Greenhouse gases are gases that are present in the Earth’s atmosphere and absorb and emit radiation within the thermal infrared range. This radiation is emitted by the Sun, and is absorbed by greenhouse gases, which trap the heat within the atmosphere and don’t allow it to go back to space. The main greenhouse gases are carbon dioxide (CO2), methane (CH4), and water vapor (H2O). At the normal level, they help keep the temperature on Earth at a life-sustaining level, but more and more GHGs are emitted into the atmosphere through various human activities, such as the burning of fossil fuels, industrial processes, and agriculture, and they play a significant role in climate change. Reducing GHG emissions is a key part of efforts to mitigate the impacts of global warming.