IPCC Synthesis Report – the Good, the Bad and the Ugly

The last gasp of IPCC AR5, the Synthesis Report, was published on Sunday, Nov 2nd. There is a full report , 116 pages, and a concise 40-page Summary for Policymakers. There’s also a short press release. The idea of this report is to summarise and collate the main points from the reports of the three working groups that have already been published, so there shouldn’t really be anything new here, though there may be a change in tone or emphasis.  The comments here are based on the full report.  There seems to be a sequence of non sequiturs between the different sections of the report, and between the report and the way it has been reported in the media – the usual game of climate chinese whispers.


The report starts well on “Topic 1”, the basic observational data. It says there has been a warming of about 0.85 [0.65-1.06] C since 1880.  It acknowledges that there’s been virtually no warming over the last 15 years, and that Antarctic sea ice has increased. It says that the current rate of sea level rise is very similar to that in the early 20th century.

On extreme weather events, the report claims very little. It says that warming causes warming – the number of cold days has decreased and warm days have increased, which reminds me of this quote. In a similar vein they say that heat-related deaths have increased while cold-related deaths have decreased.  There is a rather tentative claim about heavy precipitation events, saying that it is likely that there have been more increases than decreases.  But exactly what is a heavy precipitation event, how is it measured, and how accurately and when and where have they been measured? They say there’s ‘low confidence’ in anything to do with flooding, droughts and tropical cyclones, which ought to quieten down the Green Blob claims of storms being caused by global warming, but probably won’t.


The report deteriorates sharply when it gets on to Topic 2, “Future Climate Changes, Risks and Impacts” (p 18). This starts with the bold claim that “Continued emission of greenhouse gases will cause further warming and long-lasting changes in all components of the climate system, increasing the likelihood of severe, pervasive and irreversible impacts for people and ecosystems”.  No uncertainty is expressed, there’s just the word “will”. No mention is made of the fact these are projections based on speculative computer models that have completely failed to predict the slow-down in warming or the increase in Antarctic ice discussed in the previous section.

There’s a prediction of 0.3-0.7C of warming over the period 2016-2035, which they say does not depend on emissions but would depend on any major volcano’s or changes in the sun’s output.  The scare-quote above about “severe, pervasive, and irreversible impacts” is repeated, leading on to claims of severe ill-health, food and water insecurity, loss of ecosystems, droughts and floods, and even violent conflict.

Topic 3 on adaptation and mitigation makes similar overconfident claims, repeating yet again the threat of severe impacts scare unless we undertake mitigation. Here the IPCC comes close to breaking its own guidelines, that it is “policy-relevant and yet policy-neutral, never policy-prescriptive”.


The next step in the exaggeration game is how the report is described in the media. The BBC said

“Fossil fuels must be phased out by 2100”

This was the headline of an article on the BBC website. The IPCC said no such thing (which would have been a clear breach of their policy guidelines) – the word ‘must’ does not appear anywhere. The BBC changed the word ‘must’ to the slightly less misleading ‘should’ – possibly as a result of a tweet I sent to them. But this incorrect statement has been widely copied, for example in the Mail. The Guardian headline is “rapid carbon emission cuts vital”, with the obligatory misleading picture of white water vapour from a cooling tower back-lit to make it look black. The Independent says it’s a “final warning” and also picks up on the fossil fuel phase-out by 2100. Even the normally more reliable Emily Gosden in the Telegraph writes incorrectly that “Global emissions must fall by at least 40 per cent by 2050 and be cut to zero by the end of the century, the report from the UN’s Intergovernment Panel on Climate Change warns”.

What the IPCC actually said about phasing out fossil fuels was (main report p 51, SPM p 19): “In the majority of low‐concentration stabilization scenarios… fossil fuel power generation without CCS is phased out almost entirely by 2100.”

Update Nov 4: Coverage elsewhere

In Spiegel Online, Axel Bojanowski says the IPCC has put alarm before accuracy, citing examples where the summary is more alarmist than the main report, in particular on the danger of extinction (comments in English here).

Jo Nova says the IPCC is recycling its message of doom, despite being consistently wrong.

Carbon Brief reports on “What’s new and interesting in the IPCC synthesis report” – which ought to be a very short blog article.

RTCC has several articles, including a summary in tweets and a claim that the report was watered down.

James Delingpole summarises the IPCC message as “Buy our snake oil or the world gets it”.

Marcel Crok has a blog post “IPCC bias in action”, saying that there is much less discussion of climate sensitivity than in AR4 (no mention at all in the SPM).

Matt Ridley says the IPCC high emission scenario “makes wildly unrealistic assumptions” and exaggerates future warming.


4 thoughts on “IPCC Synthesis Report – the Good, the Bad and the Ugly

  1. No mention is made of the fact these are projections based on speculative computer models that have completely failed

    My impression: they don’t seem to have admitted they “completely failed” yet. I doubt they will ever admit “completely failed”. We are being treated with explanations for discrepancies with no clear admission that the discrepancies exist.

    They sort of had to mention the hiatus. There really was no way around admitting it has not warmed at 0.2C/decade since the AR4 was published.

  2. Thank you for this overview. The sorry saga continues – they are, after all, trapped in the narrow confines of their goal-directed beginning and the consequent, all but predetermined, crescendo of alarm and assurance over the years.

  3. Thanks for the summary.
    One thing that the IPCC recognizes – possibly for the first time – is that policy can have an impact on economic growth. The middle estimate of 0.06% of GDP is tiny compared to any likely effect, and they totally ignore the impacts of failed policy, or the re distributional impacts on growth between policy and non-policy countries – but it is there.
    The BBC misrepresented this but implying that the 0.06% would be average lost output. Over decades this massively understates the issue.

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