Three thousand non-science major undergraduates at the University of Chicago have taken this class since 1996, and learned the science behind the forecast for a human influence on Earth's climate. The story combines physics, chemistry, biology, and Earth and atmospheric science.
The content of this class is now being served to the internet world at large. You can watch video lectures followed by quizzes to stimulate your understanding, and work your way through tutorial exercises letting you get hands-on with interactive models and simple mathematical ideas. You can work at your own pace, on your own time. You don't get University of Chicago credit, but it's free, and if you complete the exercises you can download a certificate of accomplishment signed by me.Open Climate Science 101
David Archer | Professor, Department of The Geophysical Sciences at the University of Chicago
(h/t Trixie in the comments)
Climate change and its effects socially, politically, and economically is going to be one of the mosts significant trends of the 21st century, if not the trend that determines everything else.