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Regional Impacts of Global Warning
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15895 |
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Section : |
NATURAL SCIENCE
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| Issue
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1 / 1989 |
2,740 Words |
| Author
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Michael H. Glantz
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Speculation abounds about whether the global atmosphere is heating up due to the increases in atmospheric carbon dioxide (CO2) and other trace gases--and, if so, at what rate. There is also much speculation about how a global warming might alter existing regional and local weather patterns. To speak of changes in global average temperatures fails to identify how those changes might affect regional temperature and precipitation variations, local and regional meteorological extremes, and other regional disparities. The average global temperature alone does not provide a true picture of impacts on a worldwide scale. It is like asking someone what his body temperature is while his feet are in a bucket of hot water and his head is in the refrigerator: On "average" it will be normal.
Providing a reliable picture of the regional impacts of a global warming is a major challenge now facing the scientific research community. Equally challenging to social scientists and policymakers is the identification of social responses that might be necessary to mitigate the regional impacts of a global warming.
To date, several attempts have been made to get a glimpse of future climate. One way has been the use of complex computer models to generate scenarios about the future. Scientists identify appropriate parameters (as well as relationships between them, such as carbon dioxide content and atmospheric temperatures) and use these as inputs to construct sophisticated models to be run on the largest and fastest computers in the world.
This sounds impressive. However, the predictions at various research centers do not agree with each other regarding either temperature or rainfall, although temperature projections associated with a CO2 increase in the atmosphere are in closer agreement than those for precipitation. Despite the fact that the best-trained scientists and the most advanced computers are working on the problem, the reliability of their findings is fairly low. So the search continues for ways to foresee the impacts of and environmental and societal responses to possible changes in the climate.
A different approach to identifying regional climate change is based on some principles associated with global warming projections. Scientists have speculated that whatever the temperature rise in the mid-latitudes of the Northern Hemisphere, it will be considerably higher in the polar regions (and considerably lower in the equatorial regions). Based on this premise, scientists have identified the 10 warmest Arctic summers of the past century in order to make a composite of what the climate was like in the mid-latitude regions during these years and to see whether recurring climatic patterns could be identified. This is an innovative approach, but it has some drawbacks. For example, a wet autumn produces soil moisture, which is important for the next year's crops as well as for the region's climate.
Yet another attempt at a glimpse of future climate impacts has focused on reconstructing global climate using paleoecological data of the period when the earth was considerably warmer than it is today. Such a period occurred between 4,000 and 8,000 years ago and is referred to as the Altithermal period. This approach, while also innovative, likewise has problems. First of all, the factors bringing about the warmer temperatures in that period were not the same as those of today. Thus, a future warming would most likely have
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