Written evidence submitted by the Royal Meteorological Society (IPC0029)

Description of submission

1. This submission is made on behalf of the Royal Meteorological Society (RMetS). The Royal Meteorological Society is the Learned and Professional Society for weather and climate. The Society is a registered charity. Its affairs are run by a Council of Trustees. Council comprises a total of nineteen Officers and Ordinary Members of Council elected at the Annual General Meeting. 

2. The submission was drafted by the Chair of the RMetS’s Climate Science Communications Group (CSCG), incorporating comments from the CSCG members and members of Council. It has been approved by RMetS Council. A list of members of the CSCG and of Council are provided in Note 1 below.

3. The inquiry invites comments with regard to the IPCC’s fifth assessment report (AR5). Our responses refer specifically to the report of Working Group 1 (WG1).

Declaration of interest

4. Members of the CSCG and of Council who were authors of the IPCC 5th assessment report did not take part in drafting or approving this submission. For these purposes “authors of the IPCC 5th assessment report” was taken to mean Lead Authors, Contributing Lead Authors and Review Editors.

5. Declaration of interests of members of the CSCG. Those marked (*) were excluded from taking part in drafting or approving this submission:

John Mitchell (Reviewer of IPCC 5th assessment report; Lead Author in the first three
assessments and Review Editor in the 4th assessment report; involved in the policy makers summary in the first and third assessment reports and the synthesis report in the third assessment)

Ed Hawkins (Contributing author to the IPCC 5th Assessment report)

Tim Palmer* (Review Editor to the IPCC 5th Assessment report)

              Rowan Sutton* (Contributing Lead Author of IPCC 5th assessment report)

6. Declaration of interests of members of Council. Those marked (*) were excluded from taking part in drafting or approving this submission:

Joanna Haigh (Contributing author to IPCC 5th assessment report and Lead Author on
the third assessment)

David Stevenson (Contributing author to IPCC 5th assessment report)

Liz Howell* (required under BBC Editorial Guidelines to maintain impartiality and
independence within the BBC)

How robust are the conclusions in the AR5 Physical Science Basis report?

7. The conclusions of the report are graded in terms of probability and confidence. We believe this provides a clear description of the robustness of the conclusions. The most robust conclusions are indicated by high levels of likelihood and/or confidence. Conversely the least robust are assigned low likelihood/confidence.

How much scope is there to question the report’s conclusions?

8. The report draws on the published peer-reviewed literature and as such represents the current scientific understanding, with the conclusions being carefully graded in terms of likelihood/confidence, noting where appropriate the levels of uncertainty.

To what extent does AR5 reflect the range of views among climate scientists?

9. Given AR5 is a comprehensive synthesis of the published literature, our judgement is that the report accurately reflects the views of the vast majority of professional climate scientists who are actively working the field.

Can any of the areas of the science now be considered settled as a result of AR5’s publication, if so which? 

10. This depends on how one defines “settled”. In its purest interpretation, no area of science is ever settled since the scientific method always allows for new evidence to overturn previously established theories. To provide readers with an accurate assessment of the state of scientific understanding, the report qualifies many of its conclusions with levels of certainty in the form of likelihood/confidence. The report also makes some unqualified statements when justified, for example, the Summary for Policymakers states that “Each of the last three decades has been successively warmer at the surface than any preceding decade since the 1850s” and “Warming of the climate system is unequivocal”.

What areas need further effort to reduce the levels of uncertainty?

11. Scientific research is an on-going process that attempts to reduce the levels of uncertainty in all relevant areas. It is important to note that in some instances it is reasonable to anticipate that further research may reduce the range of uncertainty, whereas in others the uncertainty is a fundamental property (for example there will always be a 50% chance of tossing a “head” on an unbiased coin). There are on-going efforts to narrow the range of uncertainty, for example, in a measure of the climate response with feedbacks to a change in atmospheric carbon dioxide concentration known as the “climate sensitivity”. A key area of climate research where it is anticipated that further progress will reduce uncertainties is in the prediction of the regional detail of climate change.

How effective is AR5 and the summary for policymakers in conveying what is meant by uncertainty in scientific terms? Would a focus on risk rather than uncertainty be useful?

12. In general it is challenging to communicate the scientific meaning of the words “uncertainty” and “risk” because they differ in subtle ways from the common-uses of the words, and indeed the words are used in subtly different ways in other fields such as economics. Given this, it is always worth testing and evaluating whether statements have been interpreted as intended and exploring alternative ways of communicating. The full AR5 report including the summary for policymakers uses a standardised framework for describing “uncertainty” based around likelihood/confidence quantifiers as described in the published guidance note on the consistent treatment of uncertainties. We note that an assessment of “risk” would typically incorporate information that is beyond the scope of WG1, but within the scope of WG2 and WG3.

Does the AR5 address the reliability of climate models?

13. The Report devotes Chapter 9 to a comprehensive, balanced and realistic evaluation of climate models which is based on the published literature and draws extensively on the results of the Coupled Model Intercomparison Project Phase 5 (CMIP5). As stated in the report (Chapter 9, final draft) climate models are based on physical principles, and they reproduce many important aspects of observed climate. We agree with the report when it states that both these aspects contribute to a “confidence in the models’ suitability for their application in detection and attribution studies and for quantitative future predictions and projections”, and when it notes that “whereas weather and seasonal climate predictions can be regularly verified, climate projections spanning a century or more cannot. This is particularly the case as anthropogenic forcing is driving the climate system toward conditions not previously observed in the instrumental record, and it will always be a limitation.”

Has AR5 sufficiently explained the reasons behind the widely reported hiatus in the global surface temperature record?

14. The report summarised the scientific understanding of recent global average surface temperature change as described in the published literature up to the WG1 publication acceptance cut-off date of 15 March 2013. This outlined the factors thought most likely to have contributed to recent changes. This is an on-going and active area of research (see for example “Coverage bias in the HadCRUT4 temperature series and its impact on recent temperature trends” by Cowtan and Way in the Quarterly Journal of the Royal Meteorological Society, accepted manuscript online: 12 Nov 2013).

Do the AR5 Physical Science Basis report’s conclusions strengthen or weaken the economic case for action to prevent dangerous climate change?

15. The scientific conclusions of the WG1 report provide an evidence base for input into economic discussions. In the majority of instances, the scientific conclusions of the AR5 WG1 report are strengthened compared with previous reports in the sense that the conclusions have remained broadly similar but are now supported by more evidence. The WG1 report does not comment on the economic case for action to prevent dangerous climate change and this is outside the regime of expertise of the Royal Meteorological Society.

Is the IPCC process an effective mechanism for assessing scientific knowledge? Or has it focused on providing a justification for political commitment?

16. We believe that the IPCC process provides a comprehensive, objective, open and transparent assessment of the state of scientific knowledge. We note that the process involves a significant commitment from the scientific community with the voluntary contribution of many thousands of scientists worldwide. We argue that it is vital that this commitment acts to stimulate scientific research rather than placing a burden that may hinder scientific progress and that the IPCC process, or any modification to it, must ensure this. The IPCC reports are neutral with respect to policy, being policy-relevant but never policy-prescriptive. By endorsing the IPCC reports, governments acknowledge the authority of their scientific content.

What relevance do the IPCC’s conclusions have in respect of the review of the fourth Carbon Budget?

17. The report concluded that “Continued emissions of greenhouse gases will cause further warming and changes in all components of the climate system. Limiting climate change will require substantial and sustained reductions of greenhouse gas emissions.” It also concluded “Cumulative emissions of CO2 largely determine global mean surface warming by the late 21st century and beyond. Most aspects of climate change will persist for many centuries even if emissions of CO2 are stopped. This represents a substantial multi-century climate change commitment created by past, present and future emissions of CO2.” We suggest that both these conclusions may be of relevance to the review of the fourth Carbon Budget.

Note 1

A list of members of the CSCG and Council

CSCG members:
Dr Emily Shuckburgh (Chair)
Dr Ed Hawkins
Ian Strangeways
Prof John Mitchell
Prof Tim Palmer
Prof Rowan Sutton

Council members:
Prof Joanna Haigh (President)
Jennie Campbell
Prof Ellie Highwood
Dr David Stevenson
Rob Varley
Dr Bob Riddaway
Alan Radford
Prof David Schultz
Cdr Derek Swannick
Prof Brian Golding
Dr Geoff Jenkins
Dr Emily Shuckburgh
John Goulding
Baden Hall
Liz Howell
Shanti Majithia
Prof David Marshall
Prof Dudley Shallcross
John Hirst

December 2013