Abstract

David B. South, Xuhui Lee and Michael G. Messina

For decades, forest researchers have known that planting trees on cropland or pastures (that is, afforestation) can lower the surface albedo and that landscapes with low albedo absorb more solar radiation than more reflective surfaces. Consequently, afforestation will typically darken the Earth’s surface (when compared to grasslands or deserts). In spite of this knowledge, many believe that afforestation will cool the Earth’s atmosphere since wood is composed of carbon molecules. Therefore, there are two schools of thought on how afforestation affects global climate. The “CO 2 School” believes that afforestation will have a cooling effect, regardless of the location of the planted trees. In contrast, the “Holistic School” believes the climate is a complex system affected by numerous variables, including clouds and the surface albedo. Many from this School say that afforestation in boreal zones could warm the Earth. This paper reviews some papers from the “Holistic School” and asks the question: will afforestation in temperate zones warm the Earth?