GLOBAL WARMING


Global warming is saidas the greatest threat facing humanity. What worries researchers, says the journal Science, “is the prospect that we’ve started a slow-moving but relentless avalanche of change”. Skeptics question this assertion. True, many agree that the earth is warming, but they are uncertain of both the causes and the consequences. Human activities may be a factor, they say, but not necessarily the primary one. Why the disagreement?
For one thing, the physical processes that underlie global climate system are complex and not fully understood. In addition, interest groups tend to put their own spin on the scientific data, such as that used to show why temperatures are rising.
According to the recent report of the UN-sponsored International Panel on Climate Change (IPCC), global warming is “unequivocal”, or a fact; and “very likely”, humankind is largely to blame. Some who differ with this conclusion, especially about the human factor, concede that cities may be heating up because they are growing in size. Moreover, concrete and steel readily absorb the sun’s heat and tend to cool down slowly at night. However, urban readings, Skeptics say, do not reflect the trend in rural areas and can distort global statistics.
In 2007, warming was also evident in the Northwest Passage, which was fully open for the first time in recorded history. “What we’ve seen this year fits the profile of lengthening melt seasons,” said a senior scientist for the National Snow and Ice Data Centre in the United States.
A reason given for such changes is an intensification of the greenhouse effect, natural phenomenavital for life on earth. When energy from the sun reaches the earth, about 70 percent is absorbed, heating air, land, and sea. The average surface temperature would be about minus 18 degrees Celsius. Eventually, the absorbed heat is released back into space as infrared radiation, thus preventing the earth from overheating. However, when pollutants change the composition of the atmosphere, less heat escapes. This can cause earth’s temperatures to rise.
Gases that contribute to greenhouse effect include carbon dioxide, nitrous oxide, and methane, as well as water vapour. The atmospheric concentration of greenhouse has increased markedly over the past 250 years, since the start of the industrial revolution and the increased use of fossil fuel, such as coal and oil. Another greenhouse-enhancing factor seems to be the rising population of farm animals, whose digestive processes produce methane and nitrous oxide. Some researchers point to other causes of warming that they say occurred before humans could have influenced the climate.
Skeptics point to the so-called ice ages, when the earth was supposedly much cooler than it is now; and in support of natural warming, they cite evidence that cold regions, such as Greenland, at one time supported vegetation that prefers warm areas. Of course, scientists concede that the further back they go, the more their certainty about climate change diminishes.

Published by MyWritings

A Writer, A Diplomat in Waiting, Climate Change Advocate and a Football Administrator

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