The Global Energy Assessment is the first fully integrated energy assessment. It investigates energy challenges, opportunities, and strategies for developing, industrialized, and emerging economies. The report finds the energy system can be transformed in to a sustainable system in the future. To achieve this, immediate action is required, starting with energy efficiency improvements and progressing to increasing use of renewable energy and changes in the use of fossil fuels. The report also finds that policy, regulations, and stable investment regimes will be crucial.