The predominant greenhouse gas emitted during human activities is carbon dioxide (CO2). CO2 is primarily released from burning fossil fuels for energy, such as coal, oil, and natural gas. Deforestation also contributes significantly to CO2 emissions, as trees that absorb CO2 are removed. This increase in atmospheric CO2 levels leads to the greenhouse effect, which traps heat in the Earth's atmosphere and contributes to global warming and climate change. Efforts to mitigate CO2 emissions include adopting renewable energy sources and enhancing energy efficiency.