Though the most vibrant colors have already faded for the fall, trees are still undergoing their yearly change as winter approaches. In recent years, the understanding of how and why leaves change colors has grown, according to Central College Associate Professor of Biology Paul Wiehe. Conventional wisdom held that the leaves possessed all those colors and they were simply revealed as the green faded. However, new studies have shown that red leaves act as a sort of sunscreen, protecting the leaf while the tree re-absorbs that energy before it falls. This also helps explain why the leaves fall at different times.