throw your reference away because of their religious bent. They say:

"based on analysis of many climate model simulations, the preponderance of scientific evidence"

Here's a news flash for you (and them): Parameterized (aka fudged)model runs are not evidence - and as of now, they're all parameterized.

P.S. the "scientists who work on this issue" are not gods, you know...

John Fleck said...

Anon -

As I said, if you're unwilling to actually read and understand the scientists' responses to the arguments you have raised, or to actually read the NRC report in question, there's not much of a basis for discussion. The questions you're raising are well asked and answered in the scientific literature, the majority of the scientists working in the field disagree with the arguments you're raising, and debating them further here seems pointless.

I'll give you an example: Svensmark is very popular in the politicized version of the climate science discussion as an alternative to the greenhouse hypothesis in mainstream scientific circles for a simple reason. We have a good five-decade record of cosmic ray flux, which shows no discernable trend. There's a clearly discernable temperature trend over that same period. So Svensmark's work, while interesting, is clearly insufficient to explain the observed increase in temperature.

As for your suggestion that "the scientists who work on the issue are not gods," sure. But let's separate the issue of the scientific analysis, with which you clearly disagree, from the appropriate response of journalism, which is the subject of this blog.

You are free as an individual to do what you are doing, which is to choose scientific outliers who are at odds with the bulk of the scientists working in this field. Journalists have a different obligation, which is to explain to readers what the bulk of the scientific view is on any given subject.

In any interesting area of science, whether politically significant (like climate change), there is a mainstream and Svensmark-like outliers.

There are a host of subjects like this, where the bulk of mainstream science has something significant to say about an issue of public importance: radiation and hazardous materials risks, for example, or genetically modified foods. In each of these debates, partisans raise scientifically outliers outside of the mainstream of science, as you have done here, and argue that we as journalists are somehow in error in citing the mainstream. In climate change, it is partisans on what might be called "the right" who do this, while in the second two issues above it is generally partisans on what might be called "the left."

Journalists who take the bait you're offering end up creating a sort of "false balance" that misleads by providing inappropriate credence to the views of a small minority.

As I said, you're free to think you're smarter than the scientists working on the issue, but journalists do not have that luxury. Our job is to explain to the public what the scientists have to say. Formalized expert assessments like this one provide a useful tool in nailing down exactly what that might be.

CEJ Admin said...

John: Many thanks for taking the time to craft such a thoughtful response.

If science journalists were to give equal time to the "outliers" on, say, cosmology, they would have to dig Fred Hoyle out of the grave to interview him on his alternative to the Big Bang theory. In all seriousness, are there problems with Big Bang cosmology? Yes. Is there a chance that the Big Bang theory is wrong? Of course. Science never definitively proves a theory correct. It can only disprove or corroborate a theory by testing its predictions. At the moment, the big bang theory is the central paradigm of cosmology, so science journalists must accurately reflect that reality in their coverage. Does that mean they should ignore the outlying evidence? No. But they must avoid false balance — the big bang theory and the outliers are not equivalent by any means. And the same can now be said within the science of climate change.

I suspect we will be getting postings about outlier science on climate change for a long to come. Just as Fred Hoyle stuck to his skepticism about the Big Bang until the day he died, there will be skeptics who will never believe that human beings are capable of significantly affecting the climate system. As journalists, we have to be open to the possibility that they are right — wouldn't that be a great story?! — but we can't cover them as if their ideas have equal standing as the consensus view.

And now we're going to get a post saying that there is no such thing as consensus in science...

-- Tom Yulsman

John Fleck said...

Tom -

On "consensus is not science", I tried to lay out the argument here:

Now, rather than rehash it every time it comes up, I can just link to it. :-)

John Fleck said...

Oops, looks like the link may have been truncated. Let's try this.

Anonymous said...

JF -

I think you are confused between the concepts of "qualitative" and "quantitative". There certainly in consensus that ghg forcings affect the temperature on the surface. However, there is no consensus about the degree to which feedbacks respond to that forcing, nor about changes in the past. Some people can call muon effects "cosmology" if they want, but that just shows they don't understand the difference between magic and physics, and are just believers in the dogma.....

John Fleck said...

"Some people can call muon effects "cosmology" if they want, but that just shows they don't understand the difference between magic and physics, and are just believers in the dogma....."

Huh? I never called muon effects "cosmology". All I did was point out that, given the fact that the cosmic ray flux shows no trend over the last five decades, it is clearly insufficient to explain the observed temperature trend over the last five decades. That's being quantitative - comparing hypothesis with data. Except it's not *me* being quantitative. It's the scientists working in the field of climate science who have done this, and you ignore this science at your own peril. The peril, that is, of not being taken seriously.

Again, this doesn't mean that Svensmark's work isn't scientifically interesting, but it rather undercuts its relevance to the discussion about possible explanations for the observed changes in the climate.

Anonymous said...

JF -

I didn't say *you* insinuated Svensmark's work was "cosmology".

I agree with you, except the temperature trend is matched by the trend from ~1910 to 1940, including the rate of change, and there is no evidence that the recent changes are the result of CO2 changes vs. other impacts of 6.5 BILLION people

John Fleck said...

Anon -

Forgive my increasing annoyance, but as a journalist, one of the things I must do is keep an open mind. You raise an argument, I have to check it out. It's what we do. Time and time again, I find that the science doesn't support what you're saying. As a result, you've wasted my time.

Today's case in point: "The temperature trend is matched by the trend from ~1910 to 1940, including the rate of change." Well, no:

1910 - 1940: ~ .13 degree C per decade
1970 - present: ~ .21 degree C per decade

Anonymous said...

From the Colorado River Delta:


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pete said...

Frank J. Trelease's First Rule of Water Law:

Water always flows downhill.

Frank J. Trelease, Dean
University of Wyoming College of Law, 1972

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