Voluntary carbon offsets are a way for individuals or companies to compensate for their greenhouse gas (GHG) emissions by purchasing carbon credits from projects that reduce, avoid, or remove emissions from the atmosphere. These projects can include activities like reforestation, renewable energy, and energy efficiency initiatives.

Here's how they work:

• Purchase of credits: Companies or individuals buy carbon credits, with each credit representing one metric ton of CO2 or equivalent GHG reduced or removed.
• Offsetting Emissions: The purchased credits are used to offset the buyer's emissions, effectively balancing out their carbon footprint.
• Verification: Independent organizations verify the projects to ensure they are genuinely reducing emissions.

Voluntary carbon offsets are part of the broader voluntary carbon market, which operates outside of mandatory regulatory frameworks. They provide flexibility for entities to meet their own emissions reduction goals and contribute to global climate change mitigation efforts.

Voluntary carbon offsets standards have been developed for many project types are administered by multiple organisations to ensure project quality (see Projects for more on this) are carbon offsets are tracked and traded in various registries and markets. ZeroGHG is active in all voluntary markets and is able to source credits of various types including from:

• The Verified Carbon Standard (VCS), developed by Verra, is the world's most widely used greenhouse gas (GHG) crediting program. It drives finance toward activities that reduce and remove emissions, improve livelihoods, and protect nature. Carbon offsets generated by VCS projects are referred to as Verified Carbon Units (VCUs). Projects must meet stringent requirements to ensure that the emission reductions are real, measurable ,and permanent. These projects include a wide variety of activities, such as reforestation, renewable energy, and energy efficiency initiatives.
• The Gold Standard for Voluntary Crediting Projects (GS VER) is a carbon offset program that focuses on the United Nations' Sustainable Development Goals (SDGs). The GS VER can be applied to independent crediting projects in the voluntary market, and as an add-on standard for Clean Development Mechanism (CDM) projects. It was established by the World Wildlife Fund (WWF) and other international NGOs in 2003.
• The American Carbon Registry (ACR), now simply known as ACR, is a leading carbon crediting program. It was established in 1996 as the world's first private voluntary greenhouse gas (GHG) registry but has since then expanded to include the development of standard and quantifying methodologies. ACR operates in both compliance and voluntary carbon markets, including California's Cap-and-Trade market, the International Civil Aviation Organization's Carbon Offsetting and Reduction Scheme for International Aviation (CORSIA), and Washington State's Cap-and-Invest market.
• The Climate Action Reserve is a leading carbon credit registry in the United States. It was established by the State of California in 2001 and has since become a trusted and experienced offset registry but also a developer of offset quality standards The Reserve supports both voluntary and compliance carbon markets, including California's Cap-and-Trade program and Washington's Cap-and-Invest market.
• The Carbon Offsetting and Reduction Scheme for International Aviation (CORSIA) is a global market-based measure developed by the International Civil Aviation Organization (ICAO) to address CO2 emissions from international aviation. The CORSIA scheme has a voluntary phase from 2021 to 2026, after which it becomes mandatory for all ICAO member states. Airlines must purchase and cancel emissions units (carbon credits) to offset their emissions above the baseline. These units must meet strict eligibility criteria defined by ICAO.