Contribution to the discussion about Anthropogenic Climate Change:  


Does Man really affect Weather and Climate? 

Are the Interactions really understood?

© Heinz Thieme


Deutsche Version siehe:



0.  Abstract 

Current plans and actions to protect the climate lack an adequate basis in the proven results of scientific research.  The group of scientists currently offering policy advice has so far failed to demonstrate the alleged mechanisms by which trace gases will damage weather and climate.  Moreover, several potentially major influences on climate are being ignored.

Enhanced scientific understanding of meteorological processes might suggest substantially different climate protection activities, if in fact these are necessary or feasible.  Substantial further research is required by experts in biology, chemistry, thermodynamics and meteorology to improve knowledge of atmospheric dynamics and assess the extent to which human activities affect climate.


1. Background 

Abundant rainfall in several parts of Europe over the summer of 2002 was grist to the mill of those who predict such weather in future if we do not soon change our behaviour, especially by controlling emissions of so-called "greenhouse-gases", mainly CO2.  These people urge us to curb our combustion of fossil fuels and stop driving cars, lest weather and climate change in a threatening manner.  Recent extreme weather, they say, is the result of man-made global warming.

But examination of a few specific scientific contributions casts doubt on the veracity of these frequently heard statements.  Thus Leroux [1] states that at present, there is no justification to speak of generalised global warming. On the contrary, regional differences continue to dominate, warming in some areas being balanced by cooling in others.

Moreover, the damage to climate supposedly wrought by "greenhouse gases" ignores key physical laws, especially those of thermodynamics and the radiation characteristics of gases. The author has discussed these points in [2] and [3].  Hug argues along similar lines in [4].

But even after we recognise the insignificance of limited variations of the CO2-content of the atmosphere for the temperature of the biosphere, the question remains whether man may be influencing weather and climate through some other mechanism.

A discernible human influence may be safely inferred in the recent (upward) movements in the temperatures in and near cities, in contrast to the lack of warming in wild or sparsely populated areas.  But it behooves us to examine this complex matter from a critical and somewhat more fundamental scientific standpoint.


2. Temperature or Enthalpy? 

It is beyond dispute that the troposphere (the lowest layer of the atmosphere, from the surface up to between 10 and 17 km altitude, depending on latitude) is a thermodynamic system.  This was stated even by the IPCC in 1990 [5].  So it should equally be beyond question that thermodynamic magnitudes, relationships and laws must form the basis for understanding and analysing this system.  To date, however, the proponents of the greenhouse hypothesis have studiously avoided this approach.

For example, in descriptions of climate change, the only physical unit normally observed or mentioned is temperature [in kelvins (K) or degrees Celsius (°C)].  A correlation with warmth is implicitly assumed.  However, in thermodynamic systems like the troposphere the correct physical measure of energy is enthalpy (i.e., the warmth or energy content of air; measured in kilojoules per kilogram).

But enthalpy is not mentioned at all.   It seems to be of no interest in theoretical climate research.  The enthalpy of air is a function of its temperature, water or water vapour content, and pressure and/or density.  Using temperature as a proxy quantity for warmth (= work, energy) instead of measuring enthalpy is problematic, and can even be very misleading.  Moreover tropospheric air is a two-component system (air and water), with changing proportions, and where one of the components, water, exists in three phases (vapor, liquid, solid) that have very different - especially radiative - characteristics.  This is an extremely complex system, for which no adequate computational treatment currently exists.  And until one does, computer model simulations of climate change may be considered premature and highly speculative. 

(By the way, the current lack of knowledge of the characteristics of moist air under tropospheric conditions (pressure range 1 to 0.1 bar, temperature 0°C to -80°C) is likely the most important reason for current gaps in scientific understanding of the processes of hurricanes/typhoons and tornados.  Until such knowledge exists, there is little chance of developing strategies to reduce the destructive force of these events.) 

We must also observe that two completely different measures of temperature are frequently conflated.  First, we have air temperature (or thermodynamic temperature) measured by a thermometer that it is in thermal equilibrium with its surroundings.  Second, there is the radiation temperature of a body, measured in terms of the quantum of radiation outgoing from the surface of this body.  In the second case, the body does not have to be in thermal equilibrium with the instrument of measurement. In fact, the instrument must be at a lower temperature in order to be able to register the radiation flux from the body. 

(Note: The dominant view in theoretical climatology at present still ignores the fact that any relatively dense atmosphere – i.e. with pressure exceeding 0.1 bar, as in the earth’s troposphere – is an energy storage system.  An example may be useful to indicate the scale of this storage.  An air layer 80 m thick contains, at pressure 1 bar, temperature 15°C and relative humidity 40%, roughly the same amount of energy as the earth, on average, receives in a 24 hour period from the sun, i.e. about 8.2 kWh/m² .  The whole of the earth’s troposphere thus contains roughly the amount of energy that the sun radiates into the earth/atmosphere system in 2.5-3 months.

Knowledge of thermodynamics is indispensable to understand the processes in such atmospheres.  The presently dominant view, however, is that the radiative transfer of energy essentially determines the processes and conditions within the atmosphere.  This ignores the real determinants of weather conditions, and thus on a larger timescale, of climate, namely processes of energy in- and output, as well the energy transfers that occur with mixing of air masses of different energetic conditions and other processes, viz. heating, cooling, evaporation, condensation, solidification, and changes in the volume of air and its optical depth in respect of light and thermal (infrared, longwave) radiation. 

The current literature of theoretical climatology betrays a pervasive lack of understanding of the principles and laws of thermodynamics, and of their correct application.  The present state of the field inhibits understanding of the drivers of climate and precludes meaningful prediction of future climate, regardless of how much computing power might be marshalled.) 

Thermodynamic temperature measures the state of thermodynamic systems such as the troposphere. If air temperature is known, and the pressure and humidity of the air is also known, then the enthalpy, or energy content, of the air can be determined.  It is important to note that cool air with a high moisture content may contain more energy (i.e. have a higher enthalpy) than dry air at a higher temperature.  For example, at typical near-surface air pressure, the enthalpy of air at 11°C with a relative humidity of 90% is almost equal to that of air at 26°C with a relative humidity of 10%.  Thus it would be wrong to draw conclusions about the enthalpy of air from a small rise in temperature: the rise may reflect either an increase in enthalpy or unchanged enthalpy combined with reduced moisture content.

We must also pay attention to diurnal and annual temperature variations.  A rise in daily averages (the usual point of comparison) can occur with falling daily maxima, if night minima rise by a larger amount.  The latter may occur, for example, if nights become more cloudy (see [6, 7]).  By the same token, if one looks only at annual averages, as is often done, one might conclude that for example Kuala Lumpur (tropical rain climate) and Zouerate/Mauretania (western Sahara, subtropical desert) have the same climate because they share the same average annual temperature of 26.2°C.


3. Is the mass of the atmosphere constant? 

Statements about the climate history of the earth always tacitly assume something that is by no means certain, namely that atmospheric mass has remained constant.  Since the troposphere is a thermodynamic system, the mass of the atmosphere, and in consequence the pressure in the troposphere, plays a dominant role in tropospheric energetic conditions and  temperature.  Atmospheric mass might therefore be the key variable affecting temperature over geologic time scales.  The influence of atmospheric mass on near-surface temperature arises from the fact that a substantial share of the energy of the earth/atmosphere system exits to space by radiation from the upper levels of the atmosphere (not from the earth’s surface), thus influencing the temperature at high altitude (see figure).

The temperature gradient (the decrease of temperature with height by about 7 K per 1000m in humid air, and 10 K every 1000m in dry air) is caused by the pressure decrease and by the thermodynamic characteristics of air and its humidity.  The thicker the tropospheric thermodynamic system is, the greater will be the distance between the surface and the radiation zone at the top, and the warmer it will be near the bottom of the troposphere - and vice versa.

If the atmosphere had a different thickness at other times during earth’s history, this would already be part of the explanation for temperature and climatic differences.  We might also note in passing that a thicker atmosphere would also increase the vigour of global energy exchange processes (by mass exchange, wind, storms) through increased circulation (larger transportation mass, lower flow resistance for transported air). 

It is obviously not at all clear whether mean atmospheric pressure, currently 1013.5 millibars at sea level, was always thus.  Nevertheless some observations suggest a slight increase in atmospheric mass over the last 20 years, with a rise in mean atmospheric pressure of about 2 millibars at some measuring stations.  Santer et al. report in [8] that between 1979 and 1999 the height of the tropopause (the boundary between the troposphere and the stratosphere)
increased by roughly 100-200 m. 

At present we lack knowledge of whether and to what extent atmospheric mass does or could fluctuate.  If atmospheric mass decreased by just 10%, so that pressure at sea level fell to what it now is at 1000 m, then we could expect corresponding decreases in sea level temperatures, possibly exacerbated by feedback effects.  A loss of atmospheric mass on this scale would quite be sufficient to produce ice ages; the converse could produce warming of comparable magnitude.

Clues to changes in atmospheric mass may be difficult to find, because the main components of the atmosphere, nitrogen and oxygen, are abundant as dissolved gas or in chemical compounds in water, and in solid form in the earth's crust.  Thus, slight variations in the transfers of matter between the atmosphere and the land or ocean surface would probably be barely detectable.


4. Does water content affect the atmosphere? 

The CO2 content of air (well under 1 part per thousand), represents an insignificant share of atmospheric mass.  By contrast, the water content of air probably is significant, even though its upper limit is fixed by the finite capacity of air to absorb water.  And human activities - agriculture and forestry, irrigation and other water-use projects, technological and energy-generation activities, even the waste products of human and animal life - may well be affecting the water cycle.  Observations, especially in Germany [9,10] already suggest a recent rise in  the water content of the atmosphere, both as humidity and precipitation. 

Nor must we forget the substantial input of humidity into the troposphere from the production of human food.  For example the average daily food intake of an exclusively vegetarian person is about 2000 kcal (equal to about 2.3 kWh) of grown biomass.  If one assumes that this food production represents plant growth additional to natural output, then it would add 90 m3  of water to the atmosphere annually (basics for this: [11] and [12]).  The current world population of 6 billion people would thus be continuously humidifying the atmosphere with about 17,000 m3 water per second; roughly eight times the mean flow of the Rhine into the North Sea.  The extent to which we eat animals themselves fed on agricultural products further increases the humidification rate (although seafood consumption does not). 

Still more water enters the troposphere from plants grown as raw materials (e.g. timber, cotton).  Some idea of the scale of this humidification can be grasped from the amount of water used to raise cotton around the Aral Sea.  So much water was taken for irrigation that the Aral Sea has largely dried up [13]. 

One can roughly estimate the present increase in the rate of water transport to the troposphere from enhanced plant growth at the equivalent of the discharge of the Amazon, or 50 times that of the Rhine.  Moreover, since vegetation changes alter the albedo of earth’s surface ("...vegetation is darker than a bare surface...", see [14]), the intensification of agriculture and forestry constitutes a further human influence on weather and climate.

By comparison, atmospheric humidification by other human activities such as respiration, burning of fossil fuel, cattle-breeding (except feed) and industrial processes (including wet cooling towers) is relatively small, perhaps in total rivalling “only” the water discharge of the Rhine. 

The total of anthropogenic humidification of the troposphere would amount to about 1% of the natural flow.  It is to be noted, however, that this additional humidification occurs only over the 10% or so of the earth's surface that is settled and managed, so that in these regions the additional humidification may increase the background rate by about 10%.  It is in just these areas that most meteorological stations are to be found, and it is these that will register any effects of increased humidity.  Note also that most settled and managed land is in the northern hemisphere, so the effects should be clearer there. 

Still more humidity would enter the troposphere if energy production were to rely more heavily on the combustion of specially grown biomass.  Producing one kWh of fuel energy from biomass would involve adding 100 l water to the atmosphere.  This is 1000 times the roughly 0.1l of water released by burning natural gas to liberate the same amount of fuel energy.   To return to our rivers, covering 10% of current annual world energy requirements from additionally produced biomass would imply increased humidification equivalent to 15 times the mean flow rate of the Rhine, or 30% of that of the Amazon.

Of course tropospheric humidity is soon discharged via clouds and then rain.  (The fact that cloudiness substantially influences the energy in and from the troposphere was among the points discussed in detail by Raschke and Quante [15].)  If however the land surface becomes wetter through increased precipitation, evaporation will again rise (since no water can evaporate from dry surfaces), tending to prolong the increased humidification of the atmosphere. 

All in all, it seems quite plausible that anthropogenically increased humidification of the atmosphere is already taking place, and that it may be having definite meteorological effects. An analogy may be sought in thermal power station processes, which show many similarities with tropospheric processes.  For example, the open gas turbine system (Cheng Cycle or similar modifications) that includes humidification of the hot gaseous stream with a simultaneous increase in fuel supply, offers increased dynamics and performance relative to comparable non-humidified processes [16].  This suggests more powerful dynamics and thus higher wind velocities in a damper troposphere.  Precipitation may also increase. 


5. Improving understanding and avoiding hasty decisions 

Clarifying whether and to what extent additional humidification of the atmosphere might affect climate in the biosphere is a worthy task for qualified experts and impartial scientists.  And other points also need clarifying, including the extent to which humans are affecting the nitrogen and oxygen cycles, e.g. via biological processes (agriculture) and - for nitrogen - also by burning fossil and biomass fuels.  Particular attention should be paid to the possible role of such activities in increasing the amount of these gases in the atmosphere, and thus raising total atmospheric mass.  It seems unlikely that fast buffer mechanisms are operating to rapidly return the released gases in solid form to the earth’s crust or the oceans.

Thus, among the most important questions about future climate and man’s possible influence on it are:  Has the mass of the atmosphere changed over geological time?  If so, what were the causes?  Is the current mass of the atmosphere mere happenstance?  Are our current activities changing atmospheric mass?  Are there reactions that stabilize atmospheric mass at its current value?  If so, what are they?  Which effects does the humidification of the atmosphere have? 

Precautionary measures to ensure the continued existence of man and nature, including guarding against threats to climate, require a clear, comprehensive and firmly established scientific basis.  The questions posed highlight the need to investigate and estimate the influence of the presence on earth of more than 6 billion people on atmospheric mass and humidification.

At a minimum, no environment protection policy should promote hasty adoption of methods of energy generation such as specially cultivated biomass that quite possibly cause avoidable disruption of the troposphere.

The present almost total neglect of the interactions sketched in this paper, despite substantial expenditure on climate research, suggests the need for substantial reform. To achieve useful results, climate research needs to broaden its basis of expertise, to involve both unbiased and objective meteorologists and climatologists, and experts in the relevant natural sciences, especially biology, chemistry and thermodynamics.



[1] Leroux, M., „Global Warming“: mythe ou réalité, Annales de Géographie, No. 624, 2002 

[2] Thieme, H., Greenhouse Gas Hypothesis Violates Fundamentals of Physics,  

[3] Thieme, H., On the Phenomenon of Atmospheric Backradiation,

[4] Hug, H., Der CO2-Effekt oder die Spur der Spur, Chemische Rundschau, No. 15, 2002 

[5] IPCC 1990, Climate Change, The IPCC Scientific Assessment, p. 49 

[6] Lehmann, A., Die Säkulare Klimareihe von Potsdam, DWD, Klimastatusbericht 2001, p. 232 

[7] Fricke, W., Kronier, M., Betrachtungen zum Klimawandel am Hohenpeißenberg, DWD, Klimastatusbericht 2001, p. 253 

[8] Santer, B. D., Contributions of Anthropogenic and Natural Forcing to Recent Tropopause Height Changes, SCIENCE, Vol. 301, 2003, p. 479-483

[9] Wasserdampf ist Treibhausgas Nr. 1, Pressemitteilung, Forschungszentrum Jülich, Mai 2001 

[10] Leiterer, U. u.a., Aerologischer Schichtaufbau der Atmosphäre und Trends über Lindenberg, DWD, Klimastatusbericht 2000 

[11] Hartmann, H., Zukunft der biogenen Festbrennstoffe: Holz oder Halmgut, BWK 47(1995) No. 6


[13] Diercke Weltatlas, 5. aktualisierte Auflage 2002, p. 155 

[14] Claussen, M., Die Rolle der Vegetation im Klimasystem, promet, Jg. 29, 2003, No. 1-4, p. 80-89

[15] Raschke, E., Quante, M., Wolken und Klima, promet, Jg.28 (2002), Nr. 3 / 4, p. 95-107 

[16] van Liere, J., Meijer, C.G., Laagland, G.H.M., Power Augmentation and NOx Reduction of Gas Turbines by SwirlFlash® Over Spray,  VGB PowerTech, 2/2002, p. 51-54

On the remarkable parallels between eugenics and global warming as ideological constructs, see Richard S. Lindzen, "Science and Politics: Global Warming and Eugenics", at 

Doubts about the estimation that the preindustrial CO2-level would have been at 0,028%, at present it is about 0,038%, arose in recent publications: 

A shorter version of this paper appeared as "Wodurch könnte der Mensch das Wetter und damit das Klima beeinflussen?", published in Fusion 3/2002 

This page first published 01.03.2003. Translation revised by S. Scott July 2003. This page was transferred to the present address on 26.07.2009

Author and Copyright: Dipl.-Ing. Heinz Thieme, Kaarst, Germany 

The author is co-author and belongs to the initial signers of the Climate Declaration of Heiligenroth 

The author is not responsible for any content contained in linked external web sites.


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