How deforestation and decreased rainfall are related?

Deforestation directly causes decreased rainfall in affected regions through disruption of the water cycle, creating a feedback loop that can transform forested areas into drier landscapes. Trees play a crucial role in rainfall generation through transpiration—the process where tree roots absorb groundwater and release water vapor through leaf pores into the atmosphere. A single large tree can transpire hundreds of liters of water daily, and forests collectively pump massive amounts of moisture into the air, forming clouds that eventually produce rain. When forests are cleared, this moisture recycling stops, reducing atmospheric humidity and cloud formation over the region. Studies show that large-scale deforestation in areas like the Amazon can reduce regional rainfall by 20-30%, as the land loses its capacity to generate precipitation.

Forests also influence rainfall patterns through their effects on temperature and air circulation. The dark green canopy absorbs solar radiation differently than bare ground or cropland, affecting local temperatures and creating air pressure differences that drive weather patterns and rainfall. Deforested areas heat up more quickly, altering wind patterns and reducing convective rainfall. Furthermore, trees slow down rainwater, allowing it to infiltrate soil and recharge groundwater rather than running off quickly—this stored water continues feeding streams and maintaining humidity during dry seasons. Without forests, landscapes experience more extreme conditions: intense but irregular rainfall events that cause flooding, alternating with prolonged droughts. This phenomenon has been documented across tropical regions where deforestation has led to declining agricultural productivity due to reduced and increasingly unpredictable rainfall, ironically undermining the very farming activities for which forests were cleared.