Global net zero emissions, or simply net zero, is a state in which human-caused emissions are balanced by human-caused carbon dioxide removals over a specified time period. In some contexts, "emissions" refers to emissions of all greenhouse gases, and in other contexts it refers only to emissions of carbon dioxide (CO2).
Achieving net zero targets requires actions to reduce emissions, such as by shifting from fossil fuel energy to sustainable energy sources. To counterbalance their residual emissions, organizations commonly offset them by buying carbon credits. The terms net zero emissions, carbon neutrality, and climate neutrality are often used interchangeably.: 22-24 In some contexts, however, the terms are given different meanings from each other. For instance, some standards bodies allow more use of offsets for carbon neutral certification than for net zero certification.
In the last few years, net zero has become the dominant framework for climate ambition with countries and organizations alike setting net zero targets. Today more than 140 countries have a net zero emissions target, including some countries which were resistant to climate action in previous decades. Country-level net zero targets now cover 92% of global GDP, 88% of emissions and 89% of the world population. At a company level, 65% of the largest 2,000 publicly traded companies by annual revenue and 63% of Fortune 500 companies have net zero targets. Company targets are a result of voluntary action as well as government regulation.
Despite an increasing prevalence of commitments and targets, however, net zero claims vary enormously in levels of credibility and most have low credibility. While 61% of global carbon dioxide emissions are covered by some sort of net zero target, credible targets cover only 7% of emissions. Low credibility in targets reflects a lack of binding regulation and the need for continued innovation and investment to permit decarbonization.
To date, 27 countries have enacted domestic net zero legislation - laws passed by the legislative branch of government that contain net zero targets or equivalent. While there is currently no national regulation in place that legally mandates companies based in that country to achieve net zero, legislation is being developed in several countries, most notably Switzerland.
The concept of net zero has its roots in research into the response of the atmosphere, oceans and carbon cycle to CO2 emissions in the late 2000s, which found global warming will only stop if CO2 emissions are reduced to net zero. Net zero was integral to the goals of the Paris Agreement, which asserted we must "achieve a balance between anthropogenic emissions by sources and removals by sinks of greenhouse gases in the second half of this century". The specific term "net zero" gained popularity after the Intergovernmental Panel on Climate Change published a Special Report on a Global Warming of 1.5 °C (SR1.5) in 2018, stating that "Reaching and sustaining net zero global anthropogenic [human-caused] CO2 emissions and declining net non-CO2 radiative forcing would halt anthropogenic global warming on multi-decadal timescales (high confidence)."
The concept of net zero emissions is often confused with "stabilization of greenhouse gas concentrations in the atmosphere", which dates from the 1992 Rio Convention. The two concepts are not the same because the carbon cycle continuously sequesters a small percentage of cumulative historical human-caused CO2 emissions into vegetation and the ocean, even after ongoing CO2 emissions are reduced to zero. If the concentration of CO2 in the atmosphere were to be kept constant, some CO2 emissions could continue but global average surface temperatures would continue to increase for many centuries due to the gradual adjustment of deep ocean temperatures. If CO2 emissions that result directly from ongoing human activities are reduced to net zero, the concentration of CO2 in the atmosphere would decline, at a rate just fast enough to compensate for this deep ocean adjustment to give approximately constant global average surface temperatures on multi-decade to century timescales.
The time frame for reaching net-zero emissions is different for CO2 alone versus for CO2 plus other greenhouse gases like methane, nitrous oxide and fluorinated gases. For non-CO2 emissions, the target net zero date is later, in part because modellers assume that some of these emissions — such as methane from agricultural sources — are more difficult to phase out. Emissions of short-lived gases such as methane do not accumulate in the climate system as CO2 does and hence do not need to be reduced to zero to halt global warming because reductions in emissions of short-lived gases cause an immediate decline in resulting radiative forcing. However, these potent but short-lived gases will drive temperatures higher in the near term, potentially pushing temperature change past the 1.5 °C threshold much earlier. A comprehensive net-zero emissions target would include all greenhouse gases, ensuring that non-CO2 gases are also reduced with urgency.
Countries, local governments, corporations, and financial institutions may announce pledges for achieving net zero emissions for themselves; these entities are known as actors.
The terms net zero, carbon neutrality, and climate neutrality are often used interchangeably.: 22-24 In some contexts, however, the terms are given different meanings from each other, as explained in the sections below. The terms have often been used without rigorous standard definitions.
Since 2015, there has been significant growth in the number of actors pledging net zero emissions. A plethora of standards have arisen that interpret the net zero concept and aim to measure progress towards net zero targets.: 38 Some of these standards are more robust than others, and weak standards have been criticized for facilitating greenwashing.: 38 More robust standards are promoted by the UN, UNFCCC, International Organization for Standardization (ISO), and the Science Based Targets initiative.
Some targets aim to reach net zero emissions only for carbon dioxide, whereas others aim to reach net zero emissions of all greenhouse gases. Robust net zero standards state that all greenhouse gases should be covered by a given actor's targets.
Some authors assert that carbon neutrality strategies solely focus on carbon dioxide, whereas net zero includes all greenhouse gases. However some publications, such as the national strategy of France, use the term "carbon neutral" to mean net reductions of all greenhouse gases. The United States has pledged to achieve "net zero" emissions by 2050, but as of March 2021 has not specified which greenhouse gases will be included in its target.
The Greenhouse Gas Protocol is a group of standards that are the most common in GHG accounting. These standards reflect a number of accounting principles, including relevance, completeness, consistency, transparency, and accuracy. The standards divide emissions into three scopes:
Corporate net zero targets vary in how widely they cover emissions related to the company's activities, and this can greatly affect the volume of emissions that are counted. Some oil companies, for instance, claim that their operations (Scopes 1 and 2) produce net zero emissions. These claims do not cover the emissions produced when the oil is burned by its customers, which are 70 - 90% of oil-related emissions, as these are as these are considered Scope 3 emissions.
Robust net zero standards require Scope 3 emissions to be counted, but "carbon neutrality" standards do not.[better source needed]
A given actor may plan to achieve net zero emissions through a combination of: 1) actions to reduce their own emissions, 2) actions to directly remove carbon dioxide from the atmosphere, and 3) purchasing carbon credits.
According to robust net zero standards, actors must reduce their own emissions as much as possible following science-based pathways and then balance their residual emissions using removals and offsets.: 12 This typically involves shifting from fossil fuels to sustainable energy sources. Residual emissions are those which cannot be feasibly reduced due technological constraints.
Experts and net zero frameworks disagree over the exact percentage of residual emissions that may be allowable, but most guidance suggests this should be limited to a small fraction of total emissions determined by sector-specific and geographical factors. SBTi directs residual emissions across most sectors should fall between 5-10% of an organization's baseline emissions, and even lower for some sectors with competitive alternatives like the power sector. Hard-to-abate sectors, such as heavy manufacturing, will likely have a higher percentage of residual emissions by 2050.
The ISO and BSI publish "carbon neutrality" standards that have higher tolerance for residual emissions, compared with their "net zero" standards. For example, the BSI PAS 2060 is a British standard for measuring carbon neutrality. Therefore, according to these standards, carbon neutrality is considered a more short-term target, with net zero being a longer term target.
To balance residual emissions, actors may take direct action to remove carbon dioxide from the atmosphere and sequester it, and/or they can buy carbon credits that "offset" emissions. Carbon credits can be used to fund carbon removal projects such as reforestation.
Strong standards such as the ISO and BSI "net zero" standards only allow removal-based offsets that are equal in permanence as the greenhouse gases that they balance, a concept known as "like for like" removals Permanence means that removals must have equally long-term storage relative to the lifetime the GHG emissions they balance. For example, methane has a lifetime of around 12 years in the atmosphere whereas carbon dioxide lasts between 300 - 1,000 years. Accordingly, removals that balance carbon dioxide must last much longer than removals that balance methane.
Carbon credits can also fund initiatives that aim to avoid emissions, such as energy efficiency retrofits or renewable energy projects. Avoided emissions offsets are those resulting from actions which reduce emissions relative to a baseline or status quo, but do not remove emissions from the atmosphere. Weak standards, such as ISO and BSI's "carbon neutrality" standards, allow organizations to use avoided-emissions carbon credits and do not specify how permanent or durable a credit must be.
Carbon offsetting has been critiqued on several fronts. One of the main concerns has been the potential for offsets to delay needed action on active emissions reductions. In 2007, for example, in a report from the Transnational Institute, Kevin Smith likens carbon offsets to medieval indulgences where people pay "offset companies to absolve them of their carbon sins." This, he contends, permits a "business as usual" attitude that stifles the required major changes. Offsets have also been widely criticised for playing a part in greenwashing, an argument which has even mobilised in a 2021 watchdog ruling against Shell.
Another critique of offsetting has been that loose regulation of claims by carbon offsetting schemes that, combined with the difficulties in calculating greenhouse gas sequestration and emissions reductions, can result in schemes that do not in reality adequately offset emissions. Moves have been made to create better regulation. The United Nations, for instance, has operated a certification process for carbon offsets since 2001 called the Clean Development Mechanism. This aims to stimulate "sustainable development and emission reductions, while giving industrialized countries some flexibility in how they meet their emission reduction limitation targets." However, the UK Government's Climate Change Committee has also noted that "Although standards both globally and in the UK are being improved, the risk remains that the emissions reduction or removal reported may have happened anyway or may not persist into the future."
Criticisms have also been levelled at the use of non-native and monocultural forest plantations as carbon offsets for its "limited—and at times negative—effects on native biodiversity" and other ecosystem services.
Most of the carbon credits on the voluntary market today do not meet UN's, UNFCCC's, ISO's or SBTi's standards for permanent carbon dioxide removals. Accordingly, significant investment in carbon capture and permanent geological storage will likely be required to achieve net-zero targets by mid-century.
To achieve net zero, actors are encouraged to set net zero targets for 2050 or earlier. Long-term net zero targets should be supplemented by interim targets for every one to five years. The UN, UNFCCC, ISO, and SBTi all assert that organizations should prioritize early, front-loaded emissions reduction and should aim to halve emissions by 2030. Specific emissions reduction targets and pathways may look different for different sectors, with some able to decarbonize more quickly and easily than others.
Per leading guidance, organizations should choose a base year to measure emissions reductions against, which is representative of their "typical GHG profile", and they should disclose "why the baseline has been chosen and how changes in conditions since the baseline will be accounted for". Financial organizations should also include the emissions within their portfolio, including all organizations they have financed, invested in, or insured. Countries and regions should include territorial emissions (emissions released within its boundaries) and consumption emissions (GHG emissions related to products and services consumed within its boundaries).
Cities and countries pose a challenge when it comes to calculating emissions since the production of products and services within their boundaries might be linked to either internal consumption or exports. Conversely, the populace also consumes imported products and services. Therefore, it should be made explicit whether emissions are counted at the location of production or consumption in order to prevent double counting. Given the lengthy manufacturing chains of a globalised market, this might be challenging. Additionally, the embodied energy and other effects of raw material extraction, which are necessary for renewable energy systems and electric vehicle batteries, are likely to present their own challenges, since their life-cycle emissions are often significant, even if the local emissions at the site of utilisation are small.
The concept of net zero has been the subject of some criticism over its potentially negative equity and distributional effects. In particular, the use of removals or carbon credits for offsetting has been controversial due to the perception offset projects themselves could have harmful effects. Considering these potential negative effects, the ISO Net Zero Guidelines assert net zero strategies should align with the United Nations Sustainable Development Goals to "support equity and global transition to a net zero economy, and any subsequent UN global goals which supersede the 2030 SDGs." Moreover, the UNFCCC's Race to Zero campaign asserts emissions reductions and removals should "safeguard the rights of the most vulnerable people and communities", and organizations should disclose how they will support communities affected by climate impacts and climate transition.
The United Nations High-Level Expert Group on the Net Zero Emissions Commitments of Non-State Entities has made several recommendations for non-state actors, i.e. cities, regional governments, financial institutions, and corporations. These recommendations include not financing new fossil fuel development, supporting strong climate policy, and ensuring that business activities and investments do not contribute to deforestation.: 12-13
According to leading standards and guidance, products (as opposed to companies) can be certified by official accreditation bodies as carbon neutral but not as net zero.[page needed] The rationale behind this is that until organizations and their supply chains are on track for net zero, allowing a product to claim to be net zero at this point would be disingenuous and lead to greenwashing.
Despite an increasing prevalence of both nations and organizations (private and public sector) committing to net zero, the credibility of these claims remains low. Given the lack of any binding regulation mandating a transition to net zero, the overwhelming majority of net zero commitments have been made on a voluntary basis. The lack of an enforcement mechanism surrounding these claims means that many are dubious. In addition, in many sectors such as steel, cement, and chemical production, the pathway to achieving net zero remains technologically unclear. Further investment in research and innovation, as well as further regulation, will likely be necessary if net zero claims are to increase in credibility.
A primary reason for the low credibility of many net zero claims is the heavy reliance on carbon credits. Carbon credits are often used for offsetting, and are a reduction or removal of emissions of carbon dioxide or other greenhouse gases made in order to compensate for emissions made elsewhere. For example, many fossil fuel companies have made pledges to be net zero by 2050, while their extraction practices continue to increase greenhouse gas emissions. These claims are based on the fossil fuel companies assertions that they will use carbon credits and carbon capture technology in order to continue extracting and burning fossil fuels, and have been condemned by the UN as dangerous examples of greenwashing.
Many companies often claim a commitment to reach net zero emissions by the year 2050. These promises are often made on the corporate level, and both governments and international agencies encourage businesses to contribute to a national, or international, net zero pledge. The International Energy Agency predicts that global investment in low carbon substitutes for fossil fuels needs to reach $4 trillion USD annually by 2030 in order for the world to get to net zero by 2050. On the national level, US president Joe Biden has also published strategies towards net zero and encouraged Americans to take steps to follow through on attaining net zero for the US, and Biden has signed an executive order for government agencies to reach net zero by 2050. Some companies which have made net zero pledges by 2050 are German train manufacturer Siemens, American automaker Ford, and Taiwanese electronics manufacturer Foxconn. In addition, the magazine Forbes has released a list of US companies which have made the most progress towards net zero with 2050 or earlier goals; as of September 2023, the companies topping such list are Moody's, MSCI, and Northrop Grumman.
Some groups have raised concerns that net zero cannot be achieved worldwide by 2050. Energy company ExxonMobil has raised concerns that the world economy could not reach net zero by 2050 given the high loss in standards of living that humanity would sacrifice in order to attain net zero, and has thus predicted that the world is "highly unlikely" to reach net zero by 2050 overall. Other groups, such as Bloomberg's editorial board and investment banker Mark Carney, have stated that net zero is only possible with nuclear power.
Climate scientists James Dyke, Robert Watson, and Wolfgang Knorr make the case that the concept of net zero has been harmful for emissions reductions by allowing actors to defer present-day emissions reductions by relying on future, unproved technological fixes (carbon offsetting, carbon dioxide removal and geoengineering): "The problems come when it is assumed that these [technological fixes] can be deployed at vast scale. This effectively serves as a blank cheque for the continued burning of fossil fuels and the acceleration of habitat destruction". By tracing the history of previous failures in climate policy at reducing emissions from 1988 to 2021, they "[arrive] at the painful realisation that the idea of net zero has licensed a recklessly cavalier 'burn now, pay later' approach which has seen carbon emissions continue to soar". They conclude by saying "Current net zero policies will not keep warming to within 1.5 °C because they were never intended to. They were and still are driven by a need to protect business as usual, not the climate. If we want to keep people safe then large and sustained cuts to carbon emissions need to happen now. [...] The time for wishful thinking is over."
In March 2021, Tzeporah Berman, chair of the Fossil Fuel Non-Proliferation Treaty Initiative, argued that the Treaty would be a more genuine and realistic way to achieve the goals of the Paris Agreement than the "Net zero" approach which, she claimed, is "delusional and based on bad science".
Eric Reguly, of The Globe and Mail states that, "The net-zero pledges are both welcome and dubious. Most are back-end loaded, meaning the majority of the cuts are to come well after 2030... Most of these targets also assume...steady technological advances and outright breakthroughs...Fossil fuel exports will not figure into the national accounting for the net-zero goal."
In his 16-page report, Dangerous Distractions, economist Marc Lee states that, "'Net zero' has the potential to be a dangerous distraction that reduces the political pressure to achieve actual emission reductions..." "A net zero target means less incentive to get to 'real zero' emissions from fossil fuels, an escape hatch that perpetuates business as usual and delays more meaningful climate action...Rather than gambling on carbon removal technologies of the future, Canada should plan for a managed wind down of fossil fuel production and invest public resources in bona fide solutions like renewables and a just transition from fossil fuels."