Rainforest
Rainforests are forests characterized by high rainfall, with annual rainfall in the case of tropical rainforests between
250 and 450 centimetres and definitions varying by region for temperate rainforests. The monsoon trough,
alternatively known as the intertropical convergence zone, plays a significant role in creating the climatic conditions
necessary for the Earth's tropical rainforests.
Around 40% to 75% of all biotic species are indigenous to the rainforests. There may be many millions of species of
plants, insects and microorganisms still undiscovered in tropical rainforests. Tropical rainforests have been called the
"jewels of the Earth" and the "world's largest pharmacy", because over one quarter of natural medicines have been
discovered there. Rainforests are also responsible for 28% of the world's oxygen turnover, sometimes misnamed
oxygen production, processing it through photosynthesis from carbon dioxide and consuming it through respiration.