Human activities such as burning of fossil fuels, industrial processes, and agriculture are driving the warming that has occurred since the mid-20th century. These activities release greenhouse gasses such as carbon dioxide, methane, nitrous oxides, and chlorofluorocarbons (among others) into the atmosphere. The industrial activities that our modern civilization depends upon have raised atmospheric carbon dioxide levels by nearly 50% since 1750. Rising concentrations of greenhouse gasses have caused air temperatures to rise 1.2℃ since pre-industrial times. These human caused forcings far outweigh natural climate forcings such as Milankovitch Cycles, volcanoes and sun spots..

Forcings are something that act upon Earth’s climate causing a change in how energy flows through it. Heat trapping greenhouse gases slow outgoing heat into the atmosphere and cause the planet to warm. This unit explores the relationships between carbon, carbon dioxide and global warming.