Is carbon dioxide a pollutant?

Is carbon dioxide a pollutant? Climate change skeptics are claiming that carbon dioxide emissions are not pollution because CO2 is a natural substance. This is a misinterpretation of the word pollution that seems to have come about by using poor definitions of the word. A quick review of the history of the word pollution gives it a proper context.

The Quadrant published a long exposition of carbon (2010) as a natural occurring, organically necessary, environmentally common substance. This had the objective of debunking the whole concept of carbon emissions as pollution. According to Quadrant carbon dioxide can’t be pollution because it is natural and a fundamental building block of life!

But the problem with this argument is that it relies on a very narrow definition of pollution? The Oxford On-line Dictionary says:

Pollution is the presence in or introduction into the environment of a substance, which has harmful or poisonous effects.

Fallacy—carbon is not harmful if you don’t believe in global warming

Therefore carbon dioxide is a pollutant only if we accept that it has harmful effects such as raising the temperature of the world by a couple of degrees. But, by this definition, a raised atmospheric carbon dioxide level is not pollution if you do not believe in global warming.

This definition of pollution only works if the contaminant has harmful or poisonous effects—if a contaminant causes harm it is pollution but if it doesn’t it is simply a foreign substance in the environment. This narrow definition has crept into mainstream usage but is neither historically right nor scientifically plausible. It is not scientifically plausible because “harmful” can be interpreted very broadly.

Wikipedia (2010), a good gauge of popular thinking, proved to be somewhat loose with its definition:

Pollution is the introduction of contaminants into a natural environment that causes [sic] instability, disorder, harm or discomfort to the ecosystem i.e. physical systems or living organisms.

This is very unscientific. Pollution can occur in all environments, natural or artificial; and an ecosystem is both the physical system and its living organisms. Pollution enters a system at one level (environment, ecosytem, niche, organism, organ, cell, organelle) and moves between levels so that it might not necessarily be an ecosystem hazard at all but cause damage to an organism living within the ecosystem.

Dictionary definition of pollution

I went back to my old Shorter Oxford English Dictionary and sought a more reliable definition. The Shorter Oxford lists three definitions:

  1. The action of polluting, or condition of being polluted; defilement; uncleanness or impurity;
  2. Ceremonial impurity or defilement; profanation; and
  3. Seminal emission apart from coition.

And of course we need to refer to pollute, the verb, as pollution is defined against it:

  1. To render ceremonially or morally impure; to profane, desecrate, to sully, corrupt
  2. To make physically impure, foul or filthy; to dirty to stain, taint, befoul

Etymology of pollution

The etymology of pollution follows the definitions in the Shorter Oxford. In the mid-14th century pollution originally referred to the non-coital discharge of semen but soon reverted to its Latin meaning of desecration or defilement.

Pollution originates from the Latin polluere which means to soil, defile, or contaminate, and is made up of por meaning before and luere meaning smear. Luere is related to lutum for mud and to lues meaning filth. It is derived from the Ancient Greek lyma meaning filth, dirt, disgrace, and lymax for rubbish, refuse.

Scientific definition of pollution

This word history suggests that the impacts of pollution need not be harm but less destructive effects such being dirty, unclean or impure. The Encyclopaedia Britannica provides a scientific definition of pollution that is consistent with this broader definition:

… the addition of any substance or form of energy (e.g., heat, sound, radioactivity) to the environment at a rate faster than the environment can accommodate it by dispersion, breakdown, recycling, or storage in some harmless form.

And the Oxford Dictionary of Geography:

A substance which causes an undesirable change in the physical, chemical, or biological characteristics of the natural environment.

and the Gale Encyclopedia of Public Health:

… a chemical or physical agent in an inappropriate location or concentration.

Pollution is the over-addition of any substance to the environment whether it has a harmful effect or not. Contamination is a similar word. We taint our environment with foreign substances, we dirty our rivers, and we increase atmosphere impurities. This is all pollution even without evidence of “harm”. Allowing the definition of pollution to require that the pollutant creates harm is dangerous and narrow.

So in answer to the question is carbon dioxide a pollutant, the answer is most certainly yes.