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Is Carbon Dioxide a Pollutant?

By Lauriston Muirhead, WATCH (Wodonga Albury Towards Climate Health)

The answer of course is no and yes!  Carbon dioxide (CO2) is just like any other compound: in the right quantity, the right place and at the right time it is not a pollutant but if any of those rights are wrong, a dangerous situation can occur.

Let’s get back to basics.  In holistic terms plants consume CO2 and release oxygen via photosynthesis whereas luckily animals release CO2 and consume oxygen via respiration.  We call it the carbon cycle.  The amounts of these gases consumed and released during human existence (the first Homo sapiens fossils appear about 200,000 years ago) has been fairly constant and balanced.

Air trapped in layers of ice in the Antarctic show that for at least 420,000 years levels of CO2 in the atmosphere have been less than 300 parts per million (ppm).  Then we started adding to it by burning carbon based fuels such as coal, oil and gas about 200 years ago.  Extracting carbon that has been buried under ground for tens of millions of years and burning it in air adds CO2 to the atmosphere.  Each carbon atom (C) combines with two of oxygen (O2) in the air to make extra CO2.  Since about 1750 the level of CO2 has risen in direct proportion to the mass of carbon fuel we have burnt.  The level is now 394 ppm. (See http://co2now.org/ )

The physics of the CO2 molecule (such as the mass of the atoms and the strength of the bonds holding them together) make it very good at absorbing heat.  The amount of CO2 in the atmosphere therefore contributes to the temperature of Earth.  More CO2 leads to higher temperatures.  We are conducting a giant experiment with Earth by adding more and more CO2.  For example, the world now burns about 200 tonnes of coal per second which makes more than 600 tonnes per second of CO2.  We know that global temperature is rising: 2010 was the hottest year of the hottest decade since records began.  Sceptics will try to argue with the facts and distract people from this basic science but we cannot afford to take risks with our one and only home – planet earth.

So whether you define CO2 as a pollutant or not, it is high time we returned the level of CO2 in the atmosphere to the levels we know are safe.