Global Human CO2 Emissions Overview
Global human CO2 emissions from fossil fuels and industry reached roughly 36.8 billion tonnes in 2024, with 2025 data pointing to a new record or near-record level as energy demand remains strong. The Global Carbon Project and International Energy Agency report that CO2 from coal, oil, and gas continues to rise, even as some regions deploy more renewables. Emissions per capita vary widely, with high-income countries typically emitting several times more than the global average. In 2024, China, the United States, India, the European Union, and Russia remained the top emitters, together accounting for more than half of global totals. The energy sector remains the dominant source, followed by industry, transport, and buildings, with land-use change still contributing a smaller but significant share. For detailed sector breakdowns and country rankings, see the Global Carbon Budget and IEA tracking tools IEA.
Atmospheric CO2 concentration surpassed 420 parts per million in 2024, a level unprecedented in at least 800,000 years, and human emissions are the primary driver of this increase. The Global Carbon Budget estimates that cumulative CO2 from human activities since the pre-industrial era has warmed the planet by roughly 1.1 to 1.3 degrees Celsius. Land sinks, mainly forests, and ocean sinks absorb about half of human emissions each year, but their efficiency may decline as climate impacts intensify. The remaining CO2 accumulates in the atmosphere for centuries, locking in long-term warming and sea-level rise. This persistent buildup makes human CO2 emissions a central risk factor for investors, insurers, and companies facing physical and transition risks.
Human CO2 Emissions by Sector
The energy supply sector, including electricity and heat production, is the single largest source of human CO2 emissions, responsible for roughly 40 to 45 percent of global fossil CO2 in 2024. Coal remains the most carbon-intensive fuel, but natural gas and oil also contribute heavily, especially in power generation and heating. In 2024, global electricity demand grew faster than low-carbon generation, pushing power-sector emissions to new highs despite record additions in solar and wind capacity. Companies in oil, gas, and coal supply chains face growing scrutiny from investors, regulators, and climate groups over their role in these emissions. The International Energy Agency and Global Carbon Project provide detailed fuel and sector data that underpin these estimates Global Carbon Project.
Industry accounts for about 25 to 30 percent of direct human CO2 emissions, with cement, steel, and chemicals among the most carbon-intensive subsectors. Process emissions from chemical reactions, such as limestone calcination in cement, make decarbonization harder than in other sectors where fuel switching is easier. Transport, including road, aviation, and shipping, contributed roughly 16 to 20 percent of global fossil CO2 in 2024, with oil-based fuels still dominant. Buildings, mainly from natural gas and diesel use for heating and cooking, add another 10 to 15 percent of direct emissions. Companies in these sectors are increasingly required to disclose emissions under frameworks such as the SEC climate disclosure rule SEC, and major investors are using this data to guide capital allocation.
Country and Company Rankings
In 2024, China's CO2 emissions from fossil fuels and industry exceeded 12 billion tonnes, making it the single largest emitter, followed by the United States, India, the EU, and Russia. Per capita emissions remain highest in the United States and some Gulf states, while India's