Clive Best

I have been reading several new books about climate science, “climategate” and the IPCC. The first is The Climate Files  by Fred Pearce who is a widely respected science journalist with New Scientist and the Guardian. The next is a new book “Climate - the counter consensus” by Robert Carter who is an Australian professor and long standing so-called “skeptic”. I also read the Hockey Stick Illusion by AK Montford and re-read John Houghton’s excellent briefing on Global warming. What is beginning to emerge in my mind is:

A group of privileged scientists who helped initiate and sustain the IPCC process, then consequently benefited from it through the ensuing flood of research funding and would then appear then to have excluded other scientists with different viewpoints. On the other hand a growing group of critics have been  attacking them sometimes justifiably and sometimes totally unjustifiably. This unfortunately caused a siege mentality of secrecy and elitism to develop among  these climate scientists, who blocked openness in the science, with attempts even to suppress publication of alternative interpretations. The CRU (Climate Research Unit) has had one of the crucial roles in measuring whether there has in fact as predicted been any warming over the last 100 years or so. It is essential that these measurements are trustworthy and completely transparent, as otherwise this debate stops being scientific.  The raw data and algorithms used to derive global temperatures should open to all to replicate because that is the way science works. Otherwise climate science will allways remain a bit like kitchen sink  alchemy because  there are a huge number of variable parameters, and there are still many “unknown unknowns”. Climate Models are huge computer programs modelling complex differential equations, with some built in assumptions, and endless knobs to twiddle.  In the end it can  only be measurements and experiments that control the science behind these models.

The basic physics of the greenhouse effect is well established and pretty much accepted by everyone. Surprisingly though, its direct  effects are really not that bad, despite all the hype of impending disaster, rising sea levels and melting glaciers. Mankind burning of fossil fuels has caused a 30% increase in CO2 concentration in the atmosphere since 1750. Absorption of infrared radiation from the earth’s surface in narrow wavelength bands by CO2 and re-emitted by CO2  results in trapping some extra heat within the earth /atmosphere system. Adding more CO2 to the atmosphere has a progressively smaller and smaller (logarithmic) effect because the absorption in these bands was already saturated at pre-industrial levels.  So if no action is taken and man were to continue burning fossil fuels to peak at a doubling of CO2 levels in the atmosphere by the end of this century, then  global temperatures could rise by about 1 degree. Far larger natural variations than this have occured over the last 100,000 years. The transition from an Ice age to a warmer interglacial period causes a rise of about 9 degrees globally. This anthropogenic rise of about 1 degree by 2100 is what the basic physics of a doubling of CO2 in the atmosphere predicts.

All the scientific controversy is actually  about  feedback effects which have been predicted. This is the crux of the argument and in reality  no-one currently really knows what will happen. These are the examples feedbacks given:

1. If ice caps recede from the poles then more solar energy will be absorbed due to a reduced  albedo leading to enhanced warming.
2. Warmer oceans lead to more evaporation and more water vapour in the atmosphere. Water vapour is the main greenhouse gas by far on Earth contributing at least 5 times as much as CO2.
3. More water vapour however leads to increased cloud cover which on average cools the Earth. Models show that an increase in cloud cover of just 3% would be enough to offset all the enhanced greenhouse effect caused by a doubling of CO2. Some estimate also that more rain will reduce water vapour from the atmosphere and thereby reduce the greenhouse effect.
4. Ocean circulation. The oceans have an enormous heat capacity and transport energy across the world through currents like the north atlantic drift which warns Europe. Any changes in these currents would have large changes regionally but probably not globally.

The IPCC estimate a net positive feedback effect giving their prediction of a much higher higher 2-5 degree rise in global temperatures. Despite all the money flowing into research and all the conferences these figures haven’t really changed much over the last 20 years. The science itself also hasn’t changed that much - it is just a question of how it is interpreted. If Milkowski turns out to be right then nothing will happen because he argues the greenhouse effect is already maximised. That is why direct experimental measurements are so important.

The climate change debate has now become far more about politics than about science. If you are green, possibly left wing, favor state intervention to  rampant capitalism, oppose globalisation and unfettered growth,  then climate change is real, very dangerous and the West is to blame. If on the other hand you are maybe right wing and believe in low taxes, free enterprise, growth, individual rights and oppose state interference, then climate change is myth and hype to bring discredit to enterprise capitalism etc. etc.

The CRU temperature data  show a rise in temperature of around 0.5 degrees C over the last 150 years, but it is not a clear linear rise and there have been cooling periods as well such as during the 1940s - 1960s, and the temperature has stopped rising for more than a decade since in 1998. This means that natural variations must also be present and an unambiguous human  effect is still not confirmed. Critics argue  that these data are also effected by a different human effect namely the large expansion of urban areas leading to local heating through urbanisation - concrete, tarmac and heat from cars and buildings. Many weather stations were naturally close to cities and therefore may need correcting for this effect. The IPCC claim  no correction is needed based on a paper by Jones et al studying chinese weather stations in different locations, whose results are now being questioned because these locations now turn out to be uncertain.  This paper claimed there was no such urban heating effect, however I know from personal experience that central Milan is always a couple of degrees hotter than where I live in the countryside. Surely the only way to arrive at the truth is to make available the raw station data, their locations and to allow others to carry out independent analysis.

The drive to a low carbon economy may be anyway a good thing for innovation and for the environment in advanced countries. However it will not help developing countries in Africa, where most transport still depends on 10-20 year old trucks, buses and cars  shipped there from Europe and Asia, which  emit choking black smoke.

We are selling our house after building it and living in it for the last 15 years. The house is too big for us now that all the children have left and we will now base ourselves in  the UK. However, It is not a good time to sell as loans are more difficult to get and less houses are being sold during the economic downturn. I would say that the UK housing market is much more fluid and dynamic than here in Italy. Families tend to own a house that gets handed down the generations, or else the father builds a house for his son or daughter. I don’t think there is any inheritance tax or capital gains tax on the primary house. This way wealth stays in the family. Probably for this reason we should hang on to it or “give it” to our kids. Travelling so much would mean that the house will be empty for longish periods though which would not be too good. So right now if someone wants to buy it we will sell it.

The house is in a nice position about one kilometer up from Lago Maggiore. It is with an agent who has  now  asked us to update the photos. So I thought I might as well put them  up here as well.  I will be sorry to leave this area but logically it makes little sense to stay here now that I have no work ties, and all our children are scattered around the world.

Price ?   Less than you would imagine.

There is an excellent new science blog http://scienceofdoom.com/ about climate science which honestly sticks to the physics and  avoids politics. In my opinion it is an improvement on  http://realclimate.com which although good scientifically, has a tendency to indulge in attacking  skeptics while defending questionable science like the famous hockey stick. The series of articles on CO2 as a greenhouse gas I would recommend to anyone interested in the greenhouse effect, and they have certainly  helped  me to better understand things.

So where are we in simple terms:

1. Doubling CO2 from pre-industrial levels is predicted to raise average global temperatures 1.2 degrees centigrade. The physics here is pretty clear. Humans have currently added about 40% more CO2 since 1700 and temperatures  have apparently risen by about 0.6 degrees. Counter arguments are that this rise is both due to natural recovery from the little ice age and to urban heat effects in the measurements.
2. The  good news is that the (direct) greenhouse effect has a logarithimic dependence on CO2 concentration. That just means that each time the concentration of CO2  in the atmosphere doubles, the radiative forcing causes about another 1 degree average rise in global temperature. Currently we have about 390 ppm (parts per million) compared with about 280 ppm 200 years ago before the industrial revolution - so about a rise of one third.  If the concentration were to continue rise to say 1200 ppm (4 times pre-industrial levels - which  is very unlikely), then the direct greenhouse effect would cause a total of 2.4 degrees rise in temperature.
3. The IPCC predictions are based on complex Global Circulation Models which include many other hypotheses about   positive feedback of extra water vapour caused by evaporated from the oceans and a decreased  albedo due to melting snow caps. These lead to  far higher predictions for global warming, and even to “run away” global warming.
4. Perhaps these feedback effects are exaggerated or simply wrong. Increased clouds lead  to less incident solar energy to the surface and more cooling. Certainly water vapour is the dominant greenhouse gas at between 60 - 90% of the total effect so small changes in water vapour can have big effects. When water condenses as water droplets in clouds then on average clouds cool the planet. The physics here is as yet unclear, complex  and probably impossible to predict anyway.
5. One hint that things may not be so bad as some predict is that life on Earth has thrived over the last 4 billion years. There is ample geological and physical evidence that concentrations of CO2  have existed previously at levels many times higher than now. If dangerous positive feedbacks really exist leading to run away global warming, as for example happended on Venus, then surely this  would have already have happened over the long history of the Earth.
6. The unique feature of the Earth seems to me to be that there is a stable climatic balance between Water, life and geology - sometimes called Gaia theory. The oceans make up 60 % of the surface and are by far the main drivers of climate. Plate tectonics, driven by internal radioactive heat maintain the continents and readjust heat balance. Changes in the earth orbit parameters lead to ice ages when the continents are distributed over the poles as now. Life continues to maintain the balance of gases in the atmosphere. Oxygen and Carbon Dioxide are gases of life.

Many threats exist for life on Earth over the next few million years namely: massive meteor impacts, super volcanoes, ice ages etc. The main danger for us over the next thousand years is profligate overpopulation of humans leading to the destruction of the environment and species extinction. Global warming is a symptom of our evolutionary success not the  cause of our  predicted eventual downfall. Whatever happens in the next million years life on Earth will continue, recover and flourish with or without us, as it always has done.

Wind Farms are being proposed as the most effective renewable energy source for the UK, but is this based on any hard evidence? I have come to the conclusion that Wind Energy does not make sense. The environmental damage caused by building them far exceeds any benefit in clean energy production. The show stopper is that they are very unreliable because on average they run at only 30% output because the wind is unpredictable. This means that no matter how much wind energy is built the Grid will need to rely on an equal amount of reserve (fossil) energy production when the wind isn’t blowing. Often flat air with high pressure conditions occur during mid winter leading to very cold temperatures.

The latest wind turbines generate a peak power of 2 Mw,  and are 130 m high with a rotor diameter of 80m. Due to wind shadow these need to spaced about 800m apart.  Therefore for a wind farm to produce the same energy at full output as a single nuclear plant of 1.5 Gw it needs to contain 700 such turbines covering  an area of about 500 square kilometers. Each turbine needs to excavate a massive foundation base from the earth filled with reinforced concrete weighing thousands of tons causing a huge impact on the countryside. They would need replacing every 10-20 years - although my guess is that they would quickly be abandoned as white elephants leaving vast areas of eyesore consisting of decaying concrete and steel structures. This is simply a repeat of the sixties concrete tower block planning scandal.

The real problem though is simply that wind is so unreliable. The average load factor of windmills in Britain is 30% because the wind has to be just right to reach peak output. Too little and no energy is produced and too much causes   the turbines to shut down in order to protect them from damage.  This consequently increases the effective area of our wind 1.5 Gw farm to 1000 sq km (probably 3000 sq km using the figures from ref 1.). The real show stopper though is that occasionally the whole country is windless and national output would fall to essentially zero.  This means that wind power can never replace fossil fuels because we will always need reserve core capacity - and the only non fossil source is nuclear.

So why does private industry and electricity utilities promote and build new wind farm developments in Britain ? The reason is simple - they receive huge  subsidies from the government ! These subsidies are actually financed by the consumers through surcharges on their electricity bills. There are two political mechanisms that fund the subsidies: the first called Renewable Options and the second a Climate Change Levy. The first is a requirement that by 2010 10% of electricity is generated from renewable sources for each utility company. If this is not achieved the utility company pays a fine because it doesn’t hold sufficient certificates called Renewable Obligation Certificates (ROC). No utility would fund wind power without these certificates which were originally worth 30 pounds/Mwh, but  are now traded on open markets at sums of around 50 pounds/MWh. These ROC certificates are funding wind farms to the tune of around 1 billion pounds per year. Taken together with CCL the effective subsidy on wind power generation is now 60 pounds/MWh. This means for the utilities that the effective value of every watt of electricity generated by Wind has  3 times the value as that generated by fossil fuels. It is no wonder they are all keen to build wind farms. Over a 25 year period the effective subsidy for each Wind turbine  of 1 Mw is 3.5 Million pounds! Without this subsidy no-one would be building wind farms today as they are simply not cost effective. For comparison : the generating costs  of nuclear energy is $30 per MWh including construction and decommissioning costs (ref 2).

The other problem with wind power is the environmental damage they cause to the natural countryside. To make a significant contribution to Britain’s energy 10% of available countryside would need to be handed over to wind power. Apart from their visual impact, these towers  kill bats and rare birds of prey like Eagles, and  cause documented noise pollution for nearby homes. They concentrate in some of the  most beautiful areas of the country - hills and western coastlines, yet despite this still give no guarantee of continuous energy supply. Windless conditions across the UK is not an infrequent occurence,and perhaps worse it is unpredictable.  Wave energy suffers from the same problem, and only tidal energy is a predictable renewable.

The world needs to get off fossil fuels not just because of CO2 emissions but because these resources are finite and insecure. However, the only viable alternative for the foreseeable future is nuclear energy. Current generating costs of nuclear power are among the cheapest available, roughly about the same as coal. Critics argue that nuclear power received hidden subsidies in the past because of weapons work. However, this is irrelevant today as that money has already spent and there are no subsidies at all for nuclear today. The environmental footprint of nuclear power plane is a tiny fraction of a wind farm and has the  advantage of 90% load factor and predictable  availability.

The political pressure of the climate change and environmental lobby has caused governments to pledge targets for CO2 emissions. Political expediency and subsidies are now  leading us down the renewable path based on figures that just don’t add up. Some renewable energy is probably a good idea - especially predictable sources like Hydro and tidal energy, but wind energy should be restricted to just a few percent of  production, or we will regret our folly once these towers rot and decay when subsidies are removed.

Right now the only non fossil fuel option that makes sense to me is nuclear power.  I understand long standing opposition  to nuclear power but this is driven by prejudice -  and unfortunately the maths says that  other options are  currently pie in the sky.

Ref 1: Sustainable Energy - without the hot air. David MacKay. http://www.withouthotair.com/

Ref 2: http://www.world-nuclear.org/info/inf02.html

Spring is at least 3 weeks later than normal after one of the worst winters in Europe I can remember. Easter monday dawned with a beautiful day for our Easter walk in Colletta. We walked up from Colletta to the original “Castel Bianco” from which the Commune takes its name. Dating back to 1200 the castle protected tha valey from various marauders - first the Albenganesi then the  Saracens. The Castello  was built on a hill comanding a panoramic view across the valley. The walk up from Colletta took about 4 hours taking us up above Varavo and Verallo into clear air and fast flowing  streams after all the recent rain.

Then back to the Osteria and a pleasant boozy lunch - what a relief after all the recent spin and polemics !

Colletta remains a unique beautiful spot.

A radical but rather elegant theory has been proposed by a Hungarian Physicist Ferenc Miskolczi (see refs) that the Earth maintains a maximised greenhouse effect  to allow the Earth to cool as efficiently as possible. This self-regulation arises  because  70% of the Earth’s surface is water allowing both cooling through evaporation (latent heat) but also warming  through H20 being a greenhouse gas. Unlike CO2 the concentration of H2O in the atmosphere is governed by thermodynamic processes. Local thermodynamic equilibrium in the atmosphere ensures equality between the absorbed IR energy by all greenhouse gases from the surface and the  IR  energy emitted back to the surface by those same gases. Water evaporation and convection drives the Earth’s weather systems. Water Vapour also dominates the greenhouse effect of the Earth but has two  subtle feedbacks. Firstly evaporation mainly from oceans is a very efficient way for the surface to loose heat through latent heat. However cloud formation then leads to a higher albedo and to night time heat retention so there is a play-off beween this and the greenhouse effect of H2O. Miskolczi and Zagoni argue that the total average greenhouse effect on Earth depends only on the input energy of the sun plus a small geothermal component. This simple conclusion is backed up by  detailed radiation transmission model calculations and data comparisons.

The total greenhouse effect remains exactly what is needed to maximise cooling of the Earth. Any man-made CO2 increases are simply offset by a small decrease in water vapour so as to maintain thermodynamic equilibrium. They claim that the data show there has been a small 1% decrease in global humidity to offset all CO2 increases caused by  human emissions. The following slides try to explain the energy balance arguements they make. The crucial proposal is that the water content of greenhouse concentrations (H2O + CO2 + CH4) are maintained to be such that half the IR energy radiated from the surface is emitted into space from the top of the atmosphere while another roughly 60 watts/m passes clean through the IR wavelength window. The physics motivation for this first proposal is the virial theorum which states that the kinetic energy (heat) of the atmosphere is half the (gravitational) potential energy. The effective radiative kinetic energy is associated with the IR radiation emitted from the atmosphere to space(Te**4). The effective potential energy is associated to the IR radiation emitted from the surface (Ts**4). The second proposal is that the amount of energy emitted back to the surface is equal to that absorbed by the atmosphere. This is based on an assumption of overall local thermodynamic equilibrium (Kirchoff law). With these two assumptions the normalised greenhouse factor is and will remain equal to  1/3. The Earth’s temperature remains fixed unless the input energy changes through volcanic or human induced aerosols,  or through changes in the Earth’s orbit. The temperature  is however independent of any anthropogenic CO2 increases.

Global Circulation models assume that  rises in CO2 concentration lead to an enhanced greenhouse effect with rising temperatures causing yet more evaporation of H2O leading to an enhanced warming . This is the positive feedback which leads IPCC to give scary predictions of 3-7 degrees rise in global temperatures in the next 50 years or so. The effect of CO2 increase on the greenhouse effect alone would lead to less than a 1 degree rise.

The Saturated Greenhouse theory says that exactly the opposite happens. The Earth has an infinite amount of greenhouse gas available to it in the form of water, but the average relative humidity today at the surface is 78% and just 37% at 9000 m. So why isn’t it 100% ? The reason Miskloczi argues is that energy balance between the surface and the atmosphere (Kirchoff: ED = AA ) plus a requirement that the kinetic energy of the atmosphere = 2* the potential gravitational energy (Virial theorum: EU = 2SU) causes a saturated greenhouse effect therefore limiting the Earth’s temperature to its current level. The normalised greenhouse effect = 1/3 and will always remain so and the Earth’s temperature remains constant unless the external energy parameters change (solar). Therefore to compensate for any  rises in CO2 levels the Earth will adjust the relative humidity to maintain the same thermal equilibrium.

The super El Nino effect in 1998 led to a rise in global temperatures. If it were the case that a temperature rise causes more water vapor through evaporation, causing yet more temperature rise, then one would expect temperatures to continue to rise after 1998, and result in a run-away effect. But the opposite happened, because temperatures fell as the greenhouse equilibrium mechanism restored the balance. The extra greenhouse gases rained out to restore the equilibrium. Miskolczi is arguing that exactly the same effect is happening now as has happened in the past with any sudden  perturbation in  CO2 levels. Energy balance of the Earth/Atmosphere  will cause water vapour content to increase or decrease in order to maintain an equilibrium situation with a saturated greenhouse effect g=1/3. In order to offset a potential  doubling of atmospheric CO2 levels caused by human activity the relative humidity would reduce by 3%. Miskolczi claims that existing data show that already a global reduction of 1% in relative humidity has occurred over the last 100 years. Data from NOAA Earth System Research Laboratory for the upper atmosphere  show that relative humidity has indeed been falling.

This theory depends on the two assumptions of local thermodynamic equilibrium (Kirchoff) and the applicability of the Virial theorem to the radiation fluxes from the surface and the top of the atmosphere. Mainstream IPCC scientists have all attacked this but direct measurements do really seem to support these assumptions. The pressure distribution of the atmosphere is a function of gravity and temperature P(h)=Po*exp(-mgh/kT). The effective black body radiation emitted by the atmosphere to space by greenhouse gases is a kind of measure of it’s “greenhouse” temperature and hence its kinetic energy, whereas the radiation emitted from the surface is related to the Po the pressure at height zero and hence the gravitational potential energy. I certainly will need to think harder about this one to be  convinced, but the theory is very attractive and if true would completely overturn mainstream climate change predictions.

References:

Ferenc M. Miskolczi, “Greenhouse Effect in Semi-Transparent Planetary Atmospheres“, Quarterly Journal of the Hungarian Meteorological Journal, Vol. 111, No. 1, January - March 2007.

Explanation by Miklos Zagoni

Model discusion

The saturated greenhouse effect

If our eyes were sensitive to the IR radiation in the main CO2 absorption bands then we would just see fog. The atmosphere is opaque to CO2 at well below pre-industrial levels with an absorption length of about 10 meters. This would be a very thick fog.  By adding more CO2 to the atmosphere man is just reducing a little that aborption length.

The CO2 greenhouse effect is caused by the reduction in IR radiation escaping into space from the higher atmosphere of the earth. As we add CO2 so the height where the fog disperses and radiation escapes increases.  The temperature is lower at these heights reducing the effective energy escaping by a small amount (Blackbody radiation proportional to T**4). The energy balance of solar input radiation to the Earth and heat loss to space by the Earth must remain in balance. Therefore the Earth warms slightly to emit a little more total IR radiation across the spectrum to compensate the small extra energy trapped by extra CO2. However the energy increase is only logarithmic because the absorption is already opaque.

All these effects based on accurate cross-sections have been included in a model of the atmosphere by the US navy. The model is called MODTRAN and has been validated by direct satellite measurements. It is very informative since one can simulate what effect CO2 has on energy output for different regions and by inference how the Earth’s temperature reacts. The atmosphere’s simulated are for different regions with different profiles of water vapour and clouds. Changing the water vapour factor actually has a much larger effect than changing the CO2 concentrations. Current concentrations of CO2 are 375 ppm.

One can also calculate the temperature rise caused by doubling current levels of CO2 from 375 ppm to 750 ppm. We do this by adjusting the Earth’s temperature as input to MODTRAN to give the same net radiated IR energy in watts/sqm as we had at 375 ppm. This is because we always need to balance the incoming solar energy against outgoing IR energy form the Earth at a given temperature and the solar energy doesn’t change. The temperature rise varies slightly from the Tropics to the Arctic and on whether we include clouds or not. However the temperature rise that results varies from about 0.7 to 0.8 degrees C. This is nothing like the predictions of the IPCC which talk of 2.5 to 7 degrees heating but more about that later.

Similarly we can use MODTRAN also to estimate the total greenhouse effect of CO2 on planet Earth. i.e. how cold would it get if there were no CO2 at all in the Earth’s atmosphere ! The results are surprisingly little change in my opinion. The temperature would fall between 5 and 7.5 degrees C i.e. about the same change seen between the  Ice ages and inter-glacial warm periods. How can that be ? The main answer is that the most important greenhouse gas is water vapour and the temperature regulation of the Earth depends far more on small  changes in water vapour than on big changes in CO2.

Why does the IPCC predict much higher temperature changes than 1 degree for a doubling of CO2 ? This is because they are assuming  positive feedbacks exist which they include in their  climate models. So for example :

• A rise in temperature causes more evaporation from oceans leading to further warming by increasing concentrations of water vapour.  In fact MODTRAN demonstrates that increasing water vapour by just 10% leads to as much warming as doubling CO2 !  Of course the opposite is also true.
• A warming Earth leads to melting of the ice caps leading to a decreasing Albedo (solar energy reflection) leading to more absorbed energy leading to a warmer Earth surface.
• A rise in temperature of the ocean leads to a drop in  CO2 take up because less can be dissolved as temperature rises. However an opposite effect to this for increasing CO2 is that the biosphere will absorb more CO2 as plants and plankton grow faster. This feedback of the carbon cycle with temperature is called gamma (ppmv increase in CO2 per degree C) and is usually assumed to be a positive feedback. It can be adjusted to give big increases in temperature. If we define gamma to be the increase in CO2 (ppm.v) for each degree rise in temperature then plugging large values into climate models lead to much higher temperature rises.

I have been struggling to understand exactly how increasing CO2 levels leads to global warming using  basic physics, and the story is complex. The trapping of certain bands of infrared radiation emitted from the Earth by greenhouse gases is well known. The effective cross-section of CO2 of absorption for CO2 in its rotational bands is also well known (HITRAN). Using the current concentration of CO2 in the atmosphere it is also clear that essentially all the radiation emitted by the surface in these bands is already absorbed by CO2 at pre-industrial levels. In fact spectra from space show that the main CO2 bands are saturated in the lower atmosphere with minimal emission from the high atmosphere. The absorption of radiation follows a logarithmic law with distance assuming a uniform concentration of CO2 in air. All that happens if you double the concentration of CO2 in air is that the absorption length is halved. So more radiant energy is absorbed and reflected back to earth at  lower levels of the atmosphere than before. However the total energy balance would appear at first sight to be almost unchanged. In fact just such an experiment was performed by Herr. Koch and led Angstrom to  dismiss theories of man induced warming already back in the early 20th century (Realclimate: what Angstrom didn’t know).

There are 3 main CO2 bands of IR absorption at wavelengths 1388, 667, 2349 cm-1 (HITRAN) and these are already saturated at current levels of CO2 in the atmosphere. Infra Red measurements from space show that the atmosphere is  opaque at these wavelengths. However at high levels in the atmosphere this is not no longer true and this is the only argument for the enhanced greenhouse warming by CO2 warming which makes sense to me (see below).

Spectra of solar radiation and outgoing Infrared radiation. Note CO2 absorption bands ref: Barry & Chorley.

There is a very interesting paper here : http://brneurosci.org/co2.html which describes the basic physics. The absorption length for the existing concentration of CO2 is around 25 meters i.e. the distance to reduce the intensity by 1/e. All agree that  direct IR radiation in the main CO2 bands is absorbed well below 1 km above the earth. Increasing levels of CO2 merely cause the absorption length to move closer to the surface. Doubling the amount of CO2 does not double the amount of global warming. Any increase could be at most logarithmic, and  this is also generally agreed by all sides.

Lab experiments using tubes filled with CO2 to represent the atmosphere show that the IR transmission is essentially saturated and doubling the amount changes the transmission very slightly . So what is wrong and how are these arguments refuted by the majority of climate scientists? There are two main arguments  why global warming is important despite apparent saturation when man adds CO2 to the atmosphere (see  Realclimate ). The first of these is rather convincing.

1. IR scatters repeatably upward through layers of the atmosphere until at between 5-9 km  the air is so thin that the the atmosphere becomes transparent allowing CO2 emissions here to radiate out into space. At these levels there is little water vapour and CO2 dominates the energy loss. As CO2 concentrations increase so this level shifts to  higher levels in the atmosphere since a critical density must be reached for the radiation to escape.  These levels are colder (until we reach the troposphere) and IR loss is proportional to T**4 (Stefan Boltzman’s law). This means that slightly LESS energy is radiated to space than before and since the total energy must balance, the Earth warms up to radiate more heat to compensate. Don’t forget that there are windows in the IR spectrum with no absorption other water vapour allows easy extra energy loss through evaporation and IR emission. The temperature profile of the atmosphere is called the (adiabatic) lapse rate and is approximately -7 degrees per km falling to -4 degrees per km in the tropics. This is valid up to the Tropopause after which temperature rises again in the stratosphere. So greenhouse warming depends on falling temperature with height, and the anthropic enhanced greenhouse effect due to CO2 emissions is equal to the reduction of IR emissions to space in CO2 bands from the upper troposphere.

2. It is not completely true that the CO2 absorption bands are saturated as the fine structure is quite complex and in the side bands there is still energy left for the atmosphere to absorb. This is a much smaller effect than the first point. The extra absorption caused by an increase of a factor 4 is just a few percent as shown in the figure. In fact already 95% of the radiant energy is absorbed by CO2 at pre-industrial levels leaving a maximum of just 5% for any increase you like. It is often estimated  that the CO2 green house warming component of  the planet is about  3 degrees C so this extra absorption and emission to the surface  would appear to only add just 0.15 degrees of warming.

Saturation now and @ 4*CO2 levels (note LOG scale)

Therefore the main physics arguement supporting enhanced global warming caused by increasing levels of CO2 is the in height and thereby lower temperature of the effective radiating level of the atmosphere to space. The first comment to make is that we never  hear this crucial explanation in  the popular descriptions of the greenhouse effect. We just hear that more CO2 absorbs more heat radiated from the earth and radiates it back to the surface thereby heating us up just  like a thicker blanket does in bed (blankets actually work by cutting down convection losses). However the real explanation above concerns just the outermost layers of the atmosphere. The enhanced greenhouse effect depends on  a decreasing temperature gradient with height so that as the effective radiating level for IR  by CO2 rises so the energy loss falls and the earth must rise in temperature to compensate. Energy balance demands that there is a perfect match between incoming solar energy and outgoing IR energy. So lets look at this in more detail.

The effective temperature for all IR emissions is around -20 degrees C radiating at a height h of 5km. Now suppose that we double CO2 concentrations and the effective last radiating level rises to say 6 km. The temperature would now be about -27 degrees C as the decrease is almost linear in the troposphere. However the effective surface area is now also greater by an amount 8*PI*R (where R is radius of the Earth = 6350) making 1.6*10**5 sq km larger than at 5 km height.  The IR radiation falls off with temperature as T**4 which gives us a reduction of about 18% relative to before.

However if we just look at the main CO2 emission band and use the measurements from space (taken from Houghton’s book Global Warming - A complete Briefing). It would appear that the effective temperature of CO2 band alone  is -53 degrees C which is almost at the tropopause ( -60 degrees). So with all else remaining the same (water vapour, methane etc.) the drop in energy loss is just 3% in that single band.

CO2 causes the  lower atmosphere to be opaque at the main absorption bands. The mean free path is only  about 25 meters, so at these wavelengths the lower atmosphere is already like a thick fog where IR radiation is scattered in all directions. As we rise up in the atmosphere so the density falls exponentially and only at heights of 8-9 kms  does the atmosphere then become transparent in the main CO2 bands allowing energy loss direct to space. Doubling concentration rises that level nearer to the tropopause  which radiates at a lower temperature. The estimate given for the Earth’s warmng in Houghton’s book is 1.2 degrees for each doubling - so 2.4 degrees would be the heating if  CO2 concentrations were to increase by a factor 4. These figures are based on a radiation reduction of 4 watts/meter**2 caused by this effect of the effective radiation level rising to a colder level. In his book Prof. Houghton says this can easily be proved, but I have not  understood where this figure comes from nor how it has been calculated.

Feedback Effects

The IPCC predictions of future warming are based on model assumptions of positive feedback effects which are supposed to result from the initial warming caused by CO2 emissions. The main feedback effect is that of increased evaporation of the oceans leading to an increased greenhouse effect of water vapour (already 80 - 90% of greenhouse effect). However it is known that cloud cover in general leads to a net cooling effect on the Earth by blocking incident solar radiation. An increase in cloud cover of 10% would be enough to cancel out global warming effcets of increased CO2 ( Barry & Chorley).

Radiative Forcing Update: I have now found this reference to the equations used to derive the 4 watts/sq m radiative forcing by doubling the amount of CO2 in the atmosphere.

rf = f * ln([CO2]/[CO2]prein)/ln(2)    in watts/m ** 2

It would appear that in order to derive the factor f the IPCC assume that all of the 0.6 degrees warming apparently seen since the industrial revoluton is due to CO2 and thereby derive the constant

AF = 5.35 ln(C/Co)

Then we get simply  5.35*ln(2)  = 3.7 watts/sq m for the radiative forcing of  doubling CO2 !

If it is really true that this formula has been derived only by assuming that all “observed” temperature rise since 1750 is caused only by CO2 increases, then I fear this is a circular argument !  Many skeptics argue that the recent rises in temperature is dominated by a natural recovery from the little Ice Age. In order to be convinced that CO2 is the primary cause of recent warming then I would prefer  that this  formula could be derived from basic physical arguments  rather than introducing a fudge factor preset to prove a theory.

Back in Sydney now for the last few days before we leave Australia alowing us to see this wonderful city. We are staying in Newtown, which is an up and coming suburb just outside the main city centre. It looks like a Victorian suburb of London or any major UK town. Better still there have been preservation orders placed on all the old buildings which stop shops and developers transforming their frontages. This is one of the tragedies of Britain where chain stores like Boots, M&S, Waterstones etc. are simply allowed to plaster their massive shop signs and transform entrances to mediaeval buildings. As a result Newtown and other suburbs look much the same as  they did 50 years ago despite massive rises in property prices.

The waterfront at Circular Quay is just stunning. It looks even better from one of the ferries taking you to Manly or elsewhere. The Opera House is a work of genius and contrasts say the Festival Hall and the  South Bank in London built around the same time. One is timeless, the other looks dated, monolithic and dirty. The Sydney Harbour Bridge looks better in real life than it does in a photo and is an iconic piece of engineering. Yesterday we went for a swim at Bondi Beach. It really is a lovely beach despite the thousands who go there during the holiday season. The sand is clean and  fine and there is enough room for everyone  but swimming between the flags is a little hard when they put the flags about 30 meters apart, but the surf was small so no problems. Strangely enough it reminded me of Newquay in Cornwall, but that may be because Newquay itself got based on Bondi . The water is cooler in Sydney than in Perth or Adelaide which is fine when you get so hot in the sun.

We flew to Sydney from Perth with Virgin Blue. The last day in Perth we went to the Aquarium which is quite a way outside Perth which we reached by train and bus. There is a trendy new resort with a Marina, water park and expensive apartments. The aquarium was really good and exhibited fish from different local areas in Western Australia. You walked through a mega tank with 15 sharks, sting rays, groupers etc. pools of coral and rays and tanks with sea snakes. While in  Glenelg I saw a huge sting ray swim into the beach from the jetty. It reached about waist high water before turning back out to see. They are harmless unless threatened and they do carry a powerful sting in their tails

We arrived in Perth on Thursday so today is our second full day in the city. It is a beautiful city with an attractive pedestrian shopping area adjoining the business part next to the Swan River estuary. Yesterday we took the boat down the river to Fremantle which shows the great situation of the city inland from the sea but still within easy reach. All along the river are beautiful waterfront houses with marinas full of expensive yachts and motor cruisers. Looks like a lot of people are getting rich in Perth. One of the houses was massive and I overheard a remark that it was recently sold for 56 million dollars - the most expensive house in Western Australia. The whole city seems affluent and the prices are higher than elsewhere - about a third higher than Adelaide. You can easily pay up to 10 dollars for a pint of beer which hasn’t stopped me buying beer yet !

Fremantle is a small town with a long maritime history. The buildings are often  stone brick type town houses which gives the place an English seaside town type of appearance.  We went back on the train and discovered that Perth has a good rail link service. Today we took the train to Cottersloe to go to the beach which has lovely white sand and clean water. There are endless beaches like this up the coast many with no-one on them.

Perth and Western Australia have got rich on minerals and mining. It is the third largest gold producer in the world and there is Zinc, Iron Ore, Uranium coal and natural gas. This probably explains why the city seems so affluent with parks and expensive suburbs. We even saw 2 Ferraris today in Cottesloe so despite the socialist government someone is getting rich. The natural environment and quality of life in Perth are probably among the best in the world.

Before arriving in Perth we spent a couple of nights again in Grenelg, Adelaide’s  seaside town. It was here that the first british settlers arrived in Western Australia around 1830. Today it is the day out at the beach spot for young people arriving on the Tram. Our swimming was tempered by the news that sharks had been seen just off the coast recently ! We took a boat ride down the river to Adelaide Zoo. The river becomes a lake in the centre of Adelaide making the town very pleasant. The queues for the famous Panda were too long for us to wait I have to admit.