A rainforest is a thick forest that gets a huge amount of rain, usually more than 2,000 millimetres a year. Rainforests cover only approx. 6% of Earth's land but contain more than half of all the animal and plant species we have ever discovered. Walking through a tropical rainforest, you can hear, see, smell and feel more life packed into a single hectare than almost anywhere else on the planet.
- Rainfall per Year2,000+ mmoften over 3,000 mm
- Largest RainforestAmazon5.5 million km², South America
- % of Earth's Landapprox. 6%down from approx. 14% a century ago
- % of Animal Species50%+live in rainforests
- Average Temperature20 to 27 °Call year round
- Oldest RainforestDaintreeapprox. 180 million years, Australia
How big are the famous rainforests?
Area in millions of square kilometres:
The Amazon dwarfs every other rainforest. It is nearly three times bigger than the Congo, the second-largest, and the only rainforest that runs through nine different countries.
What is a rainforest?
A rainforest is a forest where rain falls almost every day. There are two kinds: tropical rainforests (warm and wet all year, near the equator) and temperate rainforests (cool and wet, found in a few places further from the equator like the west coast of Canada or southern Chile).
The four layers of the rainforest
A tropical rainforest is built like a four-storey building, each floor with its own kind of life.
- Emergent layer (top): a few giant trees poke above the rest, up to 60 metres tall. Eagles and large monkeys live up here.
- Canopy (30 to 45 m): the leafy ceiling. Around 60 to 90% of the forest's animals live in the canopy.
- Understorey (a few metres up): shaded, hot and damp. Vines, ferns and small trees grow here.
- Forest floor: very dark because only 2% of sunlight reaches the bottom. Fallen leaves break down fast in the warm wet air.
Wildlife of the rainforest
Rainforests are the planet's biggest libraries of life. The Amazon alone is home to jaguars, sloths, anacondas, pink river dolphins, hundreds of frog species, and over 1,300 species of bird. The Congo has gorillas, forest elephants and okapis. Borneo has orangutans. New rainforest species are still being discovered every year.
Why rainforests matter
Rainforests produce huge amounts of oxygen, soak up carbon dioxide that would otherwise warm the planet, and create their own rain by pumping water vapour into the sky. Indigenous people have lived in rainforests for thousands of years and know more about their plants and animals than any scientist.
Threats to rainforests
Rainforests are being chopped down faster than they can grow back. Roughly an area the size of a football pitch disappears every two seconds, mostly to make room for cattle ranches, soy and palm-oil plantations, and roads. Saving them is one of the most important environmental jobs of this century.
Deeper dive: tropical vs temperate rainforests
Most rainforests are tropical and sit in a band around the equator (Amazon, Congo, Borneo). But there are also temperate rainforests in cooler parts of the world.
- Tropical rainforests: hot (20 to 27 °C all year), very wet (2,000 to 10,000 mm of rain), and packed with species. The canopy stays green all year.
- Temperate rainforests: cool (4 to 12 °C), still very wet, but with fewer species and giant evergreen trees. The Tongass in Alaska, the Valdivian in Chile, and the rainforests of British Columbia are the main examples.
Pick a rainforest below to read its fact file.