Narrator: Listen to part of a lecture in an environmental science class. Professor: Today, we're going to discuss a surprising factor in climate change: the role of forests. While most people know that trees absorb carbon dioxide, recent research shows that forests also release compounds called terpenes. These organic chemicals, which give pines their smell, react with sunlight and oxygen to form aerosols. Aerosols are tiny particles that can either cool the Earth by reflecting sunlight back into space or warm it by trapping heat. The net effect depends on the size and altitude of these particles. In clean, remote areas, terpenes lead to more low-altitude clouds that reflect sunlight, causing a cooling effect. However, near industrial regions, these terpenes mix with pollutants, creating particles that can trap heat, worsening warming. So, forests are not just carbon sinks; they have a complex, two-sided impact on our climate. This means that planting more trees, while beneficial, may not always be a simple fix for global warming.
❓ Question What is the main point the professor makes about forests and climate?
A. Forests only help cool the climate by absorbing carbon dioxide.
B. Forests have a complex impact on climate, including both cooling and warming effects.
C. Terpenes from forests always cause a warming effect.
D. Planting more trees is the most effective solution to global warming.
✅ Correct Answer
Forests have a complex impact on climate, including both cooling and warming effects.
TOEFL Listening Tips
Skim the questions first to predict the content
Watch for signal words in lectures and conversations (however, actually, in fact)
For main idea questions, focus on the beginning; for detail questions, focus on examples and data
For attitude questions, pay attention to the speaker's tone and word choice
Take notes on keywords; don't try to write down every word