Global warming is the gradual increase in Earth's average temperature, primarily caused by greenhouse gases like carbon dioxide trapping heat in the atmosphere. When we burn fossil fuels such as coal, oil, and natural gas to power cars, factories, and power plants, these gases build up like an invisible blanket around the planet, preventing some of the sun's heat from escaping back into space.

Scientists measure this warming carefully using thermometers, satellites, and ocean sensors. Over the past century, Earth's average temperature has risen about 1-2 degrees Fahrenheit. That might sound small, but even slight temperature changes affect weather patterns, ocean levels, and ecosystems worldwide. Glaciers melt faster, sea levels rise gradually, and some regions experience more intense storms or droughts.

The term global is important because the warming happens across the whole planet, not just in one place. A hot summer in your town isn't global warming, but decades of data showing rising temperatures across continents, oceans, and seasons reveal the larger pattern.

Global warming is closely related to climate change, though they're not identical. Climate change refers to all the ways Earth's climate is shifting, including changes in rainfall, wind patterns, and extreme weather, while global warming specifically describes the temperature increase driving many of those changes.