What are greenhouse gases and CO2 equivalent (CO2e)?
Which gases warm the planet, how CO2 equivalent and global warming potential work, why reports use different GWP values, and where India's emissions come from.
Overview
Greenhouse gases are gases such as carbon dioxide, methane and nitrous oxide that trap heat given off by the Earth and so warm the planet. CO2 equivalent (CO2e) is a common unit that converts each gas into the amount of carbon dioxide that would cause similar warming over a chosen period, usually 100 years.
Photo: "Rajpura Thermal Power Plant" by Npl-User1234, CC BY-SA 4.0, via Wikimedia Commons
Using one unit lets a farmer, a factory or a whole country add different gases together and compare them. This article explains which gases matter, how the conversion works and why reports sometimes use different numbers.
Sources: IPCC AR6 Working Group I, Summary for Policymakers (2021); IPCC AR6 Working Group I, Chapter 7: The Earth's Energy Budget, Climate Feedbacks and Climate Sensitivity (2021); IPCC AR6 Working Group III, Annex I: Glossary (2022); GHG Protocol, IPCC Global Warming Potential Values, Version 2.0 (August 2024); MoEFCC, India First Biennial Transparency Report (BTR-1) to the UNFCCC; MoEFCC, India Fourth Biennial Update Report (BUR-4), December 2024; UNFCCC Decision 18/CMA.1, Modalities, procedures and guidelines for the transparency framework; UNFCCC Decision 5/CMA.3, Guidance for operationalizing the modalities, procedures and guidelines for the enhanced transparency framework; Press Information Bureau / PM India: Cabinet approves ratification of Kigali Amendment to the Montreal Protocol (August 2021); 2006 IPCC Guidelines for National Greenhouse Gas Inventories, Volume 2, Chapter 1
This article was prepared with AI assistance and checked by the GreenEye team against the sources shown in each section.
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