Response on the carbon debate

As an ex-teacher of science, I can’t let the letter from Steven Harrison of Killarney (SFT 10/06) go unanswered. With regard to carbon dioxide rising through the air to the atmosphere, the air and the atmosphere are the same thing, so his question is meaningless.
While it is true that carbon dioxide is heavier than air, it is only in exceptionally still conditions that carbon dioxide might sink to the ground. There is more than enough turbulence in the atmosphere, due to winds and thermals, to pretty evenly mix carbon dioxide throughout.
While it is also true that there is natural movement of carbon dioxide into and out of the atmosphere due to the action of living things and geological processes, through our burning of fossil fuels we are pumping far more carbon dioxide into the atmosphere than natural processes can cope with.
Hence the well-known and undisputed fact that carbon dioxide levels in the atmosphere have risen substantially in percentage terms over the last 100 years or so.
As carbon dioxide is widely acknowledged as a greenhouse gas, it stands to reason that the extra carbon dioxide we are putting into the atmosphere must cause a rise in temperature.
The concern is that, if we don’t take steps to limit further increases in carbon dioxide levels, climate change may reach a tipping point at which the consequences could be disastrous.
Surely it is far better to try to alleviate the problem now than to continue on as we are and just hope for the best.
With regard to his final comment about evolution, anti-evolutionists keep trotting out the old furphy of the second law of thermodynamics.
While it is true that the law implies that you can’t create order out of chaos or complexity out of simplicity, this applies only to closed systems.
A closed system is one in which there is no movement of energy or matter between the system and the external environment.
A living organism is not a closed system – living organisms take in energy from the surroundings (light in the case of plants, food in the case of animals) and use this to create complex systems from simple ingredients.
An example would be making an ordered protein molecule from a random collection of amino acids obtained by digestion of food.
Given a continual input of energy and materials and an ample amount of time, pure chance dictates that from time to time more complex systems will arise from simpler ones, which is basically what biological evolution does.
Ed Diery, Warwick