The release of the IPCC 5th Assessment Report Synthesis document on Sunday was a useful reminder of the wealth of measurements, observations and science behind the reality of the anthropocene era and the impact it is having on global ecosystems. While some may embrace this material as proof of society’s “wicked ways” and others may contest it on the grounds of conspiracy or hoax, the real job at hand is to find a way of dealing with the challenge that is posed. Within the 100+ pages of text of the longer report, two parts in particular highlight the scope of what needs to be done.
Despite a growing number of climate change mitigation policies, annual GHG emissions grew on average by 1.0 GtCO2eq (2.2%) per year, from 2000 to 2010, compared to 0.4 GtCO2eq (1.3%) per year, from 1970 to 2000. Total anthropogenic GHG emissions from 2000 to 2010 were the highest in human history and reached 49 (±4.5) GtCO2eq yr-1 in 2010.
Within 3.2 and 3.4:
Global mean surface warming is largely determined by cumulative emissions, which are, in turn, linked to emissions over different timescales. Limiting risks across reasons for concern would imply a limit for cumulative emissions of CO2. Such a limit would require that global net emissions of CO2 eventually decrease to zero.
There are multiple mitigation pathways that are likely to limit warming to below 2 °C relative to pre- industrial levels. Limiting warming to 2.5 °C or 3 °C involves similar challenges, but less quickly. These pathways would require substantial emissions reductions over the next few decades, and near zero emissions of CO2 and other long-lived GHGs over by the end of the century.
The IPCC have now fully embraced the cumulative emissions concept and taken it to its logical conclusion; near zero emissions within this century. This wasn’t explicitly mentioned in the 2007 4th Assessment Report, but was only really there by inference in the mitigation scenario charts that extend beyond 2050. Anyway, the reference is very clear this time around.
This represents a formidable task given the other half of the problem statement also shown above; that emissions are rising faster than ever. There is a second uncomfortable truth buried within this paragraph, which is the implication that current mitigation policies aren’t working.
So there we have it in a nutshell;
Emissions are rising faster than ever, current policies to stop this aren’t working, but we need to be at zero in 85 years.
Eighty five years is the lifetime of an individual. It means that someone born today will need to see a radical change in energy production within the course of their life, to the extent that it is constantly changing for all 85 years, not just locally but everywhere in the world. Arguably someone born in England around 1820 saw this as the industrial revolution unfolded and the Victorian era took hold. But someone born in 1930 hasn’t actually seen a fundamental change in the energy system, rather an enormous scaling up of what was starting to become commonplace at the time of their birth.
This is the issue that I explore in my new book and which is tackled in the Shell New Lens Scenarios released last year. Both the scenarios show that this puzzle is solvable, albeit in very different ways and with different policy approaches but with different levels of success. A critical factor in both scenarios is the timing and deployment rates of carbon capture and storage (CCS). The earlier this starts and the faster it scales up, the higher the chance of limiting warming to around 2°C. This is also highlighted in the IPCC Synthesis Report which says in Section 3.4;
Many models could not limit likely warming to below 2 °C over the 21st century relative to pre-industrial levels, if additional mitigation is considerably delayed, or if availability of key technologies, such as bioenergy, CCS, and their combination (BECCS) are limited (high confidence).
CCS is of course dependent on a price for carbon dioxide or in its absence a standard of some description to implement capture and storage. These policies are larg