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Carbon Dioxide and Global Warming

The Copenhagen 2009 summit had climate change high on the agenda, yet polls suggest that the general population is divided on the issue.  Let me briefly summarise the proposition:

  1. That the world climate is changing, more specifically - the planet is warming up
  2. The warming of the planet is due to Carbon Dioxide build-up in the atmosphere
  3. The additional Carbon Dioxide in the atmosphere is the result of human generated pollution

What follows is that the undesirable affects of the global warming will be more extreme weather, alterations to rainfall across the globe which is likely to have the greatest affect on the farmers in third world countries (no rain = no crops), and rising sea levels leading to some island nations disappearing underwater.

A section of the population is pushing for global reforms, and the imposition of carbon tax not only on nations but also on individuals.  The idea is to measure energy consumption by how much carbon dioxide each and every one of us creates.  The tax collected would go towards assisting third world countries cope with the changing climate patterns.

I am going to challenge the points above, but first let me say:

Unfortunately, there is a lot of propoganda and politics going on, and it is hard to discern the truth.  I challenge the propositions that many people are taken as proven - check out Ian Plimer's book Heaven and Earth for the skeptics view on climate change.

Is the Earth warming?

Is the climate indeed changing?  It is hard to determine if the planet is indeed warming.  I have a weather station at my house and my temperature records for the last two years show that 2009 was on average about 1 degree Celcius cooler than 2008.  Of course, the temperature at my house is not necessarily indicative of the average across the whole planet.  How do you measure the average temperature for the whole planet? Some places may be getting warmer and others coolers.  How do you average it?  What is the sampling resolution - do we really have the capability to measure the temperature on every square kilometre of the planet?

It seems to me that the weather is showing more extremes in recent decades, but we only have accurate records going back a few hundred years.  There have been periods of warming and cooling on the planet including mini Ice Ages.  Wikipedia has a graph showing several models going back 2000 years - note that these are models for various regions, not actual measurements!  The variations over the last 1900 years are all due to "natural" events, not humankind.  We seem to be heading in to a particularly warm patch, but this could be due to greater measurement accuracy in recent times (ie predictions made for temperature in the past has been averaged over a longer time period, so 5 or 10 year warm anomalies may be missed).

2000 year temperature comparison

In terms of planetary ages, 2000 years is a blink of an eye.  The planet was a much warmer place during the time of the dinosaurs (65 - 180 million years ago).  It has been unusually cool over the past couple of million years.  It could be that the planet is returning to normal.  That is not necessarily bad for the planet, but could indeed be bad for the survival of the human race!

Carbon Dioxide

If we do accept that the planet is warming, is this due solely to the build up of Carbon Dioxide in the atmosphere?  I first started to investigate the affect of Carbon Dioxide when I heard that the concentration had doubled from around 300 ppm to 600 ppm.  A change of 300 parts per million is only a trace - 0.038% is the atmosphere.  Can such a minute percentage really result in major climatic changes. 

The proposed theory runs like this - first review a model from NASA of incident energy upon the planet.

 

Suns Energy
(the above picture from Nasa)

The sun supplies heat to the earth, with an incident energy of about 1,365 Watts per square metre, which translates to about 342 Watts per square metre on the surface of the earth (disk to flat horizontal surface ratio is about 1/4).  As shown in the diagram above, about 30% is reflected by clouds and the atmosphere, so about 240 Watts actually reaches the surface of the earth.  This is re-radiated back in to space, apart from a small amount which is absorbed by the atmosphere, and it is this amount that becomes trapped in greenhouse gases which is said to be responsible for global warming.  If the amount of greenhouse gas increases then more incident radiation is retained, and hence the planet slowly warms up.

It should also be noted that if it were not for greenhouse gases, the average temperature of the planet would be 33 degrees Celcius lower than it currently is - that is below freezing across the majority of the planet!  Greenhouse gases are our friend!

The amount of radiation varies during the year and with sunspot activity.  Changes in the incident radiation from the sun do result in changes to the temperature of the planet, for example a mini ice age resulted in 1645 - 1720 when sunspot activity diminished (the Maunder Minimum).  Some sites have appeared showing a good correlation between natural sun variations and the temperature of the earth.

Greenhouse gases

Data from the table below was lifted from here.  Many people have done theoretical calculations, and I don't want to endorse this source as the final word.  A review does make one question the affect of Carbon Dioxide.  Water vapour is actually the most prevalent greenhouse gas, and most of this is generated naturally by the action of the sun on the vast water expanses of the earth.  Of the other minor gases, man has contributed to a rise in Carbon Dioxide, but the potency (the ability of the gas to absorb and retain heat) of many other gases is much higher that CO2.  Of the naturally occuring gases, man has made the most significant increases in fluorocarbons which are significantly more potent than CO2.  Although there are now restrictions on the release of fluorocarbons, are we currently reaping the results of releases over the past 50 years into the atmosphere?  ie for Carbon Dioxide the affect of man is 0.117% * 1 = 0.117%; for methane the affect is 21 x 0.066% = 1.38% and for fluorocarbons the affect is say 10,000 * 0.047% = 470%.  I am not certain of the accuracy of these figures or the percentages, but whilst Carbon Dioxide may be a factor it doesn't stand out amongst the others.  Methane is released in large quantities from areas of intensive farming, eg from cows.

Greenhouse Gas % in atmosphere % increase due to man Potency
Water vapour 95% 0.001%  
Carbon Dioxide 3.6% 0.117% 1
Methane 0.36% 0.066% 21
Nitrous Oxide 0.95% 0.047% 310
Fluorocarbons 0.07% 0.047% -700 to +23,900

Carbon Dioxide concentrations vary widely across the planet, being much higher around industrial and urban areas. 

It is also worth noting that water vapour is by far the most predominant greenhouse gas, and almost all of this is generated naturally.

Climatic models

Let's move out of the realm of speculation and make one statement of truth.  We do not have accurate climatic models.  Many intelligent people are working on them and they are improving, but modelling the planet is extremely complex.  We do not have computer models for all the variables that can influence planetary temperature:

Scientific view - on balance

Currently, when pressed about the affect of Carbon Dioxide on global warming, scientists say "on balance , the evidence suggests ...."  This is not a definitive statement.  Politicians address the media with political statements along the lines of "most scientists agree ...".  The truth is that we do not have accurate climatic models, and we do not know for sure.  In a court of law a jury is required to convict a person only if the case can be proved "beyond reasonable doubt".  Such a case has not yet been proved for Carbon Dioxide. The statement "on balance" really means that it is currently the best hypothesis. This is far from "beyond reasonable doubt".  It may well be that Carbon Dioxide is one of a number of factors, or it may be that the Carbon Dioxide trend line follows the increase in global temperature but as another symptom or indicator rather than the actual cause. 

I therefore consider it premature to start imposing global carbon taxes and promulgating guilt to the citizens of the world that the daily activities of each of us are responsible for the slow destruction of the planet.  This only fuels conspiracy theories about the motives of the "secret government" and their desires to enslave and burden us with more tax - those of us in the western world already pay about 70% of our income in taxes of various types, and what do we get in return?

Conclusions

My conclusions thus far are as follows:

  1. Science does not currently have sufficiently accurate climatic models to make any definitive statements of the affect of Carbon Dioxide or any of the other many factors that may contribute to global warming  
  2. It has not been positively verified that human beings are responsible for climate change
  3. It has not been positively verified that Carbon Dioxide is the sole or even major factor responsible for climate change
  4. Global warming is not necessarily bad for the planet, but it may be a problem for the human race
  5. It would be better to invest effort in understanding and adapting to climate change rather than attempting to control it
  6. There is no basis for Carbon tax to be applied to each and every citizen by the world government.  However, it may be justifiable to tax certain industries who pollute the atmosphere and waterways with toxic substances..

© In the Light, 18 March, 2011 , Disclaimer, Son of Suckerfish drop-downs from HTML dog