The Facts
new internationalist
issue 206 - April 1990
Kurbandurdy Muradov / CAMERA PRESS
Seen from space, our planet is a green and blue orb floating in an
apparently lifeless cosmos. A fragile balance, a fine ecological interdependence,
exists in the natural world which keeps the earth pulsing with life. Here the NI
details how that balance is now being upset by the depredations of humans.
The difference between climate and weather is like the difference between the forest and the trees. Advert Weather is what we experience (and complain about) on a daily basis. We understand it in the familiar terms of the weather report: cloudy, windy, rainy, humid, sunny or snowy. Climate is a description of average weather conditions over time, a period of at least 30 years or more.
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Climate results from interaction between the atmosphere, the oceans, the land surface, the polar ice caps and biological life (plants, animals and humans). Our climate is constantly changing, but most of the change takes place over generations and goes unnoticed. However, a sudden extraordinary event in one place can bring about rapid change all over the globe. For example:
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Carbon dioxide is the single most important greenhouse gas and is linked directly to industrial development and deforestation.
The West (15% of world pop.) - 46%
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A layer of gases in the atmosphere acts like an insulating blanket trapping solar energy that would otherwise escape into space. Without these 'greenhouse gases' the earth would be frozen, barren and lifeless.
HOW IT WORKS |
By analyzing gas trapped in glacial ice scientists have found CO2 levels have risen steadily since the Industrial Revolution. CO2 concentrations are presently rising by 3-4% a decade and have increased by 25% over the last 300 years.
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Over the past 300 years, as a result of human activity, concentrations of the main greenhouse gases have increased significantly. There are strong indications that global warming has already begun as a result.
Estimated contribution to global warming of main greenhouse gases in the 1980s.
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THE MAIN GREENHOUSE GASES
Carbon dioxide (CO2)
Methane (CH4)
Chlorofluorocarbons (CFCs)
Nitrous oxide (N2O)
Surface Ozone (03) |
Sophisticated computer models predict the earth's surface temperature will rise between 3 and 5°C by the middle of the next century - change unprecedented in human history. The exact impact of such a change is unclear. But scientists predict12:
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1 The Gaia Atlas of Planetary Management, ed. Norman Myers (Doubleday, 1984). |
This article is from
the April 1990 issue
of New Internationalist.
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