What is net zero? Definition, targets and credible claims explained

Net zero means balancing emissions released with emissions removed. It is the most used phrase in climate policy. There is no single binding definition across policy, corporate, product and investment claims. Governments, companies and investors all use it differently. Here is what it actually means, where it came from, and how to tell the difference between a credible commitment and a marketing claim.

For related reading, see our guides to the Seventh Carbon Budget, Science Based Targets initiative (SBTi) explained, climate transition plans, Scope 1, 2 and 3 emissions, carbon offsetting for UK businesses, the Paris Agreement and environmental, social and governance (ESG) explained.

The UK has a legally binding net zero target. Thousands of companies have made net zero commitments. Investment portfolios worth trillions are described as net zero aligned. And there is no single binding definition of what net zero means across policy, corporate, product and investment claims.

All of these things are simultaneously true.

The Intergovernmental Panel on Climate Change (IPCC) uses the term precisely: net zero carbon dioxide (CO2) emissions are achieved when human-caused CO2 emissions are balanced globally by human-caused CO2 removals over a specified period. When the term moved from scientific assessments into corporate press releases, fund names and political speeches, the precision did not travel with it. The ambiguity did.

A company can claim to be net zero while continuing to emit millions of tonnes of CO2, as long as it purchases carbon credits to offset them. A government can have a legally binding net zero target while approving new oil and gas development licences. A fund can be described as net zero aligned under one methodology while another methodology would ask harder questions about portfolio emissions, stewardship, exclusions and real-world transition plans. Some of these claims may be technically defensible depending on the methodology. Others may be misleading. The problem is that the same phrase can describe very different levels of substance.

This guide explains the scientific definition, the four distinct ways the term is used, the honest state of progress in 2026, and how to evaluate a net zero claim from any source.

Quick answer

What net zero actually means: the scientific definition

Net zero CO2 emissions are achieved when anthropogenic CO2 emissions are balanced globally by anthropogenic CO2 removals over a specified period. This is the definition used by the IPCC in its 2018 Special Report on Global Warming of 1.5°C (SR1.5) and subsequent assessments. Reaching and sustaining net zero CO2 emissions halts global warming from CO2 on multi-decadal timescales. The total amount of CO2 emitted between now and reaching net zero determines the peak temperature, which is why the timing matters as much as the destination.

The "net" is doing most of the work. Net zero allows for residual emissions from processes that cannot be fully eliminated, hard-to-abate sectors like cement production, certain agricultural emissions, and parts of aviation and shipping, as long as those residual emissions are permanently balanced by equivalent removal of CO2 from the atmosphere.

The distinction that underpins most of the confusion

Net zero CO2 and net zero all greenhouse gases (GHGs) are different things. This distinction is under-explained in almost all public coverage of net zero.

Net zero CO2: the point at which human-caused CO2 emissions are balanced by human-caused CO2 removal. This halts warming from CO2. The IPCC found this is needed by around 2050 for a 1.5°C pathway.

Net zero all greenhouse gases: the point at which all greenhouse gas emissions, CO2, methane, nitrous oxide and fluorinated gases, are collectively balanced by removals. Because methane and nitrous oxide have different atmospheric lifetimes and warming profiles from CO2, this is a harder and later target. Net zero all GHGs occurs decades after net zero CO2 in most IPCC climate scenarios. When achieved, it implies slowly declining rather than stable temperatures.

The UK's legally binding target is net zero all greenhouse gases by 2050, the harder target. When a company announces "net zero by 2050" without specifying scope, it is often unclear which target it is working toward.

What carbon removal actually involves

Net zero implies reliance on carbon removal for residual emissions that cannot be eliminated. This matters for evaluating claims because removal mechanisms vary significantly in their permanence and credibility.

Natural sinks, forests, soils, wetlands and oceans, absorb CO2. They are existing but affected by land use change, climate feedbacks and degradation.

Nature-based solutions involve deliberate enhancement of natural uptake through tree planting, peatland restoration and soil carbon management. These are subject to permanence risk: a forest planted to sequester carbon can burn, be cleared or be damaged by drought. The UK Woodland Carbon Code progress check shows why validated woodland creation is a real signal, but not the same as verified removals today. Our guide to carbon offsetting for UK businesses explains the quality criteria for nature-based carbon removal.

Technology-based removal includes direct air capture (DAC), which removes CO2 directly from the atmosphere, and bioenergy with carbon capture and storage (BECCS). Both are currently expensive and deployed at limited scale. IPCC scenarios that require large-scale technology-based removal in the second half of the century carry significant uncertainties about whether this can be achieved at the pace required.

The distinction between removal types matters for evaluating claims. A company reaching net zero by purchasing forestry carbon credits is relying on a different mechanism, with different permanence characteristics, from one investing in engineered removal. See our guide to how carbon credits work.

What net zero is not

Net zero is not zero emissions. A genuinely net zero entity may still emit, as long as those emissions are permanently balanced by equivalent removal.

Net zero is not carbon neutral. Carbon neutral is an older term that typically refers to CO2 only and can be achieved by purchasing offsets against current emissions without reducing them first. Net zero, properly defined, requires deep emissions reduction and only then addresses residual emissions through permanent removal.

Net zero is not carbon negative or climate positive, terms implying more removal than emissions, producing a net cooling effect. These are a higher standard than net zero.

A terminology guide

Where the term came from

The term net zero predates the IPCC's 2018 special report, but the SR1.5 made net zero CO2 by around 2050 the central benchmark of 1.5°C climate pathways, bringing it into mainstream policy use.

The SR1.5 found that limiting warming to 1.5°C would require global net human-caused CO2 emissions to fall by about 45% from 2010 levels by 2030 and reach net zero around 2050. This gave policymakers a single, scientifically grounded and memorable target. The Paris Agreement (2015) had already established the goal of balancing sources and sinks of greenhouse gases in the second half of the century, the underlying concept, but had not made net zero the organising term.

From 2018 onwards, net zero spread rapidly through policy, corporate communications and investment frameworks. Governments legislated it. Companies committed to it. Fund managers adopted it as a portfolio descriptor. The precision of the IPCC's definition did not consistently accompany it.

The United Nations Framework Convention on Climate Change (UNFCCC) Race to Zero campaign, launched in 2020, coordinates voluntary net zero commitments and has developed minimum criteria, including covering all greenhouse gases, setting a target year and committing to interim milestones. Many self-described net zero commitments do not meet even these criteria.

Four kinds of net zero

Net zero is used in at least four distinct ways that are frequently conflated. Understanding which kind of net zero is being described is the first step in evaluating any claim.

1. Scientific net zero

The IPCC's definition: anthropogenic emissions balanced by anthropogenic removals. Specific, measurable, requires permanent removal not just temporary offsetting, and applies at global scale over a specified timeframe. This is what IPCC models use when assessing 1.5°C pathways. It is the most precise and least ambiguous use of the term.

2. Policy net zero

Government targets set under domestic legislation or international commitments. In the UK, the Climate Change Act 2008, as amended by the Climate Change Act 2008 (2050 Target Amendment) Order 2019, legally requires the net UK carbon account to be at least 100% lower than the 1990 baseline by 2050. This covers all greenhouse gases, not CO2 only.

The legal target is enforceable through judicial review. The accountability mechanism operates through the Climate Change Committee (CCC), which publishes annual progress reports to Parliament and provides independent advice on carbon budgets. Five-year carbon budgets provide the interim milestones.

On 2 June 2026, the government laid the draft Carbon Budget 7 Order before Parliament, proposing a seventh carbon budget of 535 million tonnes of carbon dioxide equivalent (MtCO2e) for the period 2038 to 2042, equivalent to approximately 87% emissions reduction from 1990 levels. This draft legislation is subject to parliamentary approval. The government has accepted the Climate Change Committee (CCC) advice on the budget level.

The legal target is binding. The policies to meet it are not always in place. The CCC's 2025 Progress Report found that 61% of the emissions reductions required for 2050 are covered by credible plans, while 39% remain at risk, particularly in buildings, agriculture and aviation.

3. Corporate net zero

Company-level commitments to reach net zero emissions by a specified date. The range is wide.

At the rigorous end, Science Based Targets initiative (SBTi)-validated net zero targets require near-term emissions reduction aligned with a 1.5°C pathway and long-term net zero requiring a minimum 90 to 95% absolute emissions reduction across Scope 1, 2 and relevant Scope 3 before any residual emissions can be addressed through permanent removal. Reaching net zero by purchasing offsets without first reducing emissions does not qualify under the SBTi standard.

At the weak end, companies have described themselves as net zero by purchasing carbon credits equivalent to their current emissions, with no reduction requirement at all. This is sometimes described as carbon neutral rather than net zero, but the terms are frequently used interchangeably in corporate communications.

Both claim to be net zero. The words are the same. The substance is not.

A clearer example: two companies can both announce net zero by 2050. One has SBTi-validated targets, covers Scope 1, 2 and 3 emissions, has a verified 2030 interim milestone and a published transition plan showing year-by-year reduction. The other covers only its office operations and purchases annual carbon credits with no specified reduction pathway. Both describe themselves as net zero. The IPCC's definition of net zero, which requires deep reduction before removal of residuals, applies clearly to the first. It does not apply to the second.

For the most rigorous independent validation framework for corporate net zero, see our guide to Science Based Targets initiative (SBTi) explained.

4. Marketing net zero

Product and service-level claims: "net zero delivery," "carbon neutral flights," "net zero data centres." These claims have historically had limited regulatory oversight.

In the UK, the Competition and Markets Authority (CMA) now has direct enforcement powers under the Digital Markets, Competition and Consumers Act 2024 to fine companies up to 10% of global turnover for misleading environmental claims. The Advertising Standards Authority (ASA) has been proactively reviewing carbon neutrality and net zero advertising claims. The risk is highest where claims are vague, unsubstantiated, omit material information, or imply emissions reductions that have not happened.

In the EU, consumer protection rules are tightening around generic environmental claims, including claims such as "climate neutral" where they rely on offsetting rather than evidence of actual product-level emissions reduction. For UK businesses making these claims, see our guide to carbon offsetting for UK businesses.

Why the definition matters

The practical consequence is simple: a net zero claim is not self-explanatory. It can mean a scientific endpoint, a legal target, a corporate transition plan or a marketing claim attached to a product. The phrase only becomes useful once the scope, gases, timeframe, reduction pathway and verification are visible.

How to evaluate a net zero claim

Before taking any net zero claim at face value, from a company, a fund, a product or a government, these eight questions help distinguish credible from weak.

1. What gases are covered? CO2 only, or all greenhouse gases including methane and nitrous oxide? A Scope 1 and 2 CO2 only target covers a fraction of most organisations' actual climate impact.

2. What emissions scopes are included? Scope 1 covers direct emissions from owned operations. Scope 2 covers purchased energy. Scope 3 covers supply chain, business travel, product use and end of life, the largest source of emissions for most companies and frequently excluded from weak net zero claims. See our guide to Scope 1, 2 and 3 emissions.

3. What year is the target? Net zero by 2050 is the common anchor. Net zero by 2030 implies much more aggressive near-term action. Net zero "by the end of the century" is not a meaningful commitment. The target year determines how urgent the current action needs to be.

4. What happens by 2030? A credible net zero commitment has a near-term 2030 milestone consistent with a 1.5°C pathway, not just a 2050 destination. The SBTi standard requires near-term targets covering the period to 2030 or within 10 years of setting.

5. How much emissions reduction is required before offsetting? The SBTi standard requires at least 90 to 95% reduction before any residual emissions can be addressed through permanent removal. A commitment that relies primarily on offsets rather than reductions is not consistent with this standard, regardless of the language used.

6. What removals or offsets are being used? Are residual emissions addressed through permanent removal mechanisms or temporary offsets? Forestry credits have permanence risk. Direct air capture is more permanent but currently expensive and limited in scale. The mechanism matters for the credibility of the claim.

7. Who verifies the target? Independent third-party validation is the credibility signal. SBTi validation is the most established standard for corporate net zero. The Transition Pathway Initiative (TPI) provides independent assessment of company climate alignment. Self-declared targets with no independent validation are the weakest category.

8. Is there a published transition plan? A net zero target without a published transition plan explaining how emissions will be reduced sector by sector, year by year, with capital allocation and governance accountability, is an aspiration not a commitment. For what a credible transition plan looks like, see our guide to climate transition plans.

UK progress: the honest picture

What is going right

The latest provisional figures put UK net territorial greenhouse gas emissions at 367 million tonnes of carbon dioxide equivalent in 2025, down 2% from 2024 and 54% from 1990. The electricity system has been significantly decarbonised, coal has been eliminated from power generation, and renewables now provide the majority of UK electricity.

For the underlying power-sector numbers, see the Progress article on the UK electricity generation mix in 2026, which compares 2010 and 2025 generation data.

For the whole-economy view, read the Progress article on UK emissions reductions in 2026, which separates the latest national emissions fall from the unresolved delivery tests in transport, buildings, industry and land use.

Recent Climate Change Committee (CCC) progress reporting has highlighted:

• Heat pump installations grew by 56% in 2024
• The Climate Change Committee (CCC) cited evidence that electric vehicle (EV) price premiums fell from 37% in 2023 to 24% in 2024, with price parity potentially reached between 2026 and 2028
• Public charge point installations increased by nearly 40%
• The CCC described the UK's 2050 target as "deliverable and affordable" with accelerated action

The Carbon Budget 7 draft legislation, laid on 2 June 2026, would set a target of approximately 87% reduction from 1990 levels for the 2038 to 2042 period. The government has accepted the Climate Change Committee (CCC) recommended level. Subject to parliamentary approval, this would be the most ambitious interim carbon budget the UK has set.

What remains at risk

The CCC's 2025 assessment found that 39% of the emissions reductions required for 2050 are at risk due to policy gaps. The hardest-to-decarbonise sectors, buildings (particularly heating), agriculture and aviation, account for most of the gap.

Buildings: the UK's housing stock is among the oldest and least energy-efficient in Europe. Retrofitting millions of homes to the standard required for heat pump operation at scale requires sustained investment and policy consistency that has been inconsistent.

Agriculture: methane from livestock and nitrous oxide from fertilisers are hard to reduce without changing food production practices at scale. Policy levers are limited and politically sensitive.

Aviation: emissions are growing with traffic recovery. The Carbon Offsetting and Reduction Scheme for International Aviation (CORSIA) provides an international offsetting framework but does not drive absolute reduction. See our guide to CORSIA explained.

The global context

The United Nations Environment Programme (UNEP) 2025 Emissions Gap Report found that current policies put the world on track for approximately 2.8°C of warming. Nationally determined contributions (NDCs), fully implemented, project only a 12% emissions reduction by 2035 against the 43% required for a 1.5°C pathway. The gap between net zero commitments made and net zero action delivered remains wide at the global level.

What is improving: renewable energy deployment is faster than most models projected in 2015. Electric vehicle (EV) adoption is ahead of schedule in many markets. Clean energy investment is at record levels. The cost of solar, wind and batteries has declined dramatically.

What is not improving fast enough: methane emissions have not peaked globally. Aviation and shipping emissions are growing with demand. Carbon removal at the scale required for the second half of the century remains unproven.

For a wider evidence-led view of what is changing, see The Planet Brief Progress tracker, which separates the headline number from the boundary, comparison and caveat.

What net zero means for UK investors

"Net zero aligned" applied to investment portfolios has no single agreed regulatory definition. The Glasgow Financial Alliance for Net Zero (GFANZ) provides a framework for financial institutions, requiring members to commit to transitioning financing activities to net zero by 2050 with interim targets. The Net Zero Asset Managers initiative, which BlackRock left in January 2025, contributing to the initiative suspending its activities, had its own framework. Neither is mandatory.

For investment funds, the most meaningful question is not whether a fund uses the "net zero aligned" label but what the underlying portfolio trajectory shows: are the companies held by the fund reducing their absolute emissions on a path consistent with 1.5°C, or simply disclosing them?

The Financial Conduct Authority (FCA) UK Sustainability Disclosure Requirements (SDR) and investment label regime provides a regulatory framework for sustainability-related claims in the UK. A fund with an SDR label has been through a regulatory process with specific criteria. A fund described as "net zero aligned" without an SDR label is using a self-description with no equivalent regulatory backing.

For detail on how major institutional investors approach net zero and engagement, see our guides to BlackRock explained, the Church of England pension fund and Norway's sovereign wealth fund. For fund labels, see FCA SDR labels explained.

Conclusion

Net zero is both the most important concept in climate policy and one of the most inconsistently applied terms in corporate communications. The scientific definition is precise. The pathway it describes is technically coherent: deep reductions first, permanent removal of residuals. Whether current policy and corporate commitments are sufficient to deliver it is a different question. The application of the same two words to commitments ranging from SBTi-validated multi-scope reduction targets to annual offset purchases with no reduction requirement is the consequence of a concept that entered policy before it entered regulation.

The UK's progress toward its legally binding 2050 target is genuine. The electricity system has been transformed. Heat pump and EV adoption is growing. The Carbon Budget 7 draft legislation, subject to parliamentary approval, would set one of the most ambitious interim UK emissions targets yet. The 39% policy gap identified by the CCC, concentrated in the hardest sectors, is also genuine.

For anyone encountering a net zero claim from a company, a fund, a product or a government, the most useful question is not whether the right words are being used. It is the eight questions in the checklist above: what is being measured, across which scopes, over what timeframe, with what reduction required before offsetting begins, and who is independently checking?

Those questions produce a better answer than the label alone ever could.

Useful source links

• IPCC: Summary for Policymakers, SR1.5 (2018)
• IPCC: SR1.5 Chapter 2, net zero CO2 definition
• Climate Change Act 2008 (2050 Target Amendment) Order 2019
• UK Parliament: Carbon Budget 7 written statement, 2 June 2026
• CCC: Progress in Reducing Emissions, 2025 Report to Parliament
• House of Commons Library: The UK's plans and progress to reach net zero by 2050
• UNEP: Emissions Gap Report 2025
• SBTi: Corporate Net-Zero Standard
• Net Zero Tracker
• UNFCCC Race to Zero: criteria and guidance
• Oxford Net Zero: what is net zero?

The Planet Brief covers net zero, environmental, social and governance (ESG) reporting, carbon markets and sustainable finance. For related reading, see our guides to Science Based Targets initiative (SBTi) explained, climate transition plans, Scope 1, 2 and 3 emissions and the Paris Agreement and US withdrawal.