I was disappointed by the recent summary for policymakers (SPM) of the intergovernmental panel on climate change (IPCC) assessment report 5, now that I finally got around to read it. Not so much because of the science, but because the way it presented the science.

The report was written by top scientists, so what went wrong?

I guess we need to recognise the limitations of the format of the SPM, and the constraints that they have to work under (word by word approval from 190 country representatives) may not have been helpful this time. The specified report length, combined with attempts from lots of people to expand on the content, may have complicated the process.

My impression is that the amount of information crammed into this report was more important than making a few strong messages.

The SPM really provides a lot of facts, but what do all those numbers mean for policy makers? There was little attempt to set the findings in a context relevant for decision making (ranging from the national scale to small businesses).

It is difficult to write a summary for a report that has not yet been published, and for that reason, the SPM is cluttered by technical details and discussions about uncertainty and confidence which have a better place in the main report.

The authors of the SPM are experts at writing scientific papers, but that is a different skill to writing for non-scientists. Often, the order of presentation for non-scientists is opposite to the way papers are presented in sciences.

A summary should really start with the most important message, but the SPM starts by discussing uncertainties. It is then difficult for non-scientists to make sense of the report. Are the results reliable or not?

I asked myself after reading the SPM – what’s the most important finding? If the IPCC hoped for good press coverage, I can imagine all journalists asking the same question.

My recommendation is that next time, the main report is published before the SPM. That way, all the space used on uncertainty and confidence in the SPM could be spared.

I also recommend that people who decide the structure of future SPMs and undertake the writing take a course effective writing for non-scientist. At MET Norway, we have had such writing lessons to improve our communication skills, and I have found this training valuable.

It takes some training to find more popular ways to describe science and spot excessive use of jargon. Many words, such as ‘positive feedback‘ have different meanings if you talk to a scientist or a non-scientist (a bad phrase to use in the context of climate change for people with very little science background). Also the word ‘uncertainty‘ is not a good choice – what does it mean really?

There are some examples of how the report could be written in a better way: The European Academies of Science Advicory Council (EASAC) followed a different strategy, where the main report was published before the summary, and hence the summary could be written as a summary and with a more coherent structure and a stronger connection to the reports target group.

The World Bank report of last year also comes to my mind – I think that is a much clearer form of presentation.

If I could have my way, I would also suggest that IPCC’s main reports in the future come with supporting material that includes the necessary data (extracted for the plotting purposes, but with meta-data providing the complete history of post-processing) and source code for generating all the figures in the report.

One way to do that could to use so-called ‘R-packages’ as suggested by Pebesma et al (2012) (PDF). It would also be good if future assessment reports pay more attention to replicating important results as a means of verification or falsification.

p.s.There exists a set of headline statements have been issued from the IPCC. THere is also a short video on the IPCC working group 1 findings

p.s. After posting this article, I was made aware of two short documents summarizing the IPCC reports – link here. I’m really grateful for this feedback. -rasmus

Update 2015: Related discussions in Nature Climate Change March 25, 2015. Also, this post motivated an article in EARTH: IPCC: A failure in communicating the impact of new findings

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