Greenhouse effect

The energy from the sun warms the earth. The earth slowly releases the heat again. By greenhouse gases such as methane and carbon dioxide (CO₂) the earth-radiated heat is detained. Luckily so. If that heat would not be detained, the earth temperature would average -18˚C instead of the present average of +15˚C. If more greenhouse gases are released into the atmosphere, more heat is retained and the temperature on earth rises. This is what is generally thought to be happening now.