Energy and Climate Change

Energy production and use is the largest source of global greenhouse-gas (GHG) emissions. As a result, the World Energy Outlook (WEO) has, for many years, assessed the impact of energy sector policies and other developments on the projected path of GHG emissions, and the implications for meeting the world’s agreed climate goal. Each year, the WEO has presented a 450 Scenario that sets out a pathway for the energy sector that is consistent with having a 50% chance of limiting the global temperature increase to less than two degrees Celsius (°C). The latest assessment of our energy-related and process-related GHG emissions (as presented in WEO-2015) shows that the emissions gap to a two degrees trajectory in the Current Policies Scenario in 2030 is 16 gigatonnes of carbon dioxide equivalents (Gt CO2-eq) and 12 Gt CO2-eq in the case of the New Policies Scenario (Table 1).

Table 1 - Global energy- and process-related greenhouse-gas emissions by scenario (Gt CO2-eq)Table 1 - Energy and climate change (2015)

Assessment of climate pledges ahead of COP21

The WEO released a Special Report on Energy and Climate Change in June 2015, and a related Special Briefing for COP21 in October 2015. Building on the June report, the Special Briefing assesses the impact of climate actions, so called Intended Nationally Determined Contributions (INDCs), on energy demand, supply, emissions and investment trends through to 2030. The IEA’s World Energy Model was used to analyse the INDCs, with the same economic and energy price assumptions as in WEO-2015. The analysis is based upon the full implementation of unconditional INDC pledges, while also taking into account domestic energy sector policies that are currently in place or under discussion across all countries (it equally takes into account the latest data on energy use in China).  Total GHG emissions have been assessed using the global warming potentials from the Intergovernmental Panel on Climate Change’s (IPCC) Fifth Assessment Report.

Table 2 - Global greenhouse-gas emissions in the INDC Scenario (Gt CO2-eq)
Table 2 - Energy and climate change 2015

Notes: There is large uncertainty about current emissions from land use, land use change and forestry (LULUCF). For example, the IPCC’s Fifth Assessment Report states an emissions level for LULUCF of 5.4 Gt CO2 in 2010, while the Food and Agriculture Organization (FAO) reports 2.4 Gt in 2010. For the assessment of current LULUCF emissions, the WEO analysis combined data from FAO with national estimates, where available, which yields an emissions level of 1.0 Gt CO2 in 2010. Non-energy related non-CO2 GHG emissions were assessed with the OECD ENV-Linkages model and updated with national sources, if available, and with data from the US Environmental Protection Agency (US EPA) for fluorinated gases (F-gases).


If climate ambition is not raised progressively, it is estimated that the path set by the INDCs leads to GHG emissions in 2100 of around 38 Gt CO2-eq. Such a pathway is consistent with an average global temperature increase of around 2.7 °C by 2100, and around 3.5 °C in the long term (i.e. after 2200). To assess the impact on average global temperature, MAGICC has been used, with a post-2050 emissions pathway in-between the representative concentration pathways (RCP) 4.5 and RCP 6 scenarios from the IPCC’s Fifth Assessment Report, as this was judged as the long-term emissions trajectory most closely aligned with IEA’s INDC Scenario.

The bridge to a two degree pathway

WEO analysis indicates that the actions taken in the INDC Scenario are not sufficient to steer the energy system onto a pathway consistent with the world’s 2 °C climate goal. The IEA has therefore proposed the Bridge Scenario in the Special Report on Energy and Climate Change, which suggests how INDCs could be enhanced by a series of immediately practicable steps. The Bridge Scenario proposes a set of actions, drawing only on known technologies and policy measures which are tried and tested, which can raise climate ambition and help keep the door to a 2 °C pathway open. The Bridge Scenario leads to a peak in energy-related GHG emissions around 2020. The proposed measures are:

  • Increasing energy efficiency in the industry, buildings and transport sectors 
  • Progressively reducing the use of the least-efficient coal-fired power plants and banning their construction 
  • Increasing investment in renewable energy technologies in the power sector to reach $400 billion in 2030
  • Gradually phasing out fossil-fuel subsidies to end-users by 2030
  • Reducing the methane emissions arising from oil and gas production

Explore WEO