An energy transition (or energy system transformation) is a significant structural change in an energy system regarding supply and consumption. Currently, a transition to sustainable energy (mostly renewable energy) is underway to limit climate change. It is also called renewable energy transition. The current transition is driven by a recognition that global greenhouse-gas emissions must be drastically reduced. This process involves phasing-down fossil fuels and re-developing whole systems to operate on low carbon electricity. A previous energy transition took place during the industrial revolution and involved an energy transition from wood and other biomass to coal, followed by oil and most recently natural gas. As of 2019, 85% of the world's energy needs are met by burning fossil fuels. Energy production and consumption are responsible for 76% of annual human-caused greenhouse gas emissions as of 2018. To meet the goals of the 2015 Paris Agreement on climate change, emissions must be reduced as soon as possible and reach net-zero by mid-century. Since the late 2010s, the renewable energy transition is also driven by the rapidly increasing competitiveness of both solar and wind power. Another motivation for the transition is to limit other environmental impacts of the energy industry. The renewable energy transition includes a shift from internal combustion engine powered vehicles to more public transport, reduced air travel and electric vehicles. Building heating is being electrified, with heat pumps as the most efficient technology by far. For electrical grid scale flexibility, energy storage and super grids are vital to allow for variable, weather-dependent technologies. An energy transition is a broad shift in technologies and behaviours that are needed to replace one source of energy with another. A prime example is the change from a pre-industrial system relying on traditional biomass, wind, water and muscle power to an industrial system characterized by pervasive mechanization, steam power and the use of coal.