Greenhouse gas emissions

People make gases that trap heat.

Many gases come from burning coal, oil, and gas. This is a main cause of heat. We use these to make power. We also use them for cars.

Farming can make these gases too. Cows in fields make a gas called methane. Changing how we use land also adds gases.

Some places make more gas than others. Richer lands often make more per person. China makes a very large amount.

We can track how much gas is made. This helps us understand our world. It is important to learn more.

Human activities release gases that trap heat. These are called greenhouse gases. They make the Earth warmer. This is called the greenhouse effect.

Carbon dioxide is the main gas. We make it by burning fossil fuels. These include coal, oil, and gas. Burning coal for power is a big source.

Other gases also matter. Methane is another gas that traps heat. Farming makes much of this gas. Cows are a large source of methane.

Changing how we use land also helps gases enter the air. Cutting down forests is one way. This is called deforestation.

Different places make different amounts of gas. China is the world's largest emitter. It makes nearly 10 billion tonnes each year. Richer countries often make more gas per person. This is called per capita emissions. In some rich lands, this is ten times higher than in poor lands.

Greenhouse gas emissions are gases released by human activities. These gases trap heat in our atmosphere. This process is called the greenhouse effect. When these gases increase, they make the Earth warmer. This warming leads to climate change. Scientists use a tool called a carbon footprint to measure this. It looks at the total gases produced during the life of a product.

Many different things cause these emissions to happen. Burning fossil fuels like coal, oil, and gas is a major cause. Coal-fired power stations alone produced 20% of greenhouse gases in 2021. Another big cause is changing how we use land. This includes deforestation, which is cutting down forests. Agriculture is also a huge source of methane. Livestock, especially cattle, are responsible for about 65% of emissions from the livestock sector.

Human activity has changed the air since the industrial era began. Around the year 1750, people started using more fossil fuels. This caused the amount of carbon dioxide in the air to rise. By 2021, levels were almost 50% higher than before the industrial age. Emissions grew very quickly after 1950 due to more people and more business. In 2025, over 60 billion tons of gases were emitted. This was higher than any year before it.

Different countries produce different amounts of these gases. China is the world's largest emitter. It releases nearly 10 billion tonnes every year. This is more than one-quarter of all global emissions. The United States also has high emissions. However, the US has higher emissions per person than many other places. In industrialized countries, emissions per person are often ten times higher than in developing countries.

We can see how these gases relate to our daily lives. Most emissions come from energy used for electricity, heat, and transport. Energy use accounts for about 73% of all emissions. Even new technology like artificial intelligence uses a lot of electricity. This will likely increase global energy demand in the future. We also use gases like hydrofluorocarbons in refrigerators. Many nations have agreed to phase these out to help the planet.

Greenhouse gas emissions are the release of specific gases into the atmosphere from human activities. These gases intensify the greenhouse effect, which is the process that traps heat around our planet. This intensification contributes directly to climate change. Scientists often use a metric called a carbon footprint to measure this impact. A carbon footprint tracks the total greenhouse gases emitted throughout the entire life cycle of a good or service. This includes everything from the production of materials to the final consumption of a product.

The mechanism of warming involves several different types of gases. Carbon dioxide (CO2) is the primary greenhouse gas resulting from human activities. It is responsible for more than half of the global warming caused by humans. Methane (CH4) is another significant gas with a similar short-term impact on the atmosphere. Nitrous oxide (N2O) and various fluorinated gases, or F-gases, also contribute, though they play a lesser role than CO2 or methane. To compare these different gases, scientists use a unit called CO2-equivalent. This calculation accounts for how long each specific gas remains in the atmosphere.

Human activities produce these gases through several distinct sectors. The energy sector is the largest contributor, accounting for approximately 73% of total emissions. This includes electricity generation, heat production, and transport. Within energy, burning fossil fuels like coal, oil, and natural gas is a massive source. Coal-fired power stations alone produced 20% of greenhouse gases in 2021. Agriculture is the largest source of anthropogenic methane emissions. Within the agricultural sector, livestock is the primary contributor, with cattle accounting for about 65% of livestock emissions.

Land-use change is another critical driver of emissions. This includes activities like deforestation, particularly in the tropical regions. Deforestation and other changes to how we use land caused about 31% of cumulative emissions between 1870 and 2022. Agriculture, forestry, and other land use (AFOLU) accounted for 22% of emissions in 2019. Other sources include the use of fertilizers in agricultural soils, which releases nitrous oxide. Additionally, fluorinated gases used in refrigerants play an outsized role in total human emissions.

History shows a massive increase in these gases since the industrial era began. Around the year 1750, the use of fossil fuels started to change the atmosphere. Since about 1950, emissions have grown rapidly due to expanding global populations and economic activity. By 2021, atmospheric concentrations of carbon dioxide were nearly 50% higher than pre-industrial levels. In 2025, global emissions exceeded 60 billion tons, which was higher than any previous year. Total cumulative emissions from 1870 to 2022 reached 703 gigatonnes of CO2-equivalent.

Global emissions vary greatly by country and wealth. China is the world's largest emitter, producing nearly 10 billion tonnes annually. This amount represents more than one-quarter of all global emissions. The United States also has high total emissions, though it has higher emissions per capita than many other nations. There is a strong link between wealth and emissions. Annual per capita emissions in industrialized countries are typically ten times higher than in developing countries. In 2019, the average emission rate was 6.6 tonnes per person per year. This is more than double the 2.3 tonnes per person required to meet the Paris Agreement goal of limiting warming to 1.5 °C.

Understanding these emissions requires careful measurement and accounting. Carbon accounting is a framework used to track and measure how much gas an organization emits. There are different ways to define these measurements, such as the territory principle or the activity principle. Scientists also use different methods for monitoring, including continuous emissions monitoring systems and mass balance methods. As technology evolves, new concerns arise. For example, the expansion of artificial intelligence is projected to significantly increase global electricity demand. This growing demand for energy will likely impact future greenhouse gas emission trends.