Summary of the IPCC’s 5th annual report at the Cambridge Centre for Climate Science


This week I wrote a blog post for the Cambridge Centre for Climate Science (CCfCS). It’s a summary of an afternoon of talks about the IPCC 5th annual report on climate change. The event was organised by both the CCfCS and the Cambridge Institute for Sustainable Leadership (CISL). UPDATE: the link to the website has broken so I have copied and pasted my report below.

A more detailed summary of both Working Group 1 (The Scientific Basis) and Working Group 2 (Impacts and Adaptation) can be found in previous posts I’ve written.

CCfCS – IPCC AR5 Synthesis Report Discussion Meeting

This week the Cambridge Centre for Climate Science (CCfCS) and the Cambridge Institute for Sustainable Leadership (CISL) hosted an afternoon of presentations and discussions about the 5th Intergovernmental Panel on Climate Change (IPCC) report (AR5).  The meeting coincided with the release of the ‘Synthesis’ report which was the final document to be released for AR5.

The meeting was organised by Dr Michelle Cain (CCfCS) and chaired by Dr Eliot Whittington (CISL). Four speakers spoke about the three working group reports and the IPCC’s impact on policy. A panel discussion followed where audience members could ask questions and give comments. Lastly, the afternoon concluded with an opportunity for networking over a wine reception.

The first of the four speakers was Prof. Eric Wolff from the Department of Earth Sciences, formally from the British Antarctic Survey. Professor Wolff gave a clear summary of the working group (WG) 1 report which assesses ‘The Physical Science Basis’, as well as a brief overview of the history of the IPCC. The IPCC is a UN indorsed organisation set up by the United Nations Environment Program (UNEP) and the World Meteorological Organisation (WMO) in 1988. The published reports released every ~5 years aim to assess “the scientific, technical and socio-economic information relevant to understanding the scientific basis of risk of human-induced climate change“.

WG1 discusses both past and present observations are conducted, and how the use of complex computer models help to understand the climatological processes occurring in the world. Observations including sea ice extent, atmospheric and ocean temperature, ocean acidity and sea level show concurrently the world is warming. The rate of change is at least 10 times faster than the warming from the last ice age. Computer analysis shows that these observed changes cannot be replicated without the consideration of anthropogenic interactions to the environment (i.e CO2 has risen 40% in the last two centuries). Future ‘pathways’ the world can adopt show at least a 2 degree warming by the year 2100, if an aggressive strategy is adopted to reduce GHG emissions. A ‘business as usual’ pathway shows an increase of 4-5 degrees. This would have major impacts on the world as the last ice age was only 5 degrees cooler than today.

The second speaker was Prof. Douglas Crawford-Brown from the Cambridge Centre for Climate Change Mitigation Research who summarised the WG2 report: Impacts, Adaptation and Vulnerability. Five themes (listed below) regarding impacts were addressed in this report. The report was criticised however for not addressing each theme with equal weighting.

  • Unique and threatened systems
  • Extreme weather events
  • Distribution of impacts
  • Global aggregate impacts
  • Large scale singular effects

Both global and regional impacts were addressed and the idea of ‘risk’ was commonly used as an analytical framework throughout the report, whereas in 2009 the AR4 WG2 report concentrated more on pure relevance scenarios. Future impacts were discussed using the same pathways described in the WG1 report. A region’s vulnerability and ability to adapt was also assessed.

The WG3 report: Mitigation of Climate Change, was summarised by the third speaker Dr David Reiner from the Energy Policy Research Group in the Judges Business School. Dr Reiner started his talk by advising that for this WG the technical summary (TS) which, although longer, provides a more detailed analysis of the scientific data than the summary for policy makers. The report starts by explaining that GHG emissions are continuing to rise on the global scale despite many reduction policies in place. This is due to increasing emission rates from more developing nations. Dr Reiner explained that the primary purpose of WG3 was to assess multiple mitigation pathways and its impact on the economy. Global baseline projections for the Kaya factors (population, GDP per capita, energy use per unit of GDP, carbon emissions per unit of energy consumed) were also shown in the report. An attempt to quantify the economic cost of mitigation strategies and other co-benefits to reducing GHG emissions (e.g better air quality) were also highlighted. Of the three working group reports, the third was the least well reviewed after publication, with the economic models being questioned.

This was also mentioned in the final speaker’s talk ‘A policy perspective on the IPCC’ by Prof David MacKay who was the former chief scientific advisor to the Department for Energy and Climate Change (DECC), and now works in the Engineering Department of Cambridge University. Professor MacKay provided constructive criticism for some areas of improvement for future reports. The quantification of risk and the clarification of uncertainty were stressed to be particularly useful for determining future policies.

A panel discussion, lasting ~90 minutes, allowed the audience to ask questions and offer comments. Topics including carbon sequestration, the format of future IPCC reports, the role of both public and private sectors in CC mitigation, and the portrayal of scientific facts and figures were all addressed. Less formal discussions then continued at the wine reception.

More information about the three working group reports can be found in their respective technical summaries (TS) or their summary for policy makers (SPM):

WG1  WG2  WG3