Greenhouse gas

Some gases in the air trap heat.

The sun warms the Earth. Then the Earth sends heat back out. These gases catch that heat. This keeps our world warm.

One gas is water vapor. It is the most common. Another gas is called carbon dioxide. People make more of it by burning fuels. This makes the Earth warmer.

This warming is happening faster now. It is a big change for our world.

Greenhouse gases are gases that trap heat. They stay in our air.

Sunlight warms the Earth's surface. Then, the Earth sends heat back out. Greenhouse gases catch this heat. This is called the greenhouse effect. Without these gases, Earth would be very cold. It would be about -18°C. Instead, our average temperature is much warmer.

There are many types of these gases. Water vapor is the most common. It causes about half of the greenhouse effect. Carbon dioxide is another major gas. People make more of it by burning fossil fuels. This has raised carbon dioxide by over 50% since 1750. Carbon dioxide causes most of the global warming. Methane is also a big factor. It comes from farms and waste. Methane is very strong at trapping heat. It stays in the air for about 12 years. Carbon dioxide stays much longer.

These changes make the Earth warmer. This warming is happening at a fast rate.

Greenhouse gases are special gases in our atmosphere that trap heat. This process is known as the greenhouse effect.

When sunlight hits the Earth, the surface warms up. The Earth then radiates this heat back toward space. Greenhouse gases absorb this heat instead of letting it escape. Without these gases, Earth would be much colder. The average temperature would be about -18°C instead of its current level.

This effect is vital for keeping our planet at a livable temperature.

How does this work on a tiny level? Most of our air is nitrogen and oxygen. These gases do not trap heat well. However, greenhouse gases have a different structure. Their molecules contain different types of atoms. This creates an asymmetry in their electrical charge. Because of this, they are infrared active. This means they can absorb and emit infrared radiation.

They catch the heat waves and send them back toward the surface. This keeps the energy inside our atmosphere.

Scientists have studied these changes for a long time. We can see how levels changed since the Industrial Revolution began around 1750. Since then, human activities have changed the air significantly. Carbon dioxide levels have increased by over 50%. Methane levels have grown by 150%.

These changes are happening at an unprecedented rate. For example, warming reached 0.27°C per decade between 2015 and 2024. This shows how much the atmosphere is changing due to human actions.

There are several important gases to know about. Water vapor is the most abundant greenhouse gas. It is responsible for about 41% to 67% of the greenhouse effect. Carbon dioxide is the next major gas. It causes about three-quarters of global warming.

Methane is also very important. It comes from things like agriculture and waste. While carbon dioxide stays in the air for a long time, methane lasts for about 12 years. Methane is much stronger at trapping heat than carbon dioxide. Other gases include nitrous oxide and ozone.

These gases link directly to our daily lives and the world around us. Many of our tools and energy use fossil fuels. Burning these fuels releases most of our carbon dioxide. Our farms and food production also release methane.

The Earth is currently in a state of energy imbalance. This means more energy is arriving than is leaving. This imbalance leads to rising temperatures. If current rates continue, warming may reach dangerous levels between 2040 and 2070. Understanding these gases helps us see how our world works.

Greenhouse gases are specific gases in a planet's atmosphere that trap heat. This process is called the greenhouse effect.

By absorbing radiation emitted by a planet, these gases raise the surface temperature. On Earth, this effect is essential for life. Without these gases, the average surface temperature would be about -18°C. Instead, the present average is much warmer. However, human-induced warming is now increasing at an unprecedented rate. Between 2015 and 2024, warming reached 0.27±0.1°C per decade.

To understand the mechanism, we must look at how molecules interact with energy. Most of Earth's dry atmosphere is nitrogen (78%) and oxygen (21%). These molecules consist of two atoms of the same element. This means they have no asymmetry in their electrical charge distribution. Consequently, they are almost totally unaffected by infrared thermal radiation. In contrast, greenhouse gases contain atoms of different elements. This creates an asymmetry in their electrical charge. This allows their molecular vibrations to interact with electromagnetic radiation. Scientists call these molecules "infrared active."

When sunlight heats the Earth's surface, the surface radiates heat back toward space. Greenhouse gases absorb this infrared radiation.

Instead of letting all the heat escape, these gases exchange thermal radiation with the surface. This limits the rate at which heat flows away from the planet. This process creates a radiative forcing. A positive forcing means more energy arrives at the top of the atmosphere than leaves it. This imbalance causes the planet to warm up.

There are several distinct greenhouse gases with different roles. Water vapor is the most abundant and causes about 41% to 67% of the greenhouse effect. It acts as a climate change feedback. This means as temperatures rise, water vapor concentrations also increase.

Carbon dioxide is another major gas. It is responsible for about three-quarters of global warming. Methane is also significant, though it lasts in the atmosphere for an average of only 12 years. Methane is much more potent; its direct effect is about 84 times stronger than carbon dioxide over 20 years. Other gases include nitrous oxide, ozone, and chlorofluorocarbons (CFCs).

Human activities have significantly altered these natural levels. Since the Industrial Revolution began around 1750, carbon dioxide has increased by over 50%. Methane levels have increased by 150%.

Most carbon dioxide comes from burning fossil fuels, agriculture, and industry. Methane emissions originate from agriculture, fossil fuel production, and waste. These emissions have pushed greenhouse gas levels to an all-time high. In the last decade (2014–2023), emissions reached 53.6±5.2 Gt CO2e per year.

Historical data shows how much the atmosphere has changed. For one million years, natural carbon flows between the ocean, ecosystems, and the atmosphere were fairly balanced. However, carbon dioxide levels are now higher than they have been for three million years.

The 2023 annual update showed that human-induced temperature rise and energy imbalance reached new records. If current emission rates continue, the IPCC says global warming will surpass dangerous levels between 2040 and 2070.

These changes connect to many different global systems. The carbon cycle takes thousands of years to fully absorb carbon dioxide from the atmosphere. This long duration means the effects of current emissions will last for a very long time. The warming also affects the structure of our atmosphere. While the lower atmosphere warms, the upper atmosphere is actually cooling and shrinking. This complex interaction shows how a change in one gas can shift the entire balance of our planet's climate system.