The IPCC released its AR6 Synthesis Report: Climate Change 2023 on Monday 20th March.

Carbon Brief have provided a detailed summary and analysis here: Q and A: IPCC Wraps Up Its Most In-Depth Analysis Of Climate Change  and there is shorter summary by Professor Kate Hayhoe via a twitter thread,

The main takeaways from the IPCC reports are:

1. “Human activities, principally through emissions of greenhouse gasses, have unequivocally caused global warming”…“Widespread and rapid changes in the atmosphere, ocean, cryosphere and biosphere have occurred as a result.  Human-caused climate change is already affecting many weather and climate extremes in every region across the globe.  This has led to widespread adverse impacts and related losses and damages to nature and people.”

2.  The impacts of increased global warming are very serious: global warming directly affects world health, crop yields, water supply, survival of animal species and more.

3.  In nearly all of the scenarios and pathways considered by the IPCC the world will continue to get hotter in the near term (2021 – 2040).  Global temperatures are more likely than not to reach 1.5C during 2021-40 (due to CO2 already accumulated in the atmosphere) even if emissions are very low.

4.  Every 10th of a degree of global warming matters. “With every increment of global warming, regional changes in mean climate and climate extremes become more widespread and pronounced”

5. The amount of warming this century largely depends on the amount of greenhouse gasses humans release into the atmosphere in the future (i.e from 2021 onwards) with cumulative net CO2 dominating.  There is, therefore, still an opportunity to control how hot it gets by the end of the century.  Future warming will be driven by future emissions.

6.  In order to stop global warming CO2 emissions are required to reach net-zero.  “Continued greenhouse gas emissions will lead to increasing warming.…Deep, rapid and sustained reductions in greenhouse gas emissions would lead to a discernible slowdown in global warming within around two decades.”

7.  The world has a rapidly narrowing window of opportunity to mitigate the worst effects of climate change and to enable the development of a climate resilient future.  Many of the solutions to enable the transition to a clean energy future are (a) readily available today, and (b) through their implementation are also capable of being linked to improvements in health, equity,  social justice, and the alleviation of poverty.

By Tony Webster