Carbon sink
A process or reservoir that takes up more carbon than it releases over a stated period.
Example
A growing forest can function as a sink under suitable conditions.
The catch
A sink can weaken or become a source after disturbance.
Related terms
Afforestation, Biodiversity, Blue carbon, Carbon stock, Deforestation, Ecosystem
In more depth
Carbon sink, explained.
Carbon sinks on land and in the ocean absorb a large share of the CO₂ people emit each year, which has slowed the build-up in the atmosphere. Much of that uptake is a natural response to higher CO₂ levels, so it does not count as carbon dioxide removal, which requires deliberate human action. A mature forest can hold a vast carbon stock while adding little each year, since a sink describes a flow and a stock describes an amount.
The IPCC projects that land and ocean sinks will take up a smaller proportion of emissions as emissions rise and the climate warms. That makes protecting existing sinks part of mitigation, and it is one reason to avoid counting on them to absorb whatever is emitted.