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Has Pacific Northwest snowpack declined? Yes.

Filed under: — eric @ 20 March 2007

There has been a bit of a flap here at the University of Washington over the state of the snowpack in United States Pacific Northwest region. The Seattle city mayor, Greg Nickels (a well known advocate for city-based CO2 reduction initiatives) wrote in an Op-Ed piece in the Seattle Times that

The average snowpack in the Cascades has declined 50 percent since 1950 and will be cut in half again in 30 years if we don’t start addressing the problems of climate change now. That snow not only provides our drinking water, it powers the hydroelectric dams that keep our lights on.

The number “50 percent decline” apparently comes from a statement in an Oregon State University report in 2004 signed by many Northwest Scientists. This is not actually the best estimate for average snowpack decline, according to published work by Phil Mote, of Climate Impacts Group at the University of Washington. Mote reviewed the Oregon report back in 2004 and pointed out that the 50% figure was erroneous. Mote’s 2003 paper in Geophysical Research Letters, highlighted in Science a few years ago, cited losses “as great as 60%” in some locations. Subsequent work (Mote et al., 2005) attempted to quantify change in total snowpack for the Cascades, and arrived at 15-30% for the period 1950-1997. This remains the best estimate, even when including the time period up to the present. Furthermore, this number represents measurements at many different elevations. If high elevation stations are excluded, the declines are generally larger, as would be expected if the chief culprit is increasing temperature, rather than declining snowfall.

So why the fuss? Well, the media can’t seem to get enough when there is apparent controversy over something. Both the local and national media were thus quick to jump on the “story” when another UW staff member, Mark Albright, sought to correct the 50% number in a series of emails to the Mayor’s office, among other places. Unfortunately, Albright didn’t simply provide the corrected information, but set up a web site entitled “The Myth of the Vanishing Cascade Mountain Snowpack”, with the very clear message that snowpack has not declined at all. Beyond the appearance of a controversy, this makes for a good newspaper story because it appears to cast doubt on Mote’s credibility. This is rather important given that Mote is Washington’s “State Climatologist” and is also the lead author on the chapter on the cryosphere in the upcoming IPCC Fourth Assessment report.

So has Pacific Northwest snowpack declined? Emphatically yes. I say “emphatically yes” for three reasons. First, because Albright illustrates the supposed lack of a trend by comparing specific periods (e.g. 1940-1949 vs. 1997-2006), in which snowpack has increased in some locations. This is not very informative, because both the spatial and temporal variability is large, and any question of decline can only be correctly addressed using all the data together, and over a statistically significant time period (30 years or more would be preferred). According to a summary statement prepared by Dennis Hartman to try to clarify the situation for the media and government, the decline is quite evident when the analysis is done correctly. (Hartmann is currently Chair of the Atmospheric Sciences Department at the University of Washington).

Second, “yes”, because lost in the media focus on controversy over the exact number is the fact that even a 15% decline would be huge. You can get this smaller number by starting in 1940 rather than 1950. This isn’t really justified because low elevations are substantially undersampled before 1945. Using a starting point of 1950 gives you about 30%. Either way, these are big numbers, and represent anything but a trivial change for water resource planners, backcountry skiers, and fisherman (not to mention fish). (For those readers that might wish to look at the data themselves, the State Climatologist’s Office has a rather nifty mapping and trend-analysis tool, here:

Third, “emphatically” because the snowpack will very likely continue to decline in the future. In his summary statement, Hartmann notes that “temperatures in the … Cascades will increase in the future as a result of global warming … and it is expected that this, by itself, should result in further decreases of snow … particularly at lower elevations.” Hartmann points out that it is less certain how precipitation will change in the future, and this could conceivably balance some or all of the increased spring time snow melt due to increasing temperatures. However, this is a pretty weak statement. It generally takes a very large increase in snowfall to offset small changes in temperature. Furthermore, precipitation is highly seasonal in this region, and an overall increase in temperature will, at a minimum, cause earlier snowmelt, even in the unlikely event that annually averaged total snowpack remains the same. This means less available water in summer, when fish, farmers, and hydroelectric dams most need it.

173 Responses to “Has Pacific Northwest snowpack declined? Yes.”

  1. 151
    Blair Dowden says:

    Re #146: “…For reasons that are still not properly understood, temperatures rose by 6C over just a few thousand years ….”

    I have read several book on the Permian extinction (eg. Michael J. Benton; Peter Ward) and never heard of this. Probably because the current state of paleoclimate science does not have the resolution to measure such a short interval. If we do not know how quickly CO2 rose in the Paleocene Eocene Thermal Maximum we cannot possibly know it for the Permian.

    Like everything else I have seen here associated with Lynas, this is rubbish. As for him being a smart guy who has read all the peer reviewed papers, the same can be said for Michael Creighton. They both appear to be in the same business: science fiction.

  2. 152
    Lynn Vincentnathan says:

    Re GW & worst-case scenarios as “nothing to lose sleep over,” I have never been personally afraid of GW, but I’d give my life, my last drop of blood to help mitigate it and get others to do likewise. GW has always been a moral issue with me. I am heartily sorry for participating in the killing and harming of people (and other of Earth’s biota) — now, in 100 years, 200 years, or 100,000 years (when the last few molecules of the CO2 I just emitted today will finally go out of the atmosphere). So there’s no limited time frame of concern for me.

  3. 153
    Chuck Booth says:

    Re #150 effects of elevated CO2 on terrestrial plants

    Refer to IPCC Climate Change 2001, section Effects of increasing atmospheric CO2 (
    In short, the stimulation of photosynthetic carbon fixation by CO2 in terrestrial plants typically reaches a plateau, or even declines, at or below 800-1000 ppm CO2, a level that could be reached in the atmosphere within a century at current rates of anthropogenic CO2 emissions. The precise response will likely vary with the plant species and its mode of photosynthesis (e.g., C3 vs C4 vs CAM), temperature, nutrient and water availability, and probably a host of other ecological and physiological factors.

    Also, note that some marine algae do not respond to CO2 fertilization (Royal Society of the UK, 2005, Ocean Acidification Due to Increasing Atmospheric Carbon Dioxide. Section 3.2;
    As marine phytoplankton provide roughly half of our annual oxygen supply, elevated CO2 levels in the atmosphere and ocean (and resulting ocean acidification) might not be such a great thing.

    (I apologize if this response was posted twice – I may have sent it accidentally while composing it the first time.)

  4. 154
    Hank Roberts says:

    So, Philippe, just to clarify, I feel a heavier responsibility for the future beyond my own time horizon, because the science gives me no way to fool myself — I think those of us who lived around the years this last millenium turned will be remembered for the choices we make, and should be making precautionary choices right now.

    Seeing the move to speed the removal of ozone-destroying refrigerants, and get them off the markets much faster, is an example of doing it right.

  5. 155
    Hank Roberts says:

    Let’s go ’round back to the stables and count the teeth with Google Scholar

    +PETM +”rate of change”

    This 2002 article isn’t inconsistent with Lynas’s figures; I’d accept “40” as “a few” thousand years, in deep geological time — and six degrees is near the low end of five to ten degrees of warming.

    “The Paleocene-Eocene Thermal Maximum (PETM) was characterized by rapid (~40 kyr) global warming (~5-10°C) … These changes were relatively short-lived lasting for less than 200 kyr.”
    TI: The P-E Boundary Carbon Isotope Excursion in ODP Leg 198 Sites from Shatsky Rise: An Initial Test of the Methane Hydrate Dissociation Model

  6. 156
    Hank Roberts says:

    Oh, and this set of papers may leave you staring a bit; I don’t recall hearing much about these, for example this one:

    The Deep Sea Carbonate Ion Decline of the Last 8 kyrs: Result of a Weakening of the Conveyor?
    AU: * Broecker, W S (et al.)

  7. 157
    Dick Veldkamp says:

    Re #146, #149, #152 Losing sleep

    I read Hank’s remark about “personally not losing sleep over the worst case scenario with 6 C warming” purely as a practical recommendation for setting priorities. We will be having trouble enough dealing with (say) 2 C warming. So why worry about an unlikely event that may happen a century after we’re all dead?

  8. 158
    stephan harrison says:

    I haven’t read Mark’s book, but I think he was just trying to speculate about the implications of 6 C warming. Are any of his predictions about the response to this level of warming that far out?

  9. 159
    Jim Crabtree says:

    Re #150:


    Here is one link to a study on rice production and GW from the Phillipines (This has also been confirmed by researchers in Japan, the US, and Viet Nam).

  10. 160
    Jim Crabtree says:

    Re #150:


    Here is some information on additional nutrients (fertilizers) required for wheat under increased CO2. Under a higher CO2 environment, most plants need more nutrients (Duke U found this to be true with a pine forest subjected to higher CO2. Other researchers have found the same thing to be true with other plants).

  11. 161
    Blair Dowden says:

    Re #153: Thanks, Chuck, that is basically how I understood it. There is positive CO2 fertilization on land, but only up to a point, it is not some infinite bonanza. It does not surprise me that the benefits stop around the levels in which plants evolved in the first place. CO2 fertilization in the ocean is much less, and more than offset by acidification.

    Re #155: Hank, Lynas was talking about the end-Permian extinction. I think his statement is wrong, or at least unsupportable. The Permian era was so different than today (eg. one super-continent, 2 million km3 of flood basalt) that it does not teach us much about today’s global warming. It is just being used as sensationalism. The Paleocene Eocene Thermal Maximum (PETM) is much more relevant. For example, this Science paper provides evidence for the effects of ocean acidification.

    Re #159: Your article claims rice is being grown at the southern end of its range. I would like to see the full relationship between climate and rice productivity. How much does productivity increase as climate cools? It must reach an optimum, then decline.

  12. 162
    Lynn Vincentnathan says:

    RE #146, “I believe the range has been narrowed…”

    I’m not sure, but I think it was the sensitivity that narrowed, not the projection (since this latest AR4 IPCC report added in ?? more positive feedbacks ??, and perhaps the greater increase in our emissions).

    I believe the high-end projection of the (leaked) AR4 is 6.4C, not 4.5C — which I think is only the high-end sensitivity for 2 X CO2, and they figure there’s a chance it could go above 2 X CO2 (correct me, if I’m wrong). We’ll know for sure soon.

    Which still puts the most likely scenario at about 3C increase for 2100. Which is quite bad enough. And even for those who favor a low end scenario, say a 2C increase, we would still have to mitigate mitigate mitigate. I don’t think our required behavior changes whatever the projection; we just have to keep on doing the very best we can to reduce GHGs.

  13. 163
    Lynn Vincentnathan says:

    And now back to the topic & “That snow [that will be diminished] … powers the hydroelectric dams that keep our lights on.”

    This seems to be another positive feedback here. They will probably have to start using more fossil-fuel based electricity as their hydropower reduces. And buy more ACs for those hot summers. I know people in India are snapping up ACs as fast as they can be produced (even though the cost for a window unit equals several months salary for the typical upper middle class family there).

    I wonder if the AR4 took those positive feedbacks into account.

  14. 164

    Re #162, Lynn,

    “Which still puts the most likely scenario at about 3C increase for 2100”

    As a professional futurist, I must disagree. If we accept AR4 and the most likely sensitivity, we must still select from the different economic scenarios. We have currently been following scenario A1FI. The only way you can come up with only 3C increase as the most probable consequence is by predicting another economic scenario as the most probable. I claim there is no scientific merit in this claim. It may be as likely that we fail to change our course fast enough. It is quite difficult to convince billions of people not to consume so much. And as we will travel through turmoil of war and suffering, we will see a lot of shortsighted goalseeking. We will also invent more and more efficient means to burn coal, oil and forests. Jared Diamond’s Collapse showed the reasons why the near and shortsighted have a high probability of winning.

  15. 165
    Hank Roberts says:

    Lynn, Philippe — I just found a much better answer, on a new weblog by a scientist, about concern and choices.


    ———- begin quote ———–

    “in reality, we’re now spending a lot of resources and effort to develop what we know is ultimately a dead end. The apologists now say “Yes, but it’s a useful bridge to better sustainability!”

    Yes, but. Wouldn’t it have been better to pick a non-dead end technology, and put all those resources into that direction? I think so. And the argument “we’ve got to take action now!” is one that often shuts down discussion.

    Greenies are human too- and quite capable of hearing only what we want to. “Hey, I’ve got this figured out, quit bugging me about it!”

    I am a scientist by training. One of the basic tenets is – never quit doubting; never quit thinking; never quit looking; even when you’re 95% sure you know an answer.

    Are you struggling with questions about how to live green? Should I give up my toilet paper? Should I sell my car?

    My very first advice – take a deep breath, and slow down. You don’t have to make these decisions instantly – in fact it will probably be far better if you don’t…..

    ———– end quote ———–

  16. 166
    Philippe Chantreau says:

    OK Hank, clarification received.

  17. 167
    Richard Ordway says:

    re. 150 Blair stated:

    [[I was not aware that any land plants actually suffered with increased carbon dioxide levels. That surprises me,]]

    This is only a tiny part of the research. -Science Journal of Biology -New Phytologist – Journal of Plant Ecology – Journal of Agricultural and Forest Entomology

    Notice how I am giving you links to the WHOLE article.

    Note: This next “CO2 SCIENCE” link that is paid largely by the fossil fuel industry is selectively quoting a study that leaves out the bad effects of CO2.

    Their version:

    Here is the actual study:

    The CO2Science site SELECTIVELY quotes parts of the study and leaves others out such as how the plant gets thinner. …It is assuming that the American public is too stupid to look up the whole study and will blindly trust the Fossil Fuel industry’s edited version that CO2 is “good for you”…

  18. 168
    Lynn Vincentnathan says:

    RE 165, I’ve already reduced my GHGs by half, so I should double them to where they were back in 1990?

    OTOH, I have not bought a Prius yet, because I’m waiting for a plug-in hybrid. But on my last move (due to a new job in a new state), I did move close to work and to a place where I could get on 100% wind power.

    So, please, everyone, do make the changes that make sense (& even dollars and cents). That should reduce our household GHG emissions across the nation by at least a quarter.

    I just don’t see what’s wrong with that.

  19. 169
    Mark A. York says:

    Bjorn Lomborg, admittedly not a scientist, yet he firmly assured the US Congress that 2.5 degrees will be no problem. They loved it. Well, the Republicans anyway. When you have so-called experts who aren’t outbilling those who are, “Houston we have a problem.”

  20. 170
    Len Conly says:

    Re: 104
    Eric: Thanks for the explanation of Nickel’s dilemma. I’m in the San Francisco Bay Area and we are lobbying the Metropolitan Transportation Commission to redefine Level of Service (LOS) standards to mean how many people are moved past a point (e.g. an intersection) in a given time, rather than the number of vehicles. This of course would give priority to buses and other forms of mass transit.

  21. 171
    Lynn Vincentnathan says:

    RE Mark Lynas’s SIX DEGREES & the Sunday Times summary I quoted above (#105), I got the lowdown from Mark himself, after I emailed him that I had started a fiasco re his new book:

    Oh dear – the truth is that I didn’t write that summary, and I don’t think my book really supports it either – don’t suppose there’s any way you could remind people of that? I agree the [Sunday Times] summary does sound alarmist…the book itself discusses all the uncertainties, and is meticulously referenced…

    Hope that clarifies that I made a BIG mistake in quoting that article as representative of Mark’s book.

    Nevertheless, 6C can’t be much fun, and I still suspect it could likely lead to a dominant positive feedback trend (of spiralling GHG emissions & warming) for centuries, if not millennia — assuming the earth eventually does reach a 6C warming next century or thereafter. I think the main point is, we really don’t want to find out the hard way. We don’t even want to go near there.

    [Response: I’m sorry for helping to mis-represent Mark Lynas’s book, and I”ll put up a post at some point (after I’ve looked at the book myself) correcting that. I suppose one might say there is no such thing as bad press, since I might never have heard of the book, and now I feel obliged to buy it! –eric ]]

  22. 172
    Blair Dowden says:

    Re #167: Thank you, Richard. The papers you provide confirm that higher carbon dioxide levels promote plant growth. But some of them also point out that nutritional value of crops does not keep up – the total nutritional value increases slightly but the proportion to crop weight declines.

    My point was that higher CO2 levels are a [small] net benefit to plants on land, and should not be in the loss column. Again, this not the case in the ocean. Your information reduces my view of that benefit.

    Please notice I did not quote CO2 Science. That source is so biased I consider it worthless, except maybe to locate relevant papers that say something quite different than what they imply. That kind of dishonesty annoys me as much as methane fireballs from 6 degrees of warming.

  23. 173
    Hank Roberts says:

    >105, 145, 145, — the Times list that was misattributed to Mark Lynas, making people think it was Lynas rather than the Times that came up with that scary exaggeration (noting I was confused too even when I tried to find the source, so the error’s in several postings above)

    Lynn, thank you _very_much_ for checking directly with the author and posting the correction.

    This is one place I really hope the hosts here put ‘pointer to correction’ comments in — pointing to your correct info in 171.

    Hope he shows up here. Now that the misinformation about him has been checked and corrected.