van der Molen, M.K., H.F. Vugts, L.A. Vruijnzeel, F.N. Scatena, R.A. Pielke, and L.J.M. Kroon, 2007: Mesoscale climate change due to lowland deforestation in the maritime tropics. In: Mountains in the Mist, Science for conserving and managing Tropical Montane Cloud Forest. L.A. Bruijnzeel, J. Juvik, F.N. Scatena, L.S. Hamilton and P. Bubb (Eds.). University of Hawaii Press, in press.

The abstract reads

“Annual precipitation on the Caribbean island of Puerto Rico decreased steadily during the 20th century, on average by 16 %. The reduced rainfall manifested itself in the form of regular water rationings during the 1990s which hit millions of inhabitants. Simultaneous with the reduction in rainfall there was widespread deforestation, notably in the coastal lowlands. This paper examines the link between the reduction in precipitation and the land cover change using a combination of energy balance measurements and mesoscale atmospheric modelling.

The explanation of the reduction in precipitation appears to be quite different than expected. Based on measurements made earlier over rainforest and pasture in the Amazon, a forest covered island would be expected to be cooler because the higher transpiration -of the forest compared to grassland- tends to cool the surface. During an intensive measurement campaign on Puerto Rico, the opposite appeared to be the case: transpiration by a coastal wetland forest proved to be less than that for a grassland. In addition, the forest albedo was 8 % lower than that for grassland. Together, these two factors caused the sensible heat flux over the forest to be twice as high as that over the grassland, whereas forest evaporation was lower.

The surface energy balance observations over forest and grassland were used to derive proper land surface parameterizations, which were implemented in a mesoscale atmospheric circulation model (RAMS) to simulate the meteorological effects of island wide deforestation. The model simulations indicated that the development of a sea breeze during the day dominates climate on the island. Sea breezes develop when the land surface is warmer than the surrounding ocean. In model runs, where the island was assumed to be completely covered with forest, the sea breeze was considerably stronger than in model runs where the vegetation had been transformed to grassland. Along the sea breeze front, convergence caused upward air motions. As this happens more strongly over a forested island, more clouds are formed but at a higher elevation, with an estimated 10-20 % enhancement of precipitation compared to a deforested island. In the deforested scenario the cloud base was typically lowered by 200 m.

Refinement of the model is required to obtain more accurate estimates of the changes in precipitation, although most likely the relevant processes have been determined. This project has offered new insights into the effects of climate change and may contribute to improved land use and water resources policies on Puerto Rico.”

Everywhere that model simulations of landscape change are completed, we are finding significant effects on the climate of the region. The 2007 IPCC failed to adequately communicate to policymakers this important component of human caused climate change.

Barnett, T. P, and D. W. Pierce, 2008: When will Lake Mead go dry? Water Resour. Res., 44, W03201, doi:10.1029/2007WR006704.

The abstract reads

“A water budget analysis shows that under current conditions there is a 10% chance that live storage in Lakes Mead and Powell will be gone by about 2013 and a 50% chance that it will be gone by 2021 if no changes in water allocation from the Colorado River system are made. This startling result is driven by climate change associated with global warming, the effects of natural climate variability, and the current operating status of the reservoir system. Minimum power pool levels in both Lake Mead and Lake Powell will be reached under current conditions by 2017 with 50% probability. While these dates are subject to some uncertainty, they all point to a major and immediate water supply problem on the Colorado system. The solutions to this water shortage problem must be time-dependent to match the time-varying, human-induced decreases in future river flow.”

The text includes the statements

“We consider human-induced reductions in runoff of 10 to 30%, in accordance with estimates from global climate models and statistical analysis, and take these reductions to be linear in time over the next 50 years (i.e., runoff slowly decreases until it reaches a total reduction of, say, 10% below current levels in 2057)”;

“….we begin with deterministic estimates of when the live storage will be depleted by global warming-driven runoff reductions alone, without the outside impacts of evaporation and natural variability in the river flow”;

“The climate models which have produced estimates of decreasing runoff have a host of problems of their own in handling the water budget from coarse resolution (little in the way of Rocky Mountains) to the variety of ways they handle soil processes and vegetation representations. However, a recent study of changes in hydrology of the western U.S. over that last 50 years shows several of the models, when run with observed anthropogenic forcings, reproduce extremely well the observed changes in river flow timing, snow pack decline and increasing air temperatures in the western United States [Barnett et al., 2008]. So these models, while not perfect, have a message to tell; a message supported by their ability to reproduce well the last 50 years of multivariate hydrological observations“;

and 

“…..the Colorado River will continue to lose water in the future, if the global climate models are correct.”

This paper correctly identifies that there is risk associated with the limited water available from the Colorado River. Indeed their statement that

“Tree ring data suggest the long term flow of the Colorado experiences more variability than has been observed over the last century [NAS, 2007]. These data also suggest prolonged droughts far worse and more extensive than seen in the last 100 years of flow record on the River are possible”

shows that the water resource is at risk regardless of how humans have altered the system. This is a conclusion we also reached in our paper

 Pielke Sr., R.A., N. Doesken, O. Bliss, T. Green, C. Chaffin, J.D. Salas, C. Woodhouse, J.L. Lukas, and K. Wolter, 2005: Drought 2002 in Colorado - An unprecedented drought or a routine drought?Pure Appl. Geophys., Special Issue in honor of Prof. Singh, 162, 1455-1479, doi:10.1007/200024-005-2679-6.

However, the paper suffers from their reliance on the multi-decadal global models as quantitative predictions of what will happen in terms of climate in the coming years. They even recognize this in their text “…..the Colorado River will continue to lose water in the future, if the global climate models are correct.” 

Thus while Climate Science agrees that there is a significant concern on water available from the Colorado River, and planning should be a major priority with respect to long-term drought, the multi-decadal global model predictions are just hypotheses and their use as part of the computation as definitive, skillful predictions to present quantitative probabilities of Lake Mead drying out is misleading to the policymakers. This is yet another example of overselling the skill that exists in using these models as predictions. The large amounts of precipitation this past winter (2007-2008) in large areas of the West should be a wake-up call on the serious limitations of the IPCC models.

Lei, M., D. Niyogi, C. Kishtawal, R. Pielke Sr., A. Beltrán-Przekurat, T. Nobis, and S. Vaidya, 2008: Effect of explicit urban land surface representation on the simulation of the 26 July 2005 heavy rain event over Mumbai, India. Atmos. Chem. Phys., accepted.

The abstract reads

“We investigate whether explicit representation of the urban land surface improves the simulation of the record-breaking 24-h heavy rain event that occurred over Mumbai, India on 26 July 2005 as the event has been poorly simulated by operational weather forecasting models. We coupled and conducted experiments using the Regional Atmosphere modeling system (RAMS 4.3), with and without an explicit urban energy balance model-town energy budget (TEB) to study the role of urban land – atmosphere interactions in modulating the heavy rain event over the Indian monsoon region. The impact of including an explicit urban energy balance on surface thermodynamic, boundary layer, and circulation changes are analyzed. The results indicate that even for this synoptically active rainfall event, the vertical wind and precipitation are significantly influenced by urbanization, and the effect is more significant during the storm initiation. Interestingly, precipitation in the upwind region of Mumbai city is increased in the simulation, possibly as a feedback from the sea breeze – urban landscape convergence. We find that even with the active monsoon, the representation of urbanization contributes to local heavy precipitation and mesoscale precipitation distribution over the Indian monsoon region. Additional experiments within a statistical dynamical framework show that an urban model by itself is not the dominant factor for the enhanced rainfall for Mumbai heavy rain event; the combination of updated SST fields using Tropical Rainfall Measurement Mission (TRMM) data with the detailed representation of urban heat island (UHI) simulated by the TEB/urban model created realistic gradients that successfully maintained the convergence zone over Mumbai. Further research will require more detailed morphology data for simulating weather events in such urban regions. The results suggest that urbanization can significantly contribute to extremes in monsoonal rain events that have been reported to be on the rise.”

This new research provides even more demostration of the important role of urban effects on the climate system.

“Comparison of Air Pollutant Emissions among Mega-Cities”by Parish et al. The article starts with the paragraph

“The world’s mega-cities represent a wide diversity of cultures and histories, with examples of mega-cities on all of the five major continents. This diversity might be expected to lead to very different patterns of air pollutant emissions. However, as mega-cities develop economically, a convergence of cultures occurs in the sense that automobile fleets and industrial processes develop in similar modes across all cultures. Our goal in this article is to compare and contrast mega-city air pollutant emissions as reflected in measured ambient concentrations of those pollutants.”

Figure 4 in their article shows the major improvement in the concentration of several important pollutants in recent years, as well as the difference among large cities. It viewing this figure, note that the left axis in is units of the logarithm of concentration such that the spread is in units of concentration are, of course, much larger.

The conclusion of the paper has the text

“The speciation of ambient hydrocarbon concentrations in the mega-cities and other U.S. cities examined here (Figures 1-4) reveal a large degree of similarity. This similarity spans the cities in North America and Asia, has remained nearly constant over the past 2 decades in the U.S., and persists over wide ranges of absolute concentrations. A two-part hypothesis most likely explains this similarity: First, on-road vehicle exhaust and the associated evaporative gasoline emissions dominate the ambient hydrocarbon concentrations in all of these urban areas. Second, there is no large difference in the hydrocarbon composition of gasoline between these urban areas.

Comparison of data sets collected in U.S. cities over the past three decades indicate that a substantial decrease in hydrocarbon emissions has occurred even while total vehicle usage has more than doubled. The ambient concentration data suggest that the emission decrease has been larger than indicated by U.S. emission inventories. Thus, U.S. strategies aimed toward controlling hydrocarbon emissions, based upon automobile catalytic converters and minimization of gasoline evaporation, have been quite successful - indeed more successful than indicated by emission inventories.”

This study documents an environmental success story in the United States (from the period 1988-1984 to the period 2005 to 1999) as well as that the United States, despite similarities around the world, has significantly lower atmospheric concentrations at present than found in Mexico City, Tokyo and Beijing. With the introduction of biofuels, there needs to be continued monitoring of a possible rise in these concentrations due to their particular emissions (e.g see

Evidence Of Health Problems With Ethanol Fuels

Will Climate Effects Trump Health Effects In Air Quality Regulations?

Readers of Climate Science are urged to read past and upcoming issues of the IGAC Newsletter for other excellent research contributions, which are expanding our understanding of the climate system. 

Schecter, D.A., M.E. Nicholls, J. Persing, A.J. Bedard Jr., and R.A. Pielke Sr., 2008: Infrasound emitted by tornado-like vortices: Basic theory and a numerical comparison to the acoustic radiation of a single-cell thunderstorm. J. Atmos. Sci., 65, 685-713.

The abstract reads,

“This paper addresses the physics and numerical simulation of the adiabatic generation of infrasound by tornadoes. Classical analytical results regarding the production of infrasound by vortex Rossby waves and by corotating ’suction vortices’ are reviewed. Conditions are derived for which critical layers damp vortex Rossby waves that would otherwise grow and continually produce acoustic radiation. These conditions are similar to those that theoretically suppress gravity wave radiation from larger mesoscale cyclones, such as hurricanes. To gain perspective, the Regional Atmospheric Modeling System (RAMS) is used to simulate the infrasound that radiates from a single-cell thunderstorm in a shear-free environment. In this simulation, the dominant infrasound in the 0.1–10-Hz frequency band appears to radiate from the vicinity of the melting level, where diabatic processes involving hail are active. It is shown that the 3D Rossby waves of a tornado-like vortex (simulated with RAMS) can generate stronger infrasound if the maximum wind speed of the vortex exceeds a modest threshold. Technical issues regarding the numerical simulation of tornado infrasound are also addressed. Most importantly, it is shown that simulating tornado infrasound likely requires a spatial resolution that is an order of magnitude finer than the current practical limit (10-m grid spacing) for modeling thunderstorms.”

This research builds on our studies

Nicholls, M.E. and R.A. Pielke, 1994: Thermal compression waves. I: Total energy transfer. Quart. J. Roy. Meteor. Soc., 120, 305-332.

Nicholls, M.E. and R.A. Pielke, 1994: Thermal compression waves. II: Mass adjustment and vertical transfer of total energy. Quart. J. Roy. Meteor. Soc., 120, 333-359

Pielke, R.A., M.E. Nicholls, and A.J. Bedard, 1993: Using thermal compression waves to assess latent heating from clouds. EOS, 74, 493.

Nicholls, M.E. and R.A. Pielke Sr., 2000: Thermally-induced compression waves and gravity waves generated by convective storms. J. Atmos. Sci., 57, 3251-3271

where

we show the diagnostic value of using sound wave information to assess meteorological dynamics. We have shown that this approach works for thunderstorms including tornadoes, and would be a very effective monitoring approach to add to the arsenal of hurricane intensity change monitoring by agencies such as the USA National Severe Storms Forecast Center and the National Hurricane Center.

• The human influence is minimal and natural variations dominate climate variations on all time scale;
• While natural variations are important, the human influence is significant and involves a diverse range of first-order climate forcings (including, but not limited to the human input of CO₂);
• The human influence is dominated by the emissions into the atmosphere of greenhouse gases, particularly carbon dioxide.

The third hypothesis, of course, is the IPCC perspective.

The challenge to the scientific community, using the scientific method, is to present observational evidence that refutes one or more of these hypotheses.

Climate Science’s perspective is that the second hypotheses is correct, which has support from the

National Research Council, 2005: Radiative forcing of climate change: Expanding the concept and addressing uncertainties. Committee on Radiative Forcing Effects on Climate Change, Climate Research Committee, Board on Atmospheric Sciences and Climate, Division on Earth and Life Studies, The National Academies Press, Washington, D.C., 208 pp.

A new Nature paper by Keenlyside et al. entitled “Advancing decadal-scale climate prediction in the North Atlantic sector” provides evidence that is inconsistent with the third hypothesis. This paper writes in the abstract

“The climate of the North Atlantic region exhibits fluctuations on decadal timescales that have large societal consequences. Prominent examples include hurricane activity in the Atlantic, and surface-temperature and rainfall variations over North America, Europe and northern Africa……Our results suggest that global surface temperature may not increase over the next decade, as natural climate variations in the North Atlantic and tropical Pacific temporarily offset the projected anthropogenic warming.”

There are several important messages from this paper:

• While this Nature paper claims that this lack of global warming is temporary due to “natural climate variations“, unless the first hypothesis is true, there are NO climate variations that are not affected by humans (i.e., the term “natural climate variations” is therefore a misnomer).  
• This new paper supports the perspective that climate variations and change (even the global average radiative imbalance) are dominated by regional alterations in circulations [as summarized in the 2005 National Research Council Report, and emphasized on Climate Science and associated papers (e.g. see) including the very important guest weblog on Climate Science by Roy Spencer (see) on this subject].
• Since the multi-decadal global climate model predictions used for the 2007 IPCC report are failing to skillfully predict these “fluctuations on decadal time scales”, there is no credible reason to accept the claim in the Nature paper that the “projected anthropogenic warming” will be accurately predicted after the next decade.

“The NY Times wraps up its main piece [by Andy Revkin] with a useful quote from Kevin Trenberth, of the US National Center for Atmospheric Research: ‘Too many think global warming means monotonic relentless warming everywhere year after year. It does not happen that way.’”

This is an amazing error.  Global warming does require a more-or-less monotonic increase in warming (in the absence of a  major volcanic eruption) as illustrated in all available multi-decadal global model runs (e.g. see the Figure in this post on Climate Science ; and see Figure 1 in Barnett et al, 2001). This essentially monotonic report is even emphasized in the 2007 IPCC Summary for Policymakers (see Figure SPM.4)!

Climate Science published a proposed test of the multi-decadal global model predictions (see A Litmus Test For Global Warming - A Much Overdue Requirement).  Clearly, so far, the models are failing to skillfully predict the rate (and even the sign for the most recent years) of global warming. Andy Revkin should follow up his article to document what the models predict in terms of global warming (in Joules) over different time periods, and what do the observations actually show. This would be excellent investigative (much needed) journalism.

Pielke Sr., R.A., C. Davey, and J. Morgan, 2004: Assessing “global warming” with surface heat content. Eos, 85, No. 21, 210-211

and 

Davey, C.A., R.A. Pielke Sr., and K.P. Gallo, 2006: Differences between near-surface equivalent temperature and temperature trends for the eastern United States - Equivalent temperature as an alternative measure of heat content. Global and Planetary Change, 54, 19–32

we urged the adoption of a more complete measure of heat content trends in the near-surface atmosphere (i.e. moist enthalpy).

 Thanks to Souleymane Fall of Purdue for alerting us to a new paper which has built on this idea with important new insight into this climate metric.

The paper is

Rogers, J.C., S.H. Wang, and J.S.M. Coleman, 2007: Evaluation of a Long-Term (1882–2005) Equivalent Temperature Time Series. J. Climate, 20, 4476–4485.

The abstract reads

“A 124 (1882-2005) summer record of total surface energy content consisting of time series of surface equivalent temperature (T_E) and its components T (mean air temperature) and Lq/c_p(moist enthalpy, denoted Lq) is developed, quality controlled, and analyzed for Columbus, Ohio, where long records of monthly dewpoint temperature are available. The analysis shows that the highest T_Eoccurs during the summer of 1995 when both T and Lq were very high, associated with a severe midwestern heat wave. That year contrasts with the hot summers of 1930-36, when Lq and T_Ehad relatively low or negative anomalies (low humidity) compared to those of T. Following the 1930-36 summers, T and Lq departures are much more typically the same sign in individual summers, and the two parameters develop a statistically significant high positive correlation into the twenty-first century. Mean T and Lq departures from the long-term normal have opposite signs, however, when summers are stratified either by seasonal total rainfall amounts or by the Palmer drought severity soil moisture index. Normalized trends of T, Lq, and T_E are downward from 1940 to 1964 with those of T_E exceeding T. Since 1965, however, significant positive T trends slightly exceed T_Ein magnitude and those of dewpoint temperature and Lq are comparatively lower. A highly significant upward trend in minimum temperatures especially dominates the T variability, creating a significant downward trend in the temperature range that dominates recent summer climate variability more than moisture trends. Regional moisture flux variations are largest away from Columbus, over the upper Midwest and western Atlantic Ocean, during its seasonal extremes in total surface energy.”

In the assessment of global warming (and global cooling), this research further shows that unless the role of near surface vapor trends are included, a quantitatively erroneous assessment will necessarily result. Thus, when a media report or scientific paper claims that a certain increase (or decrease) in temperatures have occurred over a period of years, this cannot by itself, be used to say this is warming or cooling (in terms of heat), unless the changes in water vapor concentrations are simultaneously assessed so that moist enthalpy changes are computed.

Monaghan, A. J., D. H. Bromwich, and D. P. Schneider (2008), Twentieth century Antarctic air temperature and snowfall simulations by IPCC climate models, Geophys. Res. Lett., 35, L07502, doi:10.1029/2007GL032630.

The abstract reads 

“We compare new observationally-based data sets of Antarctic near-surface air temperature and snowfall accumulation with 20th century simulations from global climate models (GCMs) that support the Intergovernmental Panel on Climate Change Fourth Assessment Report. Annual Antarctic snowfall accumulation trends in the GCMs agree with observations during 1960–1999, and the sensitivity of snowfall accumulation to near-surface air temperature fluctuations is approximately the same as observed, about 5% K⁻¹. Thus if Antarctic temperatures rise as projected, snowfall increases may partially offset ice sheet mass loss by mitigating an additional 1 mm y⁻¹of global sea level rise by 2100. However, 20th century (1880–1999) annual Antarctic near-surface air temperature trends in the GCMs are about 2.5-to-5 times larger-than-observed, possibly due to the radiative impact of unrealistic increases in water vapor. Resolving the relative contributions of dynamic and radiative forcing on Antarctic temperature variability in GCMs will lead to more robust 21st century projections.”

The conclusion of the paper states

“The annual snowfall trends in the GCMs agree with the observations during 1960–1999, but annual NSAT trends for 1880–1999 are too large by a factor of 2.5-to-5. Our results suggest that the larger-than-observed GCM NSAT trends may be related to unrealistic increases in atmospheric water vapor over Antarctica which enhances longwave radiative forcing at the surface. When applied to the longwave radiation trend, the regression relationship presented in Figure 2b suggests that the positive contribution of longwave radiation to 1880–1999 Antarctic NSAT trends in the GCMs is about 4 times larger than the (overall) negative contribution of the SAM (and at least 2 times larger during 1960–1999 when SAM trends are largest). The monotonic increase of Antarctic NSAT in the GCMs may thus be related to the steady rise in GHGs since the 19th century, perhaps leading to an amplified GHG-temperature-water-vapor feedback that is contributing to the larger-than-observed NSAT trends. IPCC AR4 GCMs project that the SAM will continue strengthening throughout the 21st century [e.g., Fyfe and Saenko, 2006], therefore it should be a priority to clarify the relative roles of the SAM and radiative forcing on Antarctic temperatures and how they may change. Until these issues are resolved, IPCC projections for 21st century Antarctic temperature should be regarded with caution.”

This paper provides further evidence that the multi-decadal global climate models are significantly overstating the water vapor input into the atmosphere, and thus are not providing quantitatively realistic estimates of how the climate system responds to the increase in atmospheric well mixed greenhouse gases in terms of the water vapor feedback. This water vapor feedback is required in order to achieve the amount of warming from radiative forcing projected in the 2007 IPCC report.

There is an important research issue with respect to the size of a perturbation of the atmosphere that must occur before it can have any effect on the larger-scale atmosphere. Ray Pierrehumbert and Gavin Schmidt on Real Climate conclude that there is no minimum spatial scale, while Issac Held states that features must be larger than a few millimeters.

Rich Eykholt and I have agreed to complete a paper on this subject over the coming months, as it clearly is an issue that has been neglected, and, in my view, is a misinterpretation of the conclusions from the seminal work of Ed Lorenz.

The real butterfly is illustrated below  

[from http://en.wikipedia.org/wiki/Chaos_theory]

“The Lorenz attractor is a 3-dimensional structure corresponding to the long-term behavior of a chaotic flow, noted for its butterfly shape. The map shows how the state of a dynamical system (the three variables of a three-dimensional system) evolves over time in a complex, non-repeating pattern.  Picture below is a plot of the Lorenz attractor for values r = 28, σ = 10, b = 8/3.”

from http://en.wikipedia.org/wiki/Chaos_theory

The interested reader can also evaluate the solution for different input values at  http://crossgroup.caltech.edu/chaos_new/Lorenz.html

In terms of what Professor Lorenz wrote, following is the text from his book The Essence of Chaos by Ed Lorenz in 1993 (from pages 14 and 15) regarding the expression “The Butterfly Effect”. The Figure 2 that he refers to in the text is of the form of the above two figures, and he labels it as “The butterfly”! Professor Lorenz wrote

“The expression has a somewhat cloudy history. It appears to have arisen following a paper that I presented at a meeting in Washington in 1972 entitled “Does the Flap of a Butterfly’s Wings in Brazil Set Off a Tornado in Texas?”  I avoided answering the question, but noted that if a single flap could lead to a tornado that would not otherwise have formed, it could equally well prevent a tornado that would otherwise have formed. I noted also that a single flap would have no more effect on the weather than any flap of any other butterfly’s wings, not to mention the activities of other species, including our own.  The paper is reproduced in its original form as Appendix A.

The thing that has made the origin of the phrase a bit uncertain is a peculiarity of the first chaotic system that I studied in detail.  Here an abbreviated graphical representation of a special collection of states known as a “strange attractor” was subsequently found to resemble a butterfly, and soon came to be known as the butterfly.   In Figure 2 we see one butterfly; a representative of a closely related species appears on the inside cover of Gleick’s book.  A number of people with whom I have talked have assumed that the butterfly effect was named after this attractor.  Perhaps it was.

Some correspondents have also called my attention to Ray Bradbury’s intriguing short story, “A Sound of Thunder,” written long before the Washington meeting.  Here the death of a prehistoric butterfly, and its consequent failure to reproduce, change the outcome of a present-day presidential election.

Before the Washington meeting, I had sometimes used a sea gull as a symbol for sensitive dependence.  The switch to a butterfly was made by the session convenor, the meteorologist Philip Merilees, who was unable to check with me when he had to submit the program titles. Phil has recently assured me that he was not familiar with Bradbury’s story. Perhaps the butterfly, with its seeming frailty and lack of power, is a natural choice for a symbol of the small that can produce the great.

Other symbols have preceded the sea gull. In George W. Stewart’s novel Storm, a copy of which my sister gave me for Christmas when she first learned I was to become a meteorology student, a meteorologist recalls his professor’s remark that a man sneezing in China may set people to shoveling snow in New York.  Stewart’s professor was simply echoing what some real-world meteorologists had been saying for many years, sometimes facetiously, sometimes seriously.”

Thus, the butterfly effect, which is described by the solution shape in the above figures, has morphed into a symbol that small perturbations can alter large-scale structure.

However, scientists such as Ray Pierrehumbert and Gavin Schmidt at Real Climate have literally interpreted Professor Lorenz’s seminal as applying to all perturbations of atmospheric flow regardless of their magnitude and spatial scale.  This clearly was not the claim of Professor Lorenz.

In the real world, very small perturbations, such as the flap of a butterfly wing cannot have any impact on the large-scale flow (such as the creation of a tornado). In order to do that, the turbulence generated by the flapping wings must retain some coherant flow structure as the nonlinear interactions create larger scale structure. However, this kinetic energy is dispersed over progressively larger and larger volumes such that it will quickly dissipate into heat as the magnitude of the disturbance to the flow at any single location becomes smaller. The atmosphere has an infinitesimal addition of heat, but the coherent information needed to alter the large-scale flow is lost.

This paragraph should, of course, be viewed as a hypothesis, and we will be evaluating this in our paper. Readers, including those at Real Climate, are invited to also seek to falsify this hypothesis.