The three IEA scenarios

1. Current scenario: assumes no changes in policies approved and applied until mid-2017, without including any new policies.
   
2. Reference scenario: assumes that policies, plans, and commitments announced by mid-2017 will be carried out, even if they have not been formally approved. It takes into consideration the fulfillment of the Paris Agreement in this regard (in particular the fulfillment of the commitments signed in Paris to reduce emissions between 2020 and 2030, the NDCs [Nationally Determined Contributions], as well as the announcements made until mid-2017 that anticipate the tougher stance, for example in China, or the looser stance, for example in the US, regarding these commitments).
3. Sustainability scenario, the challenge: assumes that the necessary policies to achieve sustainability are applied to three areas: 1) universal access to modern energy in 2030 (electricity, gas for domestic use, etc.); 2) limiting greenhouse gas emissions from energy to fulfill the Paris Agreement's objectives (reaching their peak as soon as possible and subsequently reducing them); and 3) reducing polluting gas emissions linked to energy (pollution), resulting in improved air quality (reducing premature deaths caused by local pollution).