climate-change--a-risk-assessment-v9-spreads

16 CLIMATE CHANGE: A RISK ASSESSMENT CLIMATE CHANGE: A RISK ASSESSMENT17Small changes in global temperature correspond to large changes in the global climate. If the world werefive degrees cooler than it is now, we would be in an ice age, last experienced some ten thousand yearsago, before the dawn of human civilization. Five degrees warmer, and we would be in a climate of heat lastexperienced by this planet more than ten million years ago, long before the beginning of human existence.That climate five degrees warmer, or more, is a very real possibility. It could occur within the lifetimes ofchildren alive today. Decisions we take now will affect its likelihood, and will continue to influence the climatefor thousands of years and hundreds of human generations into the future.Why do we need a risk assessment?Our starting point is that we have an interest in understanding what the consequences of our decisionsmight be. When the consequences could be so far-reaching in space and in time, we have an interest inunderstanding them as fully as possible.A risk is something bad that might happen. A risk assessment asks the questions: ‘What might happen?’,‘How bad would that be?’ and ‘How likely is that?’ The answers to these questions can inform decisions abouthow to respond.Climate change fits the definition of a risk (more academically described as ‘the effect of uncertainty onobjectives’, 6 or ‘an uncertain, generally adverse consequence of an event or activity with respect to somethingthat humans value’ 7 ), because it is likely to affect human interests in a negative way, and because many ofits consequences are uncertain. We know that adding energy to the Earth system will warm it up, raisingtemperatures, melting ice, and raising sea levels. But we do not know how fast or how far the climate willwarm, and we cannot predict accurately the multitude of associated changes that will take place. The answerto the question ‘how bad could it be?’ is far from obvious.Limiting climate change will take some effort. Although many of the policies that would reduce greenhousegas emissions could also be good for public health, quality of life, and economic growth, 8 they will notnecessarily be easy to put in place. They will require the investment of both political and financial capital.Governments and societies will have to decide how much effort they are prepared to make, and how toprioritize this issue in relation to their other objectives. An assessment of the risks will be a necessary basisfor judging what would be a proportionate response.It is sometimes argued that a full assessment of the risks of climate change would be counterproductive,because the risks may be so large and the solutions so difficult that people will be overwhelmed with afeeling of helplessness, and will look the other way. In some cases, this may be true. The anthropologist JaredDiamond, in addressing the question: ‘Why do some societies make disastrous decisions?’, writes:…consider a narrow river valley below a high dam, such that if the dam burst, theresulting flood of water would drown people for a considerable distance downstream.When attitude pollsters ask people downstream of the dam how concerned theyare about the dam’s bursting, it’s not surprising that fear of a dam burst is lowestfar downstream, and increases among residents increasingly close to the dam.Surprisingly, though, after you get just a few miles below the dam, where fear of thedam’s breaking is found to be highest, concern then falls off to zero as you approachcloser to the dam! That is, the people living immediately under the dam, the onesmost certain to be drowned in a dam burst, profess unconcern. That’s because ofpsychological denial: the only way of preserving one’s sanity while looking up everyday at the dam is to deny the possibility that it could burst. Although psychologicaldenial is a phenomenon well established in individual psychology, it seems likely toapply to group psychology as well. 9This report does not pretend to give all the answers. Its purpose is to be illustrative: to present a newframework for a climate change risk assessment, and to put forward our best – in some cases rough– estimates of what the findings of such an assessment might be. We hope that these findings will bechallenged, updated, and improved. It is less important that readers should agree with us, than that theyshould understand why we have asked the questions that we have.We have ended with some thoughts on the question of risk management. A risk assessment is a way to betterunderstand a problem, not a guide to solving it, and so this is a small part of our report. We provide a fewindividual perspectives on how our national and global responses to climate change could be made moreeffective, in proportion to the scale of the risk, simply because we would not wish to leave readers with theimpression that the situation is hopeless. That, we believe, is far from the case.Endnotes1. Hansen, J.E. and Sato, M. (2012). Climate Sensitivity Estimated from Earth’s Climate History. Available at http://www.columbia.edu/~jeh1/mailings/2012/20120508_ClimateSensitivity.pdf2. Figure by Jeremy Shakun, data from Lüthi et al., 2008 and Jouzel et al., 2007. Source: Figure 3, (2014). ClimateChange: Evidence and Causes. National Academy of Sciences, The Royal Society. https://nas-sites.org/americasclimatechoices/more-resources-on-climate-change/climate-change-evidence-and-causes/climatechange-evidence-and-causes-figure-gallery/3. Figure 14.1 from Young, O.R. and Steffen, W. (2009). ‘The Earth System: Sustaining Planetary Life-SupportSystems’. From Folke, C., Kofinas, G. P. and Chapin, F.S. (eds.) (2009). Principles of Ecosystem Stewardship.Springer New York. pp 295-315. http://www.cs.toronto.edu/~sme/PMU199-climate-computing/pmu199-2012F/notes/Discovery_of_Global_Warming.html4. Source: FigBox 3.1-1 from Rhein, M., S.R. Rintoul, S. Aoki, E. Campos, D. Chambers, R.A. Feely, S. Gulev, G.C.Johnson, S.A. Josey, A. Kostianoy, C. Mauritzen, D. Roemmich, L.D. Talley and F. Wang (2013). ‘Observations:Ocean’. Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the FifthAssessment Report of the Intergovernmental Panel on Climate Change [Stocker, T.F., D. Qin, G.-K. Plattner, M.Tignor, S.K. Allen, J. Boschung, A. Nauels, Y. Xia, V. Bex and P.M. Midgley (eds.)]. Cambridge University Press,Cambridge, United Kingdom and New York, NY, USA.5. Schellnhuber, H. J. (2013). ‘Avoiding the unmanageable, managing the unavoidable’. From Chatham Houseevent on ‘Delivering Concrete Climate Change Action’. Available ay http://www.chathamhouse.org/sites/files/chathamhouse/home/chatham/public_html/sites/default/files/0900%20John%20Schellnhuber.pdf6. International Organization for Standardization definition7. International Risk Governance Council (2012). An Introduction to the IRGC Risk Governance Framework.Available at http://www.irgc.org/wp-content/uploads/2015/04/An_introduction_to_the_IRGC_Risk_Governance_Framework_final_v2012.pdf8. See The New Climate Economy online report, available at: http://newclimateeconomy.report/9. Diamond, J. (2011) ‘Collapse – How Societies Choose to Fail or Survive’. Penguin Books, p436.10. As quoted in ‘The New Nuclear Age’. The Economist, 6 March 2015.Our premise for writing this risk assessment is that we can all choose whether or not to look up at the dam.Governments can choose either to ignore it, or to send their best experts to inspect it closely. We have takenthe view that it is better to be well informed than not. As the American nuclear strategist Albert Wohlstetterwrote during the Cold War, “We must contemplate some extremely unpleasant possibilities, just becausewe want to avoid them.” 10