How do greenhouse gas emissions from fossil fuels contribute to global warming?

The combustion of fossil fuels—such as coal, oil, and natural gas—is the primary human activity driving global warming through the release of greenhouse gases, most notably carbon dioxide (CO₂).123

The Greenhouse Effect

Earth’s surface temperature is regulated by the greenhouse effect, a process where atmospheric gases absorb and reradiate infrared radiation emitted from the planet's surface. While solar energy reaches Earth as shortwave radiation, the surface emits energy back toward space as longwave infrared radiation.142

Greenhouse gases act as a thermal blanket:
* Absorption: CO₂ molecules allow incoming solar radiation to reach the surface but absorb the outgoing longwave infrared radiation.24
* Reradiation: These gases reemit a portion of that absorbed energy in all directions, including back toward the surface and lower atmosphere.12
* Warming: This process increases the total radiation directed downward, forcing the surface and lower atmosphere to remain warmer than they would be in the absence of these gases.12

By significantly increasing the concentration of these gases, human activity has enhanced this natural effect, leading to a rise in global mean temperatures.12