The theory of global warming was initially based on scientists’ models of the atmosphere, which found that increasing certain gases in the atmosphere would lead to a small rise in temperature. In years past, many people have disputed this theory, leading to great political controversy over the issue of global warming. Is there now evidence to support this theory? (To answer this question, you may consult online sources, but LIST all your sources, and for each source explain why you think the source is trustworthy.)