What is the natural greenhouse effect?

When the sun’s energy reaches Earth, some trace gases in the Earth’s atmosphere ensure that part of the energy from solar radiation is not completely reflected back into space in the form of infrared radiation. Instead, some of it remains in the atmosphere as thermal energy. These gases are called greenhouse gases, and their impact is known as the greenhouse effect. The most important greenhouse gases are water vapor, carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O).

If there were no greenhouse gases (and all other conditions remained the same), the Earth’s surface would have an average temperature of approximately -18 degrees Celsius. The greenhouse effect therefore makes our planet habitable in the first place, with the temperature rising by some 32 degrees Celsius to around 14 degrees Celsius. These fundamental relationships have been known for more than 150 years and are undisputed by scientists, who have proved them through numerous experiments and measurements.¹