Know your Global Warming Facts #2

Atmospheric Carbon Dioxide

Carbon Dioxide is a "Greenhouse Gas". This means that, when the sun's rays hit our atmosphere, visible light passes through but infrared light is absorbed by some of the gases therein. Any Greenhouse gas that absorbs this light essentially absorbs its energy, which means, in simple terms, the gas gets hotter.

There are a number of different sorts of Greenhouse gas, but the most common one is Carbon Dioxide. Of course, Carbon Dioxide is an integral part of our atmosphere and is essential to the development of life on our planet. As we all know, the process of photosynthesis in plants turns sunlight and carbon dioxide into energy for the plant to grow. A byproduct of photosynthesis is the production of oxygen.

The argument of modern climate scientists is that the increase in carbon dioxide in our atmosphere will result in higher global temperatures. The reason for this is both scientific and historical.

In terms of science, an increase in carbon dioxide into the atmosphere will result in more infrared radiation from the sun being stored in the atmosphere - which essentially means that the atmosphere gets hotter. Moreover, as light reflects from earth, greenhouses gases (including CO2) help to reduce our planet's albedo (the ability to reflect light and not absorb it).

Here in Australia, a lot of us drive white cars. One reason we do is because white reflects the sunlight better and makes cars cooler than those painted darker colours. If Greenhouse gases in our atmosphere increase, it is like having a darker paint on your car.

This is backed up by historical data. Ice core samples taken from places like Greenland and Antarctica give us a "snapshot" of what atmospheric conditions were like up to 400 thousand years ago. What it shows us is that during periods where the earth was relatively warm, CO2 levels were correspondingly high, while when earth was cool, the CO2 levels were quite low.

Moreover, these same studies indicated that CO2 levels ranged between 180 - 210 ppm (parts per million) during cold periods, and between 280 - 300 ppm during warm periods.

According to historical data measured at Mauna Loa, Hawaii, for the past 40 years or so, CO2 levels around the world have been increasing steadily for some time. Presently, CO2 levels are 384ppm - substantially higher than at any time in the last 400 thousand years. The Mauna Loa figures date back to 1957, but other CO2 measurements around the world since that time have validated these figures, which show a marked increase in atmospheric CO2. Moreover, the ice core samples I spoke of earlier contain much evidence from the last few centuries, and not just the last 400 thousand years. What these samples show is that CO2 levels around the world began to increase in the early-mid 19th century - the period known as the "Industrial Revolution".

While the specifics of Global Warming are yet to be determined, the broad implications are clear - recent measurements clearly indicating global warming have their basis in increased levels of Carbon Dioxide in the atmosphere which, in turn, have their basis in human activity for the past 200 years. The burning of oil and coal and other fossil fuels to produce energy is beginning to heat up the atmosphere.

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