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Keywords:

  • climate change;
  • projections;
  • risk assessment;
  • stakeholders;
  • uncertainty

Abstract

  1. Top of page
  2. Abstract
  3. Introduction
  4. Design and uptake of UKCP09
  5. Working with probabilistic projections
  6. Future priorities
  7. Concluding remarks
  8. Acknowledgement
  9. References

The 2008 Climate Change Act and ‘adaptation reporting power’ afforded to the UK Government have generated demand for information on future climate risks. The UK Climate Projections 2009 (UKCP09) are the latest generation of national climate change scenarios. This Commentary reflects on the enduring scientific and political contribution of UKCP09 as evidenced by academic literature, adaptation reports and media perspectives. It is contested that the more explicit treatment of uncertainty by the UKCP09 projections compared with the predecessor (UKCIP02) was a significant step forward. User unfamiliarity with the probabilistic format can be managed through support and guidance, so the complexity of UKCP09 need not be limiting. Some may question the value added by climate modelling (and downscaling) to adaptation planning given present fiscal retrenchment. However, the benefit of UKCP09 could be greater than expected, especially if new ways of responding to climate uncertainty emerge.


Introduction

  1. Top of page
  2. Abstract
  3. Introduction
  4. Design and uptake of UKCP09
  5. Working with probabilistic projections
  6. Future priorities
  7. Concluding remarks
  8. Acknowledgement
  9. References

Extreme weather in the UK in 2012 reignited calls for information about future climate risks to support adaptation and mitigation decisions. This Commentary reflects on the extent to which the legacy of the UK Climate Projections 2009 (UKCP09) is meeting such demands.

Design and uptake of UKCP09

  1. Top of page
  2. Abstract
  3. Introduction
  4. Design and uptake of UKCP09
  5. Working with probabilistic projections
  6. Future priorities
  7. Concluding remarks
  8. Acknowledgement
  9. References

UKCP09 made explicit three aspects of uncertainty in future climate: modelling errors (parameter and structural); natural climate variability; and greenhouse gas emissions. According to Murphy et al. the scientists ‘developed a new approach aimed at sampling [these] key uncertainties systematically’ (2009, 49). Instead of a few scenarios from one model as in UKCIP02, UKCP09 presented probabilistic projections for land and ocean surface variables with likelihoods inferred from over 300 model runs. UKCP09 also provided observed climate datasets, marine projections and a weather generator (Street et al. 2009).

The new approach divided opinion. Myles Allen, Oxford University, argued that the method was ‘untested’ and should have offered better grounds for comparison (Ghosh 2009); conversely the developers describe UKCP09 as ‘appropriate for informing decisions on adaptation to long-term climate change’ (Murphy et al. 2009, 44). However, because the UK's first Climate Change Risk Assessment stipulated use of UKCP09, it is difficult to separate the political from the corporate, and business behaviour becomes an indicator of UKCP09's political legacy. For example, Ofwat (2008, 24) acknowledged that some water companies will need to make ‘significant investment’ to manage supply–demand imbalances under climate change, but would not accept expenditure plans until UKCP09 became available. Ofwat (2008, 8) justified this stance on the basis that UKCP09 would produce a ‘step change’ in knowledge. Consequently, UKCP09 indirectly affected UK residents, as company investment plans influence water bills.

Working with probabilistic projections

  1. Top of page
  2. Abstract
  3. Introduction
  4. Design and uptake of UKCP09
  5. Working with probabilistic projections
  6. Future priorities
  7. Concluding remarks
  8. Acknowledgement
  9. References

Perhaps the most controversial aspect of UKCP09 was the switch to probabilistic information. This had two implications. First, moving from four scenarios in UKCIP02 to an ensemble of projections created difficulty for some users, as evidenced by the adaptation reports of Transport Scotland (Jacobs Engineering 2011) and Hertfordshire County Council (AEA 2010). Conversely, EDF Energy (2011) and Scottish Natural Heritage (Land Use Consultants 2011) show how probabilistic projections can be used in decision making. Tang and Dessai (2012) note trade-offs whereby probabilistic projections better capture uncertainty and improve confidence in the data, but at the expense of usability. Although UKCP09 projections cannot be spatially combined, this does not affect all users and for some, training in handling probabilistic data may counter foregone saliency.

Second, UKCP09 shows that the future cannot be predicted precisely. Leonard Smith, London School of Economics, claims that the uncertainty of probabilistic projections renders them of little use (Ghosh 2009), whereas others believe that UKCP09 ‘represents a significant step forward and facilitates consideration of climate change adaptation in a risk framework’ (Street et al. 2009, 227). In a Newsnight interview, Hilary Benn (June 2009) defended UKCP09 by observing ‘it comes with caveats, it comes with health warnings, and we have to be honest about the uncertainty … people then have to assess, for themselves, what degree of risk are they prepared to live with and plan accordingly’.

While UKCP09 may fulfil calls for honesty about uncertainty in future climate (Patt and Dessai 2005), it could also be argued that probabilistic terminology is potentially misleading. According to Hall (2007), decisionmakers need to be aware that probabilistic projections are based on relatively few models, which themselves simplify reality. This means that true uncertainty is likely to be underestimated. Beven (2011) is concerned that probabilistic projections might be perceived as the probability of an outcome in reality, instead of the probability of an outcome in a model world.

Two more points emerge. First, UKCP09 lends support for a more robust approach to adaptation with greater focus on flexible options and appraisal, rather than on the climate model projections themselves (Wilby and Dessai 2010). If this change in perspective leads to smarter use of climate projections in adaptation planning, UKCP09 could have wider ramifications for scientific and user communities alike.

Second, had reliance on a few deterministic scenarios continued (rather than planning for a range of conditions), inappropriate adaptations could have emerged (Harris et al. 2012). Hence, there may be a ‘return’ on the £11 million invested in UKCP09 in terms of avoidance of costly maladaptation. This benefit is lessened by the fact that some users made little practical change between UKCIP02 and UKCP09 (e.g. Anglian Water 2011; Jacobs Engineering 2011; Land Use Consultants 2011). Others assert that sole reliance on UKCIP02 or UKCP09 for planning does not hold for all sectors (Arnell 2011).

Future priorities

  1. Top of page
  2. Abstract
  3. Introduction
  4. Design and uptake of UKCP09
  5. Working with probabilistic projections
  6. Future priorities
  7. Concluding remarks
  8. Acknowledgement
  9. References

Divergent views about the treatment of uncertainty could shape the future of UK climate services. Some stress the need for climate information (and communication of uncertainty) to be tailored to the needs of decisionmakers (Tang and Dessai 2012). This suggests that efforts to translate projections into sector-specific climate change factors should be a priority.

The author's experience in using Environment Agency (2011) climate change factors (derived from UKCP09) for a flood damage study in York supports this view (Kelly et al. 2012). Applying change factors to modelled river flows was straightforward and demonstrated how uncertainty in future flood risk at the catchment scale can be rapidly appraised. Moreover, the UKCP09 web-interface affords undergraduates an opportunity to gain a more ‘tangible’ impression of the challenges in applying climate model information to adaptation planning. Hands-on engagement with UKCP09 also provides acquaintance with data extraction and visualisation, as well as deeper appreciation of the range of scientific uncertainties in the climate outlook.

Others concentrate on the uncertainty in climate projections, and advocate further investment in process understanding and model development (Kay and Jones 2012). In this case, models are being used as laboratories for exploring hypotheses about the behaviour of the climate system. Another community asserts that highly uncertain outputs from climate models and downscaling should not drive adaptation planning in deterministic ways. Beven claims models are not yet ‘fit for purpose in assessing the impacts of climate change’ (2012, 308), and that adaptation costs can be determined without them. Betz (2010) presents the ‘possibilistic’ methodology, which uses climate models only to create ideas of what could happen.

Concluding remarks

  1. Top of page
  2. Abstract
  3. Introduction
  4. Design and uptake of UKCP09
  5. Working with probabilistic projections
  6. Future priorities
  7. Concluding remarks
  8. Acknowledgement
  9. References

UKCP09 offers a new methodology to the scientific community with more rigorous treatment of climate uncertainty but reduced saliency for some users. Given a less receptive public attitude to climate change in an age of austerity, politicians may struggle to justify major expenditure on another generation of UK climate projections. Meanwhile, there is debate within the scientific community about the value added by regional climate change scenarios (Kerr 2013). These factors could delay commissioning of new projections and thereby extend the life of UKCP09. Benefits from low regret adaptations may continue to accrue and, given that the additional public funding dedicated to UKCP09 was less than 18 pence per citizen, the societal value and legacy of UKCP09 could far outweigh the initial investment and expectations.

Acknowledgement

  1. Top of page
  2. Abstract
  3. Introduction
  4. Design and uptake of UKCP09
  5. Working with probabilistic projections
  6. Future priorities
  7. Concluding remarks
  8. Acknowledgement
  9. References

Thanks to Professor Robert Wilby for editorial suggestions. Thanks also to the anonymous reviewer for their constructive feedback.

References

  1. Top of page
  2. Abstract
  3. Introduction
  4. Design and uptake of UKCP09
  5. Working with probabilistic projections
  6. Future priorities
  7. Concluding remarks
  8. Acknowledgement
  9. References
  • AEA 2010 Hertfordshire UKCP09 headlines report. A report to Hertfordshire County Council AEA Group, Didcot
  • Anglian Water 2011 Climate change adaptation report January 2011 Anglian Water Services, Huntingdon
  • Arnell N W 2011 Incorporating climate change into water resources planning in England and Wales Journal of the American Water Resources Association 47 541549
  • Betz G 2010 What's the worst case? The methodology of possibilistic prediction Analyse and Kritik 32 87106
  • Beven K J 2011 I believe in climate change but how precautionary do we need to be in planning for the future? Hydrological Processes 25 15171520
  • Beven K J 2012 Rainfall-runoff modelling: the primer Wiley-Blackwell, Oxford
  • EDF Energy 2011 Report on adaptation under the Climate Change Act 2008 EDF Energy Adaptation Report 2011 EDF Energy, London
  • Environment Agency 2011 Adapting to climate change: advice for flood and coastal erosion risk management authorities Environment Agency, Bristol
  • Ghosh P 2009 Climate warning's error margins BBC News 18 June (http://news.bbc.co.uk/1/hi/8106513.stm) Accessed 6 March 2013
  • Hall J 2007 Probabilistic climate scenarios may misrepresent uncertainty and lead to bad adaptation decisions Hydrological Processes 21 11271129
  • Harris C N P, Quinn A D and Bridgeman J 2012 The use of probabilistic weather generator information for climate change adaptation in the UK water sector Meteorological Applications doi:10.1002/met.1335
  • Jacobs Engineering 2011 Scottish road network climate change study: UKCP09 update. A report to Transport Scotland Jacobs Engineering, London
  • Kay A L and Jones R G 2012 Comparison of the use of alternative UKCP09 products for modelling the impacts of climate change on flood frequency Climatic Change 114, 211230
  • Kelly N, Palopoli G, Philpott J, Shaw A and Thornhill C 2012 The potential damages to buildings in the City of York associated with a one in 100 years flood event under climate change scenarios Unpublished report, Loughborough University
  • Kerr R A 2013 Forecasting regional climate change flunks its first test Science 339 638
  • Land Use Consultants 2011 An assessment of the impacts of climate change on Scottish landscapes and their contribution to quality of life: Phase 1 – Final report. A report to Scottish Natural Heritage Land Use Consultants, London
  • Murphy J M, Sexton D M H, Jenkins G J, Boorman P M, Booth B B B, Brown C C, Clark R T, Collins M, Harris G R, Kendon E J, Betts R A, Brown S J, Howard T P, Humphrey K A, McCarthy M P, McDonald R E, Stephens A, Wallace C, Warren R, Wilby R and Wood R A 2009 UK climate projections science report: climate change projections Met Office Hadley Centre, Exeter
  • Ofwat 2008 Capital expenditure for 2010–15: Ofwat's view on companies’ draft business plans Ofwat, Birmingham
  • Patt A and Dessai S 2005 Communicating uncertainty: lessons learned and suggestions for climate change assessment. Comptes Rendus Geoscience 337, 425441
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  • Wilby R and Dessai S 2010 Robust adaptation to climate change Weather 65 180185