12.2

1. 1. Listen to Track 106.

      Now answer the questions.

   1. What aspect of global warming is the lecture primarily about?

      1. Human behavior that has led to the increase in greenhouse gases
      2. The sharp decline in many endangered species
      3. The impact of global temperatures on sea ice formation
      4. Factors influencing global ocean currents

   2. According to the professor, why do geologists track the amount of sea ice over time?

      1. To determine the reflective quality of ice
      2. To understand how the greenhouse effect impacts global temperatures
      3. To study how sea ice and glaciers are related
      4. To track global warming

   3. What is the greenhouse effect, according to the professor?

      1. The reflective quality of snow and ice
      2. The trapping of the Sun’s energy by the atmosphere
      3. The melting and refreezing of sea ice
      4. The pattern of ocean currents around the globe

   4. According to the professor, what is one unique aspect of sea ice?

      1. It forms in the ocean rather than on land.
      2. It is the main way for scientists to track global warming.
      3. It indicates that the North and South polar regions should not be compared.
      4. It provides an example of a natural phenomenon of less interest to scientists.

   5. Why are scientists confused by sea ice in the Antarctic?

      1. It forms on land rather than in the ocean.
      2. There is much less sea ice in the Antarctic than in the Arctic.
      3. It is experiencing a trend similar to that of Arctic sea ice.
      4. It is increasing in volume even as global temperatures rise.

2. 1. Listen to Track 107.

      Now answer the question.

   6. 1. To provide evidence that proves his point
      2. To use a potentially familiar concept to help explain a new concept
      3. To encourage students to visit greenhouses to experience the effect directly
      4. To point to a flaw in the theory of global warming