Net-zero greenhouse gas emissions means that the amount of man-made greenhouse gas emissions corresponds to the amount of CO₂ removed from the atmosphere by humans. Net-zero therefore aims to keep the proportion of greenhouse gases in the atmosphere constant and prevent it from rising further. Not all emissions can be reduced to zero in the foreseeable future, which is why, in addition to reducing emissions, removing CO₂ from the atmosphere is essential to achieving net zero. Methods for CO₂ removal and storage must therefore be rapidly developed and expanded to offset the remaining, hard-to-avoid emissions. Achieving net zero for the most important greenhouse gas, CO₂, is an important intermediate step in halting the rise in global average temperature. In Switzerland, the net-zero target is to be achieved by 2050. The Climate and Innovation Act (KIG), which was approved by Swiss voters on 18 June 2023, also sets out further interim targets and a pioneering role for the federal government and the cantons.

Carbon is stored in biomass and soils in forest ecosystems and/or harvested wood is used in durable products. Possible measures include (re)forestation, forest expansion through (controlled) natural succession, and permanent or temporary closure of commercial forests.

Land use systems in various forms, in which woody plants (trees, hedges, shrubs) are combined with agricultural land. This combination also ensures higher carbon enrichment in the soil. 

Restoration of moorlands/wetlands & paludiculture: Moorland restoration can transform drained moorlands from GHG sources into CO₂ sinks. Paludiculture encompasses all types of biomass use. It ranges from harvesting spontaneous vegetation in near-natural locations to newly established crops in rewetted locations, under conditions that preserve the peat body or even promote new peat accumulation.

Soil carbon sequestration refers to the binding and long-term storage of carbon in the soil in the form of organic or inorganic compounds. Carbon that was previously present in the atmosphere as carbon dioxide (CO₂) is fixed by plants and then stored in the soil as organic matter. This requires changes in soil management practices, e.g. through year-round soil cover, organic fertilisers and compost as soil additives, direct sowing with reduced tillage, conversion of arable land to permanent grassland, agroforestry and biochar as a soil additive. 

By expanding vegetation-rich coastal ecosystems such as salt marshes, seagrass beds, mangrove forests and kelp forests, these ecosystems absorb CO₂ from the atmosphere and store it over long periods of time in plant biomass and sediments. This increases CO₂ uptake in ocean and coastal areas.

Seaweed and algae are cultivated to bind CO₂, which is then used or stored in biomass or other products. One option for storage is to sink or deposit the biomass, another is pyrolysis or processing into biochar or bio-oil. 

The cultivation or management of marine biomass and ecosystems with the aim of removing carbon dioxide (CO₂) from the atmosphere and storing it long-term. One example of this is the cultivation of seaweed/macroalgae, which absorbs large amounts of CO₂ during growth. CO₂ removal occurs when part of the biomass is sunk into the deep sea or converted into stable carbon products.

The use of wood and other bio-based materials in construction enables the long-term storage of biogenic carbon in buildings. As they grow, trees absorb CO₂ from the atmosphere and bind the carbon in their biomass. When this wood is then used in durable products such as building structures or insulation materials, the carbon remains stored for decades or longer. In addition, bio-based building materials can replace energy-intensive materials such as concrete or steel, thereby avoiding additional emissions.

Biochar is a carbon-rich, solid product produced by the pyrolysis of biomass. This involves the thermal decomposition of organic material at temperatures between 400 and 700 °C in the absence of oxygen. The carbon produced in this process remains bound for the long term, thus contributing to CO₂ removal. Biochar has many uses, including as a soil improver, in animal husbandry, as a material or additive in building materials, and in environmental and energy technology.

Hydrochar is produced by hydrothermal carbonisation (HTC), a process in which moist biomass is converted into a stable, carbon-rich substance under increased pressure and at temperatures of around 180–250 °C. This "aqueous carbonisation process" is particularly suitable for biomass residues with a high water content that are not suitable for pyrolysis. Similar to biochar, hydrochar can be used as a soil improver, raw material for other materials or energy storage, and enables the long-term sequestration of biogenic carbon.

This method uses biomass to generate energy and combines it with the capture and permanent storage of the carbon dioxide (CO₂) produced in the process. In BECCS systems, plants initially absorb CO₂ from the atmosphere as they grow. When the biomass is later used to generate electricity, heat or fuels, the CO₂ released during combustion or fermentation is captured before it enters the atmosphere and then permanently stored.

With suitable pre-treatment and suitable storage facilities, carbon-rich plant material (e.g. algae, wood waste) can be stored long-term in landfills or underground. Pyrolysis and HTC can play a role in pre-treatment. 

When rocks weather, CO₂ is permanently removed from the atmosphere – but natural weathering is a slow geochemical process. This process can be accelerated by breaking down rocks, processing them into rock flour and then spreading them on agricultural soils. Depending on the type of rock, varying amounts of CO₂ can be returned to the Earth's system. In carbonation, for example, demolition concrete is directly gassed with CO₂ (see building materials).

When CO₂ is bound in building materials, it is chemically converted into solid mineral compounds. It reacts with materials containing calcium, magnesium or silicon and is bound in the form of stable carbonates – a process known as mineralisation. This process can be used both in industrial waste materials (e.g. steelworks slag, cement dust) and in the manufacture of new building materials. The bound CO₂ remains trapped in the material for geological periods of time, thus contributing to permanent CO₂ removal.

The carbonation of concrete utilises the material's natural ability to absorb CO₂ from the air and chemically bind it. This process can be accelerated by targeted technical procedures, such as introducing CO₂ during concrete hardening or into demolition concrete. The CO₂ reacts with calcium compounds in the cement stone and forms solid calcium carbonates. This reduces the carbon footprint of concrete production and achieves permanent storage of CO₂ in the material. 

Increased CO₂ absorption by adding acid-binding minerals from weathered rocks (silicate and carbonate rocks). Comparable to enhanced rock weathering, but applied in the ocean instead of on land.

CO₂ is removed directly from the ambient air by filtration and stored permanently. Two main types of processes are used for this purpose: adsorption, in which CO₂ is bound to solids at low temperatures, and absorption, in which CO₂ is dissolved in liquids at higher temperatures. Storage takes place primarily in geological storage sites.

Dissolved carbon is removed directly from seawater through a series of electrochemical processes. The treated seawater is then returned. The ocean contains 150 times more carbon dioxide than the atmosphere, so DOC could potentially become more efficient than DAC.

Nutrients from deep ocean water are pumped up so that algae, zooplankton and fish can naturally absorb carbon. Nutrients are often lacking in surface water. The resulting additional biomass absorbs CO₂ and sinks when it dies. The carbon remains in the deep sea or as sediment on the sea floor.

Nutrients such as iron are introduced into the ocean to promote the growth of phytoplankton, which absorbs CO₂ and sinks when it dies. The carbon remains in the deep sea or as sediment on the sea floor.