Intergovernmental Panel on Climate Change Fifth Assessment Report: Review of Working Group I contribution - Energy and Climate Change Contents

Conclusions and recommendations


1.  The IPCC has continued to strengthen and improve its Assessment Report procedure. The IPCC has put a series of measures in place to help to minimise the risk of errors creeping in, and quickly rectify them if they emerge. The IPCC has responded extremely well to the constructive criticism of the InterAcademy Council (IAC). With regard to the IAC's recommendations, we would like to see the appointment of non-climate scientists to the Executive Committee. (Paragraph 10)

2.  For future Assessment Reports the Government should recommend to the IPCC that they recruit a small team of experts who are not climate scientists to observe the review process from start to finish. The team would not constitute an extra stage of review, but rather oversee the process and arbitrate when controversies arise. The testimony of this independent team would improve the credibility of the report when it is released, and potentially protect it from any unnecessary and unfounded criticism. The team could also feed back to the IPCC in order to facilitate continuous improvement. (Paragraph 12)

Inclusivity and objectivity

3.  The Assessment Report procedure depends to a large extent on the integrity of the authors and editors involved, but we have found no evidence to suggest that this should give cause for concern. The authors drew upon a wide pool of peer-reviewed literature, highlighting areas of disagreement as readily as areas of agreement. We are satisfied that there was no systemic bias of any kind, be it financial, political or otherwise that would jeopardise the accuracy of the reported scientific conclusions. The procedures in place to safeguard against the influence of such biases appear to be sufficiently robust. (Paragraph 20)

4.  Although the terms "consensus" and "settled science" with regards to climate change were generally not thought to be helpful, as uncertainty and debate are required to drive research forward, we conclude that there is clearly strong agreement that the IPCC has captured the prevailing scientific opinion, notwithstanding some disagreement from a number of reputable scientists. (Paragraph 22)


5.  There are mixed views regarding the frequency and size of IPCC Assessment Reports. Transition to smaller, more frequent reports would arguably relieve the burden on contributing authors and ensure policymakers were kept up to date, but the finished document would lack the comprehensive and authoritative nature of the current Assessment Reports. Any revision of the tried and tested IPCC formula should only be introduced after careful consultation with both the governments who use the IPCC reviews and the scientists who write them. The aftermath of AR5 is an optimum time for this period of reflection to take place. (Paragraph 26)

Summary for Policymakers

6.  Including policymakers in the final stage of the report writing process does not seem to have had any substantial negative effects on the Summary for Policymakers (SPM) and very likely serves to improve the relevance and accessibility of the finished document. (Paragraph 31)

7.  It is inevitable that the distillation of such a complex and lengthy report will lead to the omission of some technical detail, but the traceability of the SPM to the full report adequately compensates for that. Any further technical detail that may be required for policymaking, such as in the setting of carbon budgets, is readily obtainable. The SPM succeeds in its purpose of keeping policymakers informed on issues surrounding climate science. (Paragraph 32)

8.  We recommend that the Government call on the IPCC to introduce a greater level of transparency in the plenary meetings to agree future Summaries for Policymakers (SPM). This may be through the admission of the independent team of observers to oversee the discussions (see paragraph 12). The feedback from the team would then serve to provide reassurance that the summary-writing process has been carried out objectively. (Paragraph 33)

Causes of climate change

9.  The WGI contribution to AR5 presents the most compelling evidence to date that many of the changes to the climate recorded in the latter half of the 20th Century were driven by post-industrial human activity. We have not found convincing evidence that challenges the IPCC's conclusion in this matter. There is increased confidence in the IPCC projections that, with rising greenhouse gas concentrations, we will continue to see warming (and the changes to the climate associated with warming) in this century and beyond. (Paragraph 42)

Sensitivity of the climate to carbon dioxide

10.  The WGI contribution to AR5 has considered the full range of both Equilibrium Climate Sensitivity and Transient Climate Response and given the best assessment possible within the constraints of the evidence available at the time. It does not appear that a consistent pattern for higher or lower sensitivities than that stated in the WGI contribution to AR5 has emerged since its publication. (Paragraph 48)

The hiatus

11.  Periods of hiatus are consistent with earlier IPCC assessments that non-linear warming of the climate is to be expected and that forced climate changes always take place against a background of natural variability. The current period of hiatus does not undermine the core conclusions of the WGI contribution to AR5 when put in the context of the overall, long-term global energy budget. Despite the hiatus, the first decade of the 2000s was the warmest in the instrumental record and overall warming is expected to continue in the coming decades. (Paragraph 53)

Climate models

12.  The models used in the IPCC's Assessment Reports have a successful history of simulating past climate and their future projection of substantial warming over the next century in all but the most aggressive mitigation scenarios is well founded and overwhelmingly clear. (Paragraph 64)

13.  In the light of the WGI contribution to AR5, the Government should commission a strategic review of UK modelling facilities to discern how current computing capacity could be used more effectively to reduce remaining uncertainties. The review should highlight areas of potential national and international collaboration between modelling centres and any funding shortfalls that need to be met. (Paragraph 65)

Economic implications

14.  The Government should ensure that the report it has commissioned to look at the benefits and opportunities in tackling climate change, The New Climate Economy, considers evidence about the costs of climate change to business. We believe that this report should be peer reviewed to avoid attracting the same criticism that was made of the Stern Review. (Paragraph 70)

Domestic climate policy

15.  We believe that the Committee on Climate Change (CCC) was right to consider a range of values for climate sensitivity (and their relative uncertainties) when reviewing the Fourth Carbon Budget. We agree with its conclusion that the IPCC's latest assessment of the sensitivity of the climate towards greenhouse gas emissions gives no grounds for a change in policy action. (Paragraph 73)

16.  The WGI contribution to AR5 re-affirms the scientific underpinning of the Climate Change Act 2008 and hence the UK's ambitious greenhouse gas emission reductions targets. We believe that there is merit in considering embedded carbon emissions alongside territorial emissions in the policy making process. (Paragraph 75)

International climate policy

17.  The WGI contribution to AR5 strengthens the scientific case for rapid, drastic action to reduce global greenhouse gas emissions in order to avoid a 2° Celsius rise in global mean surface temperature (GMST). It is generally agreed that such dramatic emissions reductions strategies could best be implemented within the framework of a unified global agreement. Attempts to reach an agreement in the past have lacked early high level leadership: a public commitment from the UK Government is required early in the preparations of COP 2015 in order to guarantee the highest chance of success. (Paragraph 78)

18.  The Government should provide an explicit commitment on the involvement of senior figures in the early stages of the Paris COP 2015. Senior Government members should be actively involved in the strategy for obtaining a global climate deal. The early commitment of the Prime Minister, Chancellor of the Exchequer and DECC ministers to the preliminary stages of the global climate negotiations will encourage other world leaders to similarly get involved. (Paragraph 79)

Overall conclusions

19.  The conclusions of this inquiry are very clear: the WGI contribution to AR5 is the best available summary of the prevailing scientific opinion on climate change currently available to policy-makers. Its conclusions are derived with a high confidence from areas of well understood science. Uncertainty remains in a small number of important areas but these are diminishing. It is important to consider all lines of evidence together when assessing climate change rather than focusing on particular aspects of the report. The overall thrust and conclusions of the report are widely supported in the scientific community and summaries are presented in a way that is persuasive to the lay reader. (Paragraph 80)

20.  The size and scale of the report reflects the huge effort by the international climate science community, who volunteer their time and expertise. We can now be more confident than ever that human activity is the dominant cause of the warming witnessed in the latter half of the 20th Century. The most significant human impact is through the release of carbon dioxide, which is predicted to continue to cause warming in the coming decades and centuries. (Paragraph 81)

21.  The IPCC has updated its processes. The WGI contribution to AR5 is the most exhaustive and heavily scrutinised Assessment Report to-date. Tightened review processes ensure that the report has been compiled to the highest standards of scholarship; a remarkable feat given the size of the operation. The authority of the reports comes not from the process and procedure, but from the evidence itself, the thousands of peer-reviewed academic papers that form a clear and unambiguous picture of the state of the climate. Collectively, this evidence reveals a pattern of expanding observations, increasing computational ability and improving understanding across the climate system. There are, as there ever will be, uncertainties in the science, but these uncertainties do not blur the overwhelmingly clear picture of a climate system changing as a result of human influence. The report offers an excellent vantage point from which the scientific community can reflect on the state of climate science, and develop research strategies for the future. (Paragraph 82)

22.  The implications of the report for policy-makers in the UK are simple: there is no scientific basis for downgrading the UK's ambition to reduce greenhouse gas emissions. It is imperative that this message is also understood by the international community. The Government must renew its commitment to achieve a global deal on climate change. (Paragraph 83)

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Prepared 29 July 2014