General information about Global Warming
The global warming is a process, that changes the climate and the atmosphere, so that the earth becomes uncomfortable for the living organisms on it. The global warming destroys the qualities on our planet, which have made it the only (known) planet with life on it. There are few things that cause this change in the climate, and the humans are responsible for 98% of them. The real thing that causes the increase of the earth's average temperature is the sun energy, and the atmosphere. The atmosphere is the thing that makes the life possible on the earth, and it is the only thing that can keep the earth's warmth during night. (For example Mercury doesn't have atmosphere, and during the day temperature there is over 100 °C, and during night it is less than -100 °C).
When the sun energy reaches the earth, some of it is reflected from the atmosphere. This prevents from too big increase of the average temperature on the earth's surface. Other part is absorbed by the clouds, but the biggest part of it is absorbed by the earth. This happens during the day. However, during night, the earth (and any other planets) starts radiating energy back in the space. However, the atmosphere on the earth lets only a small part of the radiated energy to leave the earth. The rest of the energy is reflected back to the earth's surface, and keeps the average temperature on the earth's surface during night. This is how the earth's atmosphere regulates the temperature on the earth's surface, and creates the pleasant conditions, that have made the life possible on our planet.
However there are some factors on which depends the ability of the atmosphere to keep any heat energy on the surface of the earth. There are some gases like the ozone and the greenhouse gases, which depend on human activities. Due to their effect on the heat energy the earth's average temperature has been increasing, and is will increase even more. This will cause great troubles to all living organisms on the earth.