IPCC's Most Essential Model Errors
by Peter Dietze
This paper, been prepared for the SEPP 2nd TAR draft review workshop on May 28-29 2000 and the meeting in the U.S. Capitol, Washington D.C. on May 30, focuses on IPCC's three most essential modelling and core parameter errors. The impacts on all modelling results would be so tremendous that if the TAR would be corrected for these errors, there would hardly be any more justification for it. So this paper addresses only few individual TAR fallacies, but focuses on the nondisclosed flawed science it is based on.
Taking into account the impact of solar variability on global warming, best fit studies have revealed that solar forcing is amplified by at least a factor 4. By leaving out this 'Svensmark factor' and using an exaggerated aerosol cooling, IPCC maintains a CO2 doubling sensitivity of 2.5 °C that is about a factor 3 too high.
Our global Carbon Cycle Model reveals a half-life time of only 38 years for any CO2 excess. With present constant global CO2 emission until 2100, the temperature would only further increase by 0.15 °C. Scenario IS92a would end up with 571 ppm only. IPCC assumed that far more fossil reserves would be burnt than being available. Using a flawed eddy diffusion ocean model, the IPCC has grossly underestimated the future oceanic CO2 uptake. Hardly coping with biomass response, limited fossil reserves and using a factor 4 temperature sensitivity, all this leads to an IPCC exaggeration factor of about 6 in yr 2100. The usable fossil reserves of 1300 GtC burnt by 2090, merely cause 548 ppm – not even a doubling. The WRE 650, 750 and 1000 ppm scenarios, projected until 2300, are infeasible. Emission reduction is absolutely useless: the realistic temperature effect of Kyoto till 2050 will be only 0.02 °C.
The additional IR absorption (being evaluated here for CO2 doubling) is the energy source for global warming. HITRAN transmission spectra – the fringes being by no means saturated yet – can be used to compute this absorption, mostly occurring near ground. A simple radiative energy equilibrium model of the troposphere yields an IPCC-conforming radiative forcing which is here defined as the additional energy re-radiated to ground. Coping with water vapor overlap on the low frequency side of the 15 µm band, the clear sky CO2 forcing is considerably reduced to 1.9 W/m². With vapor feedback and for cloudy sky the equilibrium ground warming will be about 0.4 to 0.6 °C only – a factor 4 to 6 less than IPCC's 'best guess' for CO2 doubling.
1. Solar impacts
The Svensmark factor being estimated in this paper, represents the amplification of global temperature changes in comparison to measured changes in direct solar radiative forcing. According to an observation-based hypothesis, the reason for this factor is that the intensity of cosmic rays which increase the cloud coverage, is strongly suppressed by solar activity (solar wind) [H. Svensmark and E. Friis-Christensen, J. Atmos. Solar-Terrestrial Phys. 59, 1225, (1997)].
A best fit climate simulation, minimizing root-mean-square errors and using variable stretch factors for increasing solar and decreasing CO2 sensitivity, was presented by Eric Posmentier, Willie Soon and Sallie Baliunas [Global Warming – the continuing debate, ESEF (1998)]. Fig. 1.1 shows the observed global temperature change (11-year running mean), the best fit for GHG alone, the best fit for solar alone and the best fit for a combination of GHG with solar. Though the temperature correlation with GHG alone is very poor, GHGs are used as base for IPCC's climate change modelling. The correlation is much better with solar alone, but becomes excellent with a proper combination of both. The fractions for the best combination, yielding an explained variance of 92 %, are shown in Fig. 1.2.
Remarkable is that Tom Wigley and P.M. Kelly published in "Solar cycle length, greenhouse forcing and global climate" [Nature 360, 328-330 (1992)] that simple energy balance models fit best to the observed data if it is assumed that there is only a solar impact. But the authors rejected this because the climate sensitivity to radiative forcing that was necessary to be assumed for this, would have yielded unrealistic (low) effects for the CO2 forcing "..given the well established case for its existence". This reasoning is of sensational logic. It reveals that IPCC (otherwise always keenly interpreting correlations) has committed a scandalous error in omitting a visually good correlation in favour of a visually bad one. To neglect greenhouse forcing, was not at all the question – this should indeed be considered as unscientifical as neglecting solar forcing effects.
So IPCC, so far only coping with a 12% solar fraction [direct solar forcing, see TAR Technical Summary Fig. 8] had to match for the missing strong part of the solar signal in the observed temperatures by using an exaggerated CO2 sensitivity in combination with "internal variability" and a properly adapted far too high aerosol cooling.
Fig. 1.1: Best fit climate simulations (E. Posmentier, W. Soon and S. Baliunas 1998)
Fig. 1.2 reveals that 57% of the warming for the last century has to be allocated to solar whereas only 43% to GHGs (of which about 60 %, i.e. 0.18 °C, is to CO2 – recently found essential warming by soot and cooling by sea salt aerosols not yet considered). Whereas the best fit sensitivity is 1.8 °C for CO2 doubling (alone), it is 0.8 °C in proper combination with solar forcing – these figures denoting the equilibrium sensitivity which is by a factor three less than IPCC's. The transient figure for CO2 doubling alone is about 1.3°C.
Fig. 1.2: Optimal fractions for combination of forcings
Eric Posmentier et al. have not applied corrections for aerosols – but as they considered the temperature increment to be even more than 0.7°C instead of 0.5°C, we can accept the result. Compare with Fig. 8.4c in [SAR, IPCC (1996)] and Fig. 1.3 (see CCCMA Canada) where the CO2 sensitivity and aerosol impact is far too high, but the parameters being adjusted to compensate for a far too small solar impact – the same as in the IPCC Tar (Fig. 1.4). Details about the estimation of realistic sensitivity parameters see in my paper Estimation of the solar fraction and Svensmark factor.
Fig. 1.3: CCCMA simulation (G. Flato, G. Boer et al. 1997)
If we compare Fig. 1.3 and 1.4b with Fig. 1.2, it is striking that for the interval between 1925 and 1970 when the solar warming was high, IPCC models simulate a too low temperature and vice versa around 1900. The "good match" beyond 1975 that IPCC emphasizes upon, does by no means prove that the models are ok – the match is a mere artifact, caused by a compensation between flawed solar, CO2 and aerosol sensitivity parameters.
Fig. 1.4a reveals that IPCC erroneously assumes a natural cooling after 1963 without GHGs (thus the GHG warming being boosted). But in fact the solar activity was increasing (see Fig. 1.2) which rather reduces GHG warming.
Fig. 1.4: IPCC TAR-SPM Fig. 3 a) using primary solar and volcanic b) using GHGs and aerosols
How "useful" aerosols are to obtain any required temperature curve – even when solar changes are left out, which should result in gross mismatches – is shown in Fig. 1.5 [Meteorol. Zeitschr. 7, 171-180 (Aug 1998)].
Fig. 1.5: Questionable statistic aerosol climate simulation (C-D. Schoenwiese et al., 1998)
The same procedures are found with Tom Wigley [Pew Center climate study 1999, p. 15]. In Fig. 1.6 the far too high warming by CO2 in yr 2000 is cancelled out to 63 % (!) by aerosols – the solar warming added, is flawed 21 % only. If IPCC believes in such an essential aerosol cooling and being so concerned about the warming problem from CO2, it logically follows that more SO2 would be the solution. So they could simply ask EPA to stop SO2 emission restrictions and permission trading in US. Kyoto could then be cancelled – the problem would mostly solve without economic impact, and billions of dollars could be saved.
Fig. 1.6: Pew Study: aerosols compensate for 63 % of the exaggerated CO2 warming (T. Wigley, 1999)
2. Carbon Cycle
One of the main reasons for an assumed future CO2 disaster has been IPCC's assumption that this greenhouse gas is accumulating in the atmosphere – leading to the frequently repeated 60% Toronto reduction demand.
But it is known that the oceans contain about 50 times more carbon than the atmosphere, but may dynamically take up only about 6 times more CO2 at equilibrium. The photosynthesis of land biota may increase by up to 18 Gt C/yr for a concentration doubling, i.e. three times today's fossil emission. At present, the oceans are still mostly on a pre-industrial level.
The IPCC's accumulation hypothesis needs to be firmly contradicted. Supposed we pour water into a bucket that has a hole. Nobody will state from observation that "about half accumulates in the bucket". This fully depends on the hole, the water level and how much water we are pouring.
The problem is easily solved when the global carbon cycle is understood as a dynamic system in the manner of control engineering. The atmosphere has a CO2 decay function with a half-life time of about 38 years as will be shown in the following. If the input function is doubling within the same time span the system response would simply be a linear concentration increase. The increase was misunderstood by IPCC as a nearly irreversible accumulation – one reason that led to hasty conclusions for negotiating an unnecessary global reduction treaty.
A simple waterbox model can be used to explain the atmospheric CO2 excess lifetime and to find a plausible value (Fig. 2.1). The atmosphere is represented by a waterbox, filled up to a level of 350 ppm (in 1988) with 743 Gt carbon (2724 Gt CO2 ). This box is placed in a larger waterbox, representing the ocean.
Fig. 2.1: Waterbox model for the excess CO2 lifetime
The atmosphere box has an outlet, releasing about 2.7 GtC/yr into the ocean. The level decreases according to an e-function if we postulate the transition flow is roughly proportional to the water level difference or pressure. The lifetime T can be defined as the time lapse until the level goes down to 1/e (37%) against the equilibrium. The value for T can be calculated dividing the amount of present excess by the present outflow, yielding 55 years:
T = (148 Gt + 33%) / (2.7 Gt/yr + 33%) = 55 yr
The 33% stands approximately for extra-atmospheric buffers (fast rotting biomass, surface water and soil moisture) and extra-oceanic sinks (e.g. trees, polar ice) respectively. For the time interval considered, the small ocean response and the long time for distribution can be neglected.
Multiplication of T by ln(2) yields a half-life time of about 38 years. So any CO2 impulse injected into the atmosphere will take about 38 years to be reduced to half the original value – the contribution to the increment in atmospheric CO2 concentration being considered. If we consider the individual CO2 molecules of the injected fossil impulse, half of them would already disappear within 3 years as the turnover time (the time natural fluxes take to exchange the atmospheric CO2 content) is about 6 years. Btw the latter is clearly proved by the fact that carbon isotope measurements show that the present atmospheric fraction of fossil CO2 is not 30 % but only 4-5 %. This fact, yet not being admitted by IPCC [isotopes discussed in SAR p. 78f], indicates that the atmospheric CO2 has been mixing during the last century with reservoirs that are about 5-6 times larger and thus the content of fossil CO2 has been thinned out.
Lacking a proper carbon model and ignoring the fact that the CO2 lifetime is closely related to sink flows, greenhouse scientists have arbitrarily manipulated this key parameter in the past, stating that no definite value exists or can be defined. The IPCC SAR said it is "variable" and IPCC used a nonlinear CO2 impulse response function [figure in SAR on p. 86] for the convolution integral, which is not permissible. In Fig. 2.1, some of the CO2 lifetime values are shown that have been used. In 1987 the e-fold time was assumed to be 400 years in Germany (e.g. H. Grassl, E. Maier-Reimer, W. Bach). In 1989 Grassl published 100 years and by 1995 it was 50 to 200 years. Though the IPCC mentioned 100 and 120 years, their scenarios mostly used about 360 years for stabilization. At the very low end of reported CO2 lifetimes we sometimes find a value of about 5 years, which is not the lifetime, but the turnover time.
H. Grassl stated, a single lifetime value cannot be defined because of different sinks. This doesn't hold up. Suppose, the atmosphere box in Fig. 2.1 has three different outlets representing small, medium and large lifetimes. The resulting value is equal to the sum of stored carbon excess, divided by the sum of sink flows. So the resulting lifetime for parallel sinks is
T = 1 / ( 1/T1 + 1/T2 + 1/T3 )
IPCC's 120 years had been erroneously derived from an arithmetic mean of different sinks of the Bern model. But the smallest T (largest sink) is leading and a small additional sink flow (large T) which would considerably increase the mean value of T, is indeed decreasing the resulting lifetime.
IPCC's eddy diffusion ocean model (H. Oeschger, U. Siegenthaler, F. Joos, J. Sarmiento) is illogical in assuming that a part of a CO2 impulse will be absorbed straight away, another part fast at the beginning and then slowing considerably (at the end e.g. to 360 years) and the rest, about 16%, to remain forever in the air. CO2 impulses are continuously injected into the atmosphere and nature should treat them all equally as it cannot distinguish between 'old' CO2 to be absorbed slowly and 'new' CO2 to be absorbed fast. Thus the half-life time of 38 years has to be considered as an operational overall value from observed sink flows at present conditions, assuming the reservoirs are big enough and the system behaves in a roughly linear/proportional manner within the operating regime.
Fig. 2.2: Electrical dynamic
CO2 model scheme (J. Goudriaan
1999 at daly/co2debat.htm)
explaining a 150 yr lifetime. Capacitors are Cs: sinks, Ca: atmosphere and Cb: buffer
A simplified linear carbon model scheme has been presented by J. Goudriaan as an electrical circuit (Fig. 2.2). It helps to explain essential flaws in IPCC's carbon model parameters, e.g. a CO2 lifetime of 150 yr and unduely coping with the fossil emissions part only. If we consider Cs rather as infinite and add up the buffer Cb and atmosphere Ca as C, we get the CO2 lifetime as T = R*C = 50 ppm/Gt * yr * (2.1+0.9) Gt/ppm = 150 yr. One reason for this high value: the buffer is quite large (43% of the atmosphere). So 30% of the (fossil only) emission, i.e. 1.5 GtC/yr, disappears straight away into the buffer, erroneously considered as to be a sink. So the remaining sink flow becomes 1.2 GtC/yr only instead of the 3.6 what it really should be (see Fig. 2.1). 1.2 GtC/yr is indeed far too small for the ocean and biomass together. This is why the modelled CO2 lifetime T is nearly trebled.
To develop a realistic dynamic global Carbon Cycle Model, the waterbox model was extended, Fig. 2.3 showing the transient state in 1988 containing no missing sinks. Net photosynthesis of land biota amounts to about 60 Gt C/yr, marine photosynthesis is roughly 20 Gt C/yr. The three upper boxes represent the land biota (650 Gt C), the atmosphere (743 Gt C) and the mixed ocean layer (800 Gt C) which is closely coupled with the atmosphere by precipitation and gas diffusion and exchanging about 100 Gt C/yr with the atmosphere. In high latitudes the icy cold salt water absorbs large amounts of CO2 . This makes the essential part of the net uptake (eddy diffusion as with IPCC is indeed a minor part), the CO2 being taken into the deep sea and mixing via the conveyor belt into all oceans. The central link is the Antarctic Circumpolar Current. In warm upwelling regions, especially where off-land trade winds are pulling up cold deep sea water, we observe an outgassing of uptaken CO2 – the time delay being about 400 to 1000 years.
Fig. 2.3: Extended waterbox model with proportional sink flows (numbers in GtC and GtC/yr for 1988)
Our sink flow approach does not use IPCC's unrealistic eddy diffusion model which leads to extremely small future uptake but we use the basic diffusional mass transfer theory that can easily be quantified by numerical-statistical treatment of well-known recent data (compare the carbon model of Jarl Ahlbeck). Given a high exchange rate with big reservoirs, 95 % of the sink flows from anthropogenic perturbation (so Ahlbeck) tend to be proportional to the concentration increment against the equilibrium state. For the system's differential equation (box), being linearized around the present operating regime, the concentration increment in ppm can be calculated with a convolution integral for the system being subjected to an arbitrary total emission E(t) given in GtC/yr.
Here 0.354 = 1/(2.123*1.33) is the conversion factor from GtC to ppm. For each 100 ppm the total buffer excess C is 100/0.354 = 282 GtC, 212 GtC hereof being buffered in the atmosphere and 70 GtC in surface water, soil moisture and fast-rotting biomass. We will first consider a constant emission scenario to demonstrate the model characteristics. For this case we get Dp = 0.354 E*T*(1-e-t/T) ppm. Setting the total emission to be E=7 Gt/yr and T=55 yr, the concentration will increase by 136 ppm for large t (Fig. 2.4).
The emission and concentration start with the preindustrial equilibrium to perform a clean cold-start. To match the actual concentration of 350 ppm in 1988 (with a sink flow of 3.6 Gt), the constant emission of 7 GtC/yr is started here in 1948. The concentration increases according to curve (a) as an e-function with a T value of 55 years. The right hand vertical axis shows the model's proportional sink flow reaching 7 Gt at a maximum concentration of no more than 416 ppm.
Fig. 2.4: Concentration
response and equilibrium temperature for
a) constant emission, b) after reduction to 50% in 1988 and c) after stopping emission
At the start the airborne fraction is 75%, which soon reduces to 36% in 1988 and to 20% in 2020. The temperature scale shows an equilibrium increment of only 0.32 K till yr 2100. After 1988 it is merely 0.15 °C which shows that reduction claims are indeed unnecessary. Here the equilibrium temperature increment is based on a (logarithmic) doubling sensitivity of 0.6 K, i.e. a quarter of IPCC's.
The dashed line at the upper part of curve (a) is a hypothetical ocean equilibrium reaction for ideal mixing after taking up nearly six times more CO2 than the atmosphere, caused by the Revelle buffer factor (50/9 = 5.6). But in fact this ocean response can be neglected as it will be mostly delayed by several hundred years. The straight cumulation line shows how the IPCC airborne fraction of about 50% would yield an increase up to 530 ppm – an 80 % higher increment than in reality. IPCC actually assumes about 500 ppm for this case.
Fig. 2.4 presents two further scenarios. Curve (b) shows the response after reduction to 50 % emission beyond 1988. As this amount equals the actual sink flows, concentration and temperature remain quite constant. The increment from start is then only 0.2 K and not 2 K (!) as has been assumed in early IPCC scenarios even claiming a reduction by 60% until 2050, and as formerly documented in the Greenpeace Report [J. Legget (edt.), Oxford Univ. Press NY (1990)]. Curve (c) shows a hypothetical stop of emissions in 1988. The concentration decays according to the e-fold lifetime of 55 years, the oceans and biomass absorbing most of the CO2 excess within 120 years.
Discussing the effect of a carbon and energy tax in Europe, an emission reduction of 4 to 5% has been estimated – this means 0.7% worldwide. The EU contribution for temperature reduction would be 0.7% of 0.32 = 0.002 °C only. But the projected taxation would be about US$ 660 billion within 12 years. This seems absurd as the effect is absolutely unnoticible.
According to a suggestion of J. Goudriaan a numerical model test for total emissions during the industrialization era till 1995 was carried out, using CDIAC data after 1970. In Fig. 2.5 the convolution integral was sequentially solved by Excel in 5 yr interval steps and a good replication of the Mauna Loa curve was obtained – i.e. a concentration of 368 ppm for the interval around yr 2000.
Fig. 2.5: Model test with total emissions until 1995 and further acc. to IS92a
After 1995 emissions were applied according to the business as usual scenario IS92a with piecewise linear increments up to 20.3 GtC/yr in 2100. The concentration increases rather linear to only 571 ppm whereas IPCC's climbs to 700 ppm in yr 2100. The IPCC curve (being parabolic) has been approximated here by simply using a 47% airborne fraction.
Our model properly reproduces the observed rather linear CO2 increment in spite of a linear increase of emission – which (according to IPCC's flawed accumulation hypothesis) should result in a quadratic or exponential increment. Most interesting is the behaviour of the airborne fraction f, here being defined as the ratio of the atmospheric increment and the total emission (i.e. not only fossil). At the beginning f is 1/1.33 = 75 % (see Fig. 2.1). For 1995 f is reduced to 35.3 % and in 2100 f becomes 19.8 %. IPCC models mostly yield an airborne fraction of roughly 50 % that results in a far too high future CO2 concentration – for yr 2100 the increment is 50 % too high with IS92a.
IPCC mostly uses an exponential increment of 1 %/yr for modelling i.e. doubling of forcing occurs within 70 yr, though the TAR Technical summary (on p. 12) says that the presently observed rate of CO2 increment is 0.4 %. For IS92a IPCC's CO2 increment is 0.62 %/yr. How unrealistic a 1 %/yr CO2 increment is, can be demonstrated as follows: With our model airborne fraction being 35 % in 1998, a total emission of 22 GtC/yr would be required for a 1 % increment, whereas it was actually only about 8.3 GtC. Debating the 1 %/yr assumption with David Schimel per email, he emphasized that IPCC only carries out case studies, mostly to test their models. The consequence is that IPCC results cannot be interpreted as to be realistic future projections and thus should not be (mis)used for political decisions.
The usable fossil fuels (secured coal reserves, 4-fold gas and 3-fold oil being assumed because of exploration and improved extraction) are estimated to be about 1300 GtC. With IS92a, this amount will be depleted until 2090. The CO2 concentration at that time only reaches 548 ppm which is even less than doubling. IPCC's CO2 increment to 700 ppm is by a factor 1.6 higher. Then, taking about four times the realistic temperature sensitivity, IPCC has boosted the yr 2100 climate impact by about a factor of 6.
The 650, 750 and 1000 ppm WRE stabilization scenarios shown in Fig. 26 and 27 of the 2nd TAR draft, are definitely infeasible. Until yr 2300 WRE 1000 would require about 3300 GtC, i.e. 2.5 times more than available. IPCC obviously has only created new scenarios but neither changed their carbon modelling nor coped with limited fuel reserves. Their stabilization emission for 550 ppm remains 2 GtC/yr only (equal to the sink flow). As in our model the total CO2 excess for atmosphere and buffer is 784 GtC, the sink flow acc. to the 1/e lifetime should be 784/55 = 14 (!) GtC/yr – IPCC's is by a factor 7 smaller.
See as well the papers Little Warming with new Global Carbon Cycle Model and discussion and the German paper Der Klima-Flop des IPCC.
3. Radiative Forcing
The radiative forcing caused by a prescribed doubling of the pre-industrial (or present or any) CO2 concentration is the imbalance in the Earth's radiation budget that is supposed to cause global warming. More CO2 means more absorption of the infrared (IR) re-radiation which the Earth emits to space to compensate for the solar short wave irradiation. To restore the radiative equilibrium between warming and cooling, the average 15 °C ground which sends most of the thermal black body Planck emission directly to space, has to warm up slightly until the withheld energy – i.e. in our definition the increased back-radiation – is re-emitted.
The IPCC used the following definition, focusing on tropopause level conditions:
"The radiative forcing of the surface-troposphere system (due to a change, for example, in greenhouse gas concentration) is the change in net (solar plus longwave irradiance) in W/m² at the tropopause AFTER allowing the stratospheric temperatures to re-adjust to radiative equilibrium, but with surface and tropospheric temperature and state held fixed at the unperturbed values".
The often quoted additional absorption for CO2 doubling within the troposphere is not the forcing itself, as formerly often (mis)understood by non-specialists, but it is the source of the (thermal) re-emission to ground which is based on the atmospheric energy equilibrium. This means, the re-emission at tropopause level plus the re-emission to ground (which causes the warming) is equal to the additionally absorbed energy.
Using HITRAN-1996 CO2 transmission spectra from Jack Barrett, an Excel diagram (Fig. 3.1) was prepared for a range of 300 cm^-1 and 560 intervals. It shows the transmission, i.e. the intensity ratio T=I/Io of an IR beam travelling from ground to the top of the troposphere, which would be a layer of 6800 m for ground pressure. T depends strongly on the wavenumber per cm (for example 15 µm means a wavenumber of 1/15*10^4=667/cm).
The data from HITRAN (high resolution transmission molecular absorption database by L.S. Rothman et al.) are extinctions E=-log(T) (or line intensities, linestrengths) given per CO2 molecule for each individual peak wavenumber. The resolution is extremely precise, about 0.0005 cm^-1. To cope with the optical density, the molecular extinction is multiplied by the number of molecules (the troposphere contains about 4.1 kg CO2/m²). HITRAN integrates the linestrengths for each interval, coping with the peak shape, pressure and temperature dependency – but the fact that nitrogen is not neutral with respect to the CO2 IR absorption which may be doubled, is omitted by HITRAN [H. Hug, CHEMKON 7, 6-14 (Jan 2000)].
The absorption is A=1-T. The residual area in Fig. 3.1 (difference between the yellow 1*CO2 and green 2*CO2 spectra) is the CO2 doubling absorption. Integrated to 16.8 cm^-1, this is 6.4 W/m² when multiplied with a medium Planck radiation of 0.38 W/m²/cm^-1 for 288 K in the range around 15 µm. The total absorption for 1*CO2 amounts to 74 W/m². Whether and how much N2 may effect the CO2 residuals, is not yet cleared.
This absorbed energy depends very little on the layer thickness (optical density) and is thus not at all sensitive to the accuracy of absorption within the troposphere (which was here simply powered up according to the Lambert-Beer law, based on a 139 m equivalent probe, to show the layer characteristics). Let us assume the residual absorption for CO2 doubling to be 7.4 W/m² in total, coping with the missing part of the yellow and green spectra at the left and right side of the diagram – here considering as well the missing hot bands around 960 und 1064 cm^-1.
Fig. 3.1: HITRAN transmission diagram based on data for 5% CO2 and 100 cm at ground pressure
The absorbed radiation is mostly thermalized and dissipated (acc. to J. Barrett and H. Hug). In thermal equilibrium this energy is re-radiated by atmospheric components as CO2 (double density yields double emission for the same temperature) and partly by other GHGs – the latter only in case the temperature profile shifts, contradicting the IPCC definition. In this case convective and latent heat processes would become involved in additional vertical energy transport. All these have to end up in thermal re-emission at tropopause level, directed to both sides, space and ground. Whereas the lower atmosphere warms, the upper atmosphere is cooling (thus increasing the lapse rate) – here doubled CO2 takes over a part of the emission from the other GHGs.
As all re-emission has to be considered as being bidirectional, we can assume in first approximation that half the total re-emission goes to space and half goes to ground. So we yield the new (by 15% reduced) IPCC TAR forcing of 3.7 W/m², as shown in Fig. 3.2. But the emission depends on the 4th power of the absolute temperature. So if we assume the bulk radiation temperature near ground (500m) as 285 K and in the upper troposphere (5500m) as 255 K, the upper emission should be only 64%. On the other hand we find very little water vapor in the upper troposphere, whereas the vapor near ground considerably absorbs the CO2 emission. We have a mixture of up and down radiation, absorption and thermal re-emission, normally being evaluated using the Schwarzschild radiative transfer equation. Here we only consider the sum of re-radiation which is known. As the correct ratio of the two emissions cannot easily be determined, it seems reasonable to assume that the total emission is split about 1:1.
Important to mention that IPCC's forcing for clear sky conditions is meant for well mixed GHGs, i.e. without water vapor overlap [G. Myhre, J. Highwood, P. Shine, F. Stordal in Geophs. Res. Letters 25, 2715-2718 (July 15, 1998)]. IPCC argues that at tropopause level the water vapor density is negligible, which is true – but in reality the forcing stems from absorption and back-radiation within the lower troposphere near ground where we find the bulk of water vapor. As by vapor overlap here practically the low frequency part (i.e. about 50%) of the radiative forcing residual is cancelled (see below), we take 1.9 W/m² as radiative forcing (Fig. 3.2).
Fig. 3.2: Radiative fluxes and forcing for CO2 doubling, atmospheric thermal equilibrium model
Now the IPCC errors become very obvious. Using the former forcing of 4.3 W/m² for tropopause level, application of the differential form of the Stefan-Boltzmann law dT/T=1/4*dS/S, with S=240 W/m² and T=255 K, yielded a temperature increment of dT=1.14 K (which is now reduced to 0.98 K with 3.7 W/m²). The IPCC assumed that this increment that doesn't exist as the upper atmosphere is rather cooling, would be transmitted 1:1 down to the ground, based on a constant lapse rate. Because water vapor is a strong greenhouse gas, the IPCC then used a factor of 2.2 as the effect of water vapor feedback – neglecting that on the other hand vapor should also reduce the radiative CO2 forcing – and thus obtained a warming of 2.5 °C for CO2 doubling, the 'best guess' – so called by T. Wigley and S. Raper in a review paper [Nature 357, 293-300 (1992)]). D. Rind titled his article about the feedback approach "Just add Water Vapor" [Science 281, 1152 (21 Aug 1998)].
But as observations did not support the exaggerated warming, the IPCC assumed, the discrepancy was an effect of aerosol cooling while other effects (e.g. amplification of solar forcing) were considered to be insignificant. Their exaggerated aerosol cooling and the gain in parameter variability was ideal to maintain a far too high CO2 climate sensitivity, thus compensating for missing solar forcing amplification and any other model discrepancies, just as required.
Of course, the argument exists that the amount of near ground moisture will increase with warming, and water vapor is a strong greenhouse gas. This argument depends on IPCC's questionable assumptions of total transfer of an unrealistic upper troposphere warming to the lower atmosphere, and a strong water vapor feedback. But here we have to consider a feedback damping because the more IR is absorbed around 15 µm by water vapor, the less remains for CO2 to be absorbed in the same overlapping bands, and the water vapor absorbtion capability is mostly saturated in this region of the IR spectrum, though not in other parts. According to a mean ratio of 1.34 between clear sky and cloudy sky forcing [Tab.1 and Tab.2 in G. Myhre et al. (1998), see above] we can adapt our forcing of 1.9 W/m² to 1.4 W/m² for cloudy sky condiditions. So at ground level and 288 K with 390 W/m², the radiative equilibrium warming of 0.35 K in Fig. 3.2 has to be modified to 0.26 K, any water vapor feedback not yet being included. We follow R. Lindzen who claims a considerably smaller feedback and we assume a factor of about 1.6 (half of IPCC's). The ground warming would increase to about 0.42 K, a factor six less than IPCC's climate sensitivity.
The solar fraction analysis sensitivity (see above) is by a factor three less than IPCC's 2.5 K. If we would assume a factor 2.2 for water vapor feedback, our doubling sensitivity would become 0.57 K, still 33% less than the solar fraction analysis figure. These values do not require an assumption of enforced aerosol cooling because they provide better agreement with observations than IPCC's 'best guess' sensitivity.
As most of the absorption for CO2 doubling occurs near ground – a doubling test for 139 m already yielded 6.5 W/m² (88% of 7.4 W/m²) – the water vapor overlap should mostly cancel the left residual (and btw. some fraction of the right one as well). H. Fischer has shown this in a graph of a position paper of the German Meteorological Society (DMG), which advocates the greenhouse effect. The "residuals" are the differences in transmission between 1*CO2 and 2*CO2 (Fig. 3.3). We can estimate the cm^-1 area of the right residual (the left was cancelled because the water vapor transmission is very small here) and multiply with the associated Planck radiation per cm^-1. The radiative clear sky forcing represented by this DMG residual is 1.7 W/m² only, of which 0.3 W/m² stems from the hot band around 960 cm^-1. So our 1.9 W/m² forcing in Fig. 3.2 is likely. H. Fischer used HITRAN data and apart from water vapor overlap he coped with other greenhouse gases and with thermal CO2 emission depending on atmosphere temperatures.
Fig. 3.3: German DMG residual (H. Fischer, IMK Karlsruhe 1999)
IPCC authors so far refused to disclose details about the modelling assumptions and computation of their core parameter, demanding us to believe in their results – which is an unprecedented offence against rules in public funded science, and the TAR again follows this line. A graph about radiative forcing of the 1994 IPCC report is shown in Fig. 3.4. As the left residual is not cancelled, here obviously water vapor overlap has hardly been considered, contrary to the statement in the note on p.174 and the approach of H. Fischer. Each residual area in W/m² from net irradiance at tropopause level roughly matches the one in Fig. 3.3 when logarithmically adapted to CO2 doubling, though IPCC claims having even coped with cloud effects. R.D. Cess et al. state in "Uncertainies in CO2 Radiative Forcing in Atmospheric GCMs" [Science 262, 1252 (19 Nov 1993)] "The forcing is substantially reduced through radiative overlap of the CO2 absorption bands by the absorption of water vapor" and "Clouds also reduce the forcing".
Surprisingly the IPCC residuals (Fig. 3.4c) come together at 15 µm, whereas in Fig. 3.3 they would be about 70 cm^-1 apart from each other. The IPCC residuals were calculated with radiative transfer equations, using the standard narrow band code of P. Shine 1991 – both not been published by IPCC and obviously available within the 'community' only. Residuals show a broad gap inbetween when only absorption is considered. Coping with thermal emission, they are shifted towards the 15 µm center – the more, if only a fractional layer (e.g. upper troposphere) is evaluated. Their area (which is important) only changes little. More details see at Estimation of the Radiative Forcing for CO2 doubling and discussion.
Fig. 3.4: IPCC 1994 p.175 radiative forcing figure 4.1
In Fig. 3.4a IPCC did not correctly model the emission characteristic to be seen in satellite measurements (Fig. 3.5) which does not show a zero emission at the bottom of the funnel around 15 µm, but a thermal emission of about 120 mW/m²/cm^-1 (the steradian-related value of 38 erg/(sec cm²) has to be multiplied by p though one would expect it to be 2p for one direction). This left out emission, being about 4 W/m² for the 1*CO2 base case, results in a too high radiative forcing as it causes an increased part of the radiative energy being withheld at tropopause level in case of CO2 doubling. The satellite clear sky measurements taken above Guam in 1970, with added theoretical black body emission curves, clarly show the water vapor impact below 575 cm^-1, a thermal tropopause CO2 emission peak from the bottom of the absorption funnel at 667 cm^-1, the ozone absorption around 1050 cm^-1 and the methane and then water vapor absorption beyond 1250 cm^-1.
Fig. 3.5: Satellite spectrum (Kunde, 1974)
For a long time we had a controversial discussion about discrepancies between satellite MSU measurements (about 1-5 km height, indicating hardly any warming trend), and ground station readings, see as well http://www.john-daly.com/graytemp/surf-msu.htm#Dietze1. Using IPCC's flexible aerosols, Ben Santer, Tom Wigley et al. tried to model-experiment away and downplay this problem [Science 287, 1227-1232 (18 Feb 2000), see as well D.E. Parker on p.1216]. The warming effect from radiative CO2 forcing occurs mostly near ground. So the GCMs which assume a parallel shift of the troposphere temperature profile (as e.g. J.F.B. Mitchell and Sir John Houghton formerly stated), instead of coping with an increased lapse rate (see Fig. 3.2), erroneously assume a well and fastly mixed troposphere.
Even the 1st TAR draft Ch.6 p.6, line 52-54 still said that surface and troposphere are closely coupled, the thermal structure being determined by a nominal lapse rate, all thus behaving as a single thermodynamical system. Because of the increasing lapse rate satellites measure a mix of cooling and warming and thus can principally not replicate the ground temperature trend.
Actually, if we apply proper physics, i.e. cooling of the upper troposphere for increasing CO2, and we use IPCC's constant lapse rate, the ground should indeed be cooling (!) instead of warming. This demonstrates one of the most absurd errors of IPCC.
H. Volz found an essential error source in ground temperatures when calculating that the energy used in Germany, being radiated off across the area of the country acc. to Stefan-Boltzmann, would already cause an average temperature increment of 0.7 °C (!). This increment remains rather constant as well as our energy demand and does hardly increase with the CO2 concentration. So this can neither be allocated to the CO2 increment nor be subject to future CO2 projections. An energy related ground bias may occur as the number of stations in developed and energy intensive countries is quite large. It is not known to what degree such effects have been corrected by IPCC.
The estimation of radiative forcing done here, shows that IPCC's CO2 climate sensitivity has indeed to be reduced considerably, just resulting in a rather harmless (if not beneficial) warming till 2100. The corrections applied (as well as those for IPCC's seriously flawed carbon cycle model), would completely turn over all simulation results presented in the TAR.
The temperature trend of ground readings (especially because of unreliable ocean surface measurements) should not be (mis)used as a "proof" for the correctness of the highly erroneous CO2 sensitivity parameter on which the IPCC model results are based on. A considerable part of the observed ground warming has to be allocated to amplification of solar forcing (via cloud coverage), as well as to urban heating and forest clearing (i.e. reduction of evaporation).
Within this century a reduction of emissions is indeed not at all necessary, as in 2090 most of the usable fossil fuel (estimated as 1300 GtC) will be depleted and the CO2 concentration will not even be 550 ppm. When fossil reserves become rare, technology can be expected turning to bulk power production from fusion reactors and thorium breeders anyway. The latter alone will be able to supply mankind with the presently used amount of energy from oil and gas for 10.000 years.
A calculation of Tom Wigley (NCAR) [Geophs. Res. Lett. 25, 2285-2288 (1998)] shows that for compliance of developed nations with Kyoto, the temperature effect till 2050 will be only 0.07 °C. As IPCC uses a far too high climate sensitivity, the realistic effect should be about 0.02 °C only. Energy and CO2 taxing within the EU will yield a contribution for temperature reduction of 0.002 °C only. Contrary to the serious economic impacts, the temperature effects of claimed emission reductions are absolutely negligible. So the international bureaucratic activism to enforce Kyoto seems rather useless and ridiculous. The planned emissions trading requires the installation of a harmful eco-fascist repression bureaucracy, CO2 counsils to allocate emission grants and limits to individual industries and carbon taxes to curb the folks. The permit to burn a ton of coal beyond the limits may cost 150 US$, four to five times the price for importing a ton of coal. Reporting and controlling facilities and drastic punishments are required as well – being already planned in most details (see the Greenbook of the EU commission) – and the WTO will trade-sanction governments that do not comply with the CO2 restrictions.
June 1st 2000, Dipl.-Ing.
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This paper: http://www.john-daly.com/forcing/moderr.htm
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