Why pick on carbon dioxide?

9 June 2008 - Richard Treadgold

For many years environmentalists have been striving to educate society first to notice, then to condemn and finally to clean up pollution of air, water and land.

Improvements have been achieved over many decades, and it is wonderful that, for example, the United States pollutes a lot less than it used to, has a greater area in forests and enjoys cleaner rivers, like many of the developed nations, including New Zealand.

There are several significant atmospheric pollutants that we still emit (not us, of course, but our engines and processes). They include carbon monoxide, oxides of sulphur and nitrogen, volatile organic compounds (VOCs) and particulates. These all carry varying dangers for the bodies of humans, other animals and plants.

If emissions of these pollutants were halted, we wouldn't miss them. (We would certainly miss the engines and processes causing the emissions, if the halt was achieved by turning them off, since we've built a comfortable society upon them, but that question can wait for another day.)

We wouldn't miss these nasties and we'd be much better off without them—we and our fellow creatures would be both healthier and more comfortable. Reducing these emissions, then, is the proper realm of environmental activism.

But instead, many activists focus on carbon dioxide as our principal enemy, on the questionable grounds that it causes dangerous global warming.

In the United States, CO2 has recently been added to the list of atmospheric pollutants, due to its effect as a so-called "greenhouse" gas. But scientists claim no toxic effect for CO2 except in extraordinarily large concentrations—around 15,000 ppm (parts per million). We now have 385 ppm in the air and everybody agrees it is indispensable to photosynthesis in plants.

Picking on CO2 is a strange development for two reasons: first, because it is axiomatic that life forms do better where it is warmer. This is a fact not commonly referred to in the popular media any more, but it is still as true as it ever was, so we can acknowledge it. A simple series of questions demonstrates its simple truth.

Do you notice how life forms become more numerous and more diverse closer to the equator—how they avoid the polar regions? Do you think that distribution is entirely random, or driven by the temperature?

Do we prefer holiday homes in cold places or warm ones? Is food more plentiful in cold places? Is our population distribution biased towards cold places or warm ones? Is it more expensive to build a comfortable dwelling where it is cold or where it is warm? Do we need more clothing in cold places or warm ones… all right, now it's getting ridiculous.

The point is that we have been induced to fear what we actually prefer. What, really, is wrong with a little warming? By a little, I mean perhaps 3°C—a moderate prediction for the end of this century. Three degrees will hardly boil water, will it?

But the second, and more important, reason this development is strange is that we know carbon dioxide is essential to life. If all the carbon dioxide somehow vanished from the air, we would feel unwell, as though we had been hyperventilating. Symptoms would include tingling in the fingers and dizziness.

Plants, though, would actually soon die, because they need it vitally.

So we're now in the tricky position of trying to limit a substance which naturally permeates the atmosphere and the ocean, is actually good for us and all the plants and creatures around us, on which almost all life depends, and which has been responsible for an extraordinary increase in plant growth rates throughout the world since the Industrial Revolution, saving our now enormous population from almost certain widespread starvation.

These are crazy times.

Nevertheless, CO2 is now ranked alongside sulphur dioxide, which gets converted to sulphuric acid in the air before falling on forests and buildings as acid rain, helping to destroy them.

Carbon dioxide is now considered in the same breath as nitrogen dioxide, which is toxic if inhaled and visible as the brown haze over the city on work days.

It is now lumped in with VOCs, some of which are suspected carcinogens and which contribute to indoor and outdoor pollution, including "sick building" syndrome.

Yet CO2 is responsible for none of these effects, nor any other effects remotely similar. It is colourless, odourless and tasteless. Its only failing is to be a rather minor greenhouse gas. Water vapour's contribution to the greenhouse effect is greatly more than mankind's CO2 and any climate scientist will tell you so.

The total human contribution to the earth's greenhouse effect, from all sources, is only about 0.28%. It's unclear whether that includes the CO2 released from champagne bottles during wedding receptions, Formula One drivers winning races and from soft drinks for little children at birthday parties.

If we caused 0.28% of the increase in global temperature since 1850 of about 0.7°C, that's far too little to detect or bother with.

Crazy, crazy times.


– Richard Treadgold is Convenor of the Climate Conversation Group.