Argument45 by zephyrqq

zephyrqqUID: 2260290

Argument45 "Arctic deer live on islands in Canada's arctic region. They search for food by moving over ice from island to island during the course of a year. Their habitat is limited to areas warm enough to sustain the plants on which they feed, and cold enough, at least some of the year, for the ice to cover the sea separating the islands, allowing the deer to travel over it. Unfortunately, according to reports from local hunters, the deer populations are declining. Since these reports coincide with recent global warming trends that have caused the sea ice to melt, we can conclude that the decline in arctic deer populations is the result of deer being unable to follow their age-old migration patterns across the frozen sea."
字数：532                  日期：2008-2-16 20:55:23

According to what is pointed out in this argument, a report from hunters in Canada's arctic region indicated that the population of arctic deer are declining and this tendency coincide with recent global warming trends which have caused the sea ice to melt. However, the author assumes that the coincidence implies causation, and therefore makes an unwarranted conclusion, which asserts that the decline in arctic deer populations is the result of deer being unable to follow their age-old migration patterns across the frozen sea.

First of all, the global warming does not necessarily prevent the deer to follow their age-old migration patterns. Although the warming have leaded sea ice to melt, it is still hopeful that the sea ice in arctic region have not melted yet, for the temperature in this area is often much lower than other district in the world. If this is the case, the deer can move over ice from island to island as ever before. Moreover, even though the arctic ice actually began to melt, as long as some of the year this region is cold enough to from ice to cover the sea separating the islands, the deer can travel over it to another island.

In addition, if the global warming influence the average temperature of Canada’s arctic region so much that these area could not be cold enough for ice, the deer might change their migration patterns. Perhaps the warm climate make the plans on which they feed grow well. As a result, even if the deer are limited in one island, they can still get sufficient food. If this is the case, it seems that there is no need for them to traveling from one island to an other, for the purpose of their age-old migration is to search for food. Accordingly, being unable to move over islands might not cause the decline in arctic deer population.

Finally, there might be other factors which are responsible for the diclining [declining] of deer. It is possible that the amount of plant on which they feed on  decreased, and the reduce of deer is a response to the shortage of their food. It is also possible that the area have been polluted by human activity, so that the natural living circumstance of the deer has been destroyed and the deer find it difficult for them to survive. Or perhaps some of the water resources of the deer is contaminated by some unknown chemical substance,  and the toxic water cause the death of some deer. Other causes, like the fact that there is an increase of the number of their natural enemy and the excessive hunt of local hunters, can also minish the population of the deer. Without ruling out all these factors, we can not accept the author’s conclusion that the reduce of deer is mainly contribute by their inability to move from island to island.

For all these reason, the author fails to convince us that it is the recent global warming, which cause the sea ice to melt, that prevent the deer to move from one island to an other and therefore lead to the declining of the deer population.

[ 本帖最后由 zephyrqq 于 2008-3-6 19:19 编辑 ]