Recent study on decreasing US wind energy not as advertised

Wind speed trends over the contiguous USA by Pryor et al. (2009, in press, JGR)

Some (read on to see who) would say that this particular wind farm energy reduction study is speculative, inconclusive, preliminary, and premature, and with the authors’ hesitant equivocation in press interviews, even they may agree with that particular straw man. [Read comment 1 for more about bad science reporting]

The Associated Press story heralds this as a “first-of-its-kind study suggests that average and peak wind speeds have been noticeably slowing since 1973, especially in the Midwest and the East.”

Quotes from various scientists:

“It’s a very large effect,” said study co-author Eugene Takle, a professor of atmospheric science at Iowa State University. In some places in the Midwest, the trend shows a 10 percent drop or more over a decade. That adds up when the average wind speed in the region is about 10 to 12 miles per hour.

The new study “demonstrates, rather conclusively in my mind, that average and peak wind speeds have decreased over the U.S. in recent decades,” said Michael Mann, director of the Earth System Science Center at Penn State University.

Jeff Freedman, an atmospheric scientist with AWS Truewind, an Albany, N.Y., renewable energy consulting firm, has studied the same topic, but hasn’t published in a scientific journal yet. He said his research has found no definitive trend of reduced surface wind speed.

Robert Gramlich, policy director at the American Wind Energy Association, said the idea of reduced winds was new to him. He wants to see verification from other studies before he worries too much about it.

Gavin Schmidt, a climate scientist at NASA’s Goddard Institute of Space Studies, told the Guardian the study had yet to establish a clear pattern of declining winds, and that it was too soon to be thinking of the effects on wind energy industry.
“It’s still very preliminary. My feeling is that it is way too premature to be talking about the impact that this makes.”

Now, this is not an example of consensus, especially when Mann and Schmidt have contrary views, which were marvelously printed one after another in the AP story. Mann’s gleaming endorsement seems a bit premature and some would wonder if he actually read the same study that his fellow Team Member did.

Now, to the study. What does the actual text, meaning the abstract, body, and conclusions actually say? Do the remarks in the press releases by the authors actually represent the research they submitted to the Journal, underwent peer-review, and was accepted for publication? The following equivocation in the AP story by the authors suggests that some hyperbole is at work here:

Still, the study, which will be published in August in the peer-reviewed Journal of Geophysical Research, is preliminary. There are enough questions that even the authors say it’s too early to know if this is a real trend or not. But it raises a new side effect of global warming that hasn’t been looked into before.

The ambiguity of the results is due to changes in wind-measuring instruments over the years, according to Pryor. And while actual measurements found diminished winds, some climate computer models — which are not direct observations — did not, she said.

Yet, a couple of earlier studies also found wind reductions in Australia and Europe, offering more comfort that the U.S. findings are real, Pryor and Takle said.

It also makes sense based on how weather and climate work, Takle said. In global warming, the poles warm more and faster than the rest of the globe, and temperature records, especially in the Arctic, show this. That means the temperature difference between the poles and the equator shrinks and with it the difference in air pressure in the two regions. Differences in barometric pressure are a main driver in strong winds. Lower pressure difference means less wind.

Even so, that information doesn’t provide the definitive proof that science requires to connect reduced wind speeds to global warming, the authors said. In climate change science, there is a rigorous and specific method — which looks at all possible causes and charts their specific effects — to attribute an effect to global warming. That should be done eventually with wind, scientists say.

Let’s get this straight: the study is inconclusive and has many outstanding questions with ambiguous results, but it is consistent with what you would expect with global warming. Presto. But, in climate science, there is a rigorous and specific method of attribution — which the authors did not do — but suggest should be eventually done with wind measurements.

Figure 2: (a) Annual percentiles for 1200 UTC observations from site 724320 (5th, 10th, 20th …
90th, 95th percentile, where the 50th and 90th percentiles are shown in the blue and red,
respectively). Despite considerable inter-annual variability, data from this station exhibit
a significant downward trend in both the 50th percentile (of approximately 0.7%/year) and
the 90th percentile (of approximately 0.6%/year) wind speed. Output from the other data
sources used herein for the grid cell containing Evansville are shown in frames (b) – (g).

The 10-meter wind speeds from the various climate model and/or reanalysis data sources are condensed in this figure to one-grid point or station location, which is a risky way to validate the observations — in this case Evansville. Originally, I thought that these medians were an area-average of the entire United States, which would be more representative of the grandiose claims in the press releases. The reanalysis data sets range from grid-spacing of 0.33 (NARR) to 2.5 degrees (ERA-40 and NCEP) and the climate models are at 50 km grid spacing, all too small to resolve the topography to be representative of a given station location. The authors do point out, importantly:

Observational data – due to instrumentation changes, station moves, changes in land-use or obstacles, and observational sites may not be regionally representative

[Note: the land surface data are described as follows]
1. 00UTC and 12UTC NCDC land-based near-surface wind speeds NCDC-6421 [Groisman, 2002] 336-stations chosen out of 1655 1973-2000
2. DS3505 surface data, global hourly, 193 stations available all stations are airports and military installations

Reanalysis products ensure the data sets are homogeneous and complete, but the near-surface wind speeds are strongly influenced by model physics and data that are assimilated.

Also, it must be noted that 10-meter wind speed is not an assimilated quantity in the models, but it is extrapolated from the lowest model-level (often 50-100 meters height) by use of Monin-Obukhov similarity theory.

With the work of Anthony Watts on the Surface Station observational records with regards to temperature, it is perhaps a good idea to investigate and pay more attention to the type and location of the anemometer. The authors helpfully point out that the “Observational data – due to instrumentation changes, station moves, changes in land-use or obstacles, and observational sites may not be regionally representative.

They go on to say:

Studies that have analyzed wind speed data from terrestrial anemometers have generally found declines over the last 30-50 years (see summary in McVicar et al. [2008] and Brazdil et al.[2009]), the cause of which is currently uncertain. In part because of the difficulties in developing long, homogeneous records of observed near-surface wind speeds, reanalysis data have also been used to quantify historical trends and variability in near-surface wind speeds either in conjunction with in situ observations or independent thereof [Hundecha et al., 2008; McVicar et al., 2008; Pryor and Barthelmie, 2003; Trigo et al., 2008].

So, with these data caveats in mind, the authors continue on in their research avenue to address the following points (from the paper):

Herein we analyze 10-m wind speeds from a variety of observational data sets, reanalysis
products and Regional Climate Model (RCM) simulations of the historical period in order to:

Quantify the magnitude and statistical significance of historical trends in wind speeds and the consistency (or not) of trends derived using different data sets; direct observations, reanalysis products and output from RCMs. As a component of this analysis we provide preliminary diagnoses of possible causes of temporal trends in the in situ observations. Specifically, we examine trends in terms of their temporal and spatial signatures, and the role that major instrumentation changes may have played in dictating those trends.

The methodology is fairly straightforward: time series analysis of the 50th and 90th percentiles of the wind speed distributions and the annual mean wind speed using the 00 and 12 UTC observations or model output from each day of the year.

Conclusions: (quoted from Pryor et al. 2009)

1. Magnitudes of trends in observed wind speed records for 1973-2000 and 1973-2005 are substantial – up to 1% per year at multiple stations.

2. Trends in reanalysis data sets and RCM output where present are generally of lesser magnitude and no other data source is as dominated by negative trends as the in situ observations.

3. Temporal trends in the data sets from in situ measurements are of largest magnitude over the eastern US, but negative at the overwhelming majority of stations across the entire contiguous USA. The trends in wind speed percentiles from in situ observations do not exhibit strong seasonality (Figure 6) or a clear signature from the introduction of the ASOS instrumentation (Figure 7). Hence the cause(s) of the declines remains uncertain.

4. Output from NARR for 1979-2006 indicate contrary trends in the 0000 UTC and 1200 UTC output with declining trends over much of the western US in the 0000 UTC wind speeds but increases in the 1200 UTC output (c.f. Figures 4 and 5).

As expected, the period of observation used in the trend analysis has a profound impact on the presence and absence of temporal trends and indeed the sign of trends.

And the most relevant for last:

Based on the analyses presented herein we conclude there are substantial differences between trends derived from carefully quality controlled observational wind speed data, reanalysis products and RCMs, and indeed between wind speeds from different reanalysis data sets and RCMs.

A few comments:

The quality of reanalysis data sets is not yet sufficient for this type of attribution study of high-resolution, regional climate change. This problem is exacerbated when looking at derived variables such as surface temperature and winds, which are not assimilated observations nor representative of station locations. Also, while the authors chose to use ERA-40, NCEP-Reanalysis, and the NARR (a regional reanalysis over North America), there are other sources of reanalysis data available that may be of significantly higher quality. A recently completed reanalysis is called the ERA-interim, which begins in 1989 and continues on to today, based upon a very recent version of the ECMWF operational forecasting numerical model, which is the best on the planet.

While it is no more the final authority on the subject, I downloaded the data and conducted a few simple experiments to verify the rather ambiguous results of Pryor and company. With access to my university servers, and a program called GrADS, it is very easy to replicate Pryor’s work with minimal effort. It is just a few lines of code and a lot of processing to sort out the distributions of 10-meter wind at each grid point over the past 20-years.


Figure: Running calculations of the distribution of 10-meter winds over the United States, domain averaged: 22.5N-51N; 232.5E-294E). So, the median each month is calculated from the ERA-interim reanalysis data 4 times a day [00,06,12,18] UTC, including a total of 1460 model data points.

Figure analysis: no trend.. Statistically and physically speaking, there is no decreasing trend in the distribution of 10-meter winds over the contiguous United States according to the new ERA-interim reanalysis. (Technical note: This also matches the results from the JRA-25 and NARR reanalysis, which extend from 1979-2008)

What about globally? A fair way to determine where downward trends in wind speed energy are occurring is to simply take the first 10-year period [1989-1998] and subtract it from the second 10-year period [1999-2008] in the reanalysis. The annual medians only are averaged to create the 10-year period. The units are meters per second [m/s]. The second figure is the difference in the 90th percentile wind speed.

The relatively large tropical differences are associated with the trade wind modulation by ENSO. The absolute differences are less than 0.2 m/s over the USA, which is well less than a knot. This is in accord with Pryor et al. (2009) who stated in their conclusions that the reanalysis data did not show a decrease like the observations.

So, what does this all mean?
First of all, it is baffling that a press release would produced for this journal manuscript, which can be described as nothing more than a simple observational vs. reanalysis/climate model comparison study, with ambiguous results, which only leads to more questions about the quality of the data used. There is no attempt to even attribute climate change or global warming to the results in the paper, so the suggestions in the press accounts is a rather egregious fear mongering or perhaps simply an example of journalistic malpractice.

This type of study is critical in the incremental improvement in understanding of micrometeorology, which is modulated by large-scale climate. It is a good question why the observations show one thing and all of the reanalysis datasets show the opposite. Thus, in this case, Gavin Schmidt’s assessment is right on the money. “It’s still very preliminary. My feeling is that it is way too premature to be talking about the impact that this makes.”

Or you can simply read the authors own equivocations in the press — in between the crazy, amateur hour so-called journalism by environmental correspondents.

Note: ECMWF ERA-Interim data used in this study/project have been provided by ECMWF/have been obtained from the ECMWF data server.


75 Comments

  1. Posted Jun 15, 2009 at 10:31 AM | Permalink

    I would like to present a brief commentary on the quality of science reporting in the mainstream press with examples on how the results of this paper were reported, and are now being perpetuated throughout the media and internet new sites and blogs.

    This wind energy study is a prime example of a researcher/University generated press-release being sexed up to garner the attention of the environmentally conscious, green mainstream media. Suzanne Goldenberg, the transparently biased US environmental correspondent writing for the very green UK Guardian, breathlessly proclaims that the “great gusting winds of the American Midwest, and possibly the hopes for the most promising clean energy source – may be dying, in part because of climate change, according to a new report.”

    The headlines of the two stories are: US wind farm energy up in the air over climate change, says study – and US wind farms face lack of fuel. The byline states that America’s most promising source of green energy may be hampered by global warming, study suggests.

    In other stories, her story headlines have incendiary and often hyperbolic language. For example, “US nuclear industry tries to hijack Obama’s climate change bill.” This is a type of journalistic bias by headline, since many people only read the headlines of news items. Another one from May 5, 2009: US climate change denier James Inhofe joins Al Gore in fight against soot. “In a surprise U-turn, the Republican senator has put forward a bill to review the dangers of black carbon to health and the environment.” Goldenberg quotes the Daily Kos for reaction of those “surprised” which obviously includes herself since she wrote the story. The picture chosen in the story of Inhofe makes him look like an angry man.

    And finally, the headline today, “New York declares war on geese to prevent airport bird strikes”. Declares war on? Come on.

    • AndyL
      Posted Jun 15, 2009 at 12:05 PM | Permalink

      Re: ryanm (#1),

      Ryan
      The Guardian have an active “Readers Editor” who looks into this kind of issue – it seems to work quite well on the issues they pick up at least.

      page is here:

      http://www.guardian.co.uk/profile/siobhainbutterworth

      Suggest you contact her: reader at guardian.co.uk

    • Dave Andrews
      Posted Jun 15, 2009 at 2:55 PM | Permalink

      Re: ryanm (#1),

      Ryan,

      I have been a reader of the Guardian since I was teenager in the 1960s. Back, then, of course it was known as the ‘Manchester Guardian’ and provided an independent corrective to the London centric/Metropolitan elite. Its reporting of the ‘Prague Spring’ of 1968 was, to my developing mind absolutely brilliant.

      Sadly it has now long ago joined that Metropolitan elite, although it still has some worthwhile contributors. I read it now largely out of loyalty to my younger self, I guess, but I must admit Ms Goldenberg’s contributions strain that loyalty severely.

  2. Anthony Watts
    Posted Jun 15, 2009 at 10:49 AM | Permalink

    Since I’m mentioned in the article, I thought I’d repost this comment I made a few days ago at Lucia’s since it speaks to the instrumentation:

    I have not read this paper, so I don’t know what instrumentation was used to arrive at the conclusions. That being said I agree with Zeke’s [Hausfather] comments about it being a “complicated task”.

    I’ll point out that measuring wind accurately over a long period is not easy, particularly because surface anemometers tend to be problematic by the nature of their mechanical design. Aerovanes are better, but still have some of the same issues.

    For the traditional anemometer –

    1) Cup anemometer accuracy is typically +/- 5% when new some are even less. It depends on cup size and how linear the detector is. Some are very non-linear at low speeds.

    2) Anemometers, being mechanical, age, just like automobile engines, they are only good for so many revs of the engine before stuff wears down, affecting accuracy.

    3) The most common aging problem of anemometers is dust/dirt accumulation in the bearings, which tends to slow them down. I used to have a collection of dead anemometers from the former California State Climatologist…the vast majority had sticky bearings. I’d use them as a prop then give them away to classrooms when I went out to give talks to kids.

    4) Aging tends to affect low wind speeds more, by virtue of friction and by the fact that the lions share of wind measurements are at low speeds below 10mph. 40+ mph winds are not an everyday occurrence in many parts of the world. Easy to see in in plot of wind speed distribution. Of course there are exceptions.

    So, depending on how good the instrumentation is to start with, and how well it is maintained, we might see the slowdown in wind caused partly by long term sensor issues.

    If maintenance of NWS/NOAA wind equipment used in this study is anything like what we’ve seen for the USHCN network, I think the answer will be self evident.

  3. Steve McIntyre
    Posted Jun 15, 2009 at 11:00 AM | Permalink

    “It’s a very large effect,” said study co-author Eugene Takle.

    Ryan, is there anything in the article itself to support this statement to the press by the coauthor? Do you know if the authors put out a press release (I took a quick look and couldn’t locate it) – I presume that there is one.

    In mining stocks, it is now mandatory that a Qualified Person, as defined in securities regulations, sign off on the language of any press release. The purpose is to ensure that communications with the public are consistent with the actual reports.

    It seems to me that climate scientists sometimes say things in interviews and press releases that go beyond the four corners of what was published in the peer reviewed study – which, if it is the case, is something that is not allowed in mining promotions.

    • Posted Jun 15, 2009 at 11:31 AM | Permalink

      Re: Steve McIntyre (#3),

      Magnitudes of trends in the observed wind speed records for 1973-2000 and 1973-2005 are substantial – up to 1%/year at multiple stations and much above that at a few. Trends in the reanalysis data sets and RCM output, where present, are generally of lesser magnitude (Figure 4, 5 and 8), and no other data source is as dominated by negative trends as the in situ observations. Temporal trends in the data sets from in situ measurements are of largest magnitude over the eastern US, but negative at the overwhelming majority of stations across the entire contiguous USA.

      Only some of the in situ obs show substantial trends. When comparing with the reanalysis data, they use words such as “discrepancy, uncertain, absence of temporal trends and indeed the sign of the trends, lack of spatial coherence of trends.”

      The station obs tell a story, but it is in contradiction to all the other data sources used in the paper. That is the focus of the paper, a simple comparison study with a marginal attempt to figure out the inconsistencies. But, that is the main story, that there are HUGE ambiguities in the data comparisons.

      The authors are disingenuous to push this work as definitive in any respect. I could not locate the original press release, but it is possible that the AGU journal, in this case JGR, may have issued a notice of publication (in August though), as an Editor’s Highlight. But, I find it more likely that the authors themselves solicited the UK Guardian environmental correspondent themselves.

      I give credit to the AP story for being suspicious, and credit Gavin Schmidt among others for being realistic about the limitations of these types of studies.

    • Posted Jun 15, 2009 at 11:42 AM | Permalink

      Re: Steve McIntyre (#3), this does dovetail with the mining analogy since the wind farm energy or “Big Wind” likely have solicited dozens of independent research consultations to determine the best and most profitable wind corridors. When a journal article like this comes out, the press release shouldn’t be used as a vehicle for making grandiose and self-aggrandizing claims about speculative changes due to climate change.

      Take for instance: the total cloud fraction from the ERA-interim. Listen up Big Solar.


      The median cloud cover averaged over the United States has fallen dramatically during the past 20-years. It is cool to see that the extended La Nina of 1999-2001 shows up as a minima in cloud cover the same way as the current dip.

      The 90th percentile of cloud-fraction mimics the MEI ENSO time series to a tee. So, looks like climate change is affecting solar activity ;-)

      • Posted Jun 15, 2009 at 12:50 PM | Permalink

        Re: ryanm (#8),

        RyanM

        That cloud cover graph is amazing. I’ve never seen this one before.

        Can you tell me where to find the raw data for this graph? It may be way too large to find easily but if it’s possible I would like to know.

        Nice post on the politics of science.

        • Posted Jun 15, 2009 at 1:03 PM | Permalink

          Re: Jeff Id (#17), the ERA-interim data is freely downloadable for research and non-commercial purposes at their website portal. The format of the data is GRIB, but can be easily converted to netCDF.

          Here are a couple example plots that were made as part of the data analysis:

          The median cloudcover is shaded from 0 to 1, with 1 being cloudy. Thus, the median conditions at higher latitudes is typically cloudy, while the desert areas are cloud free. Shocking. The 33rd and 90th percentiles are contoured red and blue for comparision purposes between the two figures, which represent 1992 and 2008.

        • rafa
          Posted Jun 16, 2009 at 2:25 AM | Permalink

          Re: ryanm (#19), Dear ryanm, re.: the plots, does 1 mean cloudy?. it seems then the Sahara and southern Spain is more cloudy than northern Spain, that is in contradiction with what I expected and with data about sunny days (i.e free from clouds) for the Iberian Peninsula. Am I misunderstanding something?. I did not read all comments, I apologize if you addressed this already. Thanks

  4. MattN
    Posted Jun 15, 2009 at 11:06 AM | Permalink

    Wait a d@mn minute. I thought everything was supposed to increase with increasing CO2. Temperature, sea level, cancer rates, kidney stones, and wind due to increase volatility in the climate system….

    • Andrew
      Posted Jun 15, 2009 at 11:20 AM | Permalink

      Re: MattN (#4), Yes, in some circles. In other circles decreased temperature gradients lead to exactly this sort of result.

  5. AnonyMoose
    Posted Jun 15, 2009 at 11:21 AM | Permalink

    … we conclude there are substantial differences between trends derived from carefully quality controlled observational wind speed data, reanalysis products and RCMs, and indeed between wind speeds from different reanalysis data sets and RCMs.

    The headline should have been “Climate model results are different from wind speed data,” instead of using the models in the descriptions of decreases.

  6. Steve McIntyre
    Posted Jun 15, 2009 at 11:56 AM | Permalink

    Bob Tisdale has an extremely interesting post on cloud cover and the adjustment in 1940s SST that got a lot of attention. I’ve been meaning to cover this post.

  7. MarkB
    Posted Jun 15, 2009 at 12:14 PM | Permalink

    Just for the heck of it, I checked the Great Blue Hill observatory web site. GBH, is just south of Boston, USA, and supposedly has the longest continuous meteorology record in the country (1885-present). The observatory is at the top of the hill – 635 ft. – with a large woodland park all around. Wind speed is certainly down since 1980.

    • Bruce
      Posted Jun 15, 2009 at 4:51 PM | Permalink

      Re: MarkB (#11),

      I wonder how tall the trees were in 1980 versus this photo:

  8. MarkB
    Posted Jun 15, 2009 at 12:14 PM | Permalink

    Let me try that link again:

  9. MarkB
    Posted Jun 15, 2009 at 12:16 PM | Permalink

    Arghhhh…. once more.

    • Anthony Watts
      Posted Jun 15, 2009 at 1:16 PM | Permalink

      Re: MarkB (#13),

      This may be instrumentation issues as I mentioned previously, but it could also coincide with urbanization roughing up the boundary layer.

      Clearings, buildings, shopping malls, subdivisions, etc. create more friction and turbulence in lower level winds than say, open fields or vast swaths of forest top. More turbulence tends to inhibit smooth flow of wind, this decreasing the wind speed.

      Granted Blue Hill is a bit higher than surrounding surface, but I think the the effect of increased turbulence and drag in the highly built up northeast will make an impact even at higher levels.

      see this report by Zhang et al on urbanization impacts in China:

      http://www.lapc.ac.cn/UpLoadFiles/File/2008meeting/dahui/zhangning.pdf

      Urbanization leads to “heat island”, “dry island” and wind speed loss over urban area …

      See the wind speed plots comparing urban/non urban on page 11

      The wind speed slowdown due to urbanization has been known for quite some time. Here’s an older book on the subject:

      http://books.google.com/books?id=Dmky95hwKr0C&pg=PA1267&lpg=PA1267&dq=urbanization+and+wind+speed&source=bl&ots=LROm0yH9QH&sig=AfBcT6Velb71bOu7NPE8J3GGCU8&hl=en&ei=mJs2SrX0Jo3sswOT7a3SBQ&sa=X&oi=book_result&ct=result&resnum=5

      page 1267:

      Yet, the surface roughness of the city serves to reduce wind speeds…

      and others:

      http://ieeexplore.ieee.org/iel5/4534879/4534880/04535390.pdf?arnumber=4535390

      Due to the friction and drag of buildings, there are wind speed losses over urban area in all cases (Fig.4). In summer, the reduce of wind speed can be 1.0 …

      It seems then, since Blue Hill Observatory is in the middle of a large area of growth for the past 50 years, that some of this wind speed reduction related to land use change and urbanization would apply?

      I’d also like to find out when they last replaced/recalibrated their wind sensors. It is one of the sensors where detecting a problem is not always obvious, especially when they clog up with dust in the bearings.

      • MarkB
        Posted Jun 15, 2009 at 3:09 PM | Permalink

        Re: Anthony Watts (#22),

        There has been development in the area, but the drop since 1980 might only correlate with a couple of buildings to one side of the hill that went up nearby during that time frame. The Boston area certainly has seen a lot of surface change, but much of it was before 1900. I’d believe instrument malfunction before land use. It certainly is a little curious, in any case.

      • Craig Loehle
        Posted Jun 16, 2009 at 6:46 AM | Permalink

        Re: Anthony Watts (#22), In addition to the buildings roughening up the boundary layer, trees do the same. In fact trees moreso because they can create a continuous cover that raises the 0 wind velocity point many meters off the ground. Most urban areas were agricultural fields before housing started (building directly into the woods is more recent phenomenon) and when people built suburbs they planted trees. I agree with Anthony also about instrument degradation–if older instruments (by wearing out) become sticky and don’t spin as easily and create the effect you think you are seeing, you had better double check that issue.

        • MarkB
          Posted Jun 16, 2009 at 8:45 AM | Permalink

          Re: Craig Loehle (#59),

          I’ve lived within sight of this hill for thirty years. Urbanization of the surrounding area doesn’t tell us anything about wind speed trends since 1980 – this is Boston we’re talking about – the city itself, to the north, has been built out for 100 years. A major highway runs along the base of the south side, but that went in post-war. There’s certainly been plenty of suburban development to the west and south of the hill, but that took place post-war as well. The television antenna was referenced above, but that change would not create a trend – it’s a one-time event. Trees have been growing gradually since a fire bared a good part of the hillside decades many ago – perhaps the early 20th century. In the last few years, they cleared a plot of scrub oak and pine to make way for a new weather museum building next to the observatory. That might have had a litte effect, but not the trend noted in the graph above.

          I don’t claim to have any knowledge of what caused the downward trend – I’m just trying to rule out the least likely sources. Instrument issues remain, but you’d think they’d figure that out at a manned station.

          Just out of curiousity, I’ll have to talk a walk up there and knock on the door and ask them about it. I can use the exercise.

  10. Fred
    Posted Jun 15, 2009 at 12:31 PM | Permalink

    Obviously the growth in the number of wind turbines is the culprit.

    Just like CO2 “traps” heat, turbines “trap” wind speed, thus providing the results reported by the sensationalistic, attention grabbing headlines.

    There is a positive feedback loop in this theory too . . our Team just haven’t identified it or how big it is or how it works. We are working on it.

    • Bob McDonald
      Posted Jun 15, 2009 at 12:56 PM | Permalink

      Re: Fred (#14),

      Absolutely. A friend of mine is going to conduct an analysis on the effect on the rotation and orbit attributes of the Earth as it relates to atmospheric and continental drag being produced by wind generators. With the increase in windmill usage, an unintended consequence could be a slower rotation (leading to longer days and longer nights); another consequence of un-even application of windmill generators (e.g: more in the Northern Hemisphere) could induce an out-of-balance condition or have a detrimental effect on plate tectonics.

      We may have no more than 5 years to solve the wind generator crisis.

  11. Clark
    Posted Jun 15, 2009 at 12:45 PM | Permalink

    There are a lot of people to blame for this sort of press-release nonsense:

    Universities push their faculty to get press releases out. They want publicity to burnish their image – which can mean more state money, more alumni giving, higher profile, etc. Individual Depts push this stuff too so that they have a higher profile within the University. We recently talked about the need for more press releases in a recent faculty meeting.

    Beyond this, the individual writing the press release is not a scientist, but a PR expert. They will undoubtedly try to put the biggest spin possible on any study so that it is picked up in the media. All doubts and caveats must be left aside – otherwise what reporter would bother to cover it?

    Scientists and faculty themselves will put public coverage of their studies on their CVs. In fact, I was reviewing a grant application yesterday in which the applicant prominently mentioned all the media coverage they received for one of their previous studies. Two of the letter writers for the applicant also mentioned the media coverage.

    Finally, granting agencies across the board are more and more pushing ‘impact’ as an important criterion for deciding how to rank grants for funding.

    • Posted Jun 15, 2009 at 1:11 PM | Permalink

      Re: Clark (#15), yes, and a feedback occurs when only “positive result” studies are published. This Pryor et al. (2009) is definitely not a positive result study but one that discusses large data platform inconsistencies. Yet, the press coverage remolds this into a positive result study related to climate change. It is thus a dangerous combination of researcher and journalistic bias which is to the detriment of the scientific process.

      Another issue lately is the increasing frequency of non-governmental environmental outfits commissioning their own studies, which aren’t peer-reviewed, and then using those results to push a particular political agenda or viewpoint. This is colloquially called greenwashing, and it infests most liberal universities.

      • Chris Schoneveld
        Posted Jun 16, 2009 at 2:56 PM | Permalink

        Re: ryanm (#21), “This is colloquially called greenwashing, and it infests most liberal universities.”

        Since you introduce this political comment I feel no hesitation to expand on it. I get my blood boiling when I hear there are such things as “liberal universities”. What has politics to do with scientific education? Any educational institution (from kindergarten, primary school, secondary school to tertiary education) should be free of any political or religious leaning. So can we agree that we should strive for a world without Christian schools, Islamic schools, Republican schools (if they exist in the US) or liberal universities etc?

        • Posted Jun 16, 2009 at 3:56 PM | Permalink

          Re: Chris Schoneveld (#71), no, we can’t agree that there should only be secular universities. Private schools with their own funding can do as they please as guaranteed by the rule of law.

          The point of the Greenwashing comment is to diagnose a feedback prevalent in public universities in which liberal policies are incubated in a disproportionate manner compared to more conservative viewpoints. This was suggested to be at work here with the Wind Farm press release. It is no secret that in climate science, the supporters and skeptics line up along the ideological divide. The feedback occurs when the reliably left-wing media successfully frames the evolution of the “debate” through the promotion of positive-result climate change studies, the selection of certain groups or individuals for quotations in stories, and the non-promotion of skeptical or contradictory viewpoints.

          The goal of the comment was not to elicit a long debate on the politics of American public universities, but provide a hypothesis for the interesting dynamics at work with this particular study. I try to adhere to Steve’s policy of not discussing politics as there are other forums for detailed exploration of the politics of climate change. But alas, sometimes I fail.

  12. PaulH
    Posted Jun 15, 2009 at 12:45 PM | Permalink

    I guess we have to depend on terrestrial observational data for wind speeds, warts and all. Does anyone know if it is possible to read wind speed and direction via satellite ala temperature data? Or will we forever be depending on airport locations and other stations that have various siting issues?

  13. Soronel Haetir
    Posted Jun 15, 2009 at 1:04 PM | Permalink

    I would think airports would be less problematic from a wind measurement standpoint than temperature. Airports tend to be great big open places where wind speed and direction actually matter to operations. And I would at least think that wind is in general a more regional phenomena than temp.

    Is my thinking on this just wrong?

  14. MikeN
    Posted Jun 15, 2009 at 1:34 PM | Permalink

    Mann and Schmidt dispute that they are contradicting each other at RealClimate.

    • Posted Jun 15, 2009 at 2:48 PM | Permalink

      Re: MikeN (#23) Re: PaulM (#29), thanks for pointing out the equivocations by Mann and Schmidt. I am all torn up inside to hear how they were supposedly misquoted. I consider it rather ironic.

      • Steve McIntyre
        Posted Jun 15, 2009 at 3:40 PM | Permalink

        Re: ryanm (#30),

        My, my. Mann confesses that the wording was “poor”.

        Borenstein had written:

        The new study “demonstrates, rather conclusively in my mind, that average and peak wind speeds have decreased over the U.S. in recent decades,” said Michael Mann, director of the Earth System Science Center at Penn State University.

        A naysayer is Gavin Schmidt, a NASA climate scientist in New York who said the results conflict with climate models that show no effect from global warming. He also doubts that any decline in the winds that might be occurring has much of an effect on wind power.

        RC responded:

        Mike was quoted as finding the evidence for a trend reasonably convincing, while Gavin was quoted as being unconvinced of the evidence for an anthropogenic climate change signal (note that the two statements are not in fact mutually inconsistent). As one should expect in any news story, these single lines don’t really do justice to the long interviews both of us gave the reporter Seth Borenstein.

        As reported above, Borenstein challenged the claim that they had given “long interviews” to him, reporting that he only communicated with them by email, receiving short responses, which Borenstein quoted at RC.

        Mann emailed Borenstein:

        It’s an interesting paper. It demonstrates, rather conclusively in my mind, that average and peak wind speeds have decreased over the u.s. in recent decades…

        This matches the statement in the article pretty much verbatim. Mann continued with some editorializing about policy that are not relevant to the contradiction between Schmidt and Mann.

        In fact, the article “don’t really do justice” to the contradiction between the two. Schmidt is quoted on models. But unlike Mann’s unconditional acceptance of the trend, Schmidt viewed the results as fragile:

        Hi Seth, a few comments. The authors are clearly very careful about noting the fragility of the trends over the different data sets and I think that is very sensible.

        Then he proceeded to comment that models didn’t predict much of a trend in the US in any event.

        So they directly contradict one another. But rather than just saying so and driving on, they invented a story about “long interviews” and have been caught out. Plus it elicited emails that confirm the contradiction that they had just attempted to pretend didn’t exist. The Team at its best.

        • stan
          Posted Jun 15, 2009 at 5:07 PM | Permalink

          Re: Steve McIntyre (#34),

          That Mann got caught in a lie isn’t really news, but the manner was kind of revealing. He sent an e-mail to a reporter and then claimed that the reporter quoted him inaccurately. The reporter (a big supporter of AGW and the team) produces the e-mail showing the quote was verbatim.

          Even my little boy thinks this is a really “dumb” move. It ranks up there with the bank robber defending himself at trial cross-examining the bank teller, “And what did you do after I pointed the gun at you and gave you the note?”

          Not the sharpest tack in the box.

        • bernie
          Posted Jun 15, 2009 at 6:45 PM | Permalink

          Re: Steve McIntyre (#34), Dr. Mann’s response to Seth’s comments is priceless: “poorly chosen” – he has to be kidding! Surely Seth will have to ask himself, “what gives with these guys?” “Can I trust what they say?”

          The rest of the thread at Real Climate is noteworthy on two counts. Nobody, and I mean nobody, follows up (or is allowed to follow up) on the obvious misleading statements and Dr. Mann’s attempt to backtrack.
          Second, the thread disappears into some other reality in terms of the comments. Finally and appropriately, Gavin asks one ardent long-time pro-AGWer poster to stop accusing members of the current scientific establishment of corruption.

          Towards the end of the thread, there is a small and unanswered voice that asks whether people can actually focus on the issue of trends in wind velocities and their relationship with climate change.

        • Posted Jun 15, 2009 at 8:28 PM | Permalink

          Re: Steve McIntyre (#34), oops I didn’t read Realclimate.org at all before putting together the draft of this post last Friday. Their comments don’t pass the smell test. Likewise, press releases are the cats meow in the hurricane and climate change arena with some dandies put out in the past few years. That’s why it is best to actually read the paper before going to bat for your allies in the alarmist AGW camp.

  15. Andrew
    Posted Jun 15, 2009 at 1:41 PM | Permalink

    You know, it’s interesting that we are discussing problems with wind data. Recall that wind data were supposed to be a substitute for temperature to detect the infamous “hot spot”. I wondered at the time “Why would wind data be anymore reliably homogeneous than temps?” I’m beginning to think I was quite right to think that at the time. Obviously the wind data are messy like all climate data seems to be.

  16. dearieme
    Posted Jun 15, 2009 at 1:41 PM | Permalink

    So the Global Warming that we were told would cause more hurricanes will also turn breezes into zephyrs? Cool! Or warm!

  17. Barclay E MacDonald
    Posted Jun 15, 2009 at 1:57 PM | Permalink

    Very interesting post and comments from so many angles.

    Interesting that ENSO affects trade winds. If you are measuring the alleged effect of global warming on tradewinds, it seems you could write a nice grant to go to Hawaii and study it, rather than do it in Kansas. They measure CO2 on Mauna Kea, there are probably wind speed measurements as well. Willis Eschenbach, isn’t this right up your alley?

  18. PaulM
    Posted Jun 15, 2009 at 2:12 PM | Permalink

    Lets not forget that according to IPCC AR4, “Mid-latitude westerly winds have strengthened in both hemispheres since the 1960s.” So are Mann and Takle both saying the IPCC is wrong? Or are both observations ‘consistent with’ climate models?

    • ianl
      Posted Jun 15, 2009 at 5:02 PM | Permalink

      Re: PaulM (#27),

      The recent devastating firestorms in Victoria, Australia were attributed in countless breathless media reports to increased ferocity of winds due to AGW.

      The winds certainly drive the firefronts (I’ve seen this, as have many people) and are typically W-NW desert-enhanced. Most of Aus biota have evolved to cope with this periodic phenomenon. Attributing this to AGW requires a mindset able to encompass opposing beliefs. I expect the puffpiece reviewed here will not receive much publicity in Aus as it would make the contradiction too obvious.

  19. Alan Bates
    Posted Jun 15, 2009 at 2:16 PM | Permalink

    First of the quotes from scientists:

    “It’s a very large effect,” said study co-author Eugene Takle …”

    As soon as a scientist uses the word “very” I know 2 things:

    1) They are protesting overmuch about a [very] small or insignificant effect
    2) I need to look for the political angle because this is not science.

  20. PaulM
    Posted Jun 15, 2009 at 2:35 PM | Permalink

    #23 MikeN, I should have looked at the source of all climate wisdom, surrealclimate. As suspected, Gavin and Mike explain that their two views are “not in fact mutually inconsistent”. They both claim to have given ‘long interviews’ with the journalist Seth Borenstein. Unfortunately, Borenstein points out in comment #33 that neither of them had long interviews – just brief emails.

  21. Andy
    Posted Jun 15, 2009 at 2:50 PM | Permalink

    Does Mann actually understand science? Cos there is nothing in the above to justify his claim if that claim is correctly reported.

  22. Brooks Hurd
    Posted Jun 15, 2009 at 3:52 PM | Permalink

    Prior to 1980, Blue Hill shows fluctuations. After 1980, the trend is universally down (10 year mean). Based on Anthony’s posts, this indicates to me that the maintanance schedule changed in 1980. The change could have been from a retirement, replacement, change in maintenance budget, or other factors having nothing to do with wind speed.

  23. M. Villeger
    Posted Jun 15, 2009 at 4:29 PM | Permalink

    It also makes sense based on how weather and climate work, Takle said. In global warming, the poles warm more and faster than the rest of the globe, and temperature records, especially in the Arctic, show this. That means the temperature difference between the poles and the equator shrinks and with it the difference in air pressure in the two regions. Differences in barometric pressure are a main driver in strong winds. Lower pressure difference means less wind.

    Sure it does… except that barometric pressure evolution since the mid 1950s -both rising pressures trends over the Azores, Africa’s Mauritania, Senegal, Mali, Soudan, Eastern Mediterranean, Europe, China, Panama etc… and winter cyclone with lows lower than 975hPa rising frequencies in the North Pacific for instance (Graham and Diaz 2001)- suggests the exact opposite! Those are signs of a renewed dynamism not the quiescence supposed by global warming…

  24. Bob H
    Posted Jun 15, 2009 at 4:52 PM | Permalink

    Since we are looking at the past 20 or 30 years, it seems to me that one could use power generating windmills as a check on the data. Since the windmills generate electricity and power companies would necessarily keep accurate records on the output of their windmills, measured in kilowatt-hours (kwh), this would serve as an effective proxy to check the main study data. If the power from a set of windmills has decreased over time, and allowing for normal degradation of output over time, it should be possible to tell whether there is an increase or decrease in wind velocities (higher wind – more electricity, slower wind – less electricity).

    Granted, this approach would be similar in many ways to the approach of Stieg et al using ground stations to calibrate satellites, but I believe it would be an equally valid approach. Obviously, 20 to 30 years ago there were fewer wind turbines, so the analysis problems would be similar, but valid results should be obtainable.

  25. Bruce
    Posted Jun 15, 2009 at 4:53 PM | Permalink

    I never have luck with photos …

    Instruments

    • Ross Berteig
      Posted Jun 16, 2009 at 12:50 AM | Permalink

      Re: Bruce (#39), Take a look at some of the other photo galleries… the wind instruments are on top of the tower, not in the enclosure. However, some of the historical shots make the hill look positively bald in the past compared to the recent photos with well developed woods. Going out on a limb, I’d hazard the guess that this has changed the surface effect to some degree….

      • Bruce
        Posted Jun 16, 2009 at 4:25 PM | Permalink

        Re: Ross Berteig (#53),

        If you look at this photo, the trees to left appear taller than the tower and the 170ft TV tower to the right might have some effect.

  26. Bruce
    Posted Jun 15, 2009 at 5:06 PM | Permalink

    “WGBH(FM) transmits with 98 kW ERP from an eight-bay antenna atop Great Blue Hill in Canton, Mass. The antenna is configured for 0.4° of electrical beam tilt; ERP in the lobe is 100 kW. Facilities were last upgraded in 1979; original plans called for a 15-kW transmitter and a larger antenna, but were scrapped because the Great Blue Hill tower did not have space for the required ten bays. The tower was at one time shared with WGBH-TV, and TV backup facilities remained there until taken down in the 1979 upgrade. In 2004, WGBH received and built a construction permit for a 22.5-kW auxiliary facility, lower down on the same tower.”

    http://www.bostonradio.org/stations/70510

    I wonder what the 1979 upgrade did to wind flow?

  27. mondo
    Posted Jun 15, 2009 at 7:25 PM | Permalink

    Isn’t it obvious why winds are slowing? All of the wind farms are increasing the drag of the planet on the atmosphere, and creating unanticipated adverse effects.

    • Pat Frank
      Posted Jun 15, 2009 at 7:43 PM | Permalink

      Re: mondo (#46), You raise an interesting point, even in jest. The air velocity must be reduced downwind of wind farms. Apart from chopping up birds, what are the impacts of wind farms on, e.g., aeolian pollination?

      There are similar unanswered questions about tidal energy. Down stream flows will be reduced. What happens to tidal flushing, organics transport, and transport of the microfauna that filter feeders need as a food source?

      Has anyone done an EIR on such things?

  28. Harry Eagar
    Posted Jun 15, 2009 at 8:01 PM | Permalink

    ‘it seems you could write a nice grant to go to Hawaii and study it, rather than do it in Kansas’

    Too late. The Pineapple Research Institute has been on the job for over 60 years.

    As for the report, it reminds me of the discussion here several months ago about the Science Daily website. Same issues, looks like to me.

    As a newspaper reporter, and without knowing more than Ryan has posted here, sure looks like malpractice. Flagrant overwriting and reaching beyond the information available.

  29. theduke
    Posted Jun 15, 2009 at 9:05 PM | Permalink

    Steve writes:

    The Associated Press story heralds this as a “first-of-its-kind study suggests that average and peak wind speeds have been noticeably slowing since 1973, especially in the Midwest and the East.”

    Might this be related to re-forestation? It’s been documented that the eastern half of the US has been largely reforested in the past century. That it had been substantially cleared of its forests by 1900 and that with the abandonment of agriculture in the region, much of the forest has returned.

    Makes you wonder what effect this might have had on the instrumentation.

  30. theduke
    Posted Jun 15, 2009 at 9:50 PM | Permalink

    Sorry, this is Ryan’s thread and I was quoting him and not Steve.

  31. BarryW
    Posted Jun 15, 2009 at 9:56 PM | Permalink

    wouldn’t radiosonde tracking data provide a rough check on the wind speed data at least at some other altitudes?

  32. rafa
    Posted Jun 16, 2009 at 2:30 AM | Permalink

    ooops!, forget the question, I was not understanding the captions of the plot, as usual, my bad.

  33. Geckko
    Posted Jun 16, 2009 at 4:27 AM | Permalink

    Can someone clear this up for me.

    Steve MRyan M posts that these “findings” are:

    consistent with what you would expect with global warming. Presto

    Gavin Schmidt is quoted as stating:

    the results conflict with climate models that show no effect from global warming

    The only way I can think of both these statements being true is if “climate models” are not consistent with global warming. It sounds strange in my head as I type it.

  34. John
    Posted Jun 16, 2009 at 6:10 AM | Permalink

    I had thought from previous studies that a warming climate would have more energy in the atmosphere, thus would be stormier and windier. I don’t think we know if we’ve had an increase in tornadoes, because we can spot so many from satellites now that wouldn’t necessarily have been counted 40 and 50 years ago, but whenever there is a tornado in the north, global warming seems to be invoked. So it is counter intuitive to now have REDUCED wind — with all the uncertainties Steve has laid out, but forget that for the moment — now cited as evidence for warming. Once again, a change in either direction — it’s global warming’s fault!

  35. tesla
    Posted Jun 16, 2009 at 7:14 AM | Permalink

    I wonder how the electronic acoustic transducers for measuring wind speed and direction hold up over time- no moving mechanical components to wear down (though I’m sure there is some electronic drift).

  36. theduke
    Posted Jun 16, 2009 at 9:07 AM | Permalink

    On the subject of reforestation, Bill McKibben, “An Explosion of Green,” Atlantic Monthly, April, 1995:

    http://www.theatlantic.com/politics/environ/green.htm

    I read this at the time and was pleasantly surprised.

  37. Kenneth Fritsch
    Posted Jun 16, 2009 at 9:32 AM | Permalink

    Come on guys, does anyone judge the Blue Hill observatory wind speed measurements as typical of the US or that the sudden rate of decline starting around 1980 is not suspicious.

    I would think that whether wind speeds have increased or decreased or remained constant is not as important as the speeds being related to AGW. Once that is accomplished, we only need to allow for the automatic connection that any thing affected by AGW has to be bad. That higher wind speeds can cause more physical damage, but higher wind speeds are better for producing wind power means lower wind speeds (caused by AGW) can thusly be considered bad.

    But wait a minute, since wind power is not economical in the market place and requires subsidies, lower wind speeds could discourage its use and that could be a beneficial development. But no, a better line of reasoning is that subsidized wind power is required to lower CO2 emissions from conventional energy sources and that in turn will increase wind speeds and make wind power more economical and less dependent on subsidies. Yeah that’s the ticket.

  38. jlc
    Posted Jun 16, 2009 at 9:55 AM | Permalink

    “Algorithmic adjusted windspeeds show no variation”, say scientists.

    Despite claims to the contrary, leading climate scientists emphasize that that raw data cannot be used to profile windspeed for wind energy optimization. “This is a typical layman’s mistake” said famous climate scientist Michael Schmidt. “They have to wait until we’ve done our processing” he said.

    “Furthermore” said his famous climate scientist colleague Gavin Mann, “Who the hell do these people think they are. Taking an anemometer reading at face value!”

  39. TJA
    Posted Jun 16, 2009 at 11:28 AM | Permalink

    It is probably due to the profusion of poison ivy and ragweed spurred on by high CO2 and a warming climate slowing down the rotation of the Earth.

  40. TJA
    Posted Jun 16, 2009 at 11:34 AM | Permalink

    Global warming is sort of like Maxwell’s Daemon. It takes the wind from good things, like operating wind turbines and powering sailboats on sunny summer lakes and moves it to bad things, like tornadoes, increased turbulence knocking planes out of the air, and hurricanes, of course. It is amazing stuff. You would think they would be embarrassed to make these kinds of claims.

  41. Richard
    Posted Jun 16, 2009 at 11:43 AM | Permalink

    realclimate seems to have removed their post on the AP article and the Mann/Schmidt difference of opinion

    Steve: It’s there as of June 16 6 pm Eastern.

  42. Phil Nizialek
    Posted Jun 16, 2009 at 1:20 PM | Permalink

    Obviously there are fewer trees around Blue Hill now then in the pre 1980 time frame. Every reputable scientist knows that wind is caused by the movement of leaves on trees.

    • Andrew
      Posted Jun 16, 2009 at 2:36 PM | Permalink

      Re: Phil Nizialek (#69), One would think fewer trees would mean easier air flow, but if not clearly the opposite is true!

  43. Bob McDonald
    Posted Jun 16, 2009 at 3:27 PM | Permalink

    Any chance these differing opinions can be explained by UWIs (Urban Wind Islands)? Also, can the angular displacement of bristlecone pines from the local vertical be used as a proxy for wind speed universally?

  44. Posted Jun 19, 2009 at 10:54 PM | Permalink

    Just goes to show ya, Climate Science is very subjective. The team can’t even decide among themselves which way they want to roll this week. AGW will increase winds, winds will decrease…….sounds to me like the same thing that’s been going on for the last 4 billions years or so. Sigh……..

    Climate Science is apparently a very nebulous art.

    neb⋅u⋅lous
    1. hazy, vague, indistinct, or confused
    2. cloudy or cloudlike.

  45. Posted Jul 28, 2009 at 11:15 AM | Permalink

    It’s true that science reporting in this country leaves a lot to be desired. And certainly this study is inconclusive. But it is important to look at wind patterns when thinking about creating a wind energy sector. I personally think the emphasis in research on wind technology should be on creating larger scale turbines capable of harnessing extreme winds like those seen in the gulf coast area during the hurricane and tropical storm seasons. That way we would be able to harvest the excess wind that will come from superstorms created by fast-rising sea temperatures.

    This study is certainly vague, and in the end will probably not have significant impact on the creation of new wind energy facilities.

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