Carbon Sequestration
Carbon sequestration is the long-term storage of carbon dioxide so that it stays out of the atmosphere. It happens biologically, in trees and soils, and geologically, by injecting captured CO₂ into deep rock formations.
Biological sequestration covers reforestation, improved forest management, soil carbon practices, and coastal habitat restoration. It is cheaper and available now, and it is reversible: a fire, a harvest, or a change of land use can release the stored carbon within a season.
Geological sequestration injects CO₂ into saline aquifers or depleted oil and gas reservoirs a kilometre or more underground. Storage lasts thousands of years when the site is chosen and monitored properly, and the cost per tonne is far higher. Mineralization, which reacts CO₂ with rock to form stable carbonates, sits at the durable end and at the highest cost.
Three attributes decide whether sequestration counts in a report: how long the carbon stays stored, how the amount is measured, and who is liable if it is released. A buyer of removals needs all three documented, because a target that depends on sequestration is only as strong as the weakest of them. Sequestration also does not substitute for reducing emissions at source, and frameworks such as SBTi require reductions first.
Frequently asked questions
What is carbon sequestration? +
Carbon sequestration is the long-term storage of carbon dioxide so it stays out of the atmosphere. It happens biologically in trees and soils, and geologically by injecting CO₂ into deep rock formations.
How long does sequestered carbon stay stored? +
Biological storage in forests and soils can reverse within years through fire, harvest, or land use change. Geological storage and mineralization can hold carbon for thousands of years when sites are monitored.
Does sequestration replace emissions reductions? +
No. Frameworks such as the Science Based Targets initiative require companies to cut emissions at source first and use removals only for the residual share that cannot be eliminated.
Related terms
Carbon Capture
Carbon capture separates CO₂ from an industrial exhaust stream or from ambient air so it can be stored or used. Carbon capture and storage (CCS) sends it underground; carbon capture, utilization and storage (CCUS) uses part of it in products such as concrete or fuels.
Carbon Sink
A carbon sink is any reservoir that absorbs more carbon than it releases. Oceans, forests, and soils are the main natural sinks, and together they remove a little over half of the CO₂ that human activity emits each year.
Carbon Cycle
The carbon cycle is the continuous movement of carbon between the atmosphere, oceans, soil, rock, and living things. Burning fossil fuels releases carbon that was locked underground for millions of years, and it enters the atmosphere far faster than natural processes remove it.
Carbon Offsets
Carbon offsets are verified emission reduction or removal credits purchased by an organization to compensate for its own greenhouse gas emissions. One carbon offset represents one tonne of CO₂e reduced or removed from the atmosphere through a project elsewhere, such as reforestation, renewable energy deployment, or methane capture.
Net Zero
Net zero means reducing greenhouse gas emissions as close to zero as possible, with any remaining residual emissions balanced by an equivalent amount of carbon removal from the atmosphere. The SBTi Corporate Net-Zero Standard requires at least 90–95% absolute emission reductions before carbon removals can be used.
SBTi (Science Based Targets initiative)
The Science Based Targets initiative (SBTi) is a partnership between CDP, WRI, the UN Global Compact, and WWF that defines and validates corporate greenhouse gas reduction targets consistent with the Paris Agreement goal of limiting warming to 1.5°C above pre-industrial levels.