Argument47【0806G desperado小组】第五次作业by坐照

wangyu0920UID: 199396

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: 457        DATE: 2007-12-17 20:42:42

1.         温度下降不一定是大量灰尘产生的云层造成，也有可能是太阳黑子，大气环流，地球运动等其他因素
2.         没有记录并不意味着没有陨石碰撞。可能记录了没有保存下来，也可能在其他无人区发生，无法被记录
3.         一声巨响与火上喷发没有必然的因果联系
4.         没有证据表明火上喷发是在气温下降之前发生的

In this argument, the arguer asserts that the cool of the earth in the mid-six century was caused by a volcanic eruption. To support the assertion, the arguer claims that accounts that mentioned a dimming of the sun and extremely cold temperatures were found both in Asia and Europe. Meanwhile, the arguer believes that either volcanic eruption or meteorite colliding with Earth could lower global temperatures significantly. After all, since there is no historical record of a sudden flash created by a meteorite collision while there were several records of volcanic eruption, the arguer assumes that it was the volcanic eruption which caused the cooling of Earth. However, I find the evidence is insufficient and hence does not lend a solid support to what the arguer assumes.

First of all, the arguer fails to provide reliable evidence that it was truly the large dust cloud that caused the cooling of the earth. As we all know, there are other factors, such as the movement of sunspot, the atmospherically circular current and the transfer of the earth running orbit, which might affect the temperature of the earth. The arguer concludes that it was the dimming of the sun led to cold temperatures too hastily.

Moreover, even if the decrease of the temperature was caused by dust cloud, the arguer fails to take into account that a large meteorite collision could still probably occur although there was no historical record. It is entirely possible that the meteorite collision was recorded while people have not found yet or the records had been lost since they were really difficult to maintain during such a long time. Or perhaps the collision occurred in solar area where no human beings lived there that it was impossible to be recorded.

Finally, even though there was not any meteorite collision, the causal relationship between a loud boom and a volcanic eruption is questionable. On one hand, it was not records that recorded the eruption of a volcano and there is no further information to prove the boom was made by the volcanic eruption. On the other hand, the evidence provided in this argument is irrelevant to validate the assumption that the eruption occurred before the decrease of the temperature. Otherwise, the cold temperatures could not be caused by the eruption definitely.

In conclusion, the argument is not well supported as it stands. To make the argument more convincing, the arguer would have to provide more evidence that (1) it was the truly the large dust cloud that caused the cold temperatures (2) there was not any meteorite collision all over the earth at that time (3) a volcanic eruption indeed occurred at that time (4) the volcanic eruption occurred before the decrease of the temperatures