What is Greenhouse Gas Emissions?

What are Greenhouse Gas Emissions?

Greenhouse gas (GHG) emissions refer to the release of gases that trap heat in the Earth's atmosphere, amplifying the natural greenhouse effect and driving global warming. The primary anthropogenic GHGs are carbon dioxide (CO2, 74% of total), methane (CH4, 17%), nitrous oxide (N2O, 8%), and fluorinated gases (1%). Global anthropogenic emissions reached approximately 57.4 gigatons of CO2 equivalent (GtCO2e) in 2023, up from 38 GtCO2e in 1990. Each gas has a different atmospheric lifetime and warming potency, expressed as Global Warming Potential (GWP) relative to CO2 over a specified time horizon.

Why It Matters

Greenhouse gas concentrations determine the trajectory of global warming. Atmospheric CO2 reached 424 ppm in 2024 — the highest level in at least 800,000 years and 50% above pre-industrial levels. The relationship between cumulative emissions and temperature rise is approximately linear: every 1,000 GtCO2 of cumulative emissions produces roughly 0.45°C of warming. With the remaining carbon budget for 1.5°C estimated at 250–400 GtCO2, the math is unforgiving at current emission rates.

GHG emissions have become a primary metric for corporate accountability. The GHG Protocol — developed by WRI and WBCSD — provides the global standard for emissions accounting, organizing emissions into Scope 1 (direct), Scope 2 (purchased energy), and Scope 3 (value chain). Over 90% of Fortune 500 companies now report emissions. Regulatory mandates are replacing voluntary disclosure: the CSRD, ISSB standards, California's SB 253, and the SEC's climate rule all require varying degrees of emissions reporting.

Carbon pricing mechanisms are putting a direct cost on emissions. The EU Emissions Trading System (ETS) covers 40% of EU emissions at prices that reached €100/tCO2 in 2023. Carbon border adjustments (CBAM) are extending this pricing to imports. Over 70 carbon pricing initiatives now operate globally, covering 23% of world emissions. For emissions-intensive industries, carbon costs are becoming a material factor in competitiveness and capital allocation.

The financial materiality extends beyond carbon pricing. Emissions exposure correlates with transition risk — the risk that policy, technology, and market shifts strand high-carbon assets. The Carbon Tracker Initiative estimates $1 trillion in potential stranded fossil fuel assets. Investors use emissions data to assess portfolio alignment with climate targets, price transition risk, and engage companies on decarbonization plans.

How It Works / Key Components

CO2 emissions from fossil fuel combustion and industrial processes account for roughly 65% of the total. Coal emits approximately 95 kg CO2/GJ, oil 73 kg, and natural gas 56 kg. The power sector is the single largest source (~25% of global emissions), followed by industry (~21%), transport (~16%), buildings (~6%), and agriculture/land use (~22%). Decarbonizing each sector requires different approaches and timelines — power generation can switch to renewables rapidly, while cement and aviation face harder-to-abate challenges.

Methane's role has received renewed attention. Though shorter-lived than CO2 (atmospheric lifetime of ~12 years versus centuries), methane's GWP is 80x that of CO2 over 20 years. Major sources include fossil fuel extraction and distribution (leaking wells, pipelines, and coal mines), livestock (enteric fermentation in cattle), rice cultivation, and landfills. The Global Methane Pledge, launched at COP26, commits over 150 countries to reduce methane emissions 30% by 2030. Satellite detection (using instruments like MethaneSAT) is revolutionizing methane monitoring, identifying super-emitter sites that were previously invisible.

The Scope 3 challenge defines current corporate emissions accounting. For most companies, Scope 3 (purchased goods, transportation, use of sold products, end-of-life treatment) represents 70–90% of total emissions. A car manufacturer's Scope 3 includes steel production, component manufacturing, fuel burned over vehicle lifetimes, and end-of-life recycling. Measuring these emissions requires data from hundreds or thousands of suppliers, many of which have limited measurement capabilities. The SBTi now requires Scope 3 target-setting for most sectors.

Emissions measurement technology is rapidly advancing. Continuous emissions monitoring systems (CEMS) provide real-time data for large point sources. Satellite remote sensing — from platforms like GHGSat, Copernicus Sentinel-5P, and NASA's OCO-3 — enables independent verification of facility and national-level emissions. Machine learning algorithms process satellite data to detect emissions events and quantify fluxes. These technologies are closing the gap between self-reported emissions and independently verified data.

Greenhouse Gas Emissions in Practice

The oil and gas sector illustrates both the scale of emissions and the complexity of reduction. The industry's direct operations (Scope 1+2) account for roughly 15% of global energy-related emissions, but its products (Scope 3) represent the majority of global CO2 emissions when burned. The Transition Pathway Initiative scores oil majors on their emission reduction commitments — as of 2024, no major oil company's targets aligned with the 1.5°C pathway across all scopes.

On the solutions side, India's renewable energy deployment cut the carbon intensity of its power sector by 21% between 2014 and 2023 while meeting rapidly growing electricity demand. The country added 73 GW of solar capacity in a decade, demonstrating that emission reductions can accompany economic development at scale.

Council Fire's Approach

Council Fire helps organizations navigate the increasingly complex emissions measurement, reporting, and reduction landscape. Our work spans Scope 1–3 accounting, science-based target setting, and development of credible decarbonization roadmaps. We bring particular expertise in emissions connected to ocean and coastal systems — including shipping, fishing, port operations, and blue carbon — where standard corporate emissions frameworks often miss significant sources and sinks. Our stakeholder strategy practice ensures that emissions data is communicated in ways that build credibility with investors, regulators, and communities.

Frequently Asked Questions

What's the difference between Scope 1, 2, and 3 emissions?

Scope 1 covers direct emissions from owned or controlled sources — fuel burned in company vehicles, natural gas in facilities, process emissions from manufacturing. Scope 2 covers indirect emissions from purchased electricity, heating, and cooling. Scope 3 encompasses all other value chain emissions, both upstream (purchased goods, business travel, employee commuting) and downstream (use of sold products, end-of-life treatment). For most companies, Scope 3 is the largest category but the hardest to measure accurately.

How are national emissions tracked and verified?

Countries report emissions through national inventories submitted to the UNFCCC, using IPCC methodologies. These self-reported inventories are subject to expert review but have historically relied on activity data and emission factors rather than direct measurement. Satellite monitoring is transforming verification — missions like Copernicus and GHGSat can now independently estimate national and facility-level emissions, increasingly revealing gaps between reported and observed figures.

Can the world reach net-zero emissions?

The IEA's Net Zero by 2050 roadmap identifies a technically feasible pathway involving massive expansion of renewables, electrification, energy efficiency, hydrogen for hard-to-abate sectors, CCUS, and behavioral change. The pathway requires no new fossil fuel development and $4 trillion in annual clean energy investment by 2030. Whether this is politically and economically feasible is the open question — current investment runs at roughly $1.8 trillion, growing rapidly but still well below the required trajectory.