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Global Greenhouse Gas Emissions by Sector
Key Idea
Understanding which human activities generate the most greenhouse gas emissions is essential for designing effective climate solutions. In 2019, global net anthropogenic GHG emissions reached 59 GtCO2-eq per year, the highest in human history. These emissions are distributed unevenly across economic sectors, geographies, and income groups.
The Global Emissions Picture in 2019
Total global net anthropogenic greenhouse gas emissions in 2019 were 59 ± 6.6 GtCO2-eq per year. This was approximately 12% higher than in 2010 and 54% higher than in 1990. The average annual rate of growth slowed from 2.1% per year in 2000-2009 to 1.3% per year in 2010-2019, but the absolute level of emissions continued to rise.
These figures come from the IPCC AR6 WGIII, Chapter 2, which compiled the most comprehensive global greenhouse gas inventory to date. A critical insight is that emissions have grown across all major gas categories since 1990, though at different rates. The largest absolute growth occurred in CO2 from fossil fuels and industry, followed by methane. The highest relative growth occurred in F-gases, though from a very low base.
Analogy: The Global Budget
Think of the 59 GtCO2-eq as a global household budget. Each economic sector is a spending category. Just as a household trying to save money needs to know which categories consume the most, climate policy requires understanding which sectors generate the most emissions. You cannot cut a budget you have not measured.
Breakdown by Economic Sector
The IPCC AR6 WGIII reports the following sectoral breakdown of global net anthropogenic GHG emissions in 2019. These figures use direct emissions accounting, meaning emissions are attributed to the sector where they physically occur rather than allocated to the sector that consumes the energy:
| Sector | Share of 2019 Global Emissions | Approximate GtCO2-eq/yr | Key Gases |
|---|---|---|---|
| Energy Supply | 34% | 20 Gt | CO2, CH4 |
| Industry | 24% | 14 Gt | CO2, F-gases |
| Agriculture, Forestry and Other Land Use (AFOLU) | 22% | 13 Gt | CH4, N2O, CO2 |
| Transport | 15% | 8.7 Gt | CO2 |
| Buildings | 6% | 3.3 Gt | CO2, CH4 |
An important caveat: if emissions from electricity and heat production are reallocated to the end-use sectors that consume that energy, the picture changes substantially. Under this "consumption-based" or "indirect emissions" approach, industry's share rises from 24% to 34%, buildings rise from 6% to 16%, and energy supply falls from 34% to 12%. This distinction matters enormously for policy: direct emissions accounting motivates action at power plants, while consumption-based accounting highlights the role of end users and efficiency.
Energy Supply: The Largest Sector
Power generation and heat supply account for the single largest slice of global emissions because the world still overwhelmingly relies on fossil fuels for electricity. Coal-fired power plants alone are responsible for a large share of energy-sector CO2. Methane leaks from natural gas extraction and distribution also contribute significantly.
Despite rapid growth in solar and wind energy since 2010, fossil fuels still provided approximately 80% of global primary energy in 2019. Decarbonising energy supply is therefore the single largest individual lever for reducing global emissions, and the sector where renewable energy deployment has been most rapid and cost-competitive.
The Electricity Sector Decarbonisation Race
Between 2010 and 2022, the cost of utility-scale solar photovoltaics fell by approximately 89% and onshore wind by approximately 69%. These cost reductions have made clean electricity often the cheapest new source of power in most markets. Many countries now generate 30-60% of their electricity from renewables. But the speed of the energy transition must accelerate substantially to align with 1.5°C or 2°C pathways, which require near-zero-carbon electricity systems by 2035-2040 in advanced economies.
Agriculture, Forestry and Land Use: The Complex Sector
AFOLU is unique because it includes both large sources and large sinks. Deforestation releases the carbon stored in trees; agricultural soils and livestock emit methane and nitrous oxide. But forests, wetlands, and soils also absorb carbon when preserved or restored. About half of total net AFOLU emissions come from CO2 from land-use change, predominantly deforestation, primarily in tropical regions such as the Amazon, Congo Basin, and Southeast Asian islands.
The non-CO2 agricultural emissions (methane from livestock and rice, nitrous oxide from fertilisers) account for the other half of AFOLU and are particularly difficult to reduce without affecting food production. This is where the tension between food security and climate goals is most direct.
Regional and Per Capita Inequalities
Emissions are distributed highly unequally across countries and populations. The IPCC AR6 WGIII reports that average global per capita net anthropogenic GHG emissions were approximately 7.8 tCO2-eq in 2019, but regional averages ranged from 2.6 to 19 tCO2-eq per person. Least Developed Countries (LDCs) had per capita emissions of only 1.7 tCO2-eq, while some high-income countries exceeded 15-20 tCO2-eq per person.
Even more striking is the household-level inequality within countries: the top 10% of households globally contribute 34-45% of consumption-based household GHG emissions, while the bottom 50% contribute only 13-15%. This inequity has profound implications for climate justice and for designing effective and fair mitigation policies.
Most national GHG inventories count emissions where they are produced, creating potential blind spots. A country that imports steel, cement, or electronics benefits from those goods but does not count the emissions from their manufacture.
Consumption-based accounting allocates emissions to where goods and services are ultimately consumed. For high-income countries that import manufactured goods, consumption-based emissions are often 10-30% higher than production-based figures. For some major exporters, production-based emissions are significantly higher than consumption-based emissions. Neither approach is inherently superior; both provide important insights.
Key Takeaways
- 1Global GHG emissions reached 59 GtCO2-eq in 2019, 54% higher than 1990 levels and the highest in human history
- 2Energy supply is the largest emitting sector at 34%, followed by industry (24%), AFOLU (22%), transport (15%), and buildings (6%) under direct emissions accounting
- 3Reallocating electricity emissions to end-use sectors shifts industry's share from 24% to 34% and buildings from 6% to 16%, revealing where efficiency gains matter most
- 4AFOLU is uniquely complex: it includes both major sources (deforestation, livestock, fertilisers) and major potential sinks (forests, soils)
- 5The top 10% of global households contribute 34-45% of consumption-based household emissions, while the bottom 50% contribute only 13-15%