Global warming refers to the long-term increase in Earth's average temperature due to the buildup of greenhouse gases like carbon dioxide in the atmosphere. This rise in temperature is largely caused by human activities such as burning fossil fuels, deforestation, and industrial pollution. Global warming leads to serious environmental issues like melting glaciers, rising sea levels, extreme weather events, and loss of biodiversity. It poses a major threat to both nature and human life, making urgent global action essential to reduce emissions and protect our planet.