Net-zero emissions

Net-zero emissions refers to a balance between anthropogenic emissions and anthropogenic removals of greenhouse gases, including carbon dioxide, methane, and nitrous oxide.¹ The Intergovernmental Panel on Climate Change (IPCC) defines net-zero as a state where "anthropogenic emissions of greenhouse gases to the atmosphere are balanced by anthropogenic removals over a specified period."³ This balance can be achieved through a combination of reducing emissions at the source and enhancing carbon sinks, such as forests, soils, and direct air capture technologies.

The distinction between net-zero and gross-zero is critical: gross-zero would require eliminating all emissions, while net-zero permits residual emissions to be offset by removals. The IPCC notes that reaching net-zero CO2 emissions is a prerequisite for stabilizing global temperatures, as the climate system responds to cumulative CO2 emissions.³

The Paris Agreement, adopted in 2015, implicitly calls for net-zero emissions in the second half of the century, and the 2018 IPCC Special Report on 1.5°C made net-zero by 2050 a central benchmark for limiting warming to 1.5°C.² Countries including the United Kingdom, France, and Japan have enshrined net-zero targets in law, while the European Union's European Climate Law sets a binding net-zero target for 2050.⁴

China, the world's largest emitter, has pledged carbon neutrality by 2060, and India has committed to net-zero by 2070.² The United Nations Framework Convention on Climate Change (UNFCCC) tracks these pledges through Nationally Determined Contributions (NDCs), and the UN Secretary-General has called for all governments to align their NDCs with net-zero pathways.⁵

Achieving net-zero requires not only rapid decarbonization of energy, transport, and industry, but also the deployment of carbon dioxide removal (CDR) technologies at scale.³ The IPCC estimates that 100–1,000 gigatonnes of CO2 must be removed cumulatively by 2100 to meet the 1.5°C goal, depending on the pace of emission reductions.³

Nature-based solutions, such as reforestation and soil carbon sequestration, are currently the most mature CDR methods, but their capacity is limited and reversible.⁶ Engineered approaches, including direct air capture and bioenergy with carbon capture and storage (BECCS), remain expensive and energy-intensive. The integrity of net-zero claims also depends on robust accounting and verification, as concerns about greenwashing have led to calls for stricter standards for carbon offsets.⁶

The term "net-zero" gained prominence in 2018, but the underlying concept of balancing emissions with removals dates to the 1990s, when the IPCC first discussed the idea of "stabilization of greenhouse gas concentrations."³ A lesser-known dimension is the distinction between net-zero CO2 and net-zero all greenhouse gases: the latter is more stringent because methane and nitrous oxide have much higher global warming potentials, and their removal is far more difficult.¹

Another niche aspect is the role of "carbon dioxide removal" in national accounting: some countries include emissions from international aviation and shipping in their net-zero targets, while others exclude them, creating inconsistencies in global accounting.⁵ Additionally, the concept of "net-zero" has been applied to individual companies and products, leading to the development of the Science Based Targets initiative (SBTi) and the ISO Net-Zero Guidelines (ISO 14068), which aim to standardize corporate net-zero claims.⁶

Carbon dioxide removal (CDR)

Techniques that remove CO2 from the atmosphere and store it durably, including reforestation, direct air capture, and bioenergy with carbon capture and storage.

Carbon neutrality

A state where emissions are balanced by offsets, often without the same emphasis on absolute emission reductions as net-zero.

Nationally Determined Contributions (NDCs)

Climate action plans submitted by countries under the Paris Agreement, outlining their emission reduction targets and strategies.