GLOBAL WARMING



Climate Change - what are the underlying facts?

The greenhouse effect issue concerns the warming of the lower part of the atmosphere, the troposphere which is about 10-15 kilometers thick, by increasing concentrations of the so-called greenhouse gases (carbon dioxide, methane, nitrous oxide, ozone, and others). This warming occurs because the greenhouse gases, while they are transparent to incoming solar radiation, absorb infrared (heat) radiation from the Earth that would otherwise escape from the atmosphere into space. The greenhouse gases then re-radiate some of this heat back towards the surface of the Earth.

The natural balance of the greenhouse gases ensures that the earth's temperature is maintained within a limit. Some activities of man also produces greenhouse gases upsetting the balance of the greenhouse gases. Because of higher emission of greenhouse gases in the atmosphere, more heat is trapped which makes the Earth warmer. This is known as GLOBAL WARMING.

We have witnessed unprecedented warming of the planet in the past 25 years but for rapid change in human activities. The years 2005 and 1998 were probably the warmest years of the last millennium. The 1990s was the warmest decade and the 20th century the warmest century.

Overwhelming scientific evidence supports the conclusion that the observed changes in the global climate are, in large part, due to human activities and primarily related to fossil fuel consumption patterns. Climate change is caused by increased levels of carbon dioxide and other gases in the Earth's atmosphere as a result of human activities such as burning coal, oil and gas for transport and energy, and cutting down forests. Greenhouse gases include methane, nitrous oxide, ozone and water vapour, but environmentalists are concentrating on carbon dioxide, as it is the one that can be controlled even at the level of individuals and institutions.

Carbon Dioxide is a global problem, but the countries that produce the greatest amount per person are in North America, Europe and Australasia.

Future Projections

'The United Nations Intergovernmental Panel on Climate Change (the IPCC - a high level, independent, scientific advisory body) has published studies which state that unrestrained greenhouse gas emissions could drive global temperatures up as much as 6 degrees centigrade by 2100, triggering raised sea levels, species destruction, economic devastation in tropical zones and mass human migrations.

The graph above, which has been produced by the IPCC shows that most of the change has been in the past century as the world industrialised and population has grown rapidly. From fluctuating in a narrow band around 0.5°C below the average 1990 temperature, it has started to rise sharply and is most likely to be between 1.5°C and 5.5°C above current temperatures by 2100.


Impact

This would have a catastrophic effect on the earth, with widespread melting of glaciers and ice-sheets, and a highly probable rise in sea level that could lead to the inundation of countries such as the Netherlands and Bangladesh. Latest scientific concern is focused on melting ice lowering salinity in the North Atlantic Ocean, which could lead to the reversal of the "Great Atlantic Conveyor" - better known as the Gulf Stream. If this were to happen, we could find that temperatures in NW Europe, including Britain, drop by up to 10°C, despite temperatures elsewhere in the world rising.


 
 

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