What is Net Zero?
In order to keep climate change within the 1.5C limit set by nations in the Paris Agreement, global net human-caused emissions of carbon dioxide (CO2) need to fall by about 45 percent from 2010 levels by 2030, reaching net zero around 2050. Global warming is proportional to cumulative CO2 emissions, which means that the planet will keep heating for as long as global emissions remain more than zero.
What is net zero?
Net zero refers to a state in which the greenhouse gases going into the atmosphere are balanced by removal out of the atmosphere.
The term net zero is important because – for CO2 at least – this is the state at which global warming stops. The Paris Agreement underlines the need for net zero, requiring states to ‘achieve a balance between anthropogenic emissions by sources and removals by sinks of greenhouse gases in the second half of this century’.
To ‘go net zero’ is to reduce greenhouse gas emissions and/or to ensure that any ongoing emissions are balanced by removals.
The ‘net’ in net zero is important because it will be very difficult to reduce all emissions to zero on the timescale needed. As well as deep and widespread cuts in emissions, we will likely need to scale up removals. In order for net zero to be effective, it must be permanent, that is, that any greenhouse gas removals do not leak into the atmosphere over time, for example through the destruction of forests or the improper storage of removed carbon dioxide.
The term net zero is important because the Paris Agreement requires the achievement of ‘ a balance between anthropogenic emissions by sources and removals by sinks of greenhouse gases in the second half of this century’.
Net Zero as the Goal
As net zero is the internationally agreed upon goal for mitigating global warming in the second half of the century, the purpose of this site is to inform effective climate action that is net zero aligned in order to advance progress towards this goal. Many actors will be able to achieve absolute zero or zero emissions in the process, hence the choice of terms in the global ‘Race to Zero’ campaign focused on raising ambition. Others will need to scale up removals either themselves directly or by supporting other project, hence the ‘net’ in net zero.
Confusingly, there are several terms related to net zero which have slightly different definitions. We explain them here so as to avoid confusion.
All of these different terms point to the different ways in which emissions sources and sinks are accounted for in context, and help to indicate what is, and is not included in the calculation or a target.
Zero Emissions and Absolute Zero
Zero emissions and Absolute Zero are two terms that imply that no greenhouse gases are released by an actor. Under this definition, no offsets or balancing of residual emissions with removals are used. The phrase absolute zero reflects a state in which there are no negative emissions technologies used to balance ongoing emissions.
The standard to achieve negative emissions goes beyond net zero emissions, requiring the removal of more emissions than are released, either through natural or technological means (often referred to as Negative Emissions technology, Carbon Dioxide Removal or Greenhouse Gas Removal).
Climate neutral is generally considered to mean the same thing as net zero. However, there are some suggestions that they could be differentiated based on which scoped emissions are allowed to be offset under the definitions.
‘Carbon neutral’ is an internationally recognised standard (PAS 2060) covering the methodology for greenhouse gas accounting, coverage, and offsetting. Under this standard, carbon neutral is defined as a period of time in which there has been no net increase in the global emission of greenhouse gases to the atmosphere as a result of the greenhouse gas emissions associated with the subject during the same period’.
Carbon neutral is generally speaking a less ambitious standard than net zero. Under this standard, carbon neutral can be differentiated from net zero in terms of its scope, boundary, ambition, and offsetting. Carbon neutral here refers to Scope 1 and Scope 2 emissions, but does not necessarily cover Scope 3 emissions, and can be confined to just a single product or service, rather than a whole company’s emissions. Additionally, under this standard, there is no requirement for the carbon neutrality to be compliant with a 1.5 degree Paris-aligned goal, nor does it require the same stringent treatment of offsets as net zero.
In addition to the above definitions, sometimes the aim is not to account for all emissions, just carbon dioxide (CO2), leading to iterations on the above definitions such as net zero carbon, zero carbon and carbon negative.
What does it mean to set a net zero aligned target?
The scope of net zero refers not only to which greenhouse gases are included, but also which activities are covered.
In terms of activity coverage, most national and sub-national actors have a standardised approach to scoping net zero, following the IPCC’s guidelines for calculating national greenhouse gas inventories, bounded geographically (emissions that occur within a given territory).
Within the private sector there are differences, but generally emissions are bounded following the Greenhouse Gas Protocol’s ‘scoped’ approach, and net zero aligned actors should attempt to cover all three scopes. The three scopes cover:
● Scope 1 – direct company owned or controlled emissions occurring at source
● Scope 2 – emissions associated with the production of energy consumed by a company
● Scope 3 – indirect emissions associated with company activities from sources not owned or controlled by a company.
While there are differing views about ambition in terms of timing for achieving net zero, there is strong international agreement across the climate community that net zero targets should:
● Reach net zero by 2050
● Set interim targets
● Act immediately
A carbon offset broadly refers to a reduction in GHG emissions – or an increase in carbon storage (e.g., through land restoration or the planting of trees) – that is used to compensate for emissions that occur elsewhere.
While there is disagreement about the widespread use of offsetting there is strong international agreement across the climate community that any offsetting to achieve net requires:
● Robust standards (e.g. additionality, permanence, verifiability, etc.)
● Specification of offsetting approach, avoided emissions, reductions, or removals.
The Oxford Principles for Net Zero Aligned offsetting also require offsetting strategies to:
● Shift from carbon reduction to carbon removal.
● Shift from carbon removal with high-risk (shorter-term) storage, to carbon removal with low-risk (longer-term) storage.
● Support the development of net zero-aligned offsetting.
There are many equity considerations involved in setting a target to align with the global goal of achieving net zero and there is variation in agreement on how to operationalise differentiation around equity considerations, but there tends to be wide agreement in the international climate community that:
● All should move to net zero, but scope and timing may differ due to capacity, responsibility, and other factors.
There are key governance considerations for setting net zero strategies. While actor-specific best practices may vary, it is wide agreement in the climate community that strong governance towards net zero targets will include:
● Formal, top-level commitment
● Interim targets
● Transparency through regular reporting and tracking
● Clear action plans with specific operational implications
Why do we need net zero?
We need to reach net zero emissions in order to achieve the ambition of the Paris Agreement, which is to hold global average temperature increase to “well below 2ºC above pre industrial levels and pursuing efforts to limit the temperature increase to 1.5°C” The IPCC’s Special Report Global Warming of 1.5ºC makes it clear that it is necessary to achieve a global balance between emissions and removals by 2050 in order to cap the rise in global temperatures below 1.5ºC.
While the Paris Agreement sets a global objective, action to achieve that objective is driven at the national level – each country is responsible for setting their own policies to achieve the common goal. The delivery of these policies will take place at the local level. All countries, cities and businesses need to develop plans as to how they intend to achieve net zero.
An image of a wind farm.