Solar Radiation Modifications (SRM)

Range of radiation modification measures not related to greenhouse gas mitigation that seek to limit global warming. Most methods involve reducing the amount of incoming solar radiation reaching the surface.

Stratospheric Aerosol injections (SAI)
 

One of SRM approaches to increase the planetary albedo. It does to by injecting highly reflective aerosols such as sulphates into the lower stratosphere. This is expected to increase the fraction of solar radiation deflected to space resulting in a planetary cooling.

Carbon dioxide removal (CDR)
 

Anthropogenic activities removing atmospheric CO2 and durably storing it in geological, terrestrial, or ocean reservoirs, or in products. It includes anthropogenic enhancement of biological or geochemical CO2 sinks and direct air carbon dioxide capture and storage (DACCS) but excludes natural CO2 uptake not directly caused by human activities.

Ocean Acidification

A reduction in ocean pH, over an extended period, typically decades or longer, caused primarily by uptake of CO2 from the atmosphere, but can also be caused by other chemical additions or subtractions from the ocean. It often refers to the component of pH reduction that is caused by human activity

Ocean Alkalinization

One of CDR methods that involves deposition of alkaline minerals or their dissociation products at the ocean surface. This increases surface total alkalinity and ocean’s capacity to absorb CO2 uptake and ameliorate surface ocean acidification.

Carbon dioxide capture and storage (CCS)

A process in which a relatively pure stream of CO2 from industrial and energy-related sources is separated (captured), conditioned, compressed and transported to a storage location for long-term isolation from the atmosphere. Sometimes referred to as carbon capture and storage.

Bioenergy carbon capture and storage (BECCS)

A CCS technology applied to a bioenergy facility. Note that depending on the total emissions of the BECCS supply chain, CO2 can be removed from the atmosphere.

Atlantic meridional overturning circulation 
(AMOC)

The main current system in the South and North Atlantic Oceans. It transports warm upper-ocean water northwards and cold, deep-water southwards, as part of the global ocean circulation system. Changes in the strength of AMOC can affect other components of the climate system.

Inter-tropical convergence zone (ITCZ)

The Inter-tropical Convergence Zone is an equatorial zonal belt of low pressure, strong convection and heavy precipitation near the equator where the north-east trade winds meet the south-east trade winds. This band moves seasonally.

Permafrost

Ground (soil or rock and included ice and organic material) that remains at or below 0°C for at least two consecutive years. Note that permafrost is defined via temperature rather than ice content and, in some instances, may be ice-free.

Coupled Model Intercomparison Project (CMIP)

A climate modelling activity from the World Climate Research Programme (WCRP) which coordinates and archives climate model simulations based on shared model inputs by modelling groups from around the world.