C-Learn is a simplified version of a climate simulator. Its primary purpose is to help users understand the long-term climate effects (CO2 concentrations, global temperature, sea level rise) of various customized actions to reduce fossil fuel CO2 emissions, reduce deforestation, and grow more trees. Students can ask multiple, customized what-if questions and understand why the system reacts as it does.

This video production is a part of a four-panel report from the National Academies' America's Climate Choices project. The video maps out the realm of our accumulated knowledge regarding climate change and charts a path forward, urging that research on climate change enter a new era focused on the needs of decision makers.

This activity uses two interactive simulations to illustrate climate change, 1) at the micro/molecular level - modeling the impact of increasing concentrations of greenhouse gases in the atmosphere on surface temperature and 2) at the macro level - modeling changes in glacier thickness and flow as a result of rising surface temperature.