Here we see the effects of deforestation in the Mau Forest Complex, which NASA describes as “Kenya's largest closed-canopy forest ecosystem and the most important water catchment in the Rift Valley and western Kenya.” On the left is Jan. 31 through Feb. 1, 1973. On the right is Dec. 21, 2009. Since 2000, as much as a quarter of the forest has been lost, as shown by the yellow arrows in the images. The loss of trees in the planet’s water cycle is critical to the advancement of climate change. Trees return water vapor back into the atmosphere, as well as provide ground cover for moist soils. Their removal exposes land to the drying effects of the sun, further aerating dry lands. What’s more, trees and vegetation play an important role in absorbing greenhouse gases.