▶ Your Answer :
The reading passage contends that there are plausible theories why global temperatures decreased from the early 1300s until the late 1800s. On the other hand, the lecturer brings up several points that contradict the reading passage.
First, the lecturer argues that diminished solar radiation would not make lower the temperature. The scientist measured a few sunspots but solar radiation did not decline. Therefore, the total amount of solar radiation is not related to the number of sunspots. This rebuts the reading passage’s claim that diminished solar radiation because of the decreased number of sunspots triggered the Little Ice Age.
Second, the lecturer claims that volcanic eruption is not likely to cause temperature drop. These volcanic eruption does not take up the whole centuries. They only last few years. However, the Little Ice Age lasts 500 years. Therefore, it does not make sense. This refutes the reading passage’s claim that the temperature dropped because a massive volcanic eruption occurred.
Finally, the lecturer maintains that the Earth’s reflectivity did not significantly increase. Glaciers and snow is not only the factor of increasing in the Earth’s reflectivity. The cloud also could be the cause, which reflects the Earth. However, in the Ice Age, the less evaporation of water made less formation of the cloud, which as a result made less reflectivity. Hence, the total reflectivity would not increase much. This casts doubt on the reading passage’s claim that global cooling can decrease global temperatures. Since ice and snow reflect about 90 percent of sunlight which results in Little Ice Age.
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