According to the National Geographic, rainforests could vanish from the planet completely within the next century if current deforestation rates continue." Here's a really cool infographic that illustrates the many, many reasons why we can't let that happen:
"Deforestation also drives climate change. Forest soils are moist, but without protection from sun-blocking tree cover they quickly dry out. Trees also help perpetuate the water cycle by returning water vapor back into the atmosphere. Removing trees deprives the forest of portions of its canopy, which blocks the sun’s rays during the day and holds in heat at night. This disruption leads to more extreme temperatures swings."