1- A natural process by which the earth warms up from trapping the heat of the sun within the atmosphere. This process has been occurring for hundreds of millions of years. For more information read a fucking book.
2- A very controversial issue that has been the topic of much debate, media coverage, lies, misinterpretations, and whatever the fuck else you can think of. Essentially the issue is represented by a few groups of people;
A) REAL scientists who research this issue using the proper scientific method in order to propose theories, and learn the facts about what is going on. In addition real scientist always have the proper education and experience in the relevant fields. Often bribed, and terrorized into saying things they know aren't true
B) The Masters, essentially the group of people who understand that global warming is much more than just an environmental issue but more importantly, a way of promoting their own agendas. The masters exist above the bullshit of the common mans world so it is they that control the planet as a whole. ex. The greatest of the political elites, major corporations, people that run the media etc.
C) Environmentalists, this group by far is the most prevalent in the public and the most outspoken, they consist of every arrogant douche bag imaginable who think that they know everything about global warming despite most likely having little to no knowledge (probably just saw An Inconvenient Truth), their sole purpose is to coax sheep, and destroy skeptics with their a system of scare tactics and brainwashing- not unlike fascist dictators and terrorists, and saying stuff like if you don't believe in global warming (man made or otherwise) your comparable to a natzi war criminal.
D) skeptics, people who generally don't follow the current belief that humans are the the major cause of the temperature rise because they have been educated better and have a mind of their own. They are systematically hunted by the environmentalists.
E)Unbelievers, a subgroup of skeptics- these people are just too lazy to believe in global warming and as an extension are dumb as shit.
F) Sheep- see sheep