Carbon dioxide is a natural part of our atmosphere even thought it forms just a tiny percentage.
But how much is there and how does it get there and who – or what – is putting it there?
As we have stated, it forms about 390 parts per million in our atmosphere, or 0.039 percent of the total volume of gases in our atmosphere.
Atmospheric carbon dioxide comes from both natural and man-made sources.
The natural sources include the simple process of breathing. We and all other animals exhale a range of gases including carbon dioxide. Natural decay of plant and other organic matter emits huge amounts of carbon dioxide. Volcanos emit carbon dioxide during explosions.
On the man-made side of the ledger, burning fossil fuels emits carbon dioxide. When we run our cars, they emit carbon dioxide among a lot of other gases. Power stations emit carbon dioxide. As an aside, the great plumes we often see on TV screens are mainly water vapour, not carbon dioxide.
But we hear about hundreds of tonnes of gases. How on Earth does one weigh a gas? Of course, we should all remember from our high school science that everything has an atomic weight. Carbon dioxide is a molecule; one carbon atom and two oxygen atoms. It has a molecular weight of approximately 44.
If you are really curious, you can actually conduct an experiment to weigh carbon dioxide. I’m not sure you should try this at home!
So we now know carbon dioxide can be weighed.
What are the greatest sources of carbon dioxide?
Natural decay releases an estimated 220 gigatonnes of carbon dioxide into the atmosphere every year (a gigatonne is a billion tonnes). Estimates of global carbon dioxide emissions from all land and submarine volcanoes are between 130 and 440 million tonnes per year (Gerlach, 1991; Varekamp et al., 1992; Allard, 1992; Sano and Williams, 1996; Marty and Tolstikhin, 1998). In 2008, 31.8 gigatonnes of carbon dioxide were released from fossil fuels worldwide and land use change contributed 1.20 gigatonnes in 2008 (Global carbon budget 2009, University of East Anglia). Humans contribute about 2 gigatonnes. And there are all the animals. The good news about humans and animals is that we are considered a closed loop. Much of the carbon dioxide we exhale is simply a release from our food. The plants we eat have carbon stored through photosynthesis and the animals we eat also store some from the plants they eat!
We can’t prevent natural decay, we can’t plug the volcanoes and I don’t think any of us want to stop breathing! If we are to slow the increase in carbon dioxide in the atmosphere it seems we must turn to the two causes that we can control.
But do we want – or need – to slow the growth in atmospheric carbon dioxide?
The carbon dioxide in the atmosphere is not going to cause us health problems on its own. It is the potential for the gas – along with other greenhouse gases – to increase the atmospheric temperature that we need to consider.
By how much is the Earth atmosphere warming? Can we blame it on the increasing levels of carbon dioxide being detected in the atmosphere?
And will warming damage the planet and the systems we rely upon for a prosperous lifestyle?
Because, even if the planet is warming and even if the warming can be attributed to human activity but the warming is not materially going to affect our lifestyles – except to make Tasmania more comfortable and to wreck our ski fields – why should we act?
[ view entry ]
( 1143 views )
| print article