They seemed inseparable. But the once-rigid link between rises in global economic activity and carbon dioxide emissions may have been broken.
The International Energy Agency has reported that CO2 emissions from energy activities such as power generation and transport have remained unchanged for the second year running – even as the global economy grew.
Annual CO2 emissions in 2015 are still where they were in 2013, at just over 32 billion tonnes, even though global economic activity has grown by 6.5 per cent (see graph, below).
This represents a dramatic reduction in the carbon intensity of the global economy. It also means the world may be on track for global emissions to reach their peak by 2020 – at least from energy production – which climate scientists say is a prerequisite for holding global warming below 2 °C, the target agreed at the Paris climate talks last December.
The biggest cause of the decoupling of global emissions from economic growth is the spread of renewable energy.
According to the IEA, 90 per cent of the electricity generating-capacity installed around the world in 2015 was for renewables, more than half of it for wind energy.
CO2 emissions growth has faltered before – in the early 1980s, 1992 and 2009. But previously this coincided with economic recession.
“In essence, the data are showing that combating climate change is perfectly compatible with continuing economic growth,” said Richard Black, director of the Energy and Climate Intelligence Unit think tank in London.
The two largest emitting nations, China and the US, both recorded declines in emissions in 2015. In the US, this was down to a move in the past five years from coal to natural gas and wind power.
In China, it is due to a reduction in burning of coal and the rising contribution of wind, solar and hydroelectricity.
The IEA’s director, Fatih Birol, called the findings “another boost to the global fight against climate change”.
But the pattern is not uniform. The IEA reported increases in CO2 emissions in much of Asia and the Middle East and even in Europe, which had previously led the way in lowering emissions.
As long as it’s falling
The new results confirm an initial analysis by an international team of climate scientists, published in Nature Climate Change in December.
However, although the headline figures coincide, there are differences in detail. December’s study, completed before the end of 2015, estimated that Chinese emissions last year fell by as much as 3.9 per cent, the IEA puts the decline at 1.5 per cent.
“The confirmation by IEA of the decoupling is good news,” says Corinne Le Quere, director of the Tyndall Centre at the University of East Anglia, who led the December study. “Now we need to increase efforts in coming years, until we bring emissions down to zero. The faster we decrease the emissions the less risk we take.”
Despite the plateauing of carbon emissions from energy production, emissions from changes in land use, such as deforestation, are likely to still be increasing.
Indeed, levels of CO2 in the atmosphere appear to be rising faster than ever, to record-breaking new levels.