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.)