Comparison of GHG emissions: sectors, countries, and energy sources

What is a GHG emission?

Greenhouse gas (GHG) emissions include different compounds such as:

• Carbon dioxide (CO2),
• Methane (CH4),
• Nitrous oxide (N2O).

These gases trap heat in the atmosphere, contributing to global warming. GHG emissions are produced by various human activities, such as the combustion of fossil fuels, agriculture, and industry. To measure their impact, emissions are expressed in tons of CO2 equivalent (tCO2e), which quantifies the effect of each gas relative to CO2, providing a unified measure of emissions.

Comparison of GHG emissions by sector

Greenhouse gas emissions vary significantly across economic sectors. The energy sector is the most polluting, accounting for about 73% of global emissions, mainly due to the combustion of fossil fuels for electricity and heat.

Transportation generates about 16% of emissions, primarily from internal combustion engine vehicles. Agriculture is responsible for 14% of emissions, through the production of methane (CH4) and nitrous oxide (N2O). The industrial sector contributes to 21% of emissions, notably through the production of cement, steel, and chemicals. Lastly, buildings account for about 6%, linked to energy consumption for heating and cooling.

While some sectors have made significant progress in reducing emissions, such as industry and transportation through improved energy efficiency and the shift to renewable energy sources, other sectors, like agriculture, remain harder to decarbonize due to their specific characteristics.

Comparison of GHG emissions by country and region

Globally, certain countries are responsible for the majority of greenhouse gas emissions. China is the largest emitter, accounting for about 27% of global emissions, mainly due to its industry and coal-based electricity production. The United States follows with about 11%, while the European Union and India emit approximately 6% and 7%, respectively.

The ranking of emissions changes when measured per capita. The United States, for example, has much higher per capita emissions than China and India, reflecting a more energy-intensive lifestyle. Historically, industrialized countries have emitted more GHGs than developing countries, but the rapid growth of emerging countries is increasing their overall emissions.

Regional differences are also influenced by the type of energy used and the level of industrialization. While industrialized countries tend to adopt stricter climate policies to reduce their emissions, developing countries must balance economic growth with sustainability goals.

Deep dive into a comparison of GHG emissions per country in our related article or read our article on France’s GHG emissions.

Comparison of GHG emissions by energy source

Greenhouse gas emissions vary widely depending on the energy source used. Fossil fuels such as coal, oil, and natural gas are responsible for the majority of global emissions. Coal is the most polluting source, generating about 2.3 tons of CO2 per megawatt-hour (MWh) produced. Oil and natural gas emit approximately 0.9 and 0.5 tons of CO2 per MWh, respectively.

In contrast, renewable energy sources such as solar, wind, and hydropower produce little or no direct CO2 emissions. Although small emissions are associated with their extraction, production, and transportation (for example, for manufacturing solar panels or wind turbines), their overall carbon footprint remains very low compared to fossil fuels.

Fossil fuels have a major climate impact, while renewable energy sources offer significant advantages for long-term emission reductions. By promoting the transition to renewable sources, companies and countries can significantly reduce their carbon footprint and contribute to global emission reduction goals.

Factors influencing the variation of GHG emissions

Greenhouse gas emissions are influenced by various factors. Economically, growth and industrialization increase energy demand, often leading to higher emissions. High energy consumption, particularly from fossil fuels, further amplifies these emissions.

Technological factors also play a key role in reducing emissions. Innovations in clean technologies and improved energy efficiency enable the production and consumption of energy while reducing the carbon footprint. For example, advances in renewable energy or electric vehicles contribute to emission reductions in certain sectors.

Finally, climate policies and local and international regulations, such as the Paris Agreement, are crucial. They encourage companies and countries to reduce their emissions through binding targets, carbon taxes, or subsidies for renewable energy.