Monthly Archives: February 2007

Unlicensed Engineers, Part 1 By Hendrik Tennekes

Unlicensed Engineers, Part 1

By Hendrik Tennekes

In the series of Weblogs I am now starting, I will lay the foundations for a theory of climate software development. I am of the opinion that most scientists engaged in the design, development, and tuning of climate models are in fact software engineers. They are unlicensed, hence unqualified to sell their products to society. In all regular engineering professions, there exists a licensing authority. If such an authority existed in climate research, I contend, the vast majority of climate modelers would vainly attempt certification. Also, they would be unable to obtain insurance against professional liability.

I am an unlicensed engineer. I was an engineering professor for many years, but I never needed to be certified as a Professional Engineer. One advantage of my University position at Penn State was that I did not need to purchase any liability insurance, which would have absorbed a sizable chunk of my modest salary.

I am also an unlicensed model builder. I have many years of experience as the builder of model sailboats based on wooden shoes, and I also contributed fresh insights in the scaling laws of sailboats, but those feats by themselves are not enough to qualify for certification. My saving grace is that model sailboats are toys, with little or no impact on the welfare of society.

Two of my favorite clog sailboats are the heroes of my story today. I renamed the black sloop with red sails two weeks ago. I had christened her Hella, in part because of the hell I’ve gone through since I was forced into early retirement. But now her name is Dallas, in honor of Roger Pielke’s superb webmaster, Dallas Jean Staley. The white schooner is called the Flying Dutchman, in memory of the threemaster skipper Willem VanderDecken, who swore at Cape Horn that he would fight the fierce headwinds he encountered until Doomsday if necessary, rather than seek refuge in a nearby bay.

dallas-at-flank-speed.jpg “Dallas”

the-flying-dutchman.jpg “The Flying Dutchman”

Both clogs have a waterline length of one foot, unsurprisingly so because human feet slip into them. Their masts are about a foot long, too. Their sail area is on the order of 90 square inches, and their weight is about 2 pounds. Their “immersion ratioâ€?, that is, their water displacement divided by the cube of their waterline length, is four times as high as in full-scale sailing yachts. This is the major fudge needed to obtain acceptable performance in the water. As a fudge, it is comparable to the excessive numerical viscosity needed in climate models in order to suppress unwanted instabilities.

My fudge consists of one pound of roofer’s lead wrapped around a length of carbon piping. Unlike full-scale flat-bottoms, my sailing clogs need this heavy keel to make them self-righting. A gust cannot topple them, no matter how strong it is. Their sails may get wet, but that does not deter them. Not all bystanders are convinced when they see me carry one of my sweethearts, but a quick experimental demonstration makes them believers. I just throw the clog upside down in the water. That quiets them. The proof is in the throwing.

As to the tuning of my models, the major problem there is that very few people understand the difference between a stabilizer and a rudder. A rudder does not provide directional stability to a ship unless it is locked in a fixed position. In the town I grew up in, fathers converted worn-down clogs into toys for their kids, and took pride in constructing a plywood rudder hung off hook-and-eye hinges. Kids liked that, naturally, because they could play helmsman in their daydreams. But this doesn’t work at all. I dare any climate modeler in this audience to provide a scientific explanation why.

My models need to be tuned. I am an engineer; I do that experimentally. I take them one by one to a large pond, a canal, or a quiet river arm, and try them out there. In earlier years, it occurred often enough that I had to sew a new set of sails, but these days I merely have to lengthen or shorten one or two sheets. For those of you not familiar with yachting jargon, sheets are the ropes by which a sailor trims his sails.

Look, I am not perfect. Occasionally, a newly-finished model on its maiden trip escapes me in an unexpected direction. Once or twice I had to come to the rescue by skinny-dipping and swimming in order to retrieve them. The laws of hydrodynamics are in my favor then: the “hull speedâ€? of surface vessels is proportional to the square root of the waterline length, so I can swim faster than they sail. Not much faster, but fast enough.

In the second part of this series, I will analyze one of the cornerstones of engineering. It is, in Karl Popper’s unforgettable words:

“We can learn from our mistakes.â€?

Yes, we can, but do we?
And will climate modelers ever learn?

Those of you who are eager to prepare for Part 2, do get hold of a copy of one of the books by Henry Petroski. My favorites are “Success Through Failure – The Paradox of Designâ€? and “Invention by Design – How Engineers Get From Thought to Thingâ€?.

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Forecast Skill Of Season-to-Interannual Climate Prediction

There is an interesting and informative article in the Fall 2006 issue of U.S. CLIVAR Variations. CLIVAR is the acronym for “U.S. Climate Variability and Predictability” program. The article is

“Practices for Seasonal-to-Interannual Climate Prediction” by Lisa Goddard and Martin P. Hoerling.

There are several candid quotes in the article that clearly show the current level of prediction skill on the seasonal time scales. Excerpts from the article that report on this skill include,

“Among a suite of empirical tools employed by NCEP in their operational seasonal forecasts, the trend of surface temperature has been found to explain a large fraction of US seasonal temperature variations during the past decades (Huang et al. 1996), and this tool explains the majority of US temperature forecast skill at lead times greater than 1 season. season. Yet, neither the strength, seasonality, nor regionality of such trends have been distinguished from possible transient decadal variations. This leaves open the question on the best practice for including trends and their climatic forcings into seasonal
prediction practices.”

“The tools used for prediction, as mentioned above, include empirical models and dynamical models. Individually, empirical models continue to be competitive with dynamical models, which attests to the dominance of the linear ENSO signal as the primary skill source over the US. It is not clear if this will continue to be the case if
anthropogenically induced changes in the mean state impact the expression of climate variability.”

“A relevant question concerns whether U.S. seasonal prediction skill is advancing with newer generation models. Considerable investment has been devoted towards improving climate models, in part for the purpose of advancing seasonal predictions….An implicit assumption behind such efforts is that newer generation dynamical models will lead to improved skill. We know, for example, that predictability exists in the extratropical climate that the current generation of models are not realizing (Anderson et al. 1999). Analogies may also be drawn from weather forecasting experience where steady improvements in models and data assimilation techniques resulted in progressively improved weather predictions. It may be that the seasonal prediction models are presently neglecting some important external forcings, such as the increasing greenhouse gasses in the atmosphere, which can affect the characterization (and bias corrections) of the model climate over periods of years. Poorly represented interactions of the atmosphere with the land surface and with the cryosphere may also hamper the skill of seasonal predictions over the US. Another aspect of the climate system that is typically not well represented in the seasonal prediction models is the interaction between the stratosphere and troposphere (Baldwin and Dunkerton, 1999), which has demonstrated occasions of predictable evolution and subsequent influence on the terrestrial climate over the northern mid-latitudes. Even if the model development improves simulations of seasonal climate variability, seasonal prediction skill will nonetheless be limited by inherent signal-to noise considerations. The relevant question becomes whether the new generation of dynamical models yield signal-to-noise ratios that more accurately reproduce those in nature.”

This is a candid assessment of the current skill in these longer range weather forecasts. There are a few consequences of this admission of the limited skill of these forecasts:

1. The finding that the “the trend of surface temperature has been found to explain a large fraction of US seasonal temperature variations” is clearly not an independent predictor as the same climate metric that is being used to make the predictions is the variable that is being validated in terms of skill! Moreover, as has been documented in the peer reviewed literature; e.g. see, there is a warm bias in this data.

2. The inability of the dynamic models to improve on the empirical models clearly documents that this is at the cutting edge of where skillful regional predictions can be made (as opposed to the claims that skillful multi-decadal regional climate forecasts are possible).

3. The reliance on ENSO for forecast skill should be severely questioned as result of the forecast that was made for this winter (e.g. see and see). The failure to anticipate the cold winter in much of the western United States, the relatively dry conditions in the southwest United States, and the extensive snow cover in the west indicates the shortcoming of both the dynamical and empirical models, as well as how little we still know of the climate system.

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Direct and indirect effects of anthropogenic aerosols on regional precipitation over east Asia

Another very good article has appeared which documents the very significant role of aerosols on regional climate (and thus through teleconnections on the global climate system) [and thanks for Dev Niyogi for alerting us of it!].The new paper is

Huang, Y., W. L. Chameides, and R. E. Dickinson (2007), Direct and indirect effects of anthropogenic aerosols on regional precipitation over east Asia, J. Geophys. Res., 112, D03212, doi:10.1029/2006JD007114.

The abstract reads

“A regional coupled climate-chemistry-aerosol model is developed. It is used to assess the direct and indirect effects of anthropogenic sulfate and carbonaceous aerosols on regional climate over east Asia with a focus on precipitation. The simulated direct and first indirect effects for the most part reduce the solar radiation and hence decrease the surface temperature, while the second indirect effect generates both negative solar forcing and a substantial positive long-wave forcing. It decreases the precipitation, but because of the cancelling effect, surface temperature does not change very much. With the interactively model-calculated current aerosol loading and the combined direct/semidirect/first indirect effect, the simulated precipitation is reduced by about 10% in the fall and winter and by about 5% in the spring and summer. The second indirect effect has the largest impact, by itself decreasing the fall and winter precipitation from about 3% to 20%, depending on the autoconversion scheme assumed. The semidirect effect on precipitation is relatively small. An empirical orthogonal function analysis of climatological precipitation over east Asia since the last century shows a decreasing trend of the leading modes over most of China in the fall and winter, which is generally geographically consistent with the distribution of the model-simulated precipitation reduction from anthropogenic aerosols.”

Excerpts from the paper state,

“This study attempts a more comprehensive assessment of anthropogenic aerosols’ impacts on precipitation over east Asia using a regional coupled climate-chemistry-aerosol model. Anthropogenic aerosol loadings over east Asia are especially large, thus the climatic effects are expected to be significant [e.g., Chameides et al., 1999; Schimel et al., 1996]. The regional climate model (RegCM2) [Giorgi et al., 1993a, 1993b] is enhanced with a sulfate module developed by Qian et al. [2001], a modified tracer convective transport/wet removal module [Tan et al., 2002], the implementation of a carbonaceous aerosol module, and the inclusion of all four aforementioned types of aerosol effects. This study advances the previous studies as follows: it includes all three major components of anthropogenic aerosols (i.e., sulfate, black carbon, and organic carbon); it simulates the distributions of these fields in a fully interactive manner with the meteorological fields thereby allowing for feedbacks between chemical and climatic processes; it simulates the direct, semidirect, and first and second indirect effects, individually and in concert, allowing us to assess the relative impacts of the various effects on precipitation and it compares the model-predicted geographic-distribution of precipitation trends over east Asia with an analysis of the long-term precipitation record for the region.”

“Our study has neglected the aerosol indirect effect on the microphysical processes of convective clouds and their consequent interactions with dynamical processes, and in turn the convective precipitation…….a more comprehensive evaluation of aerosol indirect effects on precipitation should address both large-scale and convective clouds from local, regional to global scales.”

“A number of uncertainties and limitations remain in both understanding and modeling of cloud physics and aerosol effects, especially the indirect ones. Various mixing states between BC and sulfate/OC aerosols (external, core-coated, and internal) lead to a range of mass absorption coefficients, with consequent radiative and climate effects [Jacobson, 2000]; Menon [2004] also mentioned that the effect from absorbing BC particles could be quite variable in both sign and magnitude depending on its vertical location relative to the clouds…”

“Although the aerosol indirect climatic effects need further clarification, our results suggest that the precipitation decreases due to both direct and indirect effects of anthropogenic aerosols, which is consistent with observations over east Asia. If pollution emissions continue to increase along with the economic development of the region, anthropogenic aerosols should become even more important in determining the climatic and environmental conditions of the region.”

The message that is reaffirmed by this study is that the role of aerosols within the climate system is significant even if there was no change in the global average temperature. The 2007 IPCC Statement for Policymakers entitled “Climate Change 2007: The Physical Basis” failed to adequately discuss this critical human climate forcing, which has such a profound impact of society (e.g. through water resources).

This failure of the IPCC assessment provide additional evidence that its goal is really not to assess the human role within the climate system, but as a very obvious vehicle to be used to make energy policy changes, irrespective of the actual effects of energy policy changes on the real climate system.

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A New Approach To Weather and Climate Modeling

A new parameterization concept has been published in the February 20, 2007 edition of EOS [the significance of this concept was also discussed on Climate Science on November 1, 2006]. The article is

Pielke Sr., R.A., D. Stokowski, J.-W. Wang, T. Vukicevic, G. Leoncini, T. Matsui, C. Castro, D. Niyogi, C.M. Kishtawal, A. Biazar, K. Doty, R.T. McNider, U. Nair, and W.K. Tao, 2007: Satellite-based model parameterization of diabatic heating. EOS, February 20 2007, pp 96-97.

This new approach of using observations to construct the parameterizations of the physics in the models, with the exception of advection and the pressure gradient force, offers an opportunity for much more computationally efficient and also accurate simulations of weather and climate. This approach also recognizes (as Henk Tennekes is emphasizing on his Climate Science weblogs), that weather and climate models are engineering tools, not fundamental physics.

Up until the present, the parameterizations of the physics in these models have used the concept of constructing models within models. However, as can be easily shown (e.g. see page 198 in

Pielke, R.A., Sr., 2002: Mesoscale meteorological modeling. 2nd Edition, Academic Press, San Diego, CA, 676 pp.),

ALL of the existing parameterizations contain tunable coefficients in which the tuning usually occurs from observations from specially selected data which does not encompass the real world variations in these physical processes. An attempt to introduce even more computationally intensive models within the parent model (which has been called “superparameterizationâ€?) is not only computationally very expensive but that framework also requires significant assumptions, such a two-dimensional cloud fields.

Since these parameterizations are not fundamental representations of the physics, however, all that is needed is that they accurately represent the real world response to a set of input forcings. It is not important that the parameterization retain the physics of the real world as long as it faithfully replicates the response in the real world to the input forcings.

We refer to this new parameterization approach as a unified parameterization, and also as a “Look-Up-Tableâ€? or “LUTâ€?, which emphasizes that this is an engineering code. The LUT will use remotely sensed and real world observations for its construction as described in our EOS paper.

This technique can be applied to both numerical weather prediction models (where the initial conditions provide the reason for much of its skill) and to climate models (where the results depend on accurately simulating the forcings and feedbacks within the climate system).

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Weblog Is Back Up After A Major Power Outage

If you are a regular reader of Climate Science, you know that the weblog was offline for two days. This was due to a major power outage where our computers are located. We are making plans to install a backup so hopefully such long outages will not reoccur.

Thank you for reading Climate Science!

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A New Quote On Regional Climate Predictability

One of the conclusions on Climate Science is that there is no predictive skill in multi-decadal regional climate predictions (see #6). Evidence for such a conclusion, for example, have been summarized in a number of weblogs (e.g. see, and see).

There is an interesting candid new quote from Mike Mann on February 14, 2007 on this issue. It reads

“…..Until we are sure how climate change impacts El Nino, regional climate change forecasts over most regions of the world are likely to remain of somewhat limited utility. Its important to keep all of this in perspective.”

This statement needs to be related to news articles which purport to claim that there is regional predictive skill on decadal climate scales (e.g. see). Such news articles are clearly not supported by current capabilities in modeling the climate system.

Indeed, since significant human climate forcings (e.g. land use/cover change, aerosols) also occur on regional scales, are of a similar magnitude of heating and cooling in the troposphere with respect to an El Nino, and last for long periods of time (e.g. see the discussion in

Pielke Sr., R.A., 2001: Influence of the spatial distribution of vegetation and soils on the prediction of cumulus convective rainfall. Rev. Geophys., 39, 151-177),

Mike Mann’s conclusion therefore also applies to our current inability to skillfully predict the multi-decadal regional climate in response to these forcings (or using Mike Mann’s wording “remain of somewhat limited utility”), and through teleconnections, the global climate response.

As written in the 2001 Pielke paper,

” The effect of well above average ocean temperatures in the eastern and central Pacific Ocean, which is referred to as ‘El Nino,’ has been shown to have a major effect on weather thousands of kilometers from this region [Shabbar et al., 1997]. The presence of the warm ocean surface conditions permits thunderstorms to occur there that would not happen with the average colder ocean surface. These thunderstorms export vast amounts of heat, moisture, and kinetic energy to the middle and higher latitudes, particularly in the winter hemisphere. This transfer alters the ridge and trough pattern associated with the polar jet stream [Hou, 1998]. This transfer of heat, moisture, and kinetic energy is referred to as “teleconnectionsâ€? [Namias, 1978; Wallace and Gutzler, 1981; Glantz et al., 1991]. Almost two thirds of the global precipitation occurs associated with mesoscale cumulonimbus and stratiform cloud systems located equatorward of 30 degrees [Keenan et al., 1994]. In addition, much of the world’s lightning occurs over tropical landmasses, with maximums also over the midlatitude land masses in the warm seasons [Lyons, 1999; Rosenfeld, 2000]. These tropical regions are also undergoing rapid landscape change [O’Brien, 2000].

As shown in the pioneering study by Riehl and Malkus [1958] and by Riehl and Simpson [1979], 1500–5000 thunderstorms (which they refer to as “hot towersâ€?) are the conduit to transport this heat, moisture, and wind energy to higher latitudes. Since thunderstorms occur only in a relatively small percentage of the area of the tropics, a change in their spatial patterns would be expected to have global consequences.

Wu and Newell [1998] concluded that sea surface temperature variations in the tropical eastern Pacific Ocean have three unique properties that allow this region to influence the atmosphere effectively: large magnitude, long persistence, and spatial coherence. Since land use change has the same three attributes, a similar teleconnection would be expected with respect to landscape patterns in the tropics.”

The same three attributes of large magnitude, long persistence, and spatial coherence apply to aerosol forcings (e.g. see

Matsui, T., and R.A. Pielke Sr., 2006: Measurement-based estimation of the spatial gradient of aerosol radiative forcing. Geophys. Res. Letts., 33, L11813, doi:10.1029/2006GL025974).

Thus the message that should be taken from Mike Mann’s comment on Real Climate is that there is “somewhat limited utility” in the prediction of multi-decadal regional climate variability and change. Statements and claims to the contrary in the media (and in scientific journals) are not mainstream views in climate science.

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Comment on The Major Role Of Land Cover/Land Use Change Within The Global Climate System – Another Ignored Issue in the 2007 IPCC Statement For Policymakers

In answer to a question from a reporter on the importance of land cover/land use change within the climate system, I wrote the response below, which briefly overviews why this climate forcing is so important. The lack of including an emphasis on this issue in the IPCC Statement for Policymakers is disappointing and shows their continued neglect of critically important issues in climate variability and change.

“The focus on a global average surface temperature obscures the actual impact of climate forcings on weather patterns. As shown, for example, in

Feddema et al. 2005: The importance of land-cover change in simulating future climates., 310, 1674-1678,

Pielke Sr., R.A., 2005: Land use and climate change. Science, 310, 1625-1626,

and

Marland, G., R.A. Pielke, Sr., M. Apps, R. Avissar, R.A. Betts, K.J. Davis, P.C. Frumhoff, S.T. Jackson, L. Joyce, P. Kauppi, J. Katzenberger, K.G. MacDicken, R. Neilson, J.O. Niles, D. dutta S. Niyogi, R.J. Norby, N. Pena, N. Sampson, and Y. Xue, 2003: The climatic impacts of land surface change and carbon management, and the implications for climate-change mitigation policy. Climate Policy, 3, 149-157.

land use/land cover change result in tropospheric warming in some regions, but cooling in others. The effect on a global average temperature is quite small (at least in the model studies performed so far), but the effect of changing the regional tropospheric heating/cooling patterns is a very significant effect on important weather events such as drought.

Thus the spatial heating change within the atmosphere due to land use/land cover change (and also from the diverse effect of anthropogenic aerosols) resuly in large changes in the the global weather patterns. This can occur irrespective of a global surface temperature trend.

For further information on this issue, see the 2002 NASA press release below is of interest:

LANDCOVER CHANGES MAY RIVAL GREENHOUSE GASES AS CAUSE OF CLIMATE CHANGE

See also the 2005 article in the NASA Earth Observatory

http://earthobservatory.nasa.gov/Study/DeepFreeze/ [last page]

where it is written,

“Local or Global Problem?

Though their results drew national media attention from many sources, all the scientists involved in the research agree that the scientific arena is where the results should be evaluated. Pielke hopes these results will convince scientists to give the land cover-climate connection more attention. In the past, he has been frustrated by the lack of attention to the topic.

Gordon Bonan is a climate modeler for the National Center for Atmospheric Research in Boulder, Colorado. ‘It’s definitely true that historically, the emphasis in global climate change research has been on other climate forcings—greenhouses gases, solar variability, aerosols—and that the role of land cover has been neglected. Roger’s work, his persistence, has really played a large role in bringing people around to the importance of it.’ Bonan thinks people are finally beginning to listen.

So far, what research has been done on the global-scale influence of land cover change on climate seems to suggest it plays a minor role. That’s not surprising, says Bonan, considering how small the Earth’s land surface is compared to its oceans and that our most common metric for climate change is global mean temperature. Even significant changes in the temperature where we live can get ‘washed out’ (at least for a while) in the global average of a world mostly covered by oceans.

‘Nobody experiences the effect of a half a degree increase in global mean temperature,’ Bonan says. ‘What we experience are the changes in the climate in the place where we live, and those changes might be large. Land cover change is as big an influence on regional and local climate and weather as doubled atmospheric carbon dioxide—perhaps even bigger.’ That’s the idea Pielke says he has been trying to get across for years. ‘Climate change is about more than a change in global temperature,’ he says. ‘It’s about changes in weather patterns across the Earth.’ Even if it turns out that land cover change doesn’t significantly alter the globally-averaged surface temperature of the Earth, it’s still critically important. ‘The land is where we live. This research shows that the land itself exerts a first order [primary] influence on the climate we experience.’

If land cover change can cause Florida to have hotter, drier summers and chillier, longer-lasting cold spells, then that is a perfect example of why, Pielke says, ‘we can’t keep looking solely at increasing carbon dioxide as the only important forcing of climate by people.’”

By neglecting the important role of land cover/land use change within the global climate system, as documented in the peer reviewed literature, the IPCC has again shown its bias and narrow perspective as an advocacy document to promote energy policy changes, but not climate policy.

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Book Available “Contributions of Agriculture to the State of Climate”

This book offer was announced this past evening at the Virtual Discussion Forum: Climate Impacts of Human-Induced Land Use.

Book Offer:

Free copies of an upcoming book based on papers presented at the WMO Commission for Agricultural Meteorology (CAgM) Expert Team meeting on “Contributions of Agriculture to the State of Climate” held in 27-30 September, 2004 in Ottawa, Canada will soon be available for distribution. Please send your request along with your complete mailing address to Dr. Ray Desjardins, co-organizer of the CAgM meeting, at the following address:

Dr. Ray Desjardins
Agriculture and Agri-Food Canada
960 Carling Avenue K.W. Neatby Building
Ottawa ON K1A 0C6
CANADA

Email: desjardins@agr.gc.ca
Fax: 613-759-1432

Note: Selected papers from this meeting were recently published in a Special Issue of Agriculture and Forest Meteorology: Volume 142, Issues 2-4, 12 February 2007. Online versions of the papers are available here: http://www.sciencedirect.com/science/journal/01681923

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Surface temperature patterns in complex terrain: daily variations and long-term change in the central Sierra Nevada,

An important new paper that further documents the difficulty of monitoring multi-decadal surface air temperature trends has been accepted. It is

Lundquist, J. D. and D. R. Cayan, 2007. Surface temperature patterns in complex terrain: daily variations and long-term change in the central Sierra Nevada, California. J. Geophys. Res., in press.

The abstract reads

“A realistic description of how temperatures vary with elevation is crucial for ecosystem studies and for models of basin-scale snowmelt and spring streamflow. This paper explores surface temperature variability using temperature data from an array of 37 sensors, called the Yosemite Network, which traverses both slopes of the Sierra Nevada in the vicinity of Yosemite National Park, California. These data indicate that a simple lapse rate is often a poor description of the spatial temperature structure. Rather, the spatial pattern of temperature over the Yosemite Network varies considerably with synoptic conditions. Empirical orthogonal functions (EOFs)were used to identify the dominant spatial temperature patterns and how they vary in time. Temporal variations of these surface temperature patterns were correlated with large-scale weather conditions, as described by NCEP-NCAR Reanalysis data. Regression equations were used to downscale larger-scale weather parameters, such as Reanalysis winds and pressure, to the surface temperature structure over the Yosemite Network. These relationships demonstrate that strong westerly winds are associated with relatively warmer temperatures on the east slope and cooler temperatures on the west slope of the Sierra, and weaker westerly winds are associated with the opposite pattern. Reanalysis data from 1948 to 2005 indicate weakening westerlies over this time period, a trend leading to relatively cooler temperatures on the east slope over decadal time scales. This trend also appears in long-term observations and demonstrates the need to consider topographic effects when examining long-term changes in mountain regions.”

Climate Science has discussed the difficulty of using point observations of surface air temperature to construct a global average surface temperature to diagnosis global warming and cooling; e.g. see

Science Questions on the Global Surface Temperature Trends

The paper by Lundquist and Cayanfurther document how even a systematic change of wind direction over time, which could occur without any area average surface air temperature change, can be misinterpreted with sparse surface temperature data is a available. The issue they raise is not only true for mountainous terrain but anywhere that there are heterogeneous landscapes.

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Several Science Errors (Or, At Best Cherrypicking) In the 2007 IPCC Statement For Policymakers

In even an overview of the section in the 2007 IPCC Statement For Policymakers on “Direct Observations of Recent Climate Change” there are errors, or at best selective information, in their findings. I am summarizing four on this weblog:

1. The IPCC SPM writes on page 7

“… snow cover have declined on average in both hemispheres.”

The Rutgers University Global Snow Lab Northern Hemisphere Snow Cover Anomalies plot through January 2007, however, shows that the areal coverage in the Northern Hemisphere has actually slightly increased since the later 1980s!

Since the inference from the IPCC SPM is that global warming is the reason for these changes, this is at best a clear example of selecting a time period that conforms to their conclusion rather than presenting an up-to-date description of snow cover trends.

2. The IPCC SPM writes on page 7

“Observations since 1961 show that the average temperature of the global ocean has increased to depths of at least 3000 m and that the ocean has been absorbing more than 80% of the heat added to the climate system.”

It is correct that the ocean is where most of the heat changes occur, but the finding conveniently neglected to report on the significant loss of heat in the period from 2003 to at least 2005;

Lyman, J. M., J. K. Willis, and G. C. Johnson (2006), Recent cooling of the upper ocean, Geophys. Res. Lett., 33, L18604, doi:10.1029/2006GL027033.

As stated in that paper,

“The decrease represents a substantial loss of heat over a 2-year period, amounting to about one fifth of the long-term upper-ocean heat gain between 1955 and 2003 reported by Levitus et al. [2005].”

In addition, even with the earlier ocean warming, this is what was found in the paper

Willis, J. K., D. Roemmich, and B. Cornuelle (2004), Interannual variability in upper ocean heat content, temperature, and thermosteric expansion on global scales, J. Geophys. Res., 109, C12036, doi:10.1029/2003JC002260.

� Maps of yearly heat content anomaly show patterns of warming commensurate with ENSO variability in the tropics, but also show that a large part of the trend in global, oceanic heat content is caused by regional warming at midlatitudes in the Southern Hemisphere. �

They report that,

“……a strong, fairly linear warming trend is visible in the Southern Hemisphere, centered on 40°S. This region accounts for a large portion of the warming in the global average.â€?

Also,

“……..the warming around 40°S appears to be much steadier over the course of the time series, as seen in Figure 7. In addition, this warming extends deeper and is more uniform over the water column than the signal in the tropics. â€?

Thus the actual global ocean warming reported in the IPCC SPM over the last several decades occured in just a relatively limited portion of the oceans and through depth such that the heat was not as readily avaiable to the atmosphere as it would be if the warming was more spatially uniform.

Moreover, if the ocean has been absorbing “more than 80% of the heat added to the climate system”, why does the SPM use the surface air temperature trends to define what is a warm year? The IPCC SPM makes such a claim on page 5, where it is written that

“Eleven of the last twelve years (1995 -2006) rank among the 12 warmest years in the instrumental record of global surface temperature (since 1850).”

If the ocean absorbs most of the heat (which Climate Science agrees with), than that is the climate metric that should be reported on with respect to global warming, rather than the global average surface temperature trend data.

3. The IPCC SPM writes on page 7,

“The average atmospheric water vapour content has increased since at least the 1980s over land and ocean as well as in the upper troposphere. The increase is broadly consistent with the extra water vapour that warmer air can hold.”

This conclusion conflicts with the finding in

Smith, T. M., X. Yin, and A. Gruber (2006), Variations in annual global precipitation (1979–2004), based on the Global Precipitation Climatology Project 2.5° analysis, Geophys. Res. Lett., 33, L06705, doi:10.1029/2005GL025393,

where they write for the period 1979–2004 that precipitation tends

“have spatial variations with both positive and negative values, with a global-average near zero.”

The global average precipitation has not changed significantly in the period.

If greater amounts of water vapor were present in the atmosphere, the evaporation/transpiration of water vapor into the atmosphere and thus the precipitation would have to increase when averaged globally and over a long enough time period.

4. The IPCC SPM writes,

“Mid-latitude westerly winds have strengthened in both hemispheres since the 1960s.”

This is perhaps the most astonishing claim made in the report. First, peer reviewed papers that have investigated this subject,

Pielke, R.A. Sr., T.N. Chase, T.G.F. Kittel, J. Knaff, and J. Eastman, 2001: Analysis of 200 mbar zonal wind for the period 1958-1997. J. Geophys. Res., 106, D21, 27287-27290.

did find a

“….tendency for the 200 mbar winds to become somewhat stronger at higher latitudes since 1958.â€?

However, what this means from basic meteorology, is that if the mid-latitude westerlies increase, this indicates a greater north-south tropospheric temperature gradient! This is why the westerlies are stronger in the winter; the troposphere becomes very cold at the higher latitudes, but the tropospheric temperatures change little in the tropics. Thus a statement that the westerlies have become stronger, in the absence of significant warming in the tropical latitudes, indicates a colder troposphere at higher latitude on average.

There is, therefore, an inconsistency in the IPCC SPM. It cannot both be the case that the troposphere in the arctic is warming high while the westerlies in the midlatitudes are increasing in speed. There is a fundamental inconsistency in these trends, which goes unaddressed by the IPCC.

These four examples illustrate the apparent selection of papers and data to promote a particular conclusion on climate change. The science community, and even more importantly, the policy community is ill-served by such cherry picking.

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