การฟัง TOEFL

🎧 บทถอดเสียง

Listen to part of a lecture in an environmental science class. Today we're going to discuss a surprising factor in climate change: the role of forests. You might think that planting more trees is always good for the environment, and in many ways, it is. Trees absorb carbon dioxide, a major greenhouse gas, during photosynthesis. However, recent research has shown that in some regions, forests can actually have a warming effect. How is that possible? Well, it's about albedo, which is the reflectivity of the Earth's surface. Snow and ice have high albedo, meaning they reflect sunlight back into space. Dark surfaces, like forests, have low albedo and absorb more heat. In snowy areas, such as the boreal forests of Canada and Russia, the dark canopy of trees absorbs sunlight that would otherwise be reflected by the snow. So, while these forests store carbon, their net effect on temperature can be warming, especially in the short term. This doesn't mean we should stop planting trees, but it highlights the need for careful planning based on local conditions.