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Public understanding of solar radiationmanagementTo cite this article A M Mercer et al 2011 Environ Res Lett 6 044006

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IOP PUBLISHING ENVIRONMENTAL RESEARCH LETTERS

Environ Res Lett 6 (2011) 044006 (9pp) doi1010881748-932664044006

Public understanding of solar radiationmanagementA M Mercer1 D W Keith2 and J D Sharp3

1 Institute for Sustainable Energy Environment and Economy University of Calgary2500 University Drive NW Calgary AB T2N 1N4 Canada2 Kennedy School Harvard University 79 John F Kennedy Street CambridgeMA 02138 USA3 Energy and Materials Research Group Simon Fraser University 8888 University DriveBurnaby BC V5A 1S6 Canada

E-mail amercerucalgaryca

Received 30 May 2011Accepted for publication 3 October 2011Published 24 October 2011Online at stacksioporgERL6044006

AbstractWe report the results of the first large-scale international survey of public perception ofgeoengineering and solar radiation management (SRM) Our sample of 3105 individuals in theUnited States Canada and the United Kingdom was recruited by survey firms that administerinternet surveys to nationally representative population samples Measured familiarity washigher than expected with 8 and 45 of the population correctly defining the termsgeoengineering and climate engineering respectively There was strong support for allowing thestudy of SRM Support decreased and uncertainty rose as subjects were asked about theirsupport for using SRM immediately or to stop a climate emergency Support for SRM isassociated with optimism about scientific research a valuing of SRMrsquos benefits and a strongerbelief that SRM is natural while opposition is associated with an attitude that nature should notbe manipulated in this way The potential risks of SRM are important drivers of publicperception with the most salient being damage to the ozone layer and unknown risks SRM is anew technology and public opinions are just forming thus all reported results are sensitive tochanges in framing future information on risks and benefits and changes to context

Keywords geoengineering solar radiation management climate change public opinion publicawareness

S Online supplementary data available from stacksioporgERL6044006mmedia

1 Introduction

Until recently scientific political and public discourse onresponses to climate change has centered on two fundamentalresponse options mitigation (reducing emissions) andadaptation Deliberate large-scale engineering to reduce oroffset climate change driven by greenhouse gas emissionsrepresents a third class of options (Shepherd et al 2009)Known as geoengineering or climate engineering this thirdresponse comprises an array of techniques that can be broadlydivided into two very different approaches carbon dioxideremoval and solar radiation management (SRM) Most SRM

techniques act by increasing the albedo of the atmospherethrough methods such as the injection of sulfate aerosols intothe stratosphere where they would reflect some solar energyback to space lowering the global temperature Comparedto other response options SRM is inexpensive (Barrett 2008Blackstock et al 2009 Shepherd et al 2009 NAS 1992)and fast-acting (Caldeira and Matthews 2007 Robock et al2008) but it canmdashat bestmdashonly partially offset the impactsof increased CO2 and caries novel environmental and socialrisks (Shepherd et al 2009 Blackstock et al 2009 Keithet al 2010 Robock et al 2009 Corner and Pidgeon 2009)Risks include changes in precipitation (Ricke et al 2010) a

1748-932611044006+09$3300 copy 2011 IOP Publishing Ltd Printed in the UK1

Environ Res Lett 6 (2011) 044006 A M Mercer et al

slowing recovery of the ozone layer (Crutzen 2006 Tilmes et al2008) and reductions in political and personal motivations todecarbonize the economy (Keith 2000) SRM constitutes aglobal intervention with both benefits and risks being felt atthis scale

Discussion of SRM within the scientific literature datesback to the 1960s While major climate change assessmentreports of the 1970s and 1980s discussed its possible useas part of a broadly inclusive framing of climate change itwas largely ignored as concerns about anthropogenic climatechange gained political visibility (Keith 2000) While sporadicarticles were published over the past few decades discussionof SRM remained on the periphery of the climate debate andshrouded in taboo due to a widespread concern that publicdiscussion of SRM would lessen the incentives for politicalaction to restrain emissions (Kiehl 2006) The taboo wasbroken in 2006 when Paul Crutzen published an editorial essayurging more systematic consideration of SRM (Crutzen 2006)We speculate that the fact that Crutzen is a Nobel Laureatefor work on ozone chemistry combined with the fact thatozone depletion is a salient risk of SRM contributed to theinfluence of this paper In any case the paper triggered rapidgrowth in research and debate on SRM within academic andclimate policy communities (figure 1) Recent debate on SRMhas been marked by hearings in the US Congress and theUK Parliament the creation of various expert panels nationalresearch programs and formal resolution by the Convention onBiological Diversity

Despite this rapidly evolving dialog virtually nosystematic data exists on the publicrsquos awareness and opinionsof geoengineering A common assumption by expertsengaged on this issue is that the public is almost whollyunaware of SRM and thus cannot currently contributeto the debate meaningfully Leiserowitz added a singlequestion on geoengineering to a larger survey and foundthat only 3 of Americans could provide a correctdescription of geoengineering (Leiserowitz 2010) TheNational Environment Research Council undertook a morecomprehensive research initiative in the UK that includedboth an extended deliberative exercise with a small group ofcitizens and a small nonrepresentative survey which suggesteda similar lack of public understanding of SRM (NationalEnvironmental Research Council 2010) Spence included a setof awareness and opinion questions on geoengineering into aUK study on energy and climate and found that about 7 ofthe sample lsquoknew a fair amountrsquo about geoengineering (Spenceet al 2010) None of these studies has yet appeared in thejournal literature

While there is a lack of studies directly assessingunderstanding and awareness of geoengineering the increasein internet and printed media coverage (figure 1) suggeststhat the public is increasingly exposed to information ongeoengineering International newspapers ran 115 stories ongeoengineering in 2007ndash2010 compared with one story in theprevious six years Similar results hold for regional papers andbulletins and popular media such as Rolling Stone and PopularScience

Deployment of SRM may well reshape humankindrsquos viewof nature Given the profound implications of this technology

Figure 1 Growth in the number of publications aboutgeoengineering from three media sources internet (dashed lines)printed (solid lines) and academic (dotted line) from 2000 to 2010Counts of internet news and blogs sites were established through datespecific searches of geoengineering on Google News and GoogleBlogs EBSCO newspaper source database was used to analyzemajor international newspaper (ex The Washington Post The Times(London) The Toronto Star etc) trends and Factiva database wasused for the worldwide regional publication trends ISI Web ofKnowledge was used for academic sources All databases wereaccessed in May 2011

leading researchers have called for public dialog (Blackstockand Long 2010 Keith et al 2010 Corner and Pidgeon2009 Shepherd et al 2009 House of Commons 2010) Asmeaningful dialog is only possible if the participants havesome coherent understanding of the technology this studyaims to inform the debate about public perceptions of SRMby addressing two primary research questions

(1) How widespread is public knowledge of geoengineeringand SRM and

(2) How does the public perceive geoengineering and SRM

The following sections present the survey method theresults and a discussion of the implications of the surveyfindings

2 Methods

An extensively pretested Internet-based survey was completedby 3105 participants in Canada the United Kingdom and theUnited States between 19 November and 7 December 2010The subjects completed an 18-question survey instrumentwhich was divided into five sections (see the supportingmaterial for the full text of the survey and screen-shots ofthe survey delivery available at stacksioporgERL6044006mmedia)

(1) Baseline knowledge assessmentmdashFive Likert-scale andopen-ended questions (questions 1B and 2B) were de-signed to assess respondentsrsquo familiarity with geoengi-neering A question assessing the respondentsrsquo support for

2


the use of geoengineering was included here and repeatedin section 4 to assess the impact of the information section

(2) Indices of global warming belief and technologicaloptimismmdashtwo multi-item Likert-scale questions wereused to establish subjectsrsquo beliefs regarding globalwarming and to assess their technological optimism

(3) Technical information about SRMmdasheducational informa-tion on climate change processes how SRM may be usedto lower the global temperature and potential benefitsand risks were given in a short bullet-point informationalsection

(4) Perception of SRMmdashin this section eight multi-itemLikert-scale opinion questions were asked about SRMrsquospotential use the importance of particular risks andbenefits of SRM and the trustworthiness of varioussources of information about SRM

(5) Demographicsmdashseven standard demographics questionswere asked at the end of the survey

The majority of the questions within the survey wereasked on a four-point Likert scale with an additional optionfor lsquoI am unsurersquo While we hypothesized that awareness ofgeoengineering might be higher than generally assumed byexperts we did not expect the public to have nuanced opinionson the use and impacts of these technologies In cases such asthis where public opinion is nascent a significant proportionof the sample can be expected to have no opinion In orderto reduce the extent to which a forced choice would generatespurious opinions we elected to use a four-point Likert scalein combination with an explicit lsquoI am unsurersquo option Thisensured that mid-scale or neutral answers could not be selectedas proxies for having no opinion

All open-ended questions were coded into broad themesby a coder blind to the goal of the study In addition the open-ended definitions of geoengineering and climate engineeringQuestions 1B and 2B respectively were independentlyevaluated by two researchers in order to determine thecorrectness of each definition and establish the samplersquos initialbaseline awareness (intercoder reliability κ = 091) Tobe deemed correct an answer had to demonstrate to theresearchers that the respondent reasonably understood theconcept of geoengineering or climate engineering includingshowing evidence of at least two of the following ideas

bull Suggest an environmental state or process was beingchanged intentionally

bull Related to climate change (but not the source of climatechange) andor

bull Artificial or human-made

21 Subjects

A representative sample of adults 18 years of age and olderwas recruited for this study In the United States thesurvey was distributed through the internet-based researchfirm Knowledge Networks while in Canada and theUnited Kingdom Knowledge Networks worked with theinternet-based research firm GMI to distribute the surveyEach firm used their established polling panels to recruit

individual subject from wide socio and economic backgroundsCompletion rates were Canada 6 UK 4 and US 66The discrepancies in the rates can be attributed to the twofirmsrsquo differing approaches to survey recruitment and panelmanagement Knowledge Networks panel is composed ofparticipants who are actively recruited using random digitdialing and address-based sampling techniques The panelis managed to ensure high completion rates by limiting thefrequency of survey requests to each individual on the panelConversely GMI uses primarily online recruiting with somesupplementation from offline methods such as print marketingand recruitment at trade shows and conferences to maintain anopt-in volunteer panel This type of panel is known for lowerparticipation rates because participants are less consistentDespite the varied recruiting methodologies (which lead tovaried completion rates) both panels are maintained to ensurea diverse nationally representative sample is included in thestudy The completion rates in this study are consistent witheach panelrsquos past performance No participant knew the subjectof the survey prior to consenting to participate introducing noselection bias

The overall sample size was 3105 However 68 ofthe participants were excluded from the study because theyappeared to have used external Internet-based sources such asWikipedia to inform themselves about the survey topic Theresearchers identified distinctive words and phrases from thetop websites found by Internet searches for lsquogeoengineeringrsquoand lsquosolar radiation managementrsquo Two of the researchersthen independently assessed each open-ended definition ofgeoengineering and solar radiation management given bysurvey respondents and if either researcher believed that ananswer was influenced by these sources then the participantrsquosresponses were removed from the study The resulting samplesize is 2893

22 Assessing bias introduced by the information section

It is unavoidable that providing the technical informationabout SRM biased the responses to some degree The surveywas designed and extensively pretested to convey scientificinformation about SRM in a neutral manner and in languageaccessible to the general public using methods described byMorgan et al (2002) When asked to rate the clarity andneutrality of the information that was presented 93 of thesubjects thought that it was clear To evaluate neutralityparticipants were asked if the information they had read wasbiased 59 thought that it was neutral 23 thought thatit opposed SRM and 38 thought that it was supportiveof SRM The effect of the educational section was furtherverified by an internal check where the question lsquoDo you thinkthat geoengineering should be used as a solution to globalwarmingrsquo was asked both before and after the subjects wereexposed to the information (questions 5 and 9 respectively) Ofpeople who answered both questions 60 did not change theiropinion following the educational section while 20 becamemore supportive of SRM and 21 less supportive lsquoUnsurersquoresponses dropped from 49 to 25 Given this data it seemsunlikely that the information substantially biased the result

3


23 Limitations of survey methods

Assessing opinions where public knowledge is low orincomplete is a methodological challenge Large opinionsurveys such as this one can be used as a form of initialassessment to observe the breadth of developing opinionsThey allow opinions to be cataloged and aggregated usingstatistical methods to establish baseline observations that canbe tracked over time (Fischhoff and Fischhoff 2001) Thereare however two important limitations of using surveys ontopics for which public opinion is not well formed First therigid question and answer format does not allow for nuancedresponses (Fischhoff 2000) and second the propensity ofsome respondents to provide an opinion based on constructedpreference not derived opinion (Slovic 1995) While theeducational section provides some information about SRM asa basis for the informed response section of the survey it doesnot resolve the problem of constructed preferences The resultsof this survey need to be tested against results from individualinterviews andor small group exercises

3 Results

31 Basic understanding and mental models ofgeoengineering concepts

When asked lsquoHave you ever heard of geoengineeringrsquo(question 1A) and lsquoHave you ever heard of climateengineeringrsquo (question 2A) 20 and 24 of the samplerespectively responded in the affirmative An analysisof questions 1B and 2B which elicited unaided open-ended definitions of geoengineering and climate engineeringsuggests that 8 of the population can correctly describegeoengineering while 45 can accurately describe climateengineering The ordering of questions was such thatsubjects were asked to define geoengineering prior to climateengineering since we expected that the term lsquoclimateengineeringrsquo was more likely to suggest the correct answer torespondents Familiarity varied little by country

By way of producing an estimate a minimum of 8 ofthe sample was able to define geoengineering and 45 ableto define climate engineering which produces a very widerange of potential familiarity While each definition showedan understanding that an environmental climate process wasbeing altered through intentional human-intervention we feelthat an overall familiarity figure is likely to be in the lowerpart of this range Some portion of participants correctlydefining climate engineering can likely be attributed to beingable to separately define climate and engineering Converselycorrectly defining geoengineering can likely be attributed tosome prior knowledge of these processes This is a decidedlyhigher estimate than the 3 estimated by Leiserowitz fromsurvey done in fall 2008 and more in line with the 7 estimateof Spence et al (2010) from a survey conducted in winter 2010While these assessments are slightly different the increaseover time may suggest a trend of growing familiarity withinthe broader public consistent with the trends shown in figure 1

Of the sim70 of subjects that did attempt to answer theopen-ended questions the term geoengineering produced a

Table 1 Distribution of incorrect definitions of geoengineering

Category Distribution ()

Energygeothermal 57Genetic Engineeringmanipulation 62Other 83Engineering (unspecified) 88Geography 112Environmental engineering 171Geotechnical engineering 426

much larger variety of responses than climate engineeringSome of the correct answers were characterized by anunexpected level of complexity showing a depth of knowledgeThese answers included descriptions of certain methods(lsquo[geoengineering] is man trying to change the weatherusing different methods such as changing an airplanes [sic]exhaustrsquo) opinions (lsquo[geoengineering is] trying to play Godand manipulating weather patterns to control climatersquo) andfacts (lsquo[geoengineering is] reconstructing the planet by meansof technological innovations to address the issue of globalwarmingclimate changersquo) Those defining geoengineeringincorrectly generally believed that it referred to one of thefollowing six broad topics shown in table 1 The twomost prominent definitions environmental engineering andgeotechnical engineering refer to the manipulation or studyof components of the earth This would suggest that somesubjects simply decomposed geoengineering into lsquogeorsquo andlsquoengineeringrsquo to derive their response

In contrast a much higher portion of the sample couldcorrectly define climate engineering The incorrect answersfor this term were rarely wrong definitions but rather showedinsufficient evidence of understanding to meet the codingcriteria Within the correct answers there was a high rate ofdescribing weather modification techniques and cloud seeding34 of correct answers were related to manipulating weatherprocesses and 6 of the correct responses directly used theterm lsquocloud seedingrsquo

32 Opinions on geoengineering

When asked if geoengineering should be used as a solutionto global warming (Q9) the mean response was 235 witha standard deviation of 086 on a four-point scale where1 = strongly disagree and 4 = strongly agree while 25of respondents selected lsquounsurersquo and did not mark the four-point scale Hereafter we will report the results of similarlyformatted questions using the format lsquoQ9 M = 235 SD =086 25 unsurersquo

The following questions explored subjectsrsquo support forstudying or using SRM in specific circumstances Therewas high support for allowing scientists to study SRM 14of the sample oppose this research while 72 somewhator strongly support it (Q10 M = 308 SD = 080413 unsure) Support progressively fell and the percentageof unsure responses rose as subjects were asked about theirsupport for using SRM to stop a climate emergency (Q11M = 249 SD = 090 25 unsure) and for deploying SRMimmediately (Q12 M = 223 SD = 094 253 unsure)

4


Table 2 Opinion elicitation based on a four-point scale (1 = strongly disagree 2 = somewhat disagree 3 = somewhat agree 4 = stronglyagree)

Exact question wording Mean SD Distribution (1 2 3 4 unsure)

Q15A Solar Radiation Management will help theplanet more than it will hurt it

249 093

Q15B With enough research I believe SolarRadiation Management will turn out to be safe andeffective

262 090

Q15C Solar Radiation Management should beused so we can continue to use oil coal andnatural gas

207 094

Q15D Solar Radiation Management is the easyway out

276 088

Q15E Research into Solar Radiation Managementwill lead to a technology that will be used nomatter what the public thinks

297 078

Q15F The earthrsquos temperature is too complicatedto fix with one technology

334 071

Q15G Humans should not be manipulating naturein this way

312 085

Q15H Solar Radiation Management is natural 209 092Q15I If scientists find that Solar RadiationManagement can reduce the impacts of globalwarming with minimal side-effects then I wouldsupport its use

301 086

When respondents were asked if SRM should never be used nomatter the situation on average respondents disagreed (Q13M = 234 SD = 010 28 unsure) Overall the supportfor use of SRM is surprisingly high Our own view and ourimpression of the dominant opinion within the research andpolicy community is that near term use of SRM would bereckless The public support for SRM found here providesempirical support for oft expressed fears of a rush towardimplementation

A number of additional questions were asked in order tobetter understand initial opinions about SRM (summarized intable 2) On average subjects do not necessarily see SRM asa way to continue to burn fossil fuels (Q15C) and are inclinedto see it as the lsquoeasy way outrsquo (Q15D) Sixty-four per cent ofsubjects agree that humans should not be manipulating naturein the way suggested by SRM (Q15G) and 75 of subjectsagree that the earthrsquos temperature is too complicated to fixwith one technology (Q15F) Characteristic of an emergingtechnology levels of uncertainty ranged across the questionsIn particular subjects are highly uncertain when asked to makespecific trade-off comparisons such as if SRM will help theplanet more than it will hurt it (Q15A unsure = 43)

33 Emerging opinion groups lsquosupportersrsquo and lsquodetractorsrsquo

A deeper analysis of question 9 and 13 revealed a trendthat suggests the emergence of two distinct opinion groupssupporters and detractors Supporters are defined as subjectswho somewhat or strongly agreed with Q9 geoengineeringshould be used as a solution to global warming and somewhator strongly disagree with Q13 SRM should never be usedno matter the situation Conversely detractors are definedas subjects who somewhat or strongly agreed with Q13 andsomewhat or strongly disagreed with Q9 29 of the entire

sample is classified as supporters while 20 of the samplecan be classified as detractors

331 General opinions Consistent with their positiondetractors oppose SRM being studied (Q10 M = 237 SD =091) used in a climate emergency (Q11 M = 162 SD =071) or used today (Q12 M = 145 SD = 066)Conversely supporters agree that SRM should be studied(Q10 M = 352 SD = 058) and support SRMrsquos use bothin a climate emergency (Q11 M = 310 SD = 053) andimmediately (Q12 M = 300 SD = 063) For each of thesequestions the difference between the means is significant atp lt 0001 (Q10 t = 257 Q11 t = 404 Q12 t = 401)More generally supporters seem to hold the position thatscience plays an important role in SRM development Alongwith strongly supporting SRM research supporters believe thatwith enough research SRM will be safe and effective (Q15B)and see SRM as helpful (Q15A) Comparisons presented intable 3 suggest detractors hold significantly different opinionson these questions

332 Opinions on global warming Opinions on globalwarming also differ significantly between supporter anddetractor groups as shown in table 4 Supporters agreethat global warming is a serious (Q6A) anthropogenic (Q6B)problem that the government should do more about (Q6D)This can be contrasted with the detractor view that sees globalwarming as less of an issue (Q6A) and with less of a humanbasis (Q6B) Despite differing views on global warming bothgroups agree that SRM should not be used as a way to continueburning fossil fuels (Q15C) and that the earthrsquos temperature istoo complicated to fix with one technology (Q15F)

5


Table 3 Mean comparisons of general opinions of SRM between supporter and detractor opinion groups (Note based on a four-point Likertscale 1 = strongly disagree 2 = disagree 3 = agree 4 = strongly agree)

Supporter Detractor

Exact question wording Mean SD Mean SD t-statistic

Q15A SRM will help the planet more than it willhurt it

300 065 175 087 252a


314 058 180 082 302a


232 090 165 082 137a

Q15D SRM is the easy way out 269 079 274 106 08Q15E Research will lead to a technology that willbe used no matter what the public thinks

313 074 300 087 09


317 074 358 071 108a


262 086 368 063 253a

Q15H SRM is natural 243 083 159 080 178a

Q15I If scientists find that SRM can reduce theimpacts of global warming with minimalside-effects then I would support its use

346 060 219 099 256a

a p lt 0001 statistically significant at a 95 confidence level (2-tailed)

Table 4 Mean comparisons of opinions on global warming betweensupporter and detractor opinion groups (Note based on a 5-pointLikert scale 1 = strongly disagree 2 = disagree 3 = neutral 4 =agree 5 = strongly agree)

Supporter Detractor


Q6A Global warming is aserious problem

415 093 340 139 112a

Q6B Humans are primarilyresponsible for globalwarming

400 103 343 146 80a

Q6C One personrsquos actionshave no impact on globalwarming

238 110 268 126 45a

Q6D My government shoulddo more to deal with globalwarming

403 095 333 143 101a

a p lt 0001 statistically significant at a 95 confidence level(2-tailed)

333 Opinions on risk and benefits In the educationalsection of the survey participants were presented with fourbenefits and five risks of SRM Table 5 shows results fromquestion 14 where subjects were asked to state how importanteach risk or benefit was in the formation of their opinionsIn general supporters assessed the benefits as being moreimportant than did the overall sample and the detractor groupwhile detractors on average did not rank any benefit as beingimportant to their decision The risks however were veryimportant across all three opinion groupings Each rankeddamages to the ozone layer and unknown risks as the two mostimportant factors

334 Supporter and detractor demographics An analysis ofthe two opinion groups suggests that the supporters are fairly

evenly distributed between all three countries (33 USA 32UK and 26 Canada) Politically 52 of this group describestheir political views as moderate with 20 and 4 describingthem as conservative and very conservative respectively Thisratio is similar for all three countries The detractor grouphowever is dominated by Americans (41 versus 28 UKand 31 Canada) and individuals holding a more conservativepolitical view (44 moderate 25 conservative and 10very conservative) Political views differ per countrymdashreported as very conservativeconservativemoderatemdashCanada81751 United States 143235 and UnitedKingdom 62350 Both groups had equal gender andage distributions Religious belief distribution did not greatlydiffer between groups with about 60 self identifying asChristian and 23 non-religious The difference betweenaverage educational levels was not significant A meancomparison suggests that country (t = 30 p lt 0005)and political views (t = 46 p lt 0001) significantly varybetween the supporter and detractor groups

335 Trusted information sources The public receivesinformation about the risks and benefits of technology frommany sources so characterizing the most trusted sourcesis important When asked lsquoHow much would you trustinformation about SRM from each of the following groupsrsquo75 of all respondents ranked university researchers astrustworthy Environmental organization (65) and friendsand family (63) were also trusted by over half the subjectsConversely less than one third of respondents trust the federalgovernment (34) religious leaders (29) private companies(29) media and reporters (26) and industries benefitingfrom SRM (22) There are notable inter-country variationsin the perceived trustworthiness of certain groups as shownin figure 2 In particular religious groups are trusted more in

6


Figure 2 Subjectsrsquo trust in different groups by country lsquoNo trustrsquo denotes the percentage of respondents that somewhat or completelydistrust a particular group while lsquotrustrsquo denotes the percentage of respondents that somewhat or completely trust that group

Table 5 Results of question 14 showing relative importance of each risk and benefit to the overall sample and the 2 opinion groupings informing opinions of SRM (Note based on a four-point Likert scale 1 = not at all important 2 = somewhat unimportant 3 = somewhatimportant 4 = very important)

Overall Supporters Detractors

Mean SD Mean SD Mean SD Unknown

Benefits

Q14A Slow global warming and give more timeto reduce GHGs

323 081 356 058 263 100 18

Q14B Slow warming more quickly than cuttingemissions because very big cuts in emissionscannot do much to slow warming in the next halfcentury

318 081 352 058 264 099 20

Q14C Stop a climate emergency before too muchdamage is done

326 080 358 058 269 098 20

Q14D Cheaper than stopping using fossil fuels 280 094 308 081 236 101 21

Risks

Q14E Change how much it rains in some parts ofthe world

352 069 351 064 350 083 16

Q14F Damage the ozone layer 365 063 366 058 363 073 20Q14G Remove peoplersquos motivation to changetheir current lifestyle

324 085 329 076 310 103 16

Q14H Allow coal oil and natural gas companiesto keep releasing greenhouse gases

317 091 319 086 301 105 19

Q14I Unknown risks 368 060 361 060 374 066 16

the United States than they are in other countries Detractorsare significantly less trusting overall Of particular notethe detractors lack trust in the federal government (Q16AM = 191 SD = 090) which is likely to be heavily involvedin SRM programs

336 Discriminant analysis To further describe these twomutually exclusive opinion groups a discriminant analysiswas completed using many of the factors described above aspredictor variables The function given in table 6 revealed asignificant association between supporter and detractor groupsand these variables (λ = 04 p lt 0001) The most important

predictor of a supporter is supporting the study of research(Q10) and detractors is the belief that humans should notbe manipulating nature in this way (Q15G) Notably bothopinions of global warming and demographic informationincluding political views and education level are not importantpredictors in this analysis

34 Conspiracy theories

One of the voices emerging in the SRM debate is thatof lsquochemtrailsrsquo believers This small group believes thatorganizations such as governments are already distributing

7


Table 6 Discriminant loadings for the important predictor factors inthe discriminant function to describe supporter and detractor opiniongroups (Note the other predictors included in the function areQ6A Q6B Q6D Q7A Q7B mean of 14E-I Q15F and politicalviews The cross validated classification shows that overall 86 ofthe cases were correctly classified)

Important predictor factors Discriminant loading

Q10 Do you think scientistsshould study Solar RadiationManagement

0697

Q15G Humans should not bemanipulating nature in this way

minus0611

Importance of benefits (mean ofQ14A-D)

0596

Q15H Solar RadiationManagement is natural

0497

Trust in organizations (mean ofQ14A-I)

0423

Q7C We must develop newtechnologies to solve globalwarming

0368

Q15C Solar RadiationManagement should be used sowe can continue to use oil coaland natural gas

0332

Q15F The earthrsquos temperature istoo complicated to fix with onetechnology

minus0314

chemicals in the atmosphere for a variety of purposes rangingfrom culling the population to mind control We found that26 of the subjects believe that it is completely true that thegovernment has a secret program that uses airplanes to putharmful chemicals into the air and 14 of the sample believesthat this is partly true Distributions across the three countriesdo not vary substantially

4 Discussion

We found that the assessed familiarity of geoengineeringis likely around 8 which is greater than past empiricalassessments While this survey represents a single assessmentwe contend that the increase available media (figure 1) andincrease in assessed familiarity from past studies suggests agrowing public interest in geoengineering Taken togetherthese results suggest an increasing public familiarity andimply that interest in geoengineering is no longer confined toacademia and policy elites Future studies should track publicawareness and emerging opinions in a systematic way

An ongoing debate in elite circles argues that the termgeoengineering is ineffective because it is difficult for thepublic to understand and derive its correct meaning Theseresearch results support that position The term geoengineeringis strongly confounded with geotechnical engineering andenvironmental engineering rather than intervention into theearthrsquos climatic system The term lsquoclimate engineeringrsquo seemsto capture this essential aspect of the technology throughhigher rates of correct definitions and fewer avenues formisunderstandings This research also suggests that weathermodification and cloud seeding may provide a strong anchorfor people to begin to conceptualize SRM While this framing

does not characterize the global scale of SRM and mayperpetuate known cofounds between weather and climate itdoes introduce the technologyrsquos salient characteristics of beinga deliberate intervention aimed at deriving human benefitswith potential unintended consequences Further testing of thesalience of this framing is required

As expected in opinion surveys of emerging technologyportions of the population do not hold strong certain opinionsWhile the share of lsquouncertainrsquo responses moderately decreasedafter subjects received the educational section provided inthe survey the proportion of uncertain respondents remainedsignificant for many questions SRM is a new technology andwhile public awareness may be growing public opinions are intheir formative stage and are sensitive to changes in framingfuture information on risks and benefits and changes to context(eg climate change)

In this initial assessment of emergent supporter anddetractor positions supporters of SRM can be characterizedby a belief in scientific research a prioritizing of SRM benefitsin their decisions and an opinion the SRM is natural Detractorscan be characterized by the opinion that humans should not bemanipulating nature in this way Interestingly demographicsand views on global warming are not predictors of eitherposition It is likely the value of more precise risk andbenefit information to these opinion groups may differ Forsupporters it is likely that more precise estimations of theextent and impacts of potential risks will help to both solidifytheir opinions and decrease their uncertainty As the detractorposition is defined as a complete rejection of SRM theiropinions are less likely to be affected by trade-off analyses thatcompare risks and benefits and more likely to be driven by theideologies underlying their rejection of the technology

It seems plausible that support for and rejection of SRMcut across environmental values in two very different waysOne framing assumes that environmentalists oppose interferingwith nature while political conservatives would support acheap technological solution to climate change Under thissimplistic framing one would expect conservatives to supportSRM and environmentalists to be opposed An alternativeframing is that environmentalists will support SRM becausethey are most concerned about action on climate changewhile conservatives will oppose SRM because it increasesgovernment power The data suggests but does not prove thatboth framings are in play within subsets of the supporter anddetractor groupings

The potential risks of SRM are an important considerationfor all groups when developing their opinions about SRMScientistsrsquo understanding of the environmental and social risksof SRM is still in its nascent stage However the publicdialog is likely to be dominated by discussion of the potentialimpacts of SRM experiments or interventions There may bea disconnect between how much is currently known by theacademic community about SRM and how much the publicwould like to know

Our results are consistent with findings that publicaudiences tend to trust scientific institutions on topics of highuncertainty (Siegrist and Cvetkovich 2000) As future policyand governance debates concerning SRM continue scientists

8


are likely in a unique and trusted position of influence Alsonoteworthy is the lack of trust that the public reported in federalgovernments especially within the detractor group As thepolitical and academic circles continue their discussions onthe future of SRM and design potential governance structuresand research programs ensuring that the science remainsdisentangled from the politics will help to preserve the publicrsquostrust in scientists on the topic of SRM When subjects werequestioned what they would like to ask or say to a researcher ordecision-maker working with SRM one response in particularsummed this position up lsquoTalk straight make sure do notscrew up and do not forget anythingrsquo

As discussions about the wisdom of research into SRMor its eventual deployment continue researchers and policymakers can no longer assume that the public is unawareof SRM Our survey data suggest that public awareness ofgeoengineering is larger than expected and growing Italso suggests (1) scientists are considered a trusted sourceof information but governments are not (2) perception ofthe risks of SRM will likely play a central role in shapingopinions about its development (3) support for SRM isassociated with an optimism about research a valuing ofSRMrsquos benefits and a belief that SRM is natural whereasskepticism of it is associated with a belief that nature shouldnot be manipulated and finally (4) public opinion on SRMis strongly contingent on how where and in what contextSRM is discussed Incorporating these findings into researchand communication efforts will increase the likelihood that thepublic will be effectively engaged in the SRM discussion andhelp us all grapple with how to proceed with future climatechange policy

Acknowledgments

This work was supported by the Center for Climate and EnergyDecision Making (SES-0949710) through a cooperativeagreement between the National Science Foundation andCarnegie Mellon University and the Fund for InnovativeClimate and Energy Research Invaluable feedback wasprovided by Dr Wandi Bruine de Bruin and the two anonymouspeer reviewers

References

Barrett S 2008 The incredible economics of geoengineering EnvironResour Econ 39 45ndash54

Blackstock J and Long J 2010 The politics of geoengineering Science327 527

Blackstock J J Battisti D S Caldeira K Eardley D M Katz J IKeith D W Patrinos A A N Schrag D P Socolow R H andKoonin S E 2009 Climate Engineering Responses to ClimateEmergencies (Santa Barbara CA Novim)

Caldeira K and Matthews H D 2007 Transient climate-carbonsimulations of planetary geoengineering Proc Natl Acad Sci104 9949ndash54

Corner A and Pidgeon N 2009 Geoengineering the climate thesocial and ethical implications Environment 52 24ndash37

Crutzen P 2006 Albedo enhancements by stratospheric sulfurinjections a contribution to resolve a policy dilemma ClimChange 77 211ndash20

Fischhoff B 2000 Informed consent in eliciting environmental valuesEnviron Sci Technol 38 1439ndash44

Fischhoff B and Fischhoff I 2001 Publicsrsquo opinions ofbiotechnologies AgBioForum 4 155ndash62

House of CommonsmdashScience and Technology Committee 2010 TheRegulation of Geoengineering (London The Stationery OfficeLimited) HC 221

Keith D Parson E and Morgan G 2010 Research on global sunblockneeded now Nature 463 426ndash7

Keith D W 2000 Geoengineering the climate history and prospectAnnu Rev Energy Environ 25 245ndash84

Kiehl J T 2006 Geoengineering climate change treating thesymptom over the cause Clim Change 77 227ndash8

Leiserowitz T 2010 Geoengineering and climate change in the publicmind Asilomar Int Conf on Climate Intervention TechnologiesMinimizing the Potential Risk of Research to Counter-BalanceClimate Change and its Impacts (Asilomar Climate Institute)

Morgan M G Fischhoff B Bostrom A and Atman C J 2002 RiskCommunication A Mental Models Approach (CambridgeCambridge University Press)

NASmdashCommittee on Science Engineering and Public Policy 1992Policy Implications of Greenhouse Warming MitigationAdaptation and the Science Base (Washington DC NationalAcademy Press) pp 433ndash64

National Environmental Research Council 2010 Experiment EarthReport on a Public Dialogue on Geoengineering (UK IpsosMori)

Ricke K L Morgan M G and Allen M R 2010 Regional climateresponse to solar-radiation management Nature Geosci3 537ndash41

Robock A Marquardt A Kravitz B and Stenchikov G 2009 Benefitsrisks and costs of stratospheric geoengineering Geophys ResLett 36 L19703

Robock A Oman L and Stenchikov G 2008 Regional climateresponses to geoengineering with tropical and Arctic SO2

injections J Geophys Res 113 D16101Shepherd J et al 2009 Geoengineering the Climate Science

Governance and Uncertainty (London The Royal Society)Siegrist M and Cvetkovich G 2000 Perception of hazards the role of

social trust and knowledge Risk Anal 20 713ndash9Slovic P 1995 The construction of preference Am Psychol

50 364ndash71Spence A Venables D Pidgeon N Poortinga W and Demski C 2010

Public Perceptions of Climate Change and Energy Futures inBritain Summary Findings of a Survey Conducted inJanuaryndashMarch 2010 (Technical Report) (Cardiff School ofPsychology) (Understanding Risk Working Paper 10-01wwwunderstanding-riskorg)

Tilmes S Muller R and Salawitch R 2008 The sensitivity of polarozone depletion to proposed geoengineering schemes Science320 1201ndash4

9

1 Introduction

2 Methods

21 Subjects



3 Results

31 Basic understanding and mental models of geoengineering concepts


33 Emerging opinion groups `supporters and `detractors


4 Discussion

Acknowledgments

References

IOP PUBLISHING ENVIRONMENTAL RESEARCH LETTERS

Environ Res Lett 6 (2011) 044006 (9pp) doi1010881748-932664044006

Public understanding of solar radiationmanagementA M Mercer1 D W Keith2 and J D Sharp3

1 Institute for Sustainable Energy Environment and Economy University of Calgary2500 University Drive NW Calgary AB T2N 1N4 Canada2 Kennedy School Harvard University 79 John F Kennedy Street CambridgeMA 02138 USA3 Energy and Materials Research Group Simon Fraser University 8888 University DriveBurnaby BC V5A 1S6 Canada

E-mail amercerucalgaryca

Received 30 May 2011Accepted for publication 3 October 2011Published 24 October 2011Online at stacksioporgERL6044006

AbstractWe report the results of the first large-scale international survey of public perception ofgeoengineering and solar radiation management (SRM) Our sample of 3105 individuals in theUnited States Canada and the United Kingdom was recruited by survey firms that administerinternet surveys to nationally representative population samples Measured familiarity washigher than expected with 8 and 45 of the population correctly defining the termsgeoengineering and climate engineering respectively There was strong support for allowing thestudy of SRM Support decreased and uncertainty rose as subjects were asked about theirsupport for using SRM immediately or to stop a climate emergency Support for SRM isassociated with optimism about scientific research a valuing of SRMrsquos benefits and a strongerbelief that SRM is natural while opposition is associated with an attitude that nature should notbe manipulated in this way The potential risks of SRM are important drivers of publicperception with the most salient being damage to the ozone layer and unknown risks SRM is anew technology and public opinions are just forming thus all reported results are sensitive tochanges in framing future information on risks and benefits and changes to context

Keywords geoengineering solar radiation management climate change public opinion publicawareness

S Online supplementary data available from stacksioporgERL6044006mmedia

1 Introduction

Until recently scientific political and public discourse onresponses to climate change has centered on two fundamentalresponse options mitigation (reducing emissions) andadaptation Deliberate large-scale engineering to reduce oroffset climate change driven by greenhouse gas emissionsrepresents a third class of options (Shepherd et al 2009)Known as geoengineering or climate engineering this thirdresponse comprises an array of techniques that can be broadlydivided into two very different approaches carbon dioxideremoval and solar radiation management (SRM) Most SRM

techniques act by increasing the albedo of the atmospherethrough methods such as the injection of sulfate aerosols intothe stratosphere where they would reflect some solar energyback to space lowering the global temperature Comparedto other response options SRM is inexpensive (Barrett 2008Blackstock et al 2009 Shepherd et al 2009 NAS 1992)and fast-acting (Caldeira and Matthews 2007 Robock et al2008) but it canmdashat bestmdashonly partially offset the impactsof increased CO2 and caries novel environmental and socialrisks (Shepherd et al 2009 Blackstock et al 2009 Keithet al 2010 Robock et al 2009 Corner and Pidgeon 2009)Risks include changes in precipitation (Ricke et al 2010) a

1748-932611044006+09$3300 copy 2011 IOP Publishing Ltd Printed in the UK1












2 Methods



2












21 Subjects






3




3 Results













4





249 093


262 090


207 094


276 088


297 078


334 071


312 085


301 086








5



Supporter Detractor



300 065 175 087 252a


314 058 180 082 302a


232 090 165 082 137a


313 074 300 087 09


317 074 358 071 108a


262 086 368 063 253a



346 060 219 099 256a



Supporter Detractor



415 093 340 139 112a


400 103 343 146 80a


238 110 268 126 45a


403 095 333 143 101a






6






Benefits


323 081 356 058 263 100 18


318 081 352 058 264 099 20


326 080 358 058 269 098 20


Risks


352 069 351 064 350 083 16


324 085 329 076 310 103 16


317 091 319 086 301 105 19

Q14I Unknown risks 368 060 361 060 374 066 16






7





0697


minus0611


0596


0497


0423


0368


0332


minus0314


4 Discussion









8




Acknowledgments


References


























9

1 Introduction

2 Methods

21 Subjects



3 Results





4 Discussion

Acknowledgments

References












2 Methods



2












21 Subjects






3




3 Results













4





249 093


262 090


207 094


276 088


297 078


334 071


312 085


301 086








5



Supporter Detractor



300 065 175 087 252a


314 058 180 082 302a


232 090 165 082 137a


313 074 300 087 09


317 074 358 071 108a


262 086 368 063 253a



346 060 219 099 256a



Supporter Detractor



415 093 340 139 112a


400 103 343 146 80a


238 110 268 126 45a


403 095 333 143 101a






6






Benefits


323 081 356 058 263 100 18


318 081 352 058 264 099 20


326 080 358 058 269 098 20


Risks


352 069 351 064 350 083 16


324 085 329 076 310 103 16


317 091 319 086 301 105 19

Q14I Unknown risks 368 060 361 060 374 066 16






7





0697


minus0611


0596


0497


0423


0368


0332


minus0314


4 Discussion









8




Acknowledgments


References


























9

1 Introduction

2 Methods

21 Subjects



3 Results





4 Discussion

Acknowledgments

References












21 Subjects






3




3 Results













4





249 093


262 090


207 094


276 088


297 078


334 071


312 085


301 086








5



Supporter Detractor



300 065 175 087 252a


314 058 180 082 302a


232 090 165 082 137a


313 074 300 087 09


317 074 358 071 108a


262 086 368 063 253a



346 060 219 099 256a



Supporter Detractor



415 093 340 139 112a


400 103 343 146 80a


238 110 268 126 45a


403 095 333 143 101a






6






Benefits


323 081 356 058 263 100 18


318 081 352 058 264 099 20


326 080 358 058 269 098 20


Risks


352 069 351 064 350 083 16


324 085 329 076 310 103 16


317 091 319 086 301 105 19

Q14I Unknown risks 368 060 361 060 374 066 16






7





0697


minus0611


0596


0497


0423


0368


0332


minus0314


4 Discussion









8




Acknowledgments


References


























9

1 Introduction

2 Methods

21 Subjects



3 Results





4 Discussion

Acknowledgments

References




3 Results













4





249 093


262 090


207 094


276 088


297 078


334 071


312 085


301 086








5



Supporter Detractor



300 065 175 087 252a


314 058 180 082 302a


232 090 165 082 137a


313 074 300 087 09


317 074 358 071 108a


262 086 368 063 253a



346 060 219 099 256a



Supporter Detractor



415 093 340 139 112a


400 103 343 146 80a


238 110 268 126 45a


403 095 333 143 101a






6






Benefits


323 081 356 058 263 100 18


318 081 352 058 264 099 20


326 080 358 058 269 098 20


Risks


352 069 351 064 350 083 16


324 085 329 076 310 103 16


317 091 319 086 301 105 19

Q14I Unknown risks 368 060 361 060 374 066 16






7





0697


minus0611


0596


0497


0423


0368


0332


minus0314


4 Discussion









8




Acknowledgments


References


























9

1 Introduction

2 Methods

21 Subjects



3 Results





4 Discussion

Acknowledgments

References





249 093


262 090


207 094


276 088


297 078


334 071


312 085


301 086








5



Supporter Detractor



300 065 175 087 252a


314 058 180 082 302a


232 090 165 082 137a


313 074 300 087 09


317 074 358 071 108a


262 086 368 063 253a



346 060 219 099 256a



Supporter Detractor



415 093 340 139 112a


400 103 343 146 80a


238 110 268 126 45a


403 095 333 143 101a






6






Benefits


323 081 356 058 263 100 18


318 081 352 058 264 099 20


326 080 358 058 269 098 20


Risks


352 069 351 064 350 083 16


324 085 329 076 310 103 16


317 091 319 086 301 105 19

Q14I Unknown risks 368 060 361 060 374 066 16






7





0697


minus0611


0596


0497


0423


0368


0332


minus0314


4 Discussion









8




Acknowledgments


References


























9

1 Introduction

2 Methods

21 Subjects



3 Results





4 Discussion

Acknowledgments

References



Supporter Detractor



300 065 175 087 252a


314 058 180 082 302a


232 090 165 082 137a


313 074 300 087 09


317 074 358 071 108a


262 086 368 063 253a



346 060 219 099 256a



Supporter Detractor



415 093 340 139 112a


400 103 343 146 80a


238 110 268 126 45a


403 095 333 143 101a






6






Benefits


323 081 356 058 263 100 18


318 081 352 058 264 099 20


326 080 358 058 269 098 20


Risks


352 069 351 064 350 083 16


324 085 329 076 310 103 16


317 091 319 086 301 105 19

Q14I Unknown risks 368 060 361 060 374 066 16






7





0697


minus0611


0596


0497


0423


0368


0332


minus0314


4 Discussion









8




Acknowledgments


References


























9

1 Introduction

2 Methods

21 Subjects



3 Results





4 Discussion

Acknowledgments

References






Benefits


323 081 356 058 263 100 18


318 081 352 058 264 099 20


326 080 358 058 269 098 20


Risks


352 069 351 064 350 083 16


324 085 329 076 310 103 16


317 091 319 086 301 105 19

Q14I Unknown risks 368 060 361 060 374 066 16






7





0697


minus0611


0596


0497


0423


0368


0332


minus0314


4 Discussion









8




Acknowledgments


References


























9

1 Introduction

2 Methods

21 Subjects



3 Results





4 Discussion

Acknowledgments

References





0697


minus0611


0596


0497


0423


0368


0332


minus0314


4 Discussion









8




Acknowledgments


References


























9

1 Introduction

2 Methods

21 Subjects



3 Results





4 Discussion

Acknowledgments

References




Acknowledgments


References


























9

1 Introduction

2 Methods

21 Subjects



3 Results





4 Discussion

Acknowledgments

References

public understanding of solar radiation management - iopscience

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