Written evidence submitted by Bob Ward and Naomi Hicks, Grantham Research Institute on Climate Change and the Environment (IPC0051)

The Centre for Climate Change Economics and Policy (CCCEP) was established in 2008 to advance public and private action on climate change through rigorous, innovative research. The Centre is hosted jointly by the University of Leeds and the London School of Economics and Political Science. It is funded by the UK Economic and Social Research Council and Munich Re. More information about the Centre for Climate Change Economics and Policy can be found at: http://www.cccep.ac.uk

The Grantham Research Institute on Climate Change and the Environment was established in 2008 at the London School of Economics and Political Science. The Institute brings together international expertise on economics, as well as finance, geography, the environment, international development and political economy to establish a world-leading centre for policy-relevant research, teaching and training in climate change and the environment. It is funded by the Grantham Foundation for the Protection of the Environment, which also funds the Grantham Institute for Climate Change at Imperial College London. More information about the Grantham Research Institute can be found at: http://www.lse.ac.uk/grantham/

This policy paper is intended to inform decision-makers in the public, private and third sectors. It has been reviewed by at least one internal referee before publication. The views expressed in this paper represent those of the author(s) and do not necessarily represent those of the host institutions or funders.
Introduction

The Grantham Research Institute on Climate Change and the Environment (http://www.lse.ac.uk/grantham) and the Centre for Climate Change Economics and Policy (http://www.cccep.ac.uk) welcome the opportunity to respond to this call for evidence by the Energy and Climate Change Committee on the “IPCC 5th Assessment Review”.

This response draws on a number of Grantham Research Institute publications, including ‘Recent and future changes in the global and UK climate’ by Bob Ward and Naomi Hicks, and a policy briefing note on ‘The UK Climate Change Act’ by Bob Ward, Samuela Bassi and Dimitri Zenghelis of the Grantham Research Institute, alongside expert reports from a number of relevant organisations including the Committee on Climate Change and the Met Office.

Response to select questions

Q1. How robust are the conclusions in the AR5 Physical Science Basis report? Have the IPCC adequately addresses criticisms of previous reports? How much scope is there to question the report’s conclusions?

1. We note that, at the time of the Select Committee’s inquiry, the IPCC has only published a version of working group I’s contribution to the Fifth Assessment Report that has not been fully copy edited. Although the main findings of the report are unlikely to be different in the final version of the report, which is due for publication in January 2014, there may be some small but significant changes to the text, for instance with respect to carbon emissions budgets.

2. Working group I’s contribution to the Fifth Assessment Report is the most comprehensive review of the evidence for the physical science basis of climate change that has ever been written. It has been prepared by 259 scientific experts from universities and research institutes in 39 countries, who have reviewed all of the available evidence and research, including thousands of scientific papers. More than 9000 individual scientific papers are cited within the report. It is also one of the most rigorously reviewed scientific documents in history, with more than 50,000 comments made during a review process for earlier drafts that was made open to all experts around the world. The report has been written for the 195 member governments of the IPCC, and represents the most authoritative assessment of the state of knowledge about the physical science basis of climate change. It should also inform decision-making at local, regional, national and international level.

3. While working group I’s contribution to the IPCC Fifth Assessment Report shows increases in knowledge and understanding about the physical science basis for climate change since the publication in 2007 of the Fourth Assessment Report, the fundamental conclusions are the same: the Earth is warming primarily due to human activities, and there is a high likelihood of a rise in global average surface temperature of much more than 2˚C, and other very significant changes in the global climate, by the end of this century if annual emissions of greenhouse gases are not sharply reduced.

4. The contribution of working group I of the Fifth Assessment Report is the most authoritative report on the physical science basis of climate change that has ever been published. However, in some minor respects, it is already out of date by virtue of the fact that no papers that were accepted after 15 March 2013 for publication have been considered. This is particularly important, for instance, in relation to the so-called recent slowdown in the rise of global average surface temperature.

5. It should also be noted that the contribution of working group I to previous IPCC assessment reports may have under-estimated the pace at which climate change is occurring. Brysse et al. (2012) concluded that “at least some of the key attributes of global warming from increased atmospheric greenhouse gases have been under-predicted, particularly in IPCC assessments of the physical science, by Working Group I”.

6. It is a matter of some concern that the contribution of working group I to the Fifth Assessment Report intentionally omitted any explicit consideration of the overall consequences of a rise in global average surface temperature of more than 2˚C, which all governments have agreed should be avoided. This omission is perhaps the biggest shortcoming of working group I’s contribution to the IPCC Fifth Assessment Report.

7. Following the discovery in 2010 of a small but significant mistake in the contribution of working group II to the Fourth Assessment Report, the IPCC invited the InterAcademy Council (IAC) to review its processes and procedures The report of the IAC’s review, published in 2010, did not make any specific criticisms of the contribution of working group I, but made a number of recommendations for improving the preparation of assessment reports. Many of these recommendations were implemented during the compilation of working group I’s contribution to the Fifth Assessment Report.

8. The IPCC sought to allow any interested individuals or organisations to participate in the review of early drafts of working group I’s contribution, including a number of so-called climate change ‘sceptics’. One of these ‘sceptics’, Alex Rawls, published a draft of working group I’s contribution, in clear breach of the agreement undertaken by all reviewers, and attempted to misrepresent its contents (see Ward, 2012). The other contributions to the Fifth Assessment Report have also suffered similar breaches in what appears to be a concerted effort by climate change ‘sceptics’ to subvert and undermine the IPCC process.

9. There was also a co-ordinated effort by the Global Warming Policy Foundation and its supporters to mislead the public and policy-makers through inaccurate articles criticising the contribution of working group I after the Summary for Policymakers was published on 27 September. Some of the most blatant efforts are described in Ward (2013a). We note that possibly the most egregious article was produced by Rt Hon Peter Lilley MP, who is a member of the Select Committee and Vice-Chairman of Tethys Petroleum, for ‘City A.M.’ (Ward 2013b). Mr Lilley not only misrepresented the content of the Summary for Policymakers, but also provided a false portrayal of the IPCC and its processes.

Q2. To what extent does AR5 reflect the range of views among climate scientists?

10. There is a clear scientific consensus that the Earth is warming due to human activities, such as burning fossil fuels and deforestation. There are four main ways in which this consensus manifests itself (Ward & Hicks, 2013). First, the 259 authors of the contribution of IPCC working group I to the Fifth Assessment Report have assessed all of the available research and evidence and concluded that it is 95 per cent probable that most of the warming since 1950 is due to human activities. Second, analyses of peer-reviewed journal papers (e.g. Oreskes, 2004; Powell, 2012; Cook et al., 2013) show that less than 1 per cent disagree that human activities are the major contributor to climate change. Third, surveys (e.g. Doran & Zimmerman, 2009) show that more than 97 per cent of climate researchers who are publishing scientific papers agree that human activity is a significant contributor to rising global average temperature. Fourth, all of the world’s major scientific organisations, including national academies of science such as the Royal Society, agree that human activities are the major contributor to recent climate change.

Q4. 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?

11. The contribution of working group I to the Fifth Assessment Report, like its contribution to the Fourth Assessment Report, combines quantified levels of confidence with probability levels, and qualifies scientific statements with a level of likelihood – ranging from “virtually certain” to “exceptionally unlikely” - with associated percentage values. Yet, these expressions of likelihood, when cited without the associated percentage values, may not be interpreted in the same way by different individuals (see Budescu et al., 2009).

12. Framing climate change in terms of uncertainties rather than risks may create an obstacle to informed decision-making about climate change mitigation, as it might lead to a misinterpretation that there is no disadvantage in delaying until further certainty is attained. Painter (2013) suggested that an argument in favour of using the language of risk is that “it shifts public debate away from the idea that decisions should be delayed until conclusive proof or absolute certainty is obtained (a criterion that may never be satisfied)”.

13. Smith and Stern (2011) discuss the importance of scientists providing information about uncertainty, particularly of possible future climate change, in a way that promotes a better understanding by policy-makers of the risks.

Q6. Has AR5 sufficiently explained the reasons behind the widely reported hiatus in the global surface temperature record?

14. There has been a campaign by climate change ‘sceptics’ to mislead the public, journalists and policy-makers about the significance of the lower rate of increase in global average surface temperature since 1998 compared with the long-term warming rate since 1951. IPCC working group I was forced to respond to this campaign by addressing the issue explicitly in its contribution to the Fifth Assessment Report. It attributed the lower rate of warming since 1998 mainly to the impact of short-term natural factors that mask the warming effect of greenhouse gases, such as an increase in the amount of heat absorbed by the deeper oceans compared with the surface, an increase in the amount of volcanic particles in the atmosphere which block out some sunlight and cause cooling, and a cyclical reduction in the amount of radiation from the sun.

15. The contribution of working group I only considered research papers that were accepted before 15 March 2013 for publication. Since that date, new papers have been published which have added to the knowledge and understanding of the apparent lower rate of warming since 1998. For instance, a paper by Cowtan and Way, published in November 2013, concluded that the Met Office’s HadCRUT4 record of global average surface temperature has significantly underestimated the rate of warming since 1997.

16. It is important to consider the lower rate of warming since 1998 within the context of the longer record of global average temperature. There are many other such temporary periods of higher and lower rates of warming, and even of cooling, within the temperature record. For instance, the linear trend in average annual temperature for the 43-year period between 1970 and 2012, as recorded in the Met Office’s HadCRUT4 dataset, is +0.165°C per decade, but there are shorter 15-year periods of lower warming rates, such as 0.098°C per decade between 1979 and 1993, and 0.044°C per decade between 1998 and 2012 (Ward and Hicks, 2013).

Annual global average surface temperature 1970-2012

Source: Met Office HadCrut4 dataset, as plotted in Ward and Hicks (2013).

Q7. Do the AR5 Physical Science Basis report’s conclusions strengthen or weaken the economic case for action to prevent dangerous climate change?

17. Working group I’s contribution to the Fifth Assessment Report does not offer an assessment of the economic impacts of climate change, which will be considered in the contribution of working group II, due for publication in 2014. However, working group I does indicate both that both atmospheric concentrations of carbon dioxide and other greenhouse gases, and some of the physical impacts of climate change, such as the reduction in the area of Arctic sea ice, have increased since the publication of the IPCC Fourth Assessment Report in 2007.

18. Stern (2013) warns that many analyses significantly under-estimate the potential economic consequences of unmanaged climate change because of their reliance on the outputs of models, including those assessed in working group I’s contribution to the Fifth Assessment Report, which omit some of the largest risks. Stern (2013) states: “Scientists describe the scale of the risks from unmanaged climate change as potentially immense. However, the scientific models, because they omit key factors that are hard to capture precisely, appear to substantially underestimate these risks. Many economic models add further gross underassessment of risk because the assumptions built into the economic modelling on growth, damages and risks, come close to assuming directly that the impacts and costs will be modest and close to excluding the possibility of catastrophic outcomes. A new generation of models is needed in all three of climate science, impact and economics with a still stronger focus on lives and livelihoods, including the risks of large-scale migration and conflicts.”

Q8. What implications do the IPCC’s conclusions in the AR5 Physical Science Basis report have for policy-making both nationally and internationally?

19. Since the publication of the IPCC Fourth Assessment Report, governments have agreed that global emissions of greenhouse gases should be reduced urgently in order to hold the increase in global average temperature below 2°C, and perhaps below 1.5˚C, to limit the risks of dangerous climate change. In addition, Parliament passed the Climate Change Act in 2008, requiring the UK to reduce its greenhouse gas emissions by at least 80 per cent by 2050, compared with 1990. The UK 2050 emissions target was set on the basis of interim advice from members of the Committee on Climate Change (Turner, 2008), who indicated that it would be consistent with the task of reducing global annual emissions of greenhouse gases covered by the Kyoto Protocol, to about 20 billion tonnes of carbon-dioxide-equivalent by 2050, in line with the goal of limiting global warming to no more than 2°C by 2100, and creating a low probability of warming of 4°C.

20. Although working group I’s contribution to the Fifth Assessment Report omits an explicit consideration of the scientific basis for the 2˚C threshold, it does point out, for instance, that during the last Ice Age interglacial period, which ended about 116,000 years ago, global mean surface temperature was at least 2°C warmer than its late 19th century level, global sea levels were about 5 to 10 metres higher than today, and the Greenland and Antarctic Ice Sheets were much smaller. This shows that there are significant risks of very serious changes in the climate, even from global warming of 2˚C, which would have severe social and economic consequences for human populations around the world.

21. Working group I’s contribution to the Fifth Assessment Report, for the first time in the IPCC’s history, concludes that to have at least a 50 per cent chance of avoiding warming of more than 2°C above pre-industrial level, the total cumulative amount of carbon dioxide that is emitted into the atmosphere by human activities must be less than about 4440 billion tonnes (equivalent to about 1210 billion tonnes of carbon), or about 3010 billion tonnes when other greenhouse gases and aerosol particles from human activities are taken into account. The amount of carbon dioxide that was emitted from the late 19th century up to 2011 was between 1630 and 2150 billion tonnes (equivalent to 445 to 585 billion tonnes of carbon), leaving a remaining budget of between about 860 and 1380 billion tonnes (equivalent to 235 to 375 billion tonnes of carbon) for carbon dioxide and all othecr emissions from human activities.

Q12. What relevance to the IPCC’s conclusions have in respect of the review of the fourth Carbon Budget?

22. The Committee on Climate Change (2013) has comprehensively assessed this issue. It stated: “Accounting for the latest evidence, our climate objective implies global emissions pathways similar to those we used previously to guide the UK’s 2050 target and fourth carbon budget”. However, it also added: “Our pathways have larger cumulative CO2 emissions than the cap suggested by IPCC AR5 for a 50% probability of remaining below 2°C. This underlines that our pathways should be viewed as a minimum level of effort.”

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December 2013