▶ Topic : In the reading passage, there is ample support for the author's claim that several factors result in increasing global temperature. However, in the lecture, the professor gives several reasons as a rebuttal to the author's claim.
First, the professor insists that methane, released from landfill, makes up for only 9 percent of the greenhouse gases and consists of 1 percent of the atmosphere. The amount is too low to affect to raise temperature. This casts doubt on the reading passage's claim that methane keeps heat from escaping into out of the earth.
Next, the professor contends that when trees die naturally, they will release all of the mount of the carbon dioxide that they absorbed. However, cutting down trees intentionally can reduce these phenomenon. This counters the reading passage's assertion that trees absorb dioxide and these matter are emitted when people harvest forest.
Finally, the professor argues that global warming is not cycle of climate change. During the medieval warm period, Northern Hemisphere is warmer while other place was cooler. In addition to, during this period, average global temperature was lower than today. This refutes the reading passage's suggestion that global warming is natural cycle. |