Nature's carbon sinks and sources

About half of CO2 emissions from human activity are swiftly absorbed by the 2 major natural reservoirs of carbon on the planet’s surface: forests and oceans.

This is lucky.

The world would be a lot warmer without this free service from nature.

So preserving these “carbon sinks” is vital to slowing the pace of climate change.

But we are failing to protect these natural reservoirs. Instead we are destroying them. And as we destroy forests, for instance, the carbon that they have been storing pours into the atmosphere.

Instead of being carbon sinks they become carbon sources.

Today, deforestation is contributing about 1/5 of all greenhouse gas emissions. While surviving forests continue to soak up CO2, deforestation is turning the world’s forests from an overall sink to an overall source.

That is why STOPPING deforestation is so important for protecting the climate.

A further big danger is that, even if we halt deforestation, under continued climate change many forests will succumb to global warming and release their carbon into the air, accelerating warming.

During a drought in 2005, many trees died or stopped growing – and became a carbon SOURCE.

That year, the Amazon rainforest emitted 5 billion tonnes of CO2, equivalent to the annual CO2 emissions of Europe and Japan combined.

Some oceans may also be losing their ability to absorb CO2 as they warm.

The Southern Ocean around Antarctica, previously one of the planet’s largest natural carbon sinks, has been absorbing less carbon in the past 25 years.

Nobody is quite sure why, but it is probably a combination of several factors, including limited absorption capacity due to rapidly rising emissions, enhanced gassing-out of CO2 from warmer waters, and warmer surface waters inhibiting the growth of algae which take up most of the excess atmospheric CO2.

I am concerned that if the temperature keeps increasing, we won’t have any living coral to take tourists to see.

Carlton Young Junior, dive master and tour operator, Belize

 / ©: Paint for the Planet - Netpakaikarn Netwong, Thailand
A tree, children and children cycling. International Children’s Painting Competition on the Environment organized by UNEP, the Foundation for Global Peace and Environment, Bayer and Nikon.
© Paint for the Planet - Netpakaikarn Netwong, Thailand

Subscribe to our mailing list

* indicates required
Donate to WWF

Your support will help us build a future where humans live in harmony with nature.