Greenhouse gases contribute to global warming by trapping heat in the Earth's atmosphere. They absorb and re-emit infrared radiation, which increases the temperature of the atmosphere and the Earth's surface. The main greenhouse gases are carbon dioxide CO2 , methane CH4 , nitrous oxide N2O , and fluorinated gases. The relative importance of each gas can be assessed based on their abundance, global warming potential GWP , and atmospheric lifetime.1. Carbon dioxide CO2 : CO2 is the most significant greenhouse gas, primarily released through the burning of fossil fuels, deforestation, and other human activities. It accounts for about 76% of total greenhouse gas emissions. CO2 has a GWP of 1 used as a reference and an atmospheric lifetime of around 100 years.2. Methane CH4 : CH4 is the second most important greenhouse gas, accounting for approximately 16% of total greenhouse gas emissions. It is released during the production and transport of coal, oil, and natural gas, as well as from livestock and other agricultural practices. Methane has a GWP of 28-36 over 100 years, meaning it is much more effective at trapping heat than CO2. However, its atmospheric lifetime is shorter, around 12 years.3. Nitrous oxide N2O : N2O accounts for about 6% of total greenhouse gas emissions. It is released from agricultural and industrial activities, as well as from burning fossil fuels. Nitrous oxide has a GWP of 265-298 over 100 years, making it even more potent than methane. Its atmospheric lifetime is around 114 years.4. Fluorinated gases: These are synthetic gases, including hydrofluorocarbons HFCs , perfluorocarbons PFCs , and sulfur hexafluoride SF6 , which are released from various industrial processes. Although they are less abundant, they have very high GWPs up to 23,000 for SF6 and long atmospheric lifetimes up to 50,000 years for some PFCs . They account for around 2% of total greenhouse gas emissions.In summary, while CO2 is the most abundant greenhouse gas and contributes the most to global warming, other gases like methane and nitrous oxide have higher global warming potentials. However, their shorter atmospheric lifetimes and lower abundance make their overall contribution to global warming smaller than that of CO2. Fluorinated gases, although less abundant, have very high GWPs and long atmospheric lifetimes, making them a concern for future climate change.