IPCC AR6 Synthesis Report Summary for Policymakers
IPCC AR6 Synthesis Report Summary for Policymakers
The latest authoritative summary of climate change
The highest-level summary of climate change, the Summary for Policymakers, or SPM, was issued yesterday by the Intergovernmental Panel on Climate Change (the IPCC). It’s a good summary of where we are, climate-wise, and is available here. It’s just 36 pages long, but it contains a lot of useful info. I will present some quotations from the Report, along with my commentary. 1.5°C.
“The choices and actions implemented in this decade will have impacts now and for thousands of years.” (p. 27.) This highlights the fact that the 2020s are a critical decade for the climate process, and what we do will affect many future generations. The Report concedes that it will be very difficult to limit global warming to 1.5°C. now. (p. 10.) In fact, we’ll have to radically increase our mitigation efforts if we’re to keep global warming below 2°C, as shown on the following Figure SPM.5 from the report:
The current trajectory, based on “implemented policies,” is for emissions to remain at their current high level through 2100. But, in order to limit global warming to 2°C, we will need immediate, drastic reductions in GHG emissions. We need to reduce total emissions by two-thirds by 2050 on our way to net-zero, or close to it, by 2100. But emissions continue to increase. To get to net zero, we’ll need “a substantial reduction in overall fossil fuel use.” (p. 30.)
“Global mean sea level increased by 0.20 m between 1901 and 2018.” (p. 5.) This is about 8 inches, and doesn’t sound like much, but it has huge implications for coastal communities, when increased storm surges and increased hurricane intensity are factored in. The current rate of rise is about 3.7 mm per year, which will add up to around 15 feet of sea-level rise in the next century if we don’t take drastic action now.
“Public and private finance flows for fossil fuels are still greater than those for cli- mate adaptation and mitigation.” (p. 11.) This is amazing and terrible! But we can see the dynamic in the US’ Inflation Reduction Act, which commits to major investments in sustaining fossil fuels. We’ve got to stop subsidizing fossil fuels. In fact, we should be doing the opposite - prohibiting additional fossil-fuel development, to avoid locking in the infrastructure, which will result in stranded assets.
“Some hard-to-abate residual GHG emissions (e.g., some emissions from agricul- ture, aviation, shipping, and industrial processes) remain and would need to be coun- terbalanced by deployment of carbon dioxide removal (CDR) methods to achieve net zero CO2 or GHG emissions.” (p. 22.) But CDR has not been developed in a way that reaches the needed scale in a cost-effective way. The 2022 California Scoping Plan for Achieving Carbon Neutrality also relies on CDR to achieve net-zero GHG emissions. The reason for including CDR, in both cases, is that the climate modeling doesn’t foresee reaching net zero without it. But this is how we fail in trying to reach the goal, when our strategy to get to the goal starts including requirements we know we can’t meet. The following graphic from page 7 of the Report shows how climate change will affect young people more than oldsters like me:
What’s missing is the stuff to the right of the diagram. What will things look like in the year 2200, or 3000? Future generations will be affected, for hundreds or thousands of years. As I explain in my book, Earthling, the number of people in future generations harmed by global heating will likely be many times the 9 billion that are currently in- habiting our planet.
The 36-page SPM is a high-level summary of the longer AR6 Synthesis Report, which hasn’t been issued yet. The previous, AR5, Synthesis Report dates from 2014, and is 169 pages long. The AR6 Synthesis Report will probably be the most reliable summary of the state of the climate when it is issued. It, in turn, summarizes three very lengthy Working Group reports:
WGI: Climate Change 2021: The Physical Science Basis (2409 pages)
WGII: Climate Change 2022: Impacts, Adaptation and Vulnerability (3068 pages)
WGIII: Climate Change 2022: Mitigation of Climate Change (1991 pages)
These Working-Group Reports, even though they’re lengthy, are themselves summaries. They each reference thousands of sources in books and scientific journals.
I will probably send out another post like this when the full AR6 Synthesis Report is released. In the meantime, if you are interested in climate change, please read my book Earthling, which is an ethics-focused tour of many climate issues.