Global Energy System Transitions

Energy systems power the world’s economies. They are pivotal to providing sustained economic prosperity that provides the goods and services that humans desire. Climate change is intimately linked with energy systems because CO2 from fossil fuel use is the most important anthropogenic greenhouse gas (GHG) emitted to the atmosphere, and cumulative anthropogenic emissions determine Earth’s concentration of CO2. Limiting climate change therefore means that global energy systems must reduce net CO2 emissions to zero and stabilize emissions of other GHGs. We compare energy system pathways as they are currently evolving with alternatives that have the potential to limit climate change over the twenty-first century. The differences are profound. We also discuss some frontier research issues that can provide a better understanding of potential pathways and their implications for decision makers.