Forests, air & climate

Just as our lungs absorb carbon dioxide from the blood and infuse it with oxygen, green plants absorb carbon dioxide during photosynthesis and release oxygen into the atmosphere in return. This is why forests are often referred to as the Earth's lungs.

Forest under mist, Kayan Mentarang National Park,Kalimantan, Borneo, Indonesia
© Alain Compost / WWF


Forest as the Earth's air purifiers

Carbon guzzlers

We all know about photosynthesis - the production of energy in the presence of light by chlorophyll-containing plant parts for the subsistence of the organism. Carbon dioxide, the major greenhouse gas, is a major requirement of photosynthesis.

This suits us just fine as it means forests form an effective sink for the carbon dioxide produced as a result of animal respiration, burning of fossil fuels, volcanoes and other natural and human-induced phenomenon.

Even better, a by-product of photosynthesis is oxygen.

Thus, the Earth's forests act as the Earth's air purifiers, soaking up large amounts of carbon dioxide absorbed from the atmosphere.
Oil Sands, Alberta, Canada. / ©: Rezac / WWF-UK
The boreal forest of Canada is a crucial carbon sink, storing 186 billion tonnes of carbon, below and above ground.
© Rezac / WWF-UK
Going, going...

However, these vital forests are being depleted at alarming rates. The lungs of the planet are increasingly being likened to those of a heavy smoker.

Many of these forests have existed for millions of years, and over a third of the world's plant and animal species live here. In some areas more than 200 tree species have been known to exist on a single hectare of land!

Conversion of forest for agriculture, logging and forest fires are all having a serious impact on forest cover globally.

 / ©: WWF / André Bärtschi
Illegal logging contributes heavily to the destruction of biodiversity and the impoverishment of millions of people that depend on forests for food and income. Madre de Dios, Peru.
© WWF / André Bärtschi

The Amazing Amazon

During the last half century, the Earth's largest rainforest has lost at least 17% of its forest cover. The economic transformation of the Amazon based on the conversion and degradation of its natural habitat is gaining momentum. Yet, as those forces grow in strength, we are also recognising that the Amazon plays a critical role in maintaining climate function regionally and globally, a contribution which everyone–rich or poor–depends on.

The Amazon’s canopy cover helps regulate temperature and humidity, and is intricately linked to regional climate patterns through hydrological cycles that depend on the forests. Given the enormous amount of carbon stored in the forests of the Amazon, there is tremendous potential to alter global climate if not properly stewarded. The Amazon contains 90-140 billion metric tons of carbon, the release of even a portion of which would accelerate global warming significantly.

Currently, land conversion and deforestation in the Amazon release up to 0.5 billion metric tons of carbon per year, not including emissions from forest fires so the Amazon is a significant  factor in regulating global climate.
 / ©: Kitt Nascimento/WWF Brazil
Aerial view of the Jari river running through the Amazon forest in the Tumucumaque mountain chain (ARPA Programme).
© Kitt Nascimento/WWF Brazil

Did you know?

    • Trees in tropical forests absorb nearly a fifth of the CO2 released by burning fossil fuels.
    • Tropical forests remove around 4.8 billion tonnes of CO2 emissions from the atmosphere each year.
    • Scientists estimate that more than 50% of the original rainforest cover has been lost since the start of the 20th century.

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