The elaboration of the National Low Carbon Roadmap (RNBC) was determined by the Resolution of the Council of Ministers n.º 93/2010, of November 26th. The objective of the RNBC is to carry out a prospective study of the technical and economic viability of paths to reduce greenhouse gas emissions in Portugal, leading to a low-carbon economy by 2050. It also aims to point out possible strategic guidelines for the various sectors of activity, in line with other similar documents, and serve as an element of information and support for the preparation of future national plans to reduce emissions, in particular the National Plan for Climate Change 2020 and the Low Carbon Sectoral Plans. The vision underlying the RNBC is in line with the European Union&#39;s objective of reducing greenhouse gas emissions by 80% - 95% in 2050, compared to 1990 levels, in order to achieve a transition to a competitive economy and low carbon. It should also be noted that this long-term vision is, in the short and medium term, framed by the energy-climate objectives² adopted in 2009, an integral part of the Europe 2020 Strategy for smart, sustainable and inclusive growth. Given the time horizon of the analysis, it is necessary to deal with the uncertainty associated with the results. Partly because the modeling is based on assumptions, which include the pace of economic growth, the size and distribution of global efforts to mitigate climate change, geopolitical developments, the evolution of energy prices on the world market and the availability of endogenous resources. Therefore, attention should be paid to trends, technological options and paradigm shifts, more than the absolute values themselves, especially for the period after 2030.