What is a carbon sink?

Maia Welbel

What is the carbon cycle?

Carbon (CO2) is the primary element of most organic matter on Earth. As a closed system, the amount of carbon on Earth never changes, just the location. Carbon is exchanged between the atmosphere and organisms as it's released or absorbed. This process is known as the carbon cycle and it has maintained a reciprocal balance for thousands of years.

What is a carbon sink?

The accumulation and storage of carbon dioxide from the atmosphere into any natural (or artificially made) reserve. Sometimes referred to as carbon banking, these reserves sequester carbon and help maintain equilibrium within the carbon cycle. This process reduces atmospheric carbon dioxide and helps mitigate climate change.

Examples of carbon sinks


Through regenerative agriculture, farmers can store (bank) carbon within the soil. Restorative farming practices replenish surrounding areas that may have been degraded through conventional industrial farming. Implementing long-term focused methods like reduced or no till growing, agroforestry, cover crops, composting, or crop rotation all contribute to the viability of soil as a long-term carbon sink. Through photosynthesis, excess atmospheric carbon travels through living root systems to be used as nutrients for soil microbes. These microbes support soil health and work to cultivate a healthy biome, contributing to a balanced carbon cycle. Another major contributing factor to soil health is soil organic carbon (SOC). A natural energy storage, SOC is a measurable component of soil organic matter and plays an important role in retention of carbon and biological function of agricultural soils.


Ocean ecosystems remove atmospheric carbon through absorption by a myriad of marine life–micro algae (phytoplankton), macro algae, seagrasses, mangroves, marshes, and coastal wetlands. Biodiverse oceanic habitats facilitate an increase in the storage and reuse of carbon, through a healthy balance of key predator and prey species. Photosynthesis through underwater root systems sequesters carbon into marine sediments, creating massive repositories that can be stored for millennia. An excess of oceanic carbon can result in an increase of hydrogen ions, the driving factor behind ocean acidification, and the eventual breakdown of these vital habitats.


Through photosynthesis, atmospheric carbon is absorbed and stored in forest biomass (leaves, roots, trunks, branches), dead organic matter, and surrounding soil. Forests can be considered a source of carbon in the case of excess carbon release during a fire or while decaying. To be considered a carbon sink, a forest must absorb more carbon from the atmosphere than it releases. This can occur with responsible forest management through maintenance and land-use changes like agroforestry or afforestation.

What is a carbon source?

The primary cause of climate change, carbon sources are any processes that result in an excess of atmospheric carbon release that disrupts the balance of the carbon cycle. Spurred by human activity, this includes any operation using fossil fuels, like burning coal for electricity or CO2 produced from gas-powered vehicles, or raising cattle en masse for consumption. The overflow of carbon released from these processes exceeds the amount most carbon sinks can naturally absorb.

Why are carbon sinks important?

Carbon can be stored in a variety of organisms, like plants and animals which facilitate carbon sequestration through nutrient absorption, creating leaves, stems, and cellular growth. Carbon is used to form some shells and skeletons for marine organisms and can be stored in oceanic sediment. Decomposing organic matter can continue to store carbon, eventually becoming sediment beneath the surface of the Earth, rocks, minerals, or fossil fuel that can release carbon back into the atmosphere when burned. Once in the atmosphere, carbon is stored in its gaseous state, CO2.

Previously, the carbon cycle maintained equilibrium through the mutual exchange of CO2 between the atmosphere and these storage reservoirs. Increased human activity has disrupted this balance, causing an excess of carbon release, more than natural sinks can absorb. A stabilized atmospheric concentration of CO2 is approximately 350 parts per million. In 2021 carbon dioxide outputs reached the highest level on record of 420 ppm. Since 2000, global output has increased by 43.5 ppm, higher today than any point in the last 800,000 years. Protecting and increasing viable carbon sink reserves and reducing global carbon emissions are essential in combating climate change. A balanced carbon cycle allows the planet to remain hospitable. Without it, temperatures will continue to rise, oceans will further acidify, and natural disasters like wildfire will become more frequent and destructive.

How does Farm participate in protecting carbon sinks?

Soil is an undervalued resource in mitigating the effects of climate change. By implementing restorative land practices on the Great Plains, Farm is creating a sustainable carbon sink across North American grasslands. Improving soil biomes through regenerative agriculture will facilitate long-term soil health and help restore the natural balance of the carbon cycle. Starting with our first parcel acquisition, we're committed to processes that further carbon sequestration.

Organizations to follow