Human-caused global warming contributed strongly to record ‘snow drought’ across the westernmost U.S. in 2015

By Tom Yulsman | November 3, 2016 2:17 am

In the Northwest, an infamous feature called “The Blob” also contributed to snow-shriveling temps, but not so much in California

snow drought

Snowpack extent at winter’s end in California’s Sierra Nevada mountains was significantly more extensive in 2013 than in 2015, as seen in this animation of satellite images. The 2013 image was acquired by NASA’s Aqua satellite on April 9, 2013; the 2015 image was captured by its sibling, the Terra satellite, on April 4, 2015. (Images: NASA Worldview. Animation: Tom Yulsman)

Exceptionally high temperatures, partly resulting from humankind’s influence on the climate, was the primary cause of record-low snowpack — a “snow drought” — in the westernmost United States last year.

That’s the conclusion of a study published in the journal Geophysical Research Letters.

We usually think of drought as meaning a lack of precipitation. But in the winter of 2014/2015, precipitation in Oregon and Washington was actually near normal levels. And while California continued to be unusually dry, the lack of precipitation that winter was not exceptional.

Yet on April 1, the end of the winter season, 80 percent of long-term monitoring sites along the spine of mountains running south through the three states showed record low snowpack. Fully a fifth of these measured no snow at all — including sites at very high elevations in the Sierra Nevada mountains where you’d expect at least some snow to have accumulated and persisted.

According to the new research, this snow drought was attributable to high temperatures that kept the white stuff from accumulating.

“The story in 2015 was really the exceptional warmth,” says UCLA’s Dennis Lettenmaier, a study co-author. “Historically, droughts in the West have mostly been associated with dry winters, and only secondarily with warmth. But 2015 was different,” he says, quoted in a press release about the new findings.

The exceptionally high temperatures in Oregon and Washington were attributable both to “The Blob” — an enormous patch of unusually warm water in the northern Pacific Ocean — and elevated concentrations of greenhouse gases in the atmosphere. Meanwhile, in California’s Sierra Nevada mountains, The Blob played only a small role in raising temperatures. But greenhouse gases caused warming of about 1°C, contributing to the snow drought, the researchers found.

As part of their work, the scientists used a novel crowdsourcing approach: Citizens volunteered to offer up computing time on their personal computers as part of an experimental setup called weather@home. Using these computers, a regional model was run thousands of times simultaneously to estimate how greenhouse gases and The Blob influenced the snow drought.

  • OWilson

    All these daily reports of dire warming warning should be put into perspective.

    No matter how many reports and studies are piled on, the rate of warming, (according to the satellite record) is not scientifically statistically significant. It does not ADD cumulatively to the RATE of warming.

    0.41 degrees in 37 years, only amounts to less than a degree by 2100. And there is some evidence that a cooler period may be imminent.

    Sea level rise 3 mm/year (satellite) is consistent with the interglacial epoch of natural warming after the last of many natural Ice Ages.

    There is no evidence of increased hurricanes, tornados and other weather events.

    In fact we are very fortunate with our relatively stable blue marble, Goldilocks planet, but always have to adapt to the challenge of inclement weather, earthquakes, volcanoes, disease epidemics, floods, droughts and the occasional nuclear winter of an asteroid.

    Mother Nature has no obligation to give you a perfect earth, but she does OK!

    And as someone wise once said, what doesn’t kill you, makes you stronger! :)

  • OWilson

    In the interests of balance, I should also mention this:

    Weather Channel Kids Video: ‘When Kids are Talking Climate – Maybe it’s Time to Listen!’

    ‘Dear Mom and Dad, science says that the impact of climate change could be very catastrophic during my lifetime.’

    ‘Rising sea levels would displace millions…It rains harder now’

    From “could” to “would” to a certainty “now” in a couple sentences.

    Hard to argue with that! :)

  • cgs

    I am choosing (today) to not respond directly to someone here as I don’t want this person to think me a pain in the butt all the time with climate stuff. If he wishes, he may respond to me. 😉

    I only have time to tackle one point and I hope this provides valuable information to other readers. The term “statistically significant” gets thrown around a lot by skeptics and I am never sure that they understand exactly what that term means. With respect to trend lines through data, this is what it means with regards to climate and temperature data:

    A trend line is drawn though a set of temperature numbers and a slope is determined. That slope has an error (standard deviation) associated with it. IF, when considering two times the standard deviation, you cannot rule out a slope of 0, then one says the slope is not “statistically significant”. At two times the standard deviation, one is saying that there is a 5% or greater chance that the slope is indeed 0 (or even negative). In other words, you cannot rule out a slope of 0 or less at the 95% confidence limit. One should realize that there is nothing special about 5%. I have seen some papers in the medical field where a looser 10% is used. But 5% is the typical choice.

    So it has been claimed that the satellite data warming trend is not statistically significant. This is a partial truth, and we can use the temperature trend viewer in the link below to show this.

    To check the statistical significance of either UAH or RSS data choose the following: ‘Trend + Significance’, ‘1979 – now’, and then choose a satellite data set. The triangular plot shown on the left may at first be confusing, but one will come to understand it quickly I think. First, what the graph shows is that there is indeed statistical significance to either satellite trend over the entire data set. Statistical significance is lost when the time period, starting with this year, drops below approximately 23 years.

    For example, looking at the trend from Oct 1993 to Jul 2016, the trend is 0.825°C/century with a range of -0.09 to 1.741°C/century. So understand, that’s what you’re hanging your hat on when you hold up “statistical significance” as a magic talisman. The shorter the trend, the more easily it fails, but statistical significance is basically a game played with data analysis. As with most things, without context it means very little and can be easily abused.

    It is interesting to note that if one compares UAH version 5.6 to UAH version 6, version 5.6 was statistically significant for even short time periods. And, of course, all surface temperature data sets are statistically significant up to the current year.

    But that’s a fuller picture that some don’t want to acknowledge.

    • CB

      “I am choosing (today) to not respond directly to someone here”

      I think that might be a good idea!

      This outcome also counts as a not failed prediction.

      Scientists nailed it over a decade ago.

      “Our results indicate that future reductions in Arctic sea ice cover could significantly reduce available water in the American west”

    • OWilson

      Thank for the non-response. :)

      I presently do statistical analysis for a health care corporation, so I’m on familiar ground here.

      The degree of slope depends on the Y Scale used.

      With a 0.41 degree rise over 37 years (the full satellite record, not a selected portion :) ) you can easily make your “slope” look like a precipitous spike pushing through the top of the chart, or you can make it a flat line, depending on the scale you choose to use.

      Anybody with a casual aquaintance with charts and graphs knows this :)

      (It’s old hat. They used to scare everybody into political correctness, with the headlines and charts that showed that HIV cases were rising 90% among high school students, while among gay men, 11%.

      As we, who read between their lines knows, that an increase from 10 cases in the country to 19 for students, is far LESS in real terms, than say 250,000 cases going up to 280,000.

      An old trick, but if you watch cable news enough or frequent the AGW web sites, you can spot the spin.

      Just a couple points!

      • cgs

        Appreciate the reply and I agree with the points you make. In fact, it is why I wrote my comment in the first place.

        Statistical significance can be a useful calculated parameter as long as everyone is on the same page concerning how it is being used. But, just as in the examples you cite, deception is easy if one is not clear, or if one is counting on the fact that most folks don’t know what the term “statistical significance” means but will likely lock onto the word “significance” and that there is a claimed lack of it.

        Your assertion that ”the rate of warming, (according to the satellite record) is not scientifically statistically significant” is clearly wrong if one looks at the entire data set. It only becomes correct if one looks at subsets of the data, and even then, some of those fail statistical significance while others do not. (And further, it is not clear why those that fail should demand more of my attention than those that do not.)

        And thus your blanket statement, revealed as only a partial truth, seems to me to be of a kind with the very thing you criticize above: spin.

        • OWilson

          But do you realize that at this current rate (satellite) the warming anomaly will only be less than 1 degree by 2100?

          That’s less than the entire U.N. Protocol and Paris Accord is defining as “acceptable”! (They’re happy with 2 degrees)

          And, to the point about scientific statistical significance, do you know the NASA/NOAA margin of error in the models that produce these one hundreths of a degree estimates, over the entire surface of the earth?

          All forecasting has a margin of error, from Presidential polls, to quantum mechanics.

          (Think of the actual vote on election day as the collapse of a probability wave, and you understand what I mean)

          The only branch of science that can outrageous claim it is “settled” is climate science, and it’s led by politicians, and the research grant system.

          Science (real science) is the one thing I believe in.

          I hate to see it used and abused by corrupt politicians.

          Fact: The most famous and influential voice of AGW fear mongering is your Obama, and he is a demonstrated liar.

          So is his likely successor, the queen bee.

          They and their appointees have so corrupted your government agencies, that any data from them should be carefully scrutinized.

          Then they announce they (Sanders, 37 Attorneys General, that they want to bring all “climate deniers” to justice, so that aint going to happen anytime soon :)

          I mean “climate denier” is not even a scientific or legal term.

          That’s why we laugh at them.

          And cry!

          • cgs

            The 2C limit is with respect to the surface temperatures and is measured with respect to the beginning of the industrial revolution. That’s how it is defined.

            Most model results are shown as ensemble results. I believe I linked to a Climate Lab Book page before that shows CMIP5 results with errors. I can link again if you want. I don’t know individual model errors. If you have any information on this, please share.

            Scientists are human, so of course they have bias’ with respect to the work they do. But t experiment decides the winner. Newton was biased to his particle theory of light, while Huygens was biased to his wave theory. Both theories could explain some things and not others. Of course the things one theory could not explain, the other could. But they both vigorously defended their ideas even though they both knew there were deficiencies.

            No one should have a problem with this.

            “Settled Science” only refers to what is currently accepted by the majority of scientists. When you look at the table of contents of an elementary physics or chemistry text, you are looking at settled science. It doesn’t mean that some of those things might turn out to be wrong in the future, but they represent what is currently accepted by the vast majority of those that work in the field.

            Climate science is no different. There are some things that are settled, such as how GHGs operate, and some that are not, such as what is the climate sensitivity to GHGs. Climate scientists are not confused on this point, but the general public certainly is.

            And based upon what I said above, that doesn’t mean that some scientists – the majority in this case – are going to vigorously argue that the data shows that the climate sensitivity is high.

            Finally, from what I know, AGs are investigating corporations, like Exxon. They are not targeting individual citizens who express opinions. If you have evidence to the contrary, please share.

          • OWilson

            We are still free to voice our opinions, but, you wouldn’t believe the names I have been called, even here, with the occasional threat, for merely questioning the scientific “current consensus”.

            I am accused of being a criminal, “a paid shill” for the oil industry, so I know there is an agenda out there, and it ain’t pretty :)

            It is obviously a very unpopular position to take, although my favorite troll accuses me of seeking “popularity”.

            My views are not popular in the places I frequent, if you are what they unscientifically call, a “climate denier”. (but, I believe the Earth is gradually warming, I believe there is a climate, and I believe it changes)

            There’s easier way to seek “popularity”, than pissing off all you folks. :)

            That is why, sadly, I have to remain anonymous. The left have vandalized property of even those just showing up to listen to the opinions of people like me.

            But back to the topic.

            The term “settled science” has been used by politicians to persuade folks to follow what are undoubtable leftist, anti-capitalist political policies.

            You yourself use the term “settled science”, casually, but what you are really referring to is “current consnsus/conventional wisdom”.

            If questioning political dogma, and conventional wisdom is a crime, then count me guilty :)

          • cgs

            Well to finish this up, I am sorry to hear that you have sometimes been threatened. Spirited, but respectful, debating is a skill which many do not have. Unfortunately, in a forum like this, name calling is something we all have to put up with, but threats obviously cross a line.

            I don’t think I use the term settled science casually, but probably this is a point we will just have to agree to disagree on.

            People who question climate science don’t make me uncomfortable. Quite the opposite. I want to see the best arguments that skeptics have. I want to be questioned closely. I have learned more about climate science through investigating skeptic claims than in any other manner.

            But the point has come where I see very little that’s new. Among the climate science community the central question that divides the skeptic and consensus community is well known: what is the climate sensitivity to CO2? Skeptics argue for a low number (not 0!) and consensus for a higher number. Both sides have their evidence, but it is an open question.

            To think and reason for ourselves is the foundation that education should lay. But emotions and rationalizations are ingrained in human nature. I certainly think I approach this subject with more honesty and openess than many. But Montaigne wrote:

            The conviction of wisdom is the plague of man.

            So to challenge my conviction, I’ll continue to engage skeptics. And as someone educated in science, I’ll continue to challenge bad science when I see it.

          • OWilson

            Let me then appeal to the scientist in you.

            When you say “nothing new” in the debate, I disagree.

            Climate is long term weather. – Wiki

            Climate forecasting is long term weather forecasting. It is estimation, projection, prediction even speculation.

            The only thing we have to evaluate predictions, is their record of success?

            With me so far?

            The most organized and Internationally approved predictive report on climate was the IPCC FAR (1990)

            It is the only report that can have it’s predictions, and models checked for accuracy over climate (30 year) time scales.

            It is proven completely wrong, at the worst case, best case and median case scenarios, in spite of the fact that Co2 has gone up to record levels during that time.

            It is a major fail, and attempts, by those who were proven wrong (including many left of center politicians, not scientists) to put lipstick on the beast, by constantly revising (after the fact) those erroneous predictions do nothing for climate science credibility.

            Each year, each season, those predictions are diverging further and further from empirically observed data.

            That is what is new!


          • cgs

            Great! I love this kind of exercise and appreciate the opportunity to explore it.

            First I want to copy two statements from your comment:

            It [FAR] is proven completely wrong, at the worst case, best case and median case scenarios, in spite of the fact that Co2 has gone up to record levels during that time.

            Each year, each season, those original “settled science” predictions are diverging further and further from empirically observed data…

            I am going to criticize you here for making qualitative statements without any supporting evidence. When I think it is critical to my argument (and most times I think it is), I provide links to supporting evidence. We’re discussing science now and if you make the statements above, I would expect you to link in this manner.

            OK, I have been able to find three assessments of FAR with current data at various times. (And just to point out the obvious, this is a comment I am writing, not a research paper. So there is work for you to do, should you choose to do it.)

            The first is from the fourth assessment report in 2007. The link is below and the relevant text is on page is 98, first column, second paragraph, and the relevant figure is 1.1. The upshot is that at that time, they felt the actual temperatures fell in-between the projections of FAR and SAR.


            The second is a paper from 2012 explicitly devoted to analyzing the FAR projections against current temperatures (linked below). Several analyses are done in this paper which I leave to you to review. Their conclusion is:

            Even though the climate research community clearly has much work to do to improve regional climate predictability…it seems highly likely that even in 1990 we understood the climate system well enough to make credible statements about how its aggregate properties would change on timescales out to a couple of decades, even in the presence of considerable uncertainty surrounding the exact forcing trajectory.


            Finally, there is the third figure in the following link, which updates figure 1.4 from AR5. In that figure, current temperatures are plotted against model simulations from FAR, SAR, TAR and AR4. That figure only went to 2012 and so the author of the blog has added 2013-2015 as black squares. I’ll take this moment to state that 2016 will likely be above 2015. That data point will probably be added to the figure in early 2017.


            This figure clearly shows that the recent warming has brought temperatures well within the projection cone of FAR.

            Now there is A LOT more scientific depth concerning the analysis here, but again, this is a comment, not a paper. If you actually read the second paper above and Ed Hawkins blog post a number of important facts that help give a much clearer picture will present themselves. But I think this is sufficient to show that your two statements above are incorrect.

          • OWilson

            I was about to follow you into the weeds again by posting a chart showing the divergency in the IPCC FAR (1990) I was discussing.

            But I see where you are going by bringing in the second, third, and fourth IPCC reports, but they have no relevance to the points I was raising.

            I’m happy to leave it at that, and I thank you for displaying your debating skills :)

          • cgs

            This is a strange and disappointing reply. You appealed to the scientist in me by posing a question and I acted in an honorable manner to investigate it. I can’t really tell from your reply, but it seems to me that you believe I am trying to muddy the waters.

            You wrote:
            Read IPCC FAR, and its predictions, then look up today’s temperature/Co2 levels from NOAA.

            That’s exactly what Ed Hawkings does. Hawkins is a climate scientist, not just some Joe Blow running a blog post. And that figure that I am pointing you to, updates the FAR temperature predictions with current temperatures – exactly what you desire.

            So I agree wholeheartedly with you on one thing: to know how current temperatures overlay with the FAR prediction, “it’s really very simple”. Third link, third image.

          • OWilson

            Mister Ed’s updates? :)

            Citing the subsequent 4 U.N. Reports, and your pal, Mr. Ed, does NOT validate the falsified, predictions contained in the IPCC FAR report, which was the subject at hand.

            That is the only one that can be checked for accuracy over “climate” time scales.

            But I can see what you are doing here. :)

            This is my second exchange with you that you have tried to take into the swamp. :)

            I gave you the benefit of the doubt, the first time.

            Adios amigo!

          • cgs

            I’m not citing the four subsequent U.N. reports. They happen to be on that graph, but you can easily ignore them and focus only on the FAR result.

            Since you are the person who actually brought this up (remember?), you are more than welcome to provide any evidence you think supports your position. But my guess is that you won’t. And the reason is that you know I, unlike you, will actually examine any evidence you post closely and comment on it.

            So until next time. 😉

          • OWilson

            There will not be a next time amigo!

            With me it’s “two strikes”, if you want my attention!

          • cgs

            Then that means you are not really into true investigation of climate change – even for those subjects, such as how the FAR projections have fared, that you initiate.

            You’ll not find a more honest and respectful person to interact with on this subject than me. So if your saying that I don’t meet your criteria for discussion, then I think that says something about the confidence you have in your own position.

          • OWilson

            Your modest too! :)

          • cgs

            Has nothing to do with modesty or the lack thereof. Has everything to do with my desire to know the scientific truth and the attitude required for that – something, that unfortunately time has shown we don’t share.

            Enjoy your post-election high. Well deserved.

          • OWilson

            Your “desire to know scientific truth” is laudable but you have to approach it from the bottom up, not the top down.

            To throw in some 20 references to various external sources without first resolving the true/false nature of my initial proposition, is a page from Alinsky’s Rules for Radicals, intended or not!


      • 7eggert

        If the message is “No, you aren’t safe just because you aren’t gay, and God did not send a punishment for gay people”, that’s not political correctness, that’s not being a stupid, uneducated a*hole having HIV.

        • OWilson

          That’s not the message.

          Our clients need accurate information (not propaganda) on where to direct their limited resources.

  • A.Alexander

    Any local(in time and place) phenomenon depends upon the permanent local temperature changes.This changes are many times bigger than the well-known 1degree per century. How can one distinguish the tiny global change from the great fluctuations? This is the mystery for me (and others).

  • TheDudeofVoo

    “record-low snowpack — a “snow drought” — in the westernmost United States last year.”
    Climate Change is not limited to the egotistical left coast of the USA.
    Earlier this year (above).
    Fall and winter snowpack for the entire Northern Hemisphere:

  • Scott Lynn

    There is no global warming. Period. End of story. The ice caps are not melting. The average temperature at the caps is -23. Nothing melts at -23. Dr. Easterbrook testified on the Senate floor and gave unquestioned, unbiased data from NASA that experts in the field agree is accurate that proves that it’s all a myth. He did not give opinion…He gave verified data.



ImaGeo is a visual blog focusing on the intersection of imagery, imagination and Earth. It focuses on spectacular visuals related to the science of our planet, with an emphasis (although not an exclusive one) on the unfolding Anthropocene Epoch.

About Tom Yulsman

Tom Yulsman is Director of the Center for Environmental Journalism and a Professor of Journalism at the University of Colorado, Boulder. He also continues to work as a science and environmental journalist with more than 30 years of experience producing content for major publications. His work has appeared in the New York Times, Washington Post, Audubon, Climate Central, Columbia Journalism Review, Discover, Nieman Reports, and many other publications. He has held a variety of editorial positions over the years, including a stint as editor-in-chief of Earth magazine. Yulsman has written one book: Origins: the Quest for Our Cosmic Roots, published by the Institute of Physics in 2003.


See More


Discover's Newsletter

Sign up to get the latest science news delivered weekly right to your inbox!

Collapse bottom bar