Rainforests help stabilize the world’s climate by absorbing carbon dioxide from the atmosphere. Scientists have shown that excess carbon dioxide in the atmosphere from human activities is contributing to climate change. Therefore, living rainforests have an important role in mitigating climate change. But when rainforests are chopped down and burned, the carbon stored in their wood and leaves is released into the atmosphere, contributing to climate change.

Rainforests also affect local weather conditions by creating rainfall and moderating temperatures.

Rainforests and rainfall

Rainforests contribute to rainfall through transpiration, which is the process of water movement through a plant and its release into the air via leaves, stems, and flowers. Plants release water as a byproduct of photosynthesis.

Water released by plants contribute to local humidity or moisture in the air. Because a forest consists of a large number of trees, the volume of water released via transpiration can contribute to the formation of rain clouds, resulting in rainfall. Very large rainforests, like the Amazon, can drive rainfall over very large areas. By one estimate, the Amazon is reponsible for 70% of rainfall in southern Brazil.

Rainforests and local temperature

Tropical forests can have a localized cooling effect by increasing humidity through transpiration and contributing to wind currents. Additionally, shade from the forest canopy can result in dramatically cooler temperatures relative to areas exposed to direct sunlight. In fact, one of the top complaints from local people following deforestation is about the increase in local temperature.

 

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Review questions

  • How do rainforests affect the climate?
  • How do rainforests affect rainfall?
  • How do rainforests affect local temperatures?
  • What is one reason why the Amazon rainforest is important?
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