What is Net Zero?

An actor’s activities result in no net effect on the climate system. Any GHG emissions or other activities with warming effects are fully compensated by GHG reductions or removals, or other activities with cooling effects — irrespective of the time period or the relative magnitude of emissions and removals involved. A near synonym for GHG neutral, but climate neutral also includes non-GHG radiative forcing effects, such as land use changes with albedo effects.

Not a valid end-state target, as it does not require “like for like” balancing, but a possible intermediate step.

An actor’s net contribution to global GHG emissions is zero. Any GHG emissions attributable to an actor’s activities are fully compensated by GHG reductions or removals exclusively claimed by the actor — irrespective of the time period or the relative magnitude of emissions and removals involved. 

Not a valid end-state target, as it does not require “like for like” balancing, but a possible intermediate step.

An actor’s net contribution to global CO2 emissions is zero. Any CO2 emissions attributable to an actor’s activities are fully compensated by CO2 reductions or removals exclusively claimed by the actor — irrespective of the time period or the relative magnitude of emissions and removals involved. 

Not a valid end-state target, as it only refers to carbon, but a possible intermediate step.

You can read more about carbon neutral and net zero on Wikipedia’s page on ‘Net zero emissions‘, which we extensively contributed to.

An actor’s GHG removals, internal and external, exceed its emissions and any removals are “like for like”. Must be specified over a declared time period, and whether removals and emissions are cumulative or represent only the time period specified.

A valid end-state target.

An actor’s carbon removals, internal and external, exceed its emissions and any removals are “like for like”. Must be specified over a declared time period, and whether removals and emissions are cumulative or represent only the time period specified.

Not a valid end-state target, as it only refers to carbon, but a possible intermediate step.

Target is aligned with scenarios that yield a long-term warming outcome of below 1.5°C with some probability (e.g. 50%, 66%) and some amount of overshoot (e.g. no, low), both of which should be explicitly specified. 

Target is aligned with what the latest climate science deems necessary to meet the goals of the Paris Agreement — limiting global warming to well-below 2°C above preindustrial levels and pursuing efforts to limit warming to 1.5°C, with no or low overshoot.

Reducing GHG emissions (including through avoided emissions), or increasing GHG removals through activities external to an actor, in order to compensate for GHG emissions, such that an actor’s net contribution to global emissions is reduced. Offsetting is typically arranged through a marketplace for carbon credits or other exchange mechanism. 

Offsetting claims are only valid under a rigorous set of conditions, including that the reductions/removals involved are additional, not over-estimated, and exclusively claimed. Further, offsetting can only be used to claim net zero status to the extent it is “like for like” with any residual emissions. 

Reducing GHG emissions (including through avoided emissions), or increasing GHG removals through an actor’s scope 1, 2, or 3 emissions, in order to compensate for GHG emissions, such that an actor’s net contribution to global emissions is reduced. 

Insetting claims are only valid under a rigorous set of conditions, including that the reductions/removals involved are additional, not overestimated, and exclusively claimed. Further, insetting can only be used to claim net zero status to the extent it is “like for like” with any residual emissions. 

GHG removals outside an actor’s emissions inventory, that balance residual GHG emissions such that an actor’s net contribution to global emissions is reduced or eliminated. May include offsetting, but also all other activities an actor makes outside its value chain that are contributions to mitigation. Near synonym of compensation, but limited to removals, and requires “like for like” balancing of residual emissions. Required if residual emissions remain after net zero status is achieved. 

Neutralization claims are only valid under a rigorous set of conditions, including that the reductions/removals involved are additional, not over-estimated, exclusively claimed, and “like for like”. 

Neutralization

Reducing GHG emissions (including through avoided emissions), or increasing GHG removals through activities outside of an actor’s emissions inventory, in order to compensate for GHG emissions such that an actor’s net contribution to global emissions is reduced. Includes offsetting, but also all other activities an actor makes outside its value chain that are contributions to mitigation. Near synonym of neutralization, but not limited to removals, and does not necessarily imply “like for like” balancing of residual emissions. Potentially helpful during the transition to net zero.

Compensation claims are only valid under a rigorous set of conditions, including that the reductions/removals involved are additional, not over-estimated, and exclusively claimed.

When a source of emissions and an emissions sink correspond in terms of their warming impact, and in terms of the timescale and durability of carbon storage. 

For example, fossil carbon is stable in the lithosphere over millennia if it is not extracted and burned, therefore mitigating measures (e.g. offsets) that aim to neutralise the effect of these emissions must persist for a comparable, geological-timescale. Although all CO2 once emitted, whether originally sourced from the lithosphere or biosphere, persists in the active carbon cycle for centuries to millennia, it may be appropriate to balance shorter-duration carbon released from biogenic carbon stocks (e.g. forests and soils) with comparably temporary storage in like stocks. The variable risks of reversal of different carbon stocks must also be considered, for example forests may suffer from unforeseen anthropogenic (e.g. illegal logging), non-anthropogenic (e.g. disease and disaster), or climate change-induced (e.g. warming) reversal risks.

Actions that reduce the quantity of GHGs attributable to an actor vis-a-vis a baseline. 

Examples include: Replacing fossil-burning power with renewable energy, reducing consumption of emissions-intensive products or inputs, avoiding damage to ecological carbon sinks, carbon capture and storage (CCS), avoided emissions from deployment of renewable energy, etc. 

Actions that remove GHGs from the atmosphere relative to baseline. 

Examples include: Afforestation and reforestation, soil carbon enhancement, bioenergy with carbon capture and storage (BECCS), direct air capture, mineralization, or enhanced weathering.