Welcome to the Global Warming lesson! Global warming is a complicated and contentious issue, with believers and skeptics lined up on either side. During this lesson we'll explain what global warming is and why there is serious debate about it. We'll also review the two sides of the global warming argument: believers who think that global warming is a huge environmental threat, and skeptics who say that global warming doesn't even exist. 

There are many global warming web sites on the Internet, and the Global Warming lesson gives you links to both believer and skeptics sites. You can explore the sites and read about global warming facts and opinions. And you're going to need that kind of information when you get to our Assignments page. 

So start the Global Warming lesson with an explanation of what global warming is.