The chart above shows global energy intensity (left axis) and CO2 emissions intensity (bottom axis).
From 1980 to 2015, there were large gains in efficiency, though energy-related CO2 emissions rose from 18 to 33 billion tonnes. The blue circle shown for 2040 indicates these emissions are projected to be about 36 billion tonnes even with significant gains in efficiency and CO2 emissions intensity.
The chart also illustrates a range of 2040 “performance levels” reflecting hypothetical combinations of global energy intensity and CO2 emission intensity levels that, if reached in 2040, might indicate the world was on a 2oC pathway. Even with the significant progress on energy and CO2 emissions intensities envisioned by 2040 in the 2018 Outlook, it is estimated that there remains a significant gap to reach performance levels in 2040 that are indicative of 2oC pathway.
To be on a 450 ppm, or hypothetical 2oC, pathway, the performance in 2040 likely needs to be significantly closer to the purple line, implying faster gains in efficiency and/or faster reductions in CO2 emissions per unit of energy.
This chart helps provide some historical context for the projected progress on these important parameters from 1980 through 2040 based on the 2018 Outlook. From 1980 to 2015, progress to slow the growth in energy-related CO2 emissions was made primarily through energy efficiency gains. Despite those gains over 35 years, emissions rose from about 18 billion tonnes to about 33 billion tonnes. From 2015 to 2040, further gains in efficiency and CO2 emissions intensity will be significant, helping slow global energy-related CO2 emissions so that they will likely peak before 2040. However, they are projected to be twice the level of 1980 and about 10 percent above the 2016 level in 2040.
In summary, transitioning toward a 2oC pathway, as suggested by the range of related 2040 performance levels shown on the chart, would imply that global emissions peak and steadily fall to close to 1980 levels by 2040. This is daunting, considering the global population may be twice as large, and the world’s economy may be five times as large by 2040 versus 1980 levels.