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IPCC 6th Assessment Synthesis Report

IPCC 6th Assessment Synthesis Report
Photo by Tania Malréchauffé on Unsplash

The IPCC 6th Assessment Synthesis report is the final report in the IPCCs sixth assessment (AR6) cycle. Released on the 19th March 2023, this will be the last report we receive from the IPCC during this critical decade for climate action.

A headline statement says with very high confidence that, “Climate change is a threat to human well-being and planetary health,” and that, “There is a rapidly closing window of opportunity to secure a liveable and sustainable future for all.” This is not a trivial statement to make, and we would be wise to treat this crisis with the urgency the report requests of us.

What is the 6th Assessment Synthesis Report?

The report is intended to be a summary of content from the sixth assessment cycle, in addition to a few other reports that have been released by the IPCC over the last few years. The synthesis report provides key information in a concise document for policymakers. It draws its information from reports including:

Why does this Synthesis Report matter?

IPCC reports like this one are used by politicians and decision-makers at the COP climate summits. IPCC reports are also used to inform national climate targets.

One reason why this particular report is significant is because it’s the last major IPCC report (as part of a collective assessment) that is likely to be released until around 2030. This decade, is the last decade we have to keep temperatures under 1.5C. As such, this is the last report that will be released to inspire climate action to meet this target.

What does the Synthesis Report say?

The headline statements lay out in no uncertain terms where we stand, and I’d advise reading them here as they’re a critical and concise warning for humanity. Some examples include:

  • “Human activities, principally through emissions of greenhouse gases, have unequivocally caused global warming, with global surface temperature reaching 1.1°C above 1850–1900 in 2011–2020. (high confidence).”
  • “Human-caused climate change is already affecting many weather and climate extremes in every region across the globe. (high confidence).”
  • There is high confidence that greenhouse gas emissions which countries intend to emit by 2030, “Make it likely that warming will exceed 1.5°C during the 21st century and make it harder to limit warming below 2°C.” This is based on what countries submitted in their NDCs in October 2021.
  • “The choices and actions implemented in this decade will have impacts now and for thousands of years (high confidence).”
  • “All global modelled pathways that limit warming to 1.5°C (>50%) with no or limited overshoot, and those that limit warming to 2°C (>67%), involve rapid and deep and, in most cases, immediate greenhouse gas emissions reductions in all sectors this decade. (high confidence).”
  • “The likelihood of abrupt and/or irreversible changes increases with higher global warming levels. (high confidence)”
  • According to the synthesis report, there is high confidence that, “Approximately 3.3–3.6 billion people live in contexts that are highly vulnerable to climate change.”
  • There is high confidence that the climate crisis has caused either ‘substantial’ or ‘irreversible’ damage on land, in freshwater ecosystems, to ice caps, and in our oceans.
  • There is very high confidence that extreme heat has led to people dying across all regions of the world.
  • There is a high or very high confidence that mental health is suffering from rising temperatures, which is linked to “trauma from extreme events”, and “loss of livelihoods and culture”.
  • There is only a medium confidence that AMOC (the Atlantic Meridional Overturning Circulation) won’t abruptly collapse by 2100. But if it does, the disappearance of this vital ocean current will have a massive impact on weather, ecosystems and human activities.
  • There is a medium to high confidence that everywhere will suffer from climate impacts. This may include: heat-related human deaths, more disease, deteriorating mental health, coastal flooding, biodiversity loss, reduced food production, reduction in water availability from glaciers/ice, and more intense and frequent heavy precipitation events, which could result in additional flooding.
  • There is high confidence that rapid reductions in emissions are needed across all sectors to, “secure a liveable and sustainable future for all.” There is very high confidence that “Deep, rapid and sustained mitigation and accelerated implementation of adaptation actions in this decade would reduce projected losses and damages for humans and ecosystems.”

In the press release, IPCC Chair, Hoesung Lee, stressed that urgent action could help us maintain a liveable planet, “This Synthesis Report underscores the urgency of taking more ambitious action and shows that, if we act now, we can still secure a liveable sustainable future for all.”


It’s difficult to sum up this report, because it feels like there’s only so many times you can talk about the increasing urgency for global action, which isn’t being heeded. We are very much at a crossroads. One path will lead us down a clean energy future, in a rewilded and afforested world, based around an economic model that gives as much of a priority to the environmental and social pillars of sustainability, as it does to the economic pillar. In effect, we’d be living within the ‘doughnut economics’ model proposed by Kate Raworth. A world in which decisions are made in a democratic manner such as through climate assemblies, with the next seven or more generations in mind. Such a world would enable us to thrive.

The other path drags us further towards a hellish future. One which even the most cautiously-minded experts are saying will jeopardise the future of civilisation. A world in which fossil fuel companies and their greed continue to prioritise environmental destruction at all of our expense. A world where politicians continue to be bought by the fossil fuel industry. Where the media continue to downplay, deny or lie about the crisis.

Every action we make is a climate action which will push us down one of these paths. Every election is a climate election, which will see politicians save or steal our future from us. We have to think and act in line with the scale of the emergency. For we risk failing in our historic duty to turn the tide on the climate crisis. And as we can all agree, failure is quite simply not an option.

List of Reports in AR6 – The IPCCs 6th Assessment Cycle

I’ve covered each of the AR6 reports and my summaries are available here:

My new cli-fi children’s picture book is Nanook and the Melting Arctic. Nanook is a caring polar bear who lives in the Arctic. But when his igloo starts melting, Nanook must find a way to save his friends and his home. He knows that the people who can help are also those who’ve caused the problem and he must find a way to convince leaders to act on the climate crisis. You can purchase Nanook from Amazon’s global stores including Amazon UK and Amazon US.

Published inThe Climate Crisis