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, specifically the difference between tropical and boreal forests. Many assume all forests absorb carbon dioxide equally. But recent research shows that while tropical forests absorb large amounts of CO2 year-round, boreal forests—those in high northern latitudes—may actually contribute to warming. How? Well, in winter, snow covers the ground, but the dark evergreen trees absorb sunlight, reducing the albedo effect, which is the reflection of sunlight back into space. Less reflection means more heat absorbed. In contrast, during summer, boreal forests do take in CO2, but the net effect over a year is complex. Meanwhile, tropical forests have high evaporation, creating clouds that reflect sunlight, enhancing cooling. So, planting trees in the wrong place might not help mitigate climate change as much as we thought. This challenges the simple idea that reforestation is always beneficial.
❓ Question According to the professor, what is the main reason boreal forests may contribute to warming?
A. They release large amounts of carbon dioxide during winter.
B. Their dark trees reduce the reflection of sunlight when snow is present.
C. They have lower evaporation rates than tropical forests.
D. They absorb less carbon dioxide than tropical forests in summer.
✅ Correct Answer
Their dark trees reduce the reflection of sunlight when snow is present.
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