You need to search the literature to find evidence to support whether one of the "myths" below is fact or fiction. Keep in mind that evidence includes the data or documentation that supports an argument. Evidence is not an opinion. Compile three separate pieces of evidence in support of your thesis (i.e., your myth is fact...or that it is fiction) and prepare a 1-3 sentence statement of each piece of evidence.
Topics: I have hand-picked a few "climate myths" that appear prevalent in the media; thus, represent plausible topics worth clarifying:
Global warming is caused by the sun (sunspot activity, solar irradiance).
Water vapor is a more important factor in global warming than carbon dioxide.
Rising temperatures are due to the urban heat island effect not global climate change.
Sea levels are static or lowering due to global warming.
Global warming has ceased since 1998.
Sources: Although you may already have your own opinion on the topic, or are aware of the popular view, you need to ensure your information is well supported. Each of your 3 pieces of evidence should come from different sources, so you should use several sources to research your topic. As always in any scientific discipline: be confident your information comes from a reliable source. Remember that scientific journals are peer-reviewed, thus undergo great scrutiny, while websites can be posted and updated daily with no check on their soundness or credibility.