0706G － CSMY作文互改小组-第5次作业

meichengyuUID: 2121098

TOPIC: ARGUMENT47 - Scientists studying historical weather patterns have discovered that in the mid-sixth century, Earth suddenly became significantly cooler. Although few historical records survive from that time, some accounts found both in Asia and Europe mention a dimming of the sun and extremely cold temperatures. Either a huge volcanic eruption or a large meteorite colliding with Earth could have created a large dust cloud throughout Earth's atmosphere that would have been capable of blocking enough sunlight to lower global temperatures significantly. A large meteorite collision, however, would probably create a sudden bright flash of light, and no extant historical records of the time mention such a flash. Some surviving Asian historical records of the time, however, mention a loud boom that would be consistent with a volcanic eruption. Therefore, the cooling was probably caused by a volcanic eruption.
WORDS: 356          TIME: 0:30:00          DATE: 2007-1-20

Citing several unfounded assumptions as well as some dubious evidence and presenting some simple analysis, the author recommends that the cooling in the mid-sixth century was probably caused by a volcanic eruption. However, we do not have to look very far to see the line of the reasoning suffers from several critical flaws which will be discussed as follows.

To begin with, the author fails to establish the casual relationship between the fact that suddern cooling of the earth and the assertion that a volcanic eruption was the main reason of the weather. Obviously, the arguer only listed two possibilities of a huge volcanic eruption and a large meteorite colliding with Earth which could have created a large dust cloud throughout Earth's atmosphere that would have been capable of blocking enough sunlight to lower global temperatures sharply. Other possibilities could also cause decreasing sunlight like the change of Earth orbit or large comet's blanching, which ignored by the arguer. Without ruling out such possibilities, the conclusion from the analysis would be unconvincing and baseless.

In addition, another point that may also weaken the logic of this argument is that because few historical records survive from that time, the arguer could not get the conclusion from few surviving Asian records of a sudden bright flash of light. It is highly possible that the bright flash was not caused by the collision of meteorite at all but maybe some comet's tail traveling by Earth. Even though it was a meteorite collision, there was no evidence to show that the collision was large enough to cause the global dust cloud and ultimately the sharp cooling of temperatures. Thus, it was a hasty summing-up from the argument.

Last but not least, before I come to my own conclusion, it is necessary to point out another flaw that also undermines the argument. The arguer fails to illustrate that the heat energy of Earth was all from the sun. If other factors like the geothermal energy could also be the source of Earth’s heat, the conclusion of the author was pretty doubtful and groundless.

All in all, although the argument seems to be plausible, it is neither sound nor persuasive. The conclusion lacks credibility because the evidence cited in the analysis fails to lend strong support in the arguer's claim. To make it more logically acceptable, the author should have to provide much more evidence concerning the giving factors above.