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 we often think of trees as carbon sinks, they also release volatile organic compounds, or VOCs. These compounds, like isoprene, can react with nitrogen oxides in the atmosphere to form aerosols. Aerosols, in turn, can either cool the planet by reflecting sunlight or warm it by absorbing heat, depending on their composition. Recent studies show that in pristine forests, these aerosols actually help form clouds, which increase reflectivity. However, in polluted areas, the same VOCs can lead to the formation of harmful ground-level ozone. So, the net climate impact of forests is not simply about storing carbon—it's a complex balance between cooling and warming effects, and human pollution can tip that balance. This complexity makes it challenging to predict future climate scenarios accurately.
❓ Question What is the main point the professor makes about forests and climate?
A. Forests exclusively help cool the climate by absorbing carbon dioxide.
B. The climate impact of forests involves complex processes beyond carbon storage.
C. VOCs released by forests always lead to cloud formation and cooling.
D. Pollution has no effect on the climate impact of forest emissions.
✅ Correct Answer
The climate impact of forests involves complex processes beyond carbon storage.
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
