A paper by Christopher Green in the February issue of Nature Climate Change titled, “Mitigation Technology: Half full or nearly empty?” provides a critique and brief summary of the “Key Indicators…” document described in an earlier post. It asks the critical question, is the world currently on track to meet the global climate challenge? The authors answer is simply, “it is difficult to be sanguine”. Several concerns are highlighted:
- While there has been a significant increase in non-hydro renewable energy (namely wind and solar) in the past 15 years, it still accounts for only 2.8% of global energy consumption and has been almost completely offset by a 2.0% reduction in nuclear energy. The net effect is that the share of fossil energy in global energy consumption has remained almost constant between 86% and 87% throughout the period 2000 and 2015.
- Absent a significant breakthrough in large-scale energy storage technology, any substantial increase in wind and solar will require a parallel increase in back-up capacity, generally from fossil fuel “spinning reserves”.
- If the primary objective of the Paris Climate Agreement of holding the global temperature increase to “well below 2oC” is to have any chance of being met, it will be necessary to reduce carbon emissions by at least 80% between now and the year 2050. This requires an average annual rate of decline in carbon emissions of ~5.0 %. If the global GDP grows at an annual rate of 2-to-3% per year then the carbon intensity of economic activity would have to decline at a rate of 7-to-8% per year. (This is some 3 to 4 times the rate of decline experienced during the period 2010-2015.)
A paper published in the February 2017 issue of Nature Climate Change, entitled “Key indicators to track current progress and future ambition of the Paris Agreement”, outlines a method whereby it would be possible to track how well country-level progress is being made in achieving the goals set forth in the Paris Climate Agreement. The method outlined is based on the so-called “Kaya identity” which relates CO2 emissions to the product of GDB, energy intensity of GDP, and carbon intensity of energy. It further decomposes the carbon intensity of energy into the share of fossil fuels in total use and carbon intensity of fossil-fuel combustion.
The authors apply the method to data covering the period 1990 through 2015 for China, the USA, the EU28 countries, India and “the rest of the world”. Interestingly, the analysis demonstrates that the decline in the carbon intensity of fuel which has occurred within the US in recent years is due more to the substitution of natural gas for coal than it is to the expansion of renewable energy. The EU carbon intensity decline is dominated by the growing share of renewables.
The study also shows that, “Although there has been strong growth in solar and wind power recently, the growth in global energy use has largely been dominated by increases in fossil-fuel use and, to a lesser extent by nuclear and hydropower.”
The study goes on to conclude that, “although many key indicators are currently broadly consistent with emission scenarios that keep temperatures below 2oC, the continued lack of large-scale carbon capture and storage threatens 2030 targets and the longer-term Paris ambition of net-zero emissions”.