Explanation : The greenhouse effect is a process by which thermal radiation from a planetary surface is absorbed by atmospheric greenhouse gases such as Carbon dioxide, and is re-radiated in all directions. Since part of this re-radiation is back towards the surface and the lower atmosphere, it results in an elevation of the average surface temperature above what it would be in the absence of the gases. Human activities, primarily the burning of fossil fuels and clearing of forests, have intensified the natural greenhouse effect, causing global warming. ....Read more