Greenhouse gas emissions facts for kids

Greenhouse gas emissions from human activities make the greenhouse effect stronger. This leads to climate change, which is a big change in Earth's weather patterns. The most important gas causing climate change is carbon dioxide (CO₂). It comes from burning fossil fuels like coal, oil, and natural gas.

The countries that release the most greenhouse gases are China and the United States. However, the United States releases more gases per person. Large oil and gas companies are the main producers of these emissions worldwide.

Human activities have increased the amount of carbon dioxide in the air by about 50% compared to before factories became common. Emissions have grown steadily for all greenhouse gases. In the 2010s, we released about 56 billion tons of greenhouse gases each year, which was more than ever before.

From 1870 to 2022, the total amount of carbon released was about 703 billion tons. A big part of this, about 484 billion tons, came from burning fossil fuels and industry. The rest, about 219 billion tons, came from changes in how land is used. For example, cutting down forests caused about 31% of all emissions between 1870 and 2022. Coal caused 32%, oil 24%, and gas 10%.

CO₂ is the main greenhouse gas from human activities. It causes more than half of the warming. Methane (CH₄) emissions have almost the same impact in the short term. Nitrous oxide (N₂O) and fluorinated gases (F-gases) play a smaller role. In 2023, emissions of CO₂, methane, and nitrous oxide were all higher than ever before.

Making electricity, heating homes, and transporting things are major sources of these gases. Together, energy use causes about 73% of all emissions. Deforestation and other land use changes also release CO₂ and methane. The biggest source of human-caused methane is farming, especially livestock. Farm soils release nitrous oxide, partly because of fertilizers. Also, fluorinated gases from refrigerants (like in fridges) contribute a lot to human emissions.

Currently, the world releases about 6.6 tons of CO₂ equivalent per person each year. This is more than twice the 2.3 tons needed to keep global warming within the 1.5°C (2.7°F) limit set by the Paris Agreement by 2030. Richer countries usually have ten times higher emissions per person than developing countries.

Your carbon footprint is a way to measure the total greenhouse gases released during the entire process of making and using a product or service.

What Are Greenhouse Gases?

Global greenhouse gas emissions by type of greenhouse gas. Most (74%) is CO₂, followed by methane (17%), in 2016.

The main greenhouse gases from human activities are carbon dioxide (CO₂), nitrous oxide (N₂O), methane, and three groups of fluorinated gases (like HFCs and PFCs). Even though water vapor is a big part of the natural greenhouse effect, human emissions of water vapor don't cause much warming.

Some gases, like CFCs, are greenhouse gases, but they are controlled by the Montreal Protocol. This agreement was made because CFCs harm the ozone layer, not mainly because they cause global warming.

Human Activities and Emissions

How much CO₂-equivalent gas has increased in the air since 1750, due to industry.

Around 1750, when the Industrial Revolution began, activities powered by fossil fuels started to greatly increase the amount of CO₂ and other greenhouse gases in the air. Emissions have grown very fast since about 1950, as the world's population and economy grew after World War II. By 2021, the amount of CO₂ in the atmosphere was almost 50% higher than before the industrial era.

The main ways human activities release greenhouse gases are:

• Burning fossil fuels: Burning oil, coal, and gas released an estimated 37.4 billion tons of CO₂ equivalent in 2023. The biggest single source is coal-fired power stations, which caused 20% of greenhouse gas emissions in 2021.
• Changes in land use: Mainly deforestation in tropical areas, accounts for about a quarter of all human-caused greenhouse gas emissions.
• Farming and waste: This includes methane from livestock (like cows burping), manure management, rice farming, and landfills. Many newer septic systems also release methane.
• Chemicals: Using chlorofluorocarbons (CFCs) in fridges and fire suppression systems.
• Fertilizers: Farm soils release nitrous oxide (N₂O), partly because of fertilizers.
• Fossil fuel industry: The biggest source of human-caused methane is agriculture, followed closely by gas venting and leaks from the fossil fuel industry. Cows are the main source of methane from livestock, causing about 65% of emissions from this sector.

Global Emissions Overview

Global greenhouse gas emissions are about 50 billion tons per year. In 2019, they were estimated at 57 billion tons of CO₂ equivalent, including 5 billion tons from land use changes.

• About 34% of emissions came from energy supply.
• 24% from industry.
• 22% from agriculture, forestry, and other land use.
• 15% from transport.
• 6% from buildings.

The current average of 6.6 tons of CO₂ equivalent per person per year is more than double the 2.3 tons needed to meet the 2030 Paris Agreement goal.

A study in 2017 found that 100 companies were responsible for 71% of global direct and indirect emissions. Most of these were state-owned companies.

China is the world's largest emitter, releasing almost 10 billion tons each year, which is more than a quarter of global emissions. Other countries with fast-growing emissions include South Korea, Iran, and Australia. On the other hand, emissions per person in the EU and the US are slowly decreasing. Emissions in Russia and Ukraine have fallen fastest since 1990 due to economic changes.

2015 was the first year that the global economy grew while carbon emissions actually went down.

Rich vs. Poor Countries

CO₂ emissions per person compared to GDP per person (2018): Generally, richer countries have higher greenhouse gas emissions per person.

Richer countries typically have ten times higher emissions per person than developing countries. Because China's economy has grown so fast, its emissions per person are getting closer to those of developed countries.

Africa and South America release much less, accounting for only 3-4% of global emissions each. This is about the same as international aviation and shipping combined.

How Emissions Are Measured

Per person CO₂ emissions increased sharply after the mid-20th century, but then slowed down.

There are different ways to measure greenhouse gas emissions.

• Where they are released: Emissions can be counted based on where they are produced (like a factory in a country) or by the country that uses the products (like imported goods).
• How long gases last: The impact of a greenhouse gas is measured as a "CO₂ equivalent." This calculation considers how long the gas stays in the atmosphere.
• Measurement methods: Emissions can be measured directly or estimated using different methods.

These different ways of measuring can make it hard to compare progress between countries.

Tracking Emissions Over Time

Emissions can be tracked over long periods, called historical or cumulative emissions. This helps us see which countries have contributed the most to the build-up of greenhouse gases in the atmosphere.

Emissions can also be measured against a specific starting year, like 1990. This year is often used in climate agreements like the United Nations Framework Convention on Climate Change (UNFCCC) and the Kyoto Protocol.

Another way to measure is "per person emissions," which divides a country's total annual emissions by its population.

Types of Greenhouse Gases

CO₂ is the main greenhouse gas released, but methane (CH
4) has a similar impact in the short term. Nitrous oxide (N₂O) and fluorinated gases (F-gases) play a smaller role.

Greenhouse gas emissions are measured in CO₂ equivalents. This is based on their global warming potential (GWP), which depends on how long they stay in the atmosphere. Some gases, like methane, stay in the air for a few years, while CO₂ can stay for thousands of years. Reducing short-lived pollutants like methane can help slow global warming quickly.

Carbon Dioxide (CO₂)

• Fossil fuels: Burning oil, gas, and coal for energy, transport, heating, and industry is the main cause of human-caused global warming. In 2019, this released 35.6 billion tons of CO₂.
• Cement production: Making cement also releases CO₂ (about 1.42 billion tons).
• Land-use change: This is when forests are cut down (deforestation) faster than new ones are planted (reforestation). This can release about 4.5 billion tons of CO₂. Wildfires alone cause about 7 billion tons of CO₂ each year.

Methane (CH₄)

How important it is to reduce short-lived climate pollutants like methane to control future temperature increases.

Methane has a strong and fast impact on warming. The current amount of methane released has about the same short-term warming effect as CO₂ emissions. Reducing methane emissions by about 30% could help stabilize its amount in the atmosphere.

• Fossil fuels: About 32% of methane emissions come from leaks during the production and transport of fossil fuels, including coal mining, gas leaks, and gas flaring in oil production.
• Livestock: About 28% comes from livestock, with cows being the biggest source.
• Human waste: About 21% comes from landfills and wastewater, where bacteria break down waste without oxygen, creating methane.
• Rice farming: About 10% comes from flooded rice fields, where organic material breaks down and produces methane.

Nitrous Oxide (N₂O)

Nitrous oxide has a high global warming potential and also harms the ozone layer. Its warming effect over 100 years is 265 times greater than CO₂. We would need to reduce N₂O emissions by more than 50% to stabilize its levels.

Most nitrous oxide emissions (56%) come from agriculture, especially from meat production (animal droppings and fertilizers). Other sources include burning fossil fuels and industrial processes.

F-gases

Fluorinated gases (F-gases) are used in things like electrical equipment, semiconductor manufacturing, and aluminum production. Reducing the use of HFCs (a type of F-gas) under the Kigali Amendment will help reduce these emissions and make appliances like air conditioners more energy-efficient.

Black Carbon

Black carbon is tiny soot particles formed from burning fossil fuels, biofuels, and biomass (like wood). It's not a greenhouse gas, but it absorbs sunlight and can make snow and ice melt faster when it lands on them. Black carbon stays in the atmosphere for only a few days to weeks. Reducing it can be done by improving industrial processes and reducing open burning.

Emissions by Economic Sector

Contributions to climate change broken down by economic sector as of 2019

2016 global greenhouse gas emissions by sector. Percentages are calculated from estimated global emissions of all Kyoto Greenhouse Gases, converted to CO₂ equivalent quantities (GtCO₂e).

Greenhouse gas emissions can be grouped by different parts of the economy. This helps us see how different activities contribute to climate change and what changes are needed.

About two-thirds of greenhouse gas emissions come from burning fuels to produce energy. The rest come from other processes.

Electricity Generation

Global greenhouse gas emissions by gas

Coal-fired power stations are the biggest single source of emissions, causing over 20% of global greenhouse gas emissions in 2018. Natural gas-fired power plants also release a lot of emissions. Just 5% of the world's power plants are responsible for almost three-quarters of carbon emissions from electricity generation.

Agriculture, Forestry, and Land Use

Agriculture

Agriculture is a major source of greenhouse gases. It produces about 10–12% of total human-caused greenhouse gas emissions. This includes methane from livestock (like cows and sheep), nitrous oxide from fertilizers and manure, and CO₂ from farming practices.

Deforestation

Deforestation, or cutting down forests, is a big source of greenhouse gas emissions. Studies show that carbon emissions from tropical deforestation have doubled in the last two decades.

Land-use Change

Changing how land is used, like clearing forests for farms, affects the amount of greenhouse gases in the air. This is because forests absorb carbon. Measuring these changes helps us understand the "net" emissions (total emissions minus what carbon sinks absorb).

Transport of People and Goods

Aviation and shipping (dashed line) produce a significant proportion of global carbon dioxide emissions.

Transportation causes 15% of worldwide emissions. Over a quarter of global transport CO₂ emissions come from road freight (trucks). Many countries are trying to reduce truck CO₂ emissions.

Maritime transport (shipping) causes 3.5% to 4% of all greenhouse gas emissions, mostly CO₂. In 2022, shipping was the sixth largest greenhouse gas emitter globally.

Aviation

Jet airliners contribute to climate change by releasing CO₂, nitrogen oxides, and other particles. In 2018, global commercial flights caused 2.4% of all CO₂ emissions. In 2020, the aviation sector was responsible for about 3.5% of the overall human impact on climate.

Buildings and Construction

In 2018, making construction materials and maintaining buildings caused 39% of CO₂ emissions from energy and industrial processes. Making glass, cement, and steel alone caused 11% of these emissions. Since many buildings will still be around in 2050, making existing buildings more energy-efficient is very important. Buildings that produce as much energy as they use are called zero-energy buildings.

In 2019, the building sector was responsible for 12 billion tons of CO₂ equivalent emissions. Most of these were CO₂. The biggest part (49%) came from producing electricity used in buildings.

Industrial Processes

Secunda CTL in South Africa is the world's largest single emitter from industry, releasing 56.5 million tons of CO₂ a year.

Mining

Burning and releasing natural gas from oil wells is a significant source of greenhouse gas emissions.

Steel and Aluminum

Making steel and aluminum also produces CO₂. In 2004, the steel industry alone released about 590 million tons of CO₂, which was 5.2% of global human-caused greenhouse gas emissions.

Plastics

Plastics are mostly made from fossil fuels. It's estimated that 3% to 4% of global greenhouse gas emissions are linked to the life cycle of plastics. Making and burning plastics released 850 million tons of CO₂ in 2019. By 2050, this could reach 56 billion tons, which is a large part of Earth's remaining carbon budget. The report suggests that only reducing how much plastic we use can solve the problem.

Pulp and Paper

The global print and paper industry causes about 1% of global CO₂ emissions. These emissions come from burning fossil fuels for raw materials, transportation, and waste treatment.

Digital Services

In 2020, data centers and data transmission each used about 1% of the world's electricity. The digital sector causes between 2% and 4% of global greenhouse gas emissions, with a large part coming from making computer chips. However, this sector can also help reduce emissions in other areas, like transport.

Mining for proof-of-work cryptocurrencies like Bitcoin uses a lot of electricity and has a big carbon footprint. By the end of 2021, Bitcoin was estimated to produce 65.4 million tons of CO₂, similar to the country of Greece.

Health Care

The healthcare sector produces 4.4–4.6% of global greenhouse gas emissions.

Tourism

According to UNEP, global tourism is a major contributor to the increasing amounts of greenhouse gases in the atmosphere.

Emissions by Wealth and Age

Richer (developed) countries release more CO₂ per person than poorer (developing) countries. Emissions generally increase with wealth per person, but the rate of increase slows down after a certain point.

The richest 5% of the world's population, fueled by their lifestyles, have caused 37% of the total increase in greenhouse gas emissions worldwide. There's a strong link between income and CO₂ emissions per person. Almost half of the increase in global emissions has been caused by the richest 10% of the population.

Studies show that the wealthiest people in the world are responsible for most environmental impacts. Strong action from them is needed to move towards safer environmental conditions.

A 2020 report found that the richest 1% of the global population caused twice as many carbon emissions as the poorest 50% between 1990 and 2015. This means the richest 1% were responsible for 15% of total emissions, compared to 7% for the poorest half. The biggest difference was in transportation.

How to Reduce Greenhouse Gas Emissions

Governments are working to reduce greenhouse gas emissions to slow down climate change. Countries are setting targets to reduce emissions, promoting energy efficiency, and supporting a shift to cleaner energy.

Future Emissions

Figure 3 from the International Energy Outlook 2023 (IEO2023) report. Total energy‑related carbon emissions stay the same until 2050 if GDP grows slowly, otherwise emissions rise a lot.

In October 2023, the US Energy Information Administration (EIA) released predictions for emissions until 2050. These predictions show that total energy-related carbon emissions will not go below 2022 levels. This suggests that much stronger action is needed to reduce emissions.

Country Examples

The top 40 countries emitting all greenhouse gases, showing both total emissions (including land use) and just the CO₂ from other sources. Per person figures are also included. Indonesia and Brazil show much higher numbers when land use is included.

In 2019, China, the United States, India, the EU27+UK, Russia, and Japan were the world's largest CO₂ emitters. Together, they accounted for 51% of the world's population, 62.5% of global wealth, and 62% of total fossil fuel use, releasing 67% of all fossil CO₂.

In 2019, China's emissions increased by 3.4%, and India's by 1.6%. On the other hand, the EU27+UK (-3.8%), the United States (-2.6%), Japan (-2.1%), and Russia (-0.8%) reduced their fossil CO₂ emissions.

United States

The United States is the second-largest emitter of greenhouse gases globally. In 2021, its emissions were 6.34 billion tons of CO₂ equivalent. The biggest sources were transportation (28%), electricity generation (25%), industry (23%), and commercial/residential buildings (13%).

China

China is the world's largest emitter of greenhouse gases. In 2021, its emissions were 14.09 billion tons of CO₂ equivalent. The main sources were electricity and heat production (51%), industry (28%), and transport (9%).

India

India is the third-largest emitter of greenhouse gases. In 2021, its emissions were 3.73 billion tons of CO₂ equivalent. The main sources were energy (75%), industry (10%), and agriculture (10%).

Society and Culture

Impact of the COVID-19 Pandemic

In 2020, carbon dioxide emissions fell by 6.4% globally due to the COVID-19 pandemic. In April 2020, nitrogen oxide emissions fell by up to 30%. In China, lockdowns led to a 26% decrease in coal use and a 50% reduction in nitrogen oxide emissions. However, greenhouse gas emissions bounced back later as countries lifted restrictions, meaning the pandemic's direct impact on climate change was small in the long term.

Global Energy-Related CO₂ Emissions Report

In March 2024, the International Energy Agency (IEA) reported that global CO₂ emissions from energy sources increased by 1.1% in 2023, reaching a record 37.4 billion tons. This was mainly due to coal. Less hydropower because of droughts also caused emissions to rise. However, new clean energy technologies like solar, wind, nuclear, heat pumps, and electric vehicles have greatly slowed down emissions growth since 2019. Without these technologies, emissions would have grown three times faster.

The last ten years have seen the slowest average annual growth in emissions since the Great Depression. Emissions in richer countries fell by 4.5% in 2023, even though their economies grew. China saw the biggest increase in emissions, partly due to less hydropower. India's emissions also increased due to strong economic growth and less hydroelectricity, but its emissions per person are still much lower than the global average.

See also

• Arctic methane emissions
• Carbon offsets and credits
• Greenhouse gas emissions from wetlands
• List of locations and entities by greenhouse gas emissions
• Low-carbon economy
• Net zero emissions
• World energy supply and consumption