The Working Group III (WG III) contribution to the Intergovernmental Panel on Climate Change’s (IPCC) Sixth Assessment Report (AR6) assesses literature on the scientific, technological, environmental, economic and social aspects of climate change mitigation.  

“The Working Group III report provides an updated global assessment of climate change mitigation progress and pledges and examines the sources of global emissions. It explains developments in emission reduction and mitigation efforts, assessing the impact of national climate pledges concerning long-term emissions goals.” –IPCC website  

This is the third instalment of the IPCC’s sixth assessment report since 1988, covering the reduction of greenhouse gas emissions. It follows the first section – published last August that warned anthropogenic changes to the climate were becoming irreversible – and a second section – published at the end of February warning of catastrophic consequences of anthropogenic global warming.  

“Emissions reduction to address climate change would need to be on the scale seen in the pandemic year after year, but in contrast with the adverse impacts of the pandemic, the options can improve quality of life.” – IPCC Working Group III Vice-Chair Diana Urge.  

The world has only a slim chance of limiting global heating to 1.5°C above pre-industrial levels and is falling far behind in changing the global economy to a low-carbon footing.   

Overshooting 1.5°C is now “almost inevitable”, however, the overshoot could be temporary, and temperatures could be returned to 1.5°C by the end of this century if countries keep to their promises and reduce greenhouse gas emissions drastically this decade. Technologies such as carbon dioxide removal are likely to be needed to limit and reduce carbon dioxide concentrations in the atmosphere. 

The world must reach net zero emissions by 2050.  

Key points from this report: 

1/ Global greenhouse gas (GHG) emissions are at their highest ever, but growth has begun to slow. 

2/ Current GHG and historical CO2 emissions are not evenly distributed globally.

The top 10% of households are responsible for 34-45% of emissions today versus the bottom half of households being responsible for 13-15%.  

Least developed countries (LDCs) contributed less than 0.4% of historical CO2, and Small Island Developing States (SIDS) only 0.5%. 

3/ It is possible to cut emissions over a sustained period.

“At least 18” countries have done so (on production and consumption emissions basis) for “longer than 10 years”. However, these reductions have only partly offset overall global emissions growth. 

4/ There have been significant declines in the unit costs of crucial technologies – solar (-85% 2010-2019), wind (-55%) and batteries (-85%) – alongside rapidly increasing deployment.   

Large-scale mitigation technology has seen “minimal cost reductions” and has “grown slowly”. 

5/ Climate policies have worked, but at a slow pace, and only 53% of global GHG emissions are covered by “direct” laws focused on cutting emissions. Climate finance flows are up 60% but remain below the $100bn by 2020 target. 

6/ Current climate policies and pledges are insufficient and poorly implemented.

If Nationally Determined Contributions (NDCs) are followed to 2030, it is “likely” the world will pass 1.5°C. There is no way to limit warming to 1.5°C with “no or limited overshoot”.  Footnote 25 under B.6 in the summary report says that mitigation efforts after 2030 are unlikely to prevent warming of 1.5°C, and that the pathways which limit warming to 1.5°C “limit warming to 1.6°C or lower throughout the 21st century [have a] 50% likelihood”. It will be even harder to stay below 2°C warming. 

7/ Developed countries already have the high-carbon infrastructure to blow the remaining carbon budget for 1.5°C. Staying below 1.5°C or 2°C would mean early retirements, retrofits with Carbon Capture and Storage (CCS), and cancelling new coal – a “major option” for aligning with the cheapest route to below 2°C. 

8/ Global GHGs peak around 2020 and “before 2025 at latest” in pathways to 1.5°C with null or limited overshoot.  

Current policies imply ~3.2°C For 1.5°C.  

Global GHGs fall 43% below 2019 by 2030 & 84% by 2050. 

CO2 -48% by 2030 and to *net-zero* in “early 2050s”. 

CH4 -34% by 2030. 

9/ If the world cuts emissions quicker, then there is a slightly larger time period before CO2 has to reach net-zero, and we will be less reliant on CO2 removal (because of the carbon budget). 

10/ There is a new way of categorising mitigation scenarios in AR6, from C1 (1.5°C with no or limited overshoot) up to C8 (4°C).  

There are also “illustrative mitigation pathways” showing different ways to limit warming. 

11/ All modelled pathways to stay below 1.5°C with no or limited overshoot involve “rapid and deep and in most cases immediate” cuts in “all sectors”.  

Cutting energy demand (IMP-LD, IMP-SD, IMP-REN) reduces the need for large-scale carbon dioxide removal (CDR), but some CDR is “unavoidable”. 

12/ Cutting emissions “requires” a “substantial reduction in overall fossil fuel use”, energy efficiency, low-emission energy sources (for example, renewables) and alternative energy carriers (for example, hydrogen).  

Renewables, EVs and efficiency would save money (blue bars on the chart). 

13/ For the first time, the IPCC has a chapter on demand-side mitigation, including shifting diets, transport patterns and material efficiency.  

These could cut 40-70% of end-use emissions by 2050 versus baseline scenarios whilst “improving basic wellbeing for all”. 

14/ Climate adaptation and mitigation are “critical” to sustainable development.

There are many synergies (+ on the chart) and though there are some potential trade-offs (-), which can be minimised. 

15/ The economic benefits of limiting warming to 2°C outweigh the costs “in most of the assessed literature”. 

Looking only at the costs, mitigation for 2°C would reduce annual global GDP growth by at most 0.14 percentage points (this excludes avoided damages, co-benefits etc). 

Looking forward 

António Guterres, the UN secretary-general, was right to say that the world “was on a fast track to climate disaster”. Nations and corporations, he candidly said, are not just turning a blind eye to a planetary disaster but adding fuel to the flames. There is very little time left to implement policies that promote the needed greener lifestyle choices and cheaper renewable solutions that would generate jobs, energy security and price stability.  

Global temperatures will likely “overshoot” the 1.5°C pledged by the Paris agreement. Even under one of the least bad scenarios, the IPCC says that temporarily exceeding this limit by a tiny 0.2°C before dropping back down to about 1.4°C by the century’s end could still unleash irreversible impacts, such as dead coral reefs. The pandemic was an opportunity to make the rapid shift required away from fossil fuels but was missed by most governments. Russia’s immoral war in Ukraine offers another chance for nations concerned about over-reliance on hydrocarbons to do the right thing.