Earth's climate is continually changing and is in a warming period now, due in part to enhanced human emissions of greenhouse gases.

Throughout this module, you will explore interactions between factors in the climate system that affect Earth's atmospheric temperature. Greenhouse gases in the atmosphere trap heat energy. Sunlight can be reflected by snow- and ice-covered surfaces, or it can be absorbed by darker surfaces.

You will examine graphs of greenhouse gas concentration and temperature change. You will run experiments with computational models to compare the effect of different levels of anthropogenic carbon dioxide emissions, and hear from a climate scientist. By the end of the module you will be able to explain how scientists can be certain that Earth’s climate is changing while not being entirely certain about how much it will warm.