argument47 [smile] 第五次作业

yxjessieUID: 194526

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: 395          TIME: 0:30:00          DATE: 2006-8-2

According to the reasons listed above, the conclusion that the significantly cooler of the earth was caused by the volcanic eruption is sound relatively right. However, the author overlooks a lot of other reasons that might cause the cooling, and misunderstands some of the available evident.

First of all, the author assumes that the dimming of the sun was caused by a large dust cloud, which is not convinced.  A lot of other reasons might lead to the decrease of the earth's temperature. It is possible that the sun at that time had some chemical or physical changes by itself so that it cannot spread more heat as much as before. Or perhaps there were other planet moving to the middle place between the sun and earth, preventing the enough heat to arrive at the earth.

Secondly, even though the cooling is caused by a large dust cloud that might from a large meteorite, no extant record mention a flash that might be created by the meteorite dose not necessarily mean there was no meteorite happened at that time. Since the meteorite cannot create a flash of light at the 100 percent, it is possible that there was a meteorite existed, which did not create a light then. The author also overlooks the long time passed by from the mid-sixth century. It is possible that the meteorite was recorded, but those records were lost. Only the mention that there is no records mention the flash cannot prove that there was no such flash happened.

Last but not the least, the mention of a loud boom may not from a volcanic eruption as what the author mentioned in this argument. Other natural changes such as earthquakes, hurricanes, even the large animals' cries might be the source of the loud boom, since the location of the boom might be so far from the listener who might make mistakes of the sound types and resource. If the boom was from other resources other than volcanic eruption which might not happened, the conclusion of this argument must be doubtful.

Before the author make a conclusion on what caused the cooling of the earth at that time, he still needs to gain more evident of what caused the less sunlight arrived at the earth, whether there were meteorite happened and what’s the truly resource of the big boom happened then.

[ 本帖最后由 yxjessie 于 2006-8-3 15:51 编辑 ]