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Carbon emissions

Carbon emissions continue to grow in the energy transition scenario, highlighting the need for a more decisive break from the past
Spencer Dale – carbon emissions
“We're likely to need to see a far more decisive break from the past if carbon emissions are going to fall to the extent thought necessary to achieve the goals set out in Paris.”

Spencer Dale, group chief economist


In the energy transition (ET) scenario, carbon emissions from energy use grow through much of the Outlook, increasing by around 10% by 2040.


This rate of growth is far slower than that seen in the past 25 years, when carbon emissions increased by 55%.


Even so, the projected rate of growth is far higher than the sharp decline thought necessary to be consistent with achieving the Paris climate goals. This highlights the need for a more decisive break from the past than implied by the ET scenario.


The ‘even faster transition’ (EFT) scenario follows the same broad decline in carbon emissions as the IEA’s ‘sustainable development scenario’, with emissions falling by almost 50% by 2040.


Most of the additional abatement of emissions in the EFT scenario, relative to the ET scenario, emanates from the power sector, which is almost entirely decarbonized by 2040. The dominant role the power sector plays in bringing about a sharp fall in carbon emissions is a common feature across many of the external scenarios which have similar falls in carbon emissions.

Carbon emissions (billion tonnes CO₂)

In the evolving transition scenario, carbon emissions from energy use increase by around 10% by 2040

Carbon emissions (billion tonnes CO₂)
55% increase

Carbon emissions have increased by 55% in the past 25 years                                                

50% decrease

In the ‘even faster transition’ scenario, emissions fall by almost 50% by 2040

The overall growth in nuclear energy is dampened by declines in both the EU and the US as ageing nuclear plants are retired and not replaced

Alternative scenario

Impact on the global energy system of a faster transition to a lower carbon economy

The continuing growth of carbon emissions in the ET scenario highlights the need for an even more decisive break from the past if climate goals are to be met. This could have significant implications for the global energy system over the next 25 years.


The EFT scenario illustrates one possible configuration of policies and outcomes achieving such a break, and is based on a sharp increase in carbon prices and a range of other polices designed to encourage more rapid gains in energy efficiency and greater fuel switching.


Energy demand continues to grow in the EFT scenario, but at a slower rate reflecting the faster gains in energy efficiency. The higher carbon price also encourages greater use of carbon capture use and storage (CCUS) in both industry and the power sector.


The carbon intensity of the fuel mix in the EFT scenario is significantly lower than in the ET scenario. Renewables account for more than the entire growth in global energy, with their share within primary energy increasing to around a third by 2040.


Even so, oil and gas together account for more than 40% of world energy in 2040.

Primary energy consumption by fuel (billion toe)

Oil and gas together account for more than 40% of world energy in 2040

Primary energy consumption by fuel (billion toe)