Global warming refers to the long-term increase in Earth's average surface temperature, primarily caused by human activities releasing greenhouse gases into the atmosphere. Since pre-industrial times, global average temperature has risen approximately 1.1°C, with most warming occurring since 1970. The primary cause is burning fossil fuels (coal, oil, natural gas) for energy, releasing carbon dioxide that traps heat. Deforestation, agriculture, and industrial processes also contribute. Global warming drives broader climate change: shifting weather patterns, more frequent extreme weather events, rising sea levels, ecosystem disruption, and threats to food and water security. Canada is warming at approximately twice the global average rate, with the Arctic warming even faster. Addressing global warming requires reducing greenhouse gas emissions through energy transition, efficiency improvements, and changes across transportation, buildings, industry, and agriculture. International coordination through agreements like the Paris Agreement aims to limit warming to 1.5-2°C.