What are the two major greenhouse gases in earths atmosphere

Many of the chemical compounds in the earth's atmosphere act as greenhouse gases. When sunlight strikes the earth’s surface, some of it radiates back toward space as infrared radiation (heat). Greenhouse gases absorb this infrared radiation and trap its heat in the atmosphere, creating a greenhouse effect that results in global warming and climate change.

Many gases exhibit these greenhouse properties. Some gases occur naturally and are also produced by human activities. Some, such as industrial gases, are exclusively human made.

Without naturally occurring greenhouse gases, the earth would be too cold to support life as we know it. Without the greenhouse effect, the average temperature of the earth would be about -2°F rather than the 57°F we currently experience.

Source: Adapted from U.S. Environmental Protection Agency (public domain)

What are the types of greenhouse gases?

• Carbon dioxide (CO2)
• Methane (CH4)
• Nitrous oxide (N2O)
• Industrial gases:
  • Hydrofluorocarbons (HFCs)
  • Perfluorocarbons (PFCs)
  • Sulfur hexafluoride (SF6)
  • Nitrogen trifluoride (NF3)

Other greenhouse gases not counted in U.S. or international greenhouse gas inventories are water vapor and ozone.

Water vapor is the most abundant greenhouse gas, but most scientists believe that water vapor produced directly by human activity contributes very little to the amount of water vapor in the atmosphere. Therefore, the U.S. Energy Information Administration (EIA) does not estimate emissions of water vapor.

Ozone is technically a greenhouse gas, but ozone is helpful or harmful depending on where it is found in the earth's atmosphere. Ozone occurs naturally at higher elevations in the atmosphere (the stratosphere) where it blocks ultraviolet (UV) light that is harmful to plant and animal life from reaching the earth’s surface. The protective benefits of stratospheric ozone outweigh its contribution to the greenhouse effect. The United States and countries all around the world ban and control production and use of several industrial gases that destroy atmospheric ozone and create holes in the ozone layer. Learn more about ozone layer protection. At lower elevations of the atmosphere (the troposphere), ozone is harmful to human health. Learn more about ground-level ozone pollution and what is being done to reduce ozone pollution.

Last updated: July 27, 2022

The greenhouse effect is the way in which heat is trapped close to Earth's surface by “greenhouse gases.” These heat-trapping gases can be thought of as a blanket wrapped around Earth, keeping the planet toastier than it would be without them. Greenhouse gases include carbon dioxide, methane, nitrous oxides, and water vapor. (Water vapor, which responds physically or chemically to changes in temperature, is called a "feedback.")Scientists have determined that carbon dioxide's warming effect helps stabilize Earth's atmosphere. Remove carbon dioxide, and the terrestrial greenhouse effect would collapse. Without carbon dioxide, Earth's surface would be some 33°C (59°F) cooler.

Greenhouse gases occur naturally and are part of our atmosphere's makeup. For that reason, Earth is sometimes called the “Goldilocks” planet – its conditions are not too hot and not too cold, but just right to allow life (including us) to flourish. Part of what makes Earth so amenable is its natural greenhouse effect, which keeps the planet at a friendly 15 °C (59 °F) on average. But in the last century or so, humans have been interfering with the planet's energy balance, mainly through the burning of fossil fuels that add carbon dioxide to the air. The level of carbon dioxide in Earth’s atmosphere has been rising consistently for decades and traps extra heat near Earth's surface, causing temperatures to rise.

READ MORE

• The Greenhouse Effect (UCAR)
• NASA's Climate Kids: Meet the Greenhouse Gases! (downloadable and printable cards)
• NASA's Climate Kids: What Is the Greenhouse Effect?