Governments have taken action to reduce greenhouse gas emissions to mitigate climate change. Assessments of policy effectiveness have included work by the Intergovernmental Panel on Climate Change, International Energy Agency,[130][131] and United Nations Environment Programme.[132] Policies implemented by governments have included[133][134][135] national and regional targets to reduce emissions, promoting energy efficiency, and support for a renewable energy transition, such as Solar energy, as an effective use of renewable energy because solar uses energy from the sun and does not release pollutants into the air.