Written evidence submitted by the Natural Environment Research Council (IPC0036)

 

 

Introduction

 

  1. The Natural Environment Research Council (NERC) is one of the UK’s seven Research Councils.  It funds and carries out impartial scientific research in the sciences of the environment and trains the next generation of independent environmental scientists.  Details of NERC’s research centres and research programmes are available at www.nerc.ac.uk.

 

  1. This response is based on input from the British Antarctic Survey (BAS), the Centre for Ecology and Hydrology (CEH), the National Centre for Atmospheric Science (NCAS), the National Centre for Earth Observation (NCEO) and the National Oceanography Centre (NOC), each of which is a research centre operated by NERC.  Taken together, these centres employ around 730 research scientists, many of whom are engaged in climate-related research, including several Intergovernmental Panel on Climate Change Working Group 1 (IPCC WG1) Lead and Contributing Authors.  The responses to the Committee’s questions below are based on the views and experience of leading climate scientists from these Centres.  We have restricted ourselves to answering those questions that focus on the science presented in the IPCC 5th Assessment Report (AR5).

 

Question 1:  How robust are the conclusions in the AR5 Physical Science Basis report? How much scope is there to question of the report’s conclusions?

 

  1. We are convinced that the headline conclusions of the report (those presented in brown boxes in the Summary for Policymakers) are robust. All findings are presented with appropriate assessed confidence levels.

 

Question 2:  Have the IPCC adequately addressed criticisms of previous reports?

 

  1. In 2010, following criticism of the 4th IPCC Assessment Report (AR4), the UN and the IPCC chair commissioned a review of the IPCC’s processes and procedures by the Inter-Academy Council.  This report (http://reviewipcc.interacademycouncil.net ) found that “the IPCC assessment process has been successful overall” but also made recommendations on changes to the IPCC’s governance, review process and the way in which uncertainty was communicated.  The IPCC implemented many of the recommendations of the Inter-Academy Council review before AR5 was produced.  We believe that, in its response to this review, the IPCC has adequately responded to criticisms of AR4 and earlier reports.

 

 

Question 3:  To what extent does AR5 reflect the range of views among climate scientists?

 

  1. Scientists at BAS, CEH, NCAS, NCEO and NOC collaborate with a wide sector of the climate science community, both in the UK and internationally.  From this perspective, we are able to say that the WG1 contribution to the AR5 does reflect the views of the mainstream climate science community.  A large number of papers written by BAS, CEH, NCAS, NCEO and NOC scientists are cited in the report.

 

Question 4:  Can any of the areas of the science now be considered settled as a result of AR5’s publication, if so which?  What areas need further effort to reduce the levels of uncertainty?

 

  1. The report states unequivocally that the climate system has warmed, that human activity has been a significant contributor to this warming, and that continued emissions of greenhouse gases will cause further warming and changes in all components of the climate system.  Global mean temperatures and sea level rose over the last century by an amount exceeding the amplitude of shorter-term variability.  However, there is still substantial uncertainty about the impacts of this warming at a regional scale (e.g. how will the frequency of extreme weather events in the UK change?), decadal variability, and the response of other elements of the climate system (e.g. the hydrological and biogeochemical cycles, global ocean circulation, polar ice sheets and sea ice) to warming.  Research now needs to focus on these areas of remaining uncertainty.

 

Question 5:  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?

 

  1. In producing AR5, the IPCC has been careful to use consistent and well-defined language to communicate uncertainty (see http://www.ipcc.ch/pdf/supporting-material/uncertainty-guidance-note.pdf).  However, users of the report may not all fully understand the concept of scientific uncertainty.  Scientists, science communicators and end users (e.g. business and policy makers) need to work together to develop a shared taxonomy of uncertainty that will enable the results of AR5 to inform business, economic and policy decisions.  WG1 generally uses likelihood language in preference to risk language because risk assessments typically involve consideration not only of likelihood but also of impacts, and may therefore involve value judgements beyond the scope of physical science.

 

Question 6:  Does the AR5 address the reliability of climate models?

 

  1. Yes, this is directly addressed in Chapter 9 of AR5. This chapter notes that models now robustly represent many aspects of the climate system (e.g. multi-decade trends in continental-scale surface temperature) but that effort is still required to improve model performance (e.g. representation of clouds and precipitation).

 

Question 7:  Has AR5 sufficiently explained the reasons behind the widely reported hiatus in the global surface temperature record?

 

  1. This topic is specifically addressed in Chapter 9 of AR5, which concludes that there is medium confidence (as defined in the document cited in paragraph 8) that the hiatus is substantially a result of natural internal variability of the climate system, which includes a possible redistribution of heat within the ocean, combined with a reduced trend in external radiative forcing.  This assessment implies that differences between observed and modelled temperature trends over 1998-2012 do not imply a lack of robustness in model projections.  Research papers published since AR5 was released add further support to this viewpoint.  Further understanding of the hiatus is a subject of ongoing research, e.g. to better quantify the role of heat absorbed into the deep ocean.

 

Question 8:  Do the AR5 Physical Science Basis report’s conclusions strengthen or weaken the economic case for action to prevent dangerous climate change?

 

  1. The major conclusions of the WG1 contribution to AR5 are in line with, and often stronger than, the conclusions of previous IPCC Assessment Reports.  The WG1 report presents a synthesis of current understanding of the physical drivers of climate change.  On its own, this does not tell us anything about the economic costs of climate change or mitigating measures but it is an essential starting point for calculating these costs.  While IPCC Working Groups 2 (Impacts) and 3 (Mitigation) will address economic questions to some degree in their contributions (to be published in 2014), to the AR5 there is a requirement for a continuing dialogue between climate scientists, economists and the business sector outside the IPCC process.  Indeed, there is a need to strengthen this dialogue.  The new NERC strategy (http://www.nerc.ac.uk/about/strategy/business.asp) places considerable emphasis on the importance of environmental scientists working with other groups to meet societal needs, and NERC is very much upping its game in this regard.

 

Question 9:  Is the IPCC process an effective mechanism for assessing scientific knowledge?  Or has it focussed on providing a justification for political commitment?

 

  1. We believe that the IPCC process is an effective mechanism for synthesising scientific understanding of climate change, and the reports have closely followed the IPCC’s mandate to be “policy relevant”, not “policy prescriptive”.  The scope of the science covered by IPCC Working Group 1 has grown considerably over the lifetime of the IPCC and the production of these reports places a considerable burden on the climate science community.  This issue, and the requirement to ensure the assessments are as useful as possible to policy makers, need to be addressed through continued reviewing and improvement of the process.  The long gaps between reports and consensus approach does lead to delays in being able to incorporate the very latest scientific understanding into the assessments. We are not aware of any evidence that the findings of the IPCC have been influenced by a need to justify political commitment.

 

December 2013