Global Ecological Problems and Issues

The greenhouse effect refers to the ability of the Earth's atmosphere to trap the Sun's infrared radiation (heat). Because of the existence of the present kind of atmosphere, the Earth is currently about 30 centigrades warmer than it should otherwise be. Without the greenhouse effect the average temperature on our planet would be about -16 degrees Celsius instead of the present +16 degrees Celsius.

Only some gases are efficient in trapping heat into the atmosphere. Ordinary oxygen and nitrogen molecules do not contribute to the greenhouse effect. Most of the natural greenhouse effect is caused by water vapour. Other substances that contribute to the natural greenhouse effect are carbon dioxide (CO₂), methane (CH₄), nitrous oxide (N₂O) and ozone (O₃).

The use of fossil fuels and the clearing of large forest areas to farmland and pasture are annually producing a lot of extra carbon dioxide. This has started to increase the atmosphere's carbon dioxide content. Also the production of concrete and the draining of peat lands have produced smaller carbon dioxide emissions. At the same time humans are also increasing the atmosphere's nitrous oxide and methane contents and the amount of ozone in the lower atmosphere. Besides this humans have invented a number of new greenhouse gases or climate warming substances that do not exist in the nature. The most important group of such substances are the freons or chlorofluorocarbons (CFCs) that also destroy ozone in the upper atmosphere.

The relative significance of the various greenhouse gases depends on the the time frame that is used in the calculations. Different substances have different lifetimes. Methane breaks down relatively quickly in the atmosphere. Ten kilograms of methane will warm the climate during the next decade as much as a ton of carbon dioxide, but during the next century the impact will only be equivalent to 200 kilograms of carbon dioxide. At this very moment methane is causing approximately one half of the already observable, man-made strengthening of the greenhouse effect. The calculations used in connection of the Kyoto Protocol, however, use a hundred-year rule: they are based on what will be the warming potential of the various substances over the next 100 years.

If the one hundred-year rule is used, carbon dioxide is most probably responsible for 55-60 per cent of the man-made global warming. Most of this is caused by the burning of fossil fuels, and a smaller part (between one seventh to one third) by the destruction of the world's forest cover.

In the one hundred-year framework methane's contribution is between 15 and 20 per cent. The amount of methane in the atmosphere has already more than doubled since 1800. Natural wetlands annually produce about 170 million tons of methane. Rice paddies produce about 110 million, livestock about 80 million, carbage dumps about 40 million, the burning of forest and grasslands about 40 million and the gas-drilling and coal-mining about 80 million tons of methane.

The CFCs used to be make almost 25 per cent of the anthropogenic (human-made) greenhouse gas emissions, but since then their production has almost stopped. Nitrous oxide is responsible for 6 per cent of the greenhouse gas emissions. Probably four-fifths of the man-made emissions are caused by nitrogen fertilizers. The best way to reduce nutrous oxide emissions would be to use organic farming methods or to prefer less harmful types of nitrogen fertilizers. When anhydrous ammonia or aqua ammonia are used, up to 5 per cent of the nitrogen can be released into the atmosphere in the form of nitrous oxide. For instance nitrogen solutions and sodium nitrate seem to be much less harmful. According to the available studies, only about 0.05 per cent of them is converted to nitrous oxide.

The fourth major problem is ozone, which acts as a climate-warming substance in the lower atmosphere. Most of the tropospheric ozone is produced when the nitrogen oxide in the cars' exhaust fumes react with sunlight.

Climate scientists say that the man-made emissions of carbon dioxide, methane and other greenhouse gases might increase the average global temperatures by 1.5-6 centigrade during the 21st century.

According to the International Panel on Climate Change (IPCC), the authoritative scientific body aiming to coordinate research on global warming, the higher temperatures could lead to a rise of 7 to 13 metres in the sea levels during the next 500 years. If sea levels were to become ten metres higher than now, about ten million square kilometres of land and most of the world's fertile farmlands would be inundated. About half of the world's people would lose their homes under the water. Most of our great cities would also be submerged.

The predicted rise is caused by two factors: heat expansion of the sea water and the partial melting of the Greenland and West Antarctic glaciers. According to the IPCC, the thermal expansion of the water "would continue to raise sea levels for many centuries after stabilization of greenhouse gas concentrations". It will take about a thousand years before the warming will reach the bottom of the sea, but during this time the warming predicted for the next century could raise the oceans by four metres.

IPCC scientists predict that a 2.7 centigrade rise in temperatures in Greenland would trigger an "irreversible" melting of its ice sheet. This would raise sea levels by 7 or 8 metres during the next one thousand years.

Some researchers claim that the West Antarctic ice sheet is also showing signs of becoming unstable. According to the latest satellite pictures the largest glacier of the West Antarctic ice sheet, the Pine Island Glacier, is already losing ice faster than snowfall can replenish it. If the glacier continues to melt at the current rate, it will disappear in 600 years, raising global sea level by five more metres. And this five metres would come on top of the rise caused by heat expansion and by the melting of the Greenland ice sheet.

If these scenarios will become true, the continuous rise in sea levels could become the most important single factor sustaining and deepening absolute poverty in the world - at least for a thousand years or so. A major part of the world's population would be pushed into the coastal areas threatened by the rising sea and by hurricanes, because no one else would like to live in these areas, and because the rich and powerful would appropriate for themselves all the good farmland in safer regions. When the sea levels would rise, little by little, the poorest people would have to escape and move, over and over again, losing their homes and a major part of their scarce properties one time after another.

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