The earth-atmosphere system is extraordinarily complex, but a simple model describes the role that greenhouse gases play in its energy balance. Increasing global temperatures are correlated with the increase in greenhouse gases, over and above what can be expected from natural climate variability. Increasing global temperatures create environmental crises and threaten individual health and safety, regional prosperity, and national and international economic, social, and political stability. Actions to reduce greenhouse gas emissions to net zero are needed to stabilize the energy balance and limit the impact of climate change