International Trends in Public Perceptions of Climate Change Over the Past Quarter Century

Overview

International trends in publicperceptions of climate change overthe past quarter century

Stuart Capstick,1,2,3 Lorraine Whitmarsh,1,2 Wouter Poortinga,1,2

Nick Pidgeon1,2,3 and Paul Upham2,4

Public perceptions of climate change are known to differ between nations andto have uctuated over time. Numerous plausible characterizations of thesevariations, and explanations for them, are to be found in the literature. However,a clear picture has not yet emerged as to the principal trends and patterns thathave occurred over the past quarter-century or the factors behind these changes.This systematic review considers previous empirical research that has addressedthe temporal aspects to public perceptions. We address ndings that have beenobtained since the 1980s and using a range of methodologies. In this review,we consider early, seminal work examining public perceptions; survey studiescarried out over long timescales and at an international scale; detailed statisticalanalyses of the drivers of changing perceptions; and qualitative research featuringa longitudinal component. Studies point to growing skepticism in the latter 2000sin some developed countries, underpinned by economic and sociopolitical factors.Even so, in many parts of the world, there has been growing concern aboutclimate change in recent years. We conclude that the imbalance in the literaturetoward polling data, and toward studies of public perceptions in Western nations(particularly the United States), leaves much unknown about the progression ofpublic understanding of climate change worldwide. More research is required thatuses inferential statistical procedures to understand the reasons behind trends inpublic perceptions. The application of qualitative longitudinal methodologies alsooffers the potential for better appreciation of the cultural contexts in which climatechange perceptions are evolving. 2014 The Authors.WIREs Climate Change published by JohnWiley & Sons, Ltd.

How to cite this article:WIREs Clim Change 2015, 6:3561. doi: 10.1002/wcc.321

Correspondence to: [email protected] of Psychology, Cardiff University, Cardiff, UK2Tyndall Centre for Climate Change Research3Climate Change Consortium of Wales4Centre for Integrated Energy Research, University of Leeds, Leeds,UK

Conflict of interest: The authors have declared no conflicts ofinterest for this article.

INTRODUCTION

The ways in which individuals, societies, and poli-ties respond to climate change are in manycases contingent on public perceptions of its causes,consequences, and wider implications.13 As such,understanding popular opinion on climate change iscritically important. Particularly (but not only) instates with electoral systems, policy legitimacy mat-ters at all stages of the policy process, for both private

Volume 6, January/February 2015 35 2014 The Authors. WIREs Climate Change published by John Wiley & Sons, Ltd.This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium,provided the original work is properly cited.

Overview wires.wiley.com/climatechange

and public entities.4 In the context of climate change,the major emissions reductions required, the develop-ment and deployment of low-carbon energy technolo-gies, and the implementation of adaptation measuresall require some degree of citizen involvement, fromthe granting of policy mandates to active behavioralchange.5,6

Alongside influences such as lobbying by incum-bent interests, and institutional and structural factors,all of which may compel or constrain politicalresponses to climate change,7 public opinion hascompounded the widespread political reluctancein many countries to enact legislation that couldbe received unfavorably by electorates and by thepowerful economic interests that both support anddepend on those electorates.811 At the individuallevel, behaviors of significance for climate changemay be influenced by a persons attitudes toward cli-mate change, but they are also subject to these widersociocultural and political factors1214, which, whilefrom a psychological perspective are considered exter-nal and contextual, from a sociological perspectiveare internal to the understanding of climate changedilemmas. The ways in which these individual andstructural factors inter-relate are complex14,15 butthe types of attitudes which have been shown to beimportant as influences on public and private sphereaction include individuals recognition of the realityof climate change, acceptance of a human componentin the causation of climate change, degree of concernabout its impacts, and beliefs about personal andwider responsibilities for addressing it.1517

For some time now, a majority of people world-wide have been of the view that climate change is aserious problem, and that people are already beingharmed by it.18 Such wide-ranging public concern andawareness have developed since the emergence of cli-mate change as a major environmental concern duringthe 1980s.19,20 This said, there has been widespreadunease expressed in more recent years that sections ofthe public appear to have lost faith in climate scienceand scientists, and that the public and experts may beincreasingly diverging in their assessments about cli-mate change.21,22 In some parts of the world, therehas been a growth in public skepticism about climatechange (however defined2329) since the late 2000s.This has been attributed to a range of factors, includ-ing climate fatigue, misleading media representations,the global financial crisis of 2008, and social attenua-tion of risk.30

Temporal changes in public perceptions ofclimate change warrant careful attention, as trendsin opinion can be consequential for national andinternational responses to climate change and may

be underpinned by a range of different social forcesand physical phenomena. With over two decades ofresearch on public perceptions of climate change,we are now in a position to take stock of the keytrends over this time period. There has, to date,been no attempt to review the full range of literaturerelating to trends in public perceptions of climatechange (though there have been earlier overviews ofpolling data in the United States,20,31 as well as somecommentary on international polling over time32,33).

Here, we present findings from a systematic lit-erature review of studies on public perceptions of cli-mate change, that have used longitudinal methods toexamine patterns of change and to identify the driversof trends in public opinion. We also include early,seminal research in order to contextualize public per-ceptions and research approaches at the time climatechange was beginning to be recognized in the publicdomain.

While acknowledging that public opinion for-mation, patterns, and trends can be analyzed andunderstood through different paradigms (e.g., polit-ical science)34,35 our primary focus here is on atti-tudinal trends as revealed through direct measuresof public perceptions. Data sources of relevance hereare primarily public polls and surveys (but also someinterview, focus group and ethnographic data), ratherthan proxy indicators of opinion such as newspapercoverage, internet searches, or membership of cam-paign groups, which are often used as measures ofissue salience or concern among citizens.11 Sur-veys provide more direct, demand-driven indica-tors of public concern than newspaper indices, whichare at least partly driven by newspaper agendas andin turn likely to influence or reinforce public opin-ion (i.e., supply driven); while internet search data(e.g., Google Trends) and campaign/political groupmembership capture more active (collective) publicresponses to social issues.11 Yet, while methods suchas surveys can provide a useful gauge of opinionandalso offer insights into knowledge, beliefs, and individ-ual responsesthey are often underpinned by individ-ualistic assumptions that may construct the publicin certain (limited) ways,36 as well as being subjectto methodological limitations (e.g., question framing),some of which we discuss later in this review.

The objectives of this review are fourfold.First, to outline international trends and patterns inpublic perceptions of climate change over the pastquarter-century; second, to summarize the availablelongitudinal evidence on what might account forthese; third, to highlight the types of approachesbeing used to examine the temporal component ofpublic perceptions of climate change; and, fourth, to

36 2014 The Authors. WIREs Climate Change published by John Wiley & Sons, Ltd. Volume 6, January/February 2015

WIREs Climate Change International trends in public perceptions of climate change

draw conclusions about the strengths and weaknessesof the available research and to point to areas as yetunder-developed.

Early studies in particular, and some continuingwork in the United States and elsewhere, have usedthe terms global warming and greenhouse effectsynonymously with climate change. For consistency,throughout this review we use only the latter term,while acknowledging that variations in terminologycan lead to different types of responses from publicparticipants,3739 a point to which we return later.

SYSTEMATIC LITERATURE REVIEW

For this study, we carried out a literature search,using the principles of a systematic literature review,to identify relevant articles addressing changes in pub-lic perceptions of climate change over time. The Webof Science database was searched for publicationspublished between 1980 and 2014, using a Booleansearch term designed to retrieve a comprehensivebody of work addressing public perceptions of climatechange.a This search identified 2610 citations, fromwhich a prospective list of 240 studies was derived,based on a preliminary inspection of article titles andabstracts. The 240 articles were fully screened by threeof the authors of this study, followingwhich 35 articleswere retained for the purpose of the present review.The criteria for inclusion were as follows: (1) the studypresents original empirical data, detailed original anal-ysis and/or commentary on pre-existing empirical data(e.g., opinion polls) concerning climate change per-ceptions; (2) the study utilizes data at more than onetime-point, in such a way as to inform understand-ing of changes in public perceptions over time; and (3)the study addresses change over time in such a wayas to be generalizable to a wider population or pop-ulation group (as opposed to, e.g., laboratory exper-iments with no clearly defined target population). Inorder to put recent trends into historical perspective,we additionally incorporate seminal cross-sectionalresearch studies of public perceptions from the late1980s and early 1990s. These were obtained throughextraction as part of the systematic review describedabove, plus three further early studies of which theauthors of the present review were previously aware.Furthermore, because many large-scale internationaland longitudinal survey studies (e.g., conducted bypolling and think-tank organizations such as Gallupand Pew Research Centre) have not been publishedin the academic literature, we incorporate 18 studiesfrom the gray literature and web-based publications,also using the inclusion criteria above. The selectionof this material has necessitated some discretion on

the authors part, given the large number of reportsavailable which have commented on changing publicopinion. One further qualitative longitudinal study ofwhich the authors were previously aware and whichmatched inclusion criteria was also included.

The final literature review included 39 peer-reviewed publications and 18 studies from the grayliterature and/or web-based reports. The reviewapproach utilized for the present study is outlined inFigure 1.

Overview of the Identified PublicationsThe studies obtained from the literature review fallinto four main types, which we use to structure ourdiscussion of changing public perceptions.

First, we consider findings from some of theearliest and relatively small-scale studies carried outin the 1980s and early 1990s. This research is usefulfor understanding the nature of public awareness ofclimate change at this early point in time, such asa commonplace conflation between climate changeand stratospheric ozone depletion. To a large extent,these early studies appraised the accuracy of peoplesknowledge in comparison to expert understanding,and were conducted only in developed nations.

Second, we provide an overview of findings fromrepresentative survey and polling data carried outsince the early 1980s across the globe. As this sec-ond type of study incorporates a large amount ofmaterial across an extended time span, we divide thissection into four time periods, reflecting broad shiftsin public perceptions. These studies enable insightsto be obtained into public perception trends at themacro level; however, for the most part do not pro-vide direct, empirical evidence of the drivers of suchtrends.

Third, we outline findings from studies utilizingtime series and other inferential statistical approachesto draw conclusions about the drivers of changingpublic perceptions, such as socioeconomic and mete-orological factors. These studies provide some of themost robust insights into the reasons behind chang-ing public perceptions. They are, however, limited toexaminations using a limited number of variables, andhave been conducted only in developed nations.

Fourth, we outline insights obtained from asmall number of qualitative (e.g., anthropological)studies that have directly considered a temporal com-ponent to public perceptions. Whilst qualitative workis able to offer in-depth insights into peoples under-standing of climate change, there has to date been littlefocused analysis undertaken of how such understand-ing has itself changed over time.

Volume 6, January/February 2015 2014 The Authors. WIREs Climate Change published by John Wiley & Sons, Ltd. 37


Publications identified in Web of Science databasen = 2,370 studies excluded following screening of titles, abstracts

Publications retained for further screening of full textn = 205 excluded following further screening

n = 2,610

n = 240

n = 35

n = 57

Publications retained for reviewAdditional studies incorporated from grey literature / web(n = 18) and of which authors previously aware (n = 4)

Publications and studies included in the reviewTypes of studies1. Early studies (n = 7)2. Descriptive polling (n = 33)3. Studies linked to events / time series (n = 12)4. Qualitative longitudinal studies (n = 5)

FIGURE 1 | Systematic review process.

The body of work obtained from the literaturereview is summarized by study type and key featuresin Table 1.

TRENDS IN PUBLICPERCEPTIONSINSIGHTSFROM THE LITERATURE

We now examine in detail the identified literature, inorder to provide an overview of changes in publicperceptions of climate change since the 1980s.

Early Cross-Sectional ResearchPublicPerceptions in the Late 1980s and Early1990s (Study Type 1)We begin by considering seven small-scale,cross-sectional studies carried out in the late 1980sand early 1990s in the United States, New Zealand,and Sweden. For ease of comparison, we also discusshere a later replication of one of these early studiesundertaken in 2009. The studies considered herewere some of the first to examine perceptions ofclimate change, at a point in time when it remained arelatively novel concept in public discourse.

One of the earliest such studies entailed ethno-graphic interviews with householders, carried outacross four U.S. states between 1989 and 1992.40,41

This work concluded that climate change was startingto feature in peoples understanding through beingintegrated into their existing conceptualizations ofenvironmental risks. For example, climate changewas often categorized as a subset of stratosphericozone depletion, such that the burning of fossilfuels was perceived to contribute to the hole inthe ozone layer. Climate change was also often con-flated in peoples understanding with localized airpollution. Interestingly, this early research found thatparticipants were of the view that the weather hadalready changed, an observation which has fre-quently been repeated in subsequent studies of publicperceptions. 42

Early research carried out in New Zealand in198943 concluded that, at this time, awareness ofthe subject of climate change was already universal(96% of a national survey sample having heard of it)although knowledge about the basic facts of climatechange was limited, with almost half the respondentsknowing nothing about its causes, and only a quarteraware of the relevance of fossil fuel use. As with earlyU.S. studies, a confusion between ozone depletion



TABLE

1Overviewof

Stud

iesRe

tained

from

theSystem

aticRe

view

Stud

yCitatio

nsStud

yType

No.Stud

ies

Overviewof

Stud

yType

Metho

dology

andDa

ta

Coun

try/Locatio

n

(No.Stud

ies)

Streng

ths

Limita

tions

Refs40

,41,

43,

454

81

7(peer-review

ed)

Early

cross-sectional

research

Primarily

small-scale,

qualita

tiveand

survey-based

US(5),Sw

eden

(1),

New

Zealand(1)

Perm

itsinsigh

tsat

anearly

time-po

int

Limite

dto

developed

natio

nsanddecit

interpretatio

n

Refs20

,25,

26,

313

3,57

59,

648

1,88

,90

94

215

(peer-review

ed)

18(grayliterature/

web-based

repo

rts)

Opinion

polls

and

large-scalesurvey

data;p

eer-review

edstud

iesproviding

overview

sof

datasets,p

lussurvey

data

repo

rtsfro

mpo

lling

organizatio

nsandthink-tanks

Publicop

inionpo

lling

,data

collectionon

line,

postal,face-to-fa

ce

US(13),

International(10

),Europe

(4),UK(4),

Germany(1),

Australia

(1)

Largerepresentative

datasetsoftenat

internationalscale;

somepo

lling

uses

repeated

measures

over

long

time

perio

ds

Polling

limite

dto

small

numbero

fsurveyite

ms

testingbasicattitud

es;

strong

bias

towardUS

data;m

ajority

ofstud

ies

containon

lydescrip

tive

statistics;cross-natio

nal

comparison

saffected

bydiffe

ringno

tions

ofwhat

constitutes

clim

ate

change

Refs96

,97,

101,

104,

105,

112

115,

122

124

312

(peer-review

ed)

Time-serie

sanalyses

andrepeated

measuresbefore/afte

rsign

icant

events

Second

aryanalysis

testingcausal

relatio

nships

betw

eenclimate

change

perceptio

nsandsocioeco-

nomic/m

eteorological

factors

US(8);US&Europe

(1),Europe

(1),

Japan&UK(1),

Australia

(1)

Inferentialstatistics

used

toanalyze

factorsbehind

changing

public

perceptio

ns

Limite

dto

developed

natio

ns;reliant

upon

second

arypo

lling

data

Refs13

513

94

4(peer-review

ed)

1(doctoralthesis)

Qualitativestud

ies

entailing

long

itudinal

analysisand/or

commentaryon

changing

perceptio

ns

Anthropo

logical/

ethn

ograph

ic/

discou

rseanalytic

Russia/Siberia(3),

UK(1),Peru

(1)

Perm

itsin-depth

insigh

tsover

time,

andapprehension

ofcultu

rally

specic

notio

nsof

climate

change

Littledeliberateuseof

qualita

tivelong

itudinal

metho

dology

Vo lume 6, January/February 2015 2014 The Authors. WIREs Climate Change published by John Wiley & Sons, Ltd. 39


and climate changewas identifiedstudy participants,e.g., suggested that ozone depletion was a causeof climate change, or related higher temperaturesassociated with climate change to increased ultravioletradiation.

This early work for the most part applied adeficit model44 in appraising public understand-ing, concluding, e.g., that peoples views wereseriously at variance with the scientific models ofglobal warming.41 Likewise, mental models andsurvey-based research carried out in 1992 in theUnited States45,46 reported that public understandingsuffer[s] from several basic misconceptions.45 Thisresearch again made the observation that most par-ticipants confused climate change with stratosphericozone depletion, and were unaware of the causal roleof anthropogenic carbon dioxide. Participants at thistime-point were, however, argued to have a reason-able understanding of the consequences of climatechange (e.g., temperature increases and changes toprecipitation).

The mental models research described above isof particular interest when tracking changes in pub-lic perceptions over time, as this has been one of theonly pieces of early academic research to have beenreplicated at a later date. Some 17 years after theiroriginal research46 was carried out, in 2009, levelsof awareness and comprehension of climate changewere found to be far higher, at least among edu-cated individuals.47 Respondents in the more recentsurvey were also more likely to mention fossil fueluse and energy use in general, as a cause of cli-mate change; conversely, the erroneous associationwith ozone depletionwasmuch diminished. Strikingly,however, this research also found that peoples convic-tion that anthropogenic climate change is occurringwas no higher in 2009 than it had been in 1992, thatnonanthropogenic causes were even more frequentlycited than previously, and that conflation of the con-cepts of weather and climate were as pronounced asthey had been at the time of the earlier research.

Another early research project, using mixedmethods and carried out in 1990 in Sweden,48

observed that whilst a majority (92%) of participantshad heard of climate change, most were unaware ofits causes and consequences. A conflation with ozonedepletion was again observed, and linkages betweenenergy use and climate change were poorly perceived.For example, around a third of respondents preferredmethod for addressing climate change was throughreducing chlorofluorocarbon (CFC)-using aerosols,with only 6% opting for energy saving.

These early studies, and the public misconcep-tions reported therein, related largely to the physical

and scientific aspects of climate change. A more com-plete exploration of perceptions surrounding the per-sonal and societal implications of climate changewould only become a focus in later work.

We next consider research which has examinedpublic perceptions of climate change over time usingnationally representative polling data taken at multi-ple time-points.

Survey DataChanges in Indicators overTime (Study Type 2)Multiple polls and research projects examining pub-lic perceptions of climate change are now regularlyundertaken across the world. Here, we consider find-ings from 33 studies, which we divide into four indica-tive time periods broadly reflecting both the typesof survey findings obtained and the shifts in empha-sis of researchers over these time periods: (1) 1980sand early 1990s, showing increases in knowledge andawareness; (2) mid-1990s to the mid-2000s, a periodmarked by growing public concern but also variabilityin opinion; (3) mid- to late-2000s, showing declin-ing public concern and increasing skepticism in somenations, with polarization of viewpoints within andbetween nations; and (4) 2010s, which so far suggestpossible stabilization of public concern about climatechange. Reflecting the greater availability of U.S. data,this is discussed in more detail; however, as far as pos-sible we have endeavored to give equal attention toother regions.

Surveys and opinion polls since the 1980s haveassessed public perceptions in a variety of domainsthrough the use of precisely worded questions. Afocus of many surveys has been to measure publicattitudes toward the physical and scientific aspects ofclimate change (e.g., beliefs about an anthropogeniccomponent); other questions have examined the extentto which people see climate change as a problemor threat; as well as gauging levels of public concernand support for action at the national and individuallevel. Although a formal thematic analysis of the typesof questions asked across these studies is beyondthe scope of the present review, some of the mainconstructs of interest are presented in Table 2, togetherwith example survey items and response categories,and illustrative citations.

Whilst we review survey studies from acrossthe globe, it is important to note that mean-ings of climate and climate change vary withinand between cultures, and that for nonscientists,local cosmologies,4951 and emotional and sensoryperceptions52,53 are critical to the way climate changeis interpreted. Rudiak-Gould,50 e.g., points out that



TABLE 2 Survey Measures of Public Perceptions

Question Focus Illustrative Survey Item Response Options

Example Studies in

Which Item Reported

Awareness andunderstanding ofclimate change

Have you heard or read anythingabout the issue of global warming?

Yes/no/not sure Refs 20, 32

Thinking about the issue of globalwarming, how well do you feel youunderstand this?

Very well/fairly well/not verywell/not at all

Ref 20

Existence of climatechange at presenttime

As far as you know, do you personallythink that the worlds climate ischanging, or not?

Yes/no/dont know Refs 73, 74, 105

Do you think that global warming ishappening?

Yes/no/dont know Ref 70

Causes of climatechange

Please list all of the things that youthink could cause global warming

Open-ended response Refs 46, 47

Assuming global warming ishappening, do you think it is ?

Caused mostly by humanactivities/caused mostly bynatural changes in theenvironment (also none of theabove and other)

Ref 70

Perceived threat fromclimate change

How much you think [the greenhouseeffect] threatens your personalhealth and safety?

7-point scale from minimal threatto clear threat

Ref 58

Please tell me how serious a problemyou personally believe globalwarming to be in the world?

Very serious/somewhat serious/notvery serious/not serious atall/dont know

Refs 33, 57

How serious a problem do you thinkclimate change is at this moment?

10-point scale from not at all aserious problem to extremelyserious

Refs 71, 88

How serious a threat is globalwarming to you and your family?

Very serious/somewhat serious/notvery serious/not serious atall/dont know

Ref 80

Seriousness of climatechange compared toother issues

Which of the following do youconsider to be the single mostserious problem facing the world asa whole?

Eight possible problemspresented, including climatechange, the economicsituation, and armed conicts

Refs 71, 88

What do you think will be the mostimportant problem facing the worldin the future?

Open-ended response (climatechange coded together withother problems)

Ref 154

Certainty of climatescience (with respectto existence,causation)

Most scientists agree that humans arecausing climate change

5-point scale from strongly agreeto strongly disagree

Refs 23, 74

To the best of your knowledge, whatpercentage of climate scientiststhink that human-caused globalwarming is happening?

0% to 100% Ref 70

Is there solid evidence that theaverage temperature on earth hasbeen getting warmer over the pastfew decades, or not?

Yes, mostly because of humanactivity/yes, mostly because ofnatural patterns/dont know

Refs 78, 79, 92, 112, 115, 122



TABLE 2 Continued

Question Focus Illustrative Survey Item Response OptionsExample Studies inWhich Item Reported

Personal concern or worryabout climate change

[Do] you personally worry aboutglobal warming a great deal, a fairamount, only a little, or not at all?

A great deal/a fair amount/only alittle/not at all

Refs 20, 31, 64, 124

Are you very worried, somewhatworried, not very worried or not atall worried about global warming?

Very worried/somewhatworried/not very worried/not atall worried

Ref 59

How concerned, if at all, are you aboutclimate change, sometimes referredto as global warming?

Very concerned/fairlyconcerned/not veryconcerned/not at allconcerned/dont know/noopinion

Refs 73, 74, 91

Requirement for action onclimate change (atnational and personallevel)

Do you think the United Statesshouldor should notagree toabide by the provisions of the Kyotoagreement on global warming?

USA should abide/USA should notabide

Ref 31

[Regarding] whether it is necessary totake steps to reduce the impact ofhuman activities thought to causeglobal warming or climate change.Would you say that you believethat ?

It is not necessary to take anysteps/it is necessary to takemodest steps over the comingyears/it is necessary to takemajor steps starting verysoon/dont know

Refs 32, 65

I am prepared to greatly reduce myenergy use to help tackle climatechange

5-point scale from strongly agreeto strongly disagree

Refs 74, 116

Open-ended/spontaneousresponse permitted

When you think of global warming,what is the rst word or phrase thatcomes to your mind?

Open-ended response Ref 26

Would you like to make any furthercomments about climate change?

Open-ended response Ref 72

Items are abridged in some cases; some studies cited conduct secondary analysis of polls or overview previous findings.

the concepts most commonly used to correspond toclimate and climate change in the Marshall Islandscan refer to a broad range of environmental andcultural phenomena, including social transitions andeven beliefs about changes to the passage of timeitself. This author suggests that similar processesare likely to be relevant in other parts of the world,particularly given that for many societies ideas ofculture and nature are not conceptually distinct.Although some separate research has argued thatshared ideas about climate change do indeed existacross diverse cultures internationally,54 the potentialfor cross-cultural variability in notions of climatechange should nevertheless be borne in mind as alimitation in the case of the international comparisonsof climate change perceptions reported in this sectionof the study.

With respect to intranational variability in cli-mate change perceptions over time, a separate issuearises as to the potential for movement on key

indicators (e.g., peoples level of concern or acceptanceof the reality of climate change) to be overinterpretedas demonstrating a significant shift in public mood,rather than as reflecting the typical variability that isto be expected between polls and over time.55,56 Withrespect to public perceptions of climate change, therehas at times been a tendency in media reportsas wellas the research literatureto assert such shifts withoutreference to criteria (particularly any statistical basis)required to confidently draw those conclusions.

Although it is unclear at the present time whatmight constitute normal variation in public per-ceptions of climate change over time, in an effort topreclude the drawing of undue inferences from pollingdata in the present review, we interpret changes overtime taking into account the margins of errors of thesurveys used. The margin of error provides an indica-tion of how reliable results are, and is dependent onpopulation and sample size. Most of the studies andpublic opinion polls reviewed in this section of the



study have a sample size of around 1000 (which yieldsan approximate margin of error of 3% at the 95%confidence level). We therefore only report differencesbetween two time-points where confidence intervalsdo not overlap (for most surveys, corresponding to adifference between two time-points of 6% or more)except in cases where findings are supported by sta-tistical tests by the original authors, or are based onthe interpretation of multiple polls by the authors ofthe studies reviewed.

1980s to Early 1990s: Increasing Knowledgeand AwarenessBeing the point in time at which data on publicopinion toward climate change was just starting tobe gauged, data from the 1980s are inevitably sparsecompared to recent years. However, such evidenceas there is suggests that during this decade publicawareness, knowledge, and concern rose steadily, soonreaching levels comparable to those obtained in recentyears.

Based on a review of several hundred pollingstudies carried out in the United States, includingat this early time period, Nisbet and Myers20 con-cluded that public awareness about climate changeunderwent a rapid increase through the second halfof the 1980s. These authors presented findings fromseparately conducted national polls that showed thatwhereas in 1986 less than a half of respondents(between 39 and 45%) reported having heard or readanything about climate change, this proportion rose toaround three-quarters (74%) of respondents by 1990.These authors noted, however, that levels of overallunderstanding were limited.

As in the earlier small-scale studies describedabove, larger-scale survey studies also point to aconflation with localized air pollution, CFCs andozone depletion in respondents attribution of causesof climate change33. Nevertheless, even at this earlypoint in time, respondents from many parts of theworld were already of the view that climate changehad begun to happen.57,b

Despite limited levels of understanding duringthis early period, polls nevertheless show public con-cern rose rapidly. In one of the first polls of its kind tobe conducted, only 43% of U.S. respondents in 1982saw climate change as either a very or somewhatserious problem. Over three subsequent survey waves,this figure reached 75% by 1989,58 as illustrated inFigure 2. This finding is paralleled in other indicatorstaken during the late 1980s measuring the perceivedlevel of threat from climate change. For example,whereas only 37% of respondents in 1984 perceivedthat climate change constituted a future problem for

ones children or grandchildren, this had risen to 65%by 1988.58

Findings from national surveys across 24 coun-tries in 199233,57 also showed that pluralities in eachof these countries already viewed climate change as asubject of concern, with just over half of all respon-dents at an international level rating it as a veryserious problem. There was substantial variabilitybetween nations at this time, howeverranging from26% of Nigerians and 34% of Finns considering cli-mate change to be very serious, to 72%of Portugueseand 73% of Germans.

Some limited polling data also offer insightsinto changing perceptions in Europe around this time.Survey research from 1988, based on over 10,000respondents from across Europe, found that morethan three-quarters of respondents were alreadyworried about climate change (43% reported beingvery worried at this time, a further 33% somewhatworried). In a subsequent survey wave in 1992, theproportion of Europeans assigning these categoriesthen rose to almost 9 of 10 respondents (with 62%very worried and 27% somewhat worried by thispoint)59 although it should be noted there were dif-ferences in question wordings used between the 1988and 1992 survey waves.

These studies, taken together, suggest that at thetime climate change was coming to have a degree ofpolitical prominence toward the end of the 1980s onboth sides of the Atlantic60,61 levels of public aware-ness and concern were already reaching relatively highlevels. Given the associations made with a range ofother topics, this may however have been connectedto a nonspecific growth in public environmentalismover previous decades62 as much as an appreciationof climate change per se.

Mid 1990s to Mid 2000s: Growthand Fluctuation in ConcernWhereas the 1980s and early 1990s were marked by agrowth in basic awareness and concern about climatechange worldwide, the period that followed entailed asustained growth of public concern overall, but withthis occurring alongside substantial international andintranational variation. The overall growth in concernmirrors a rise in media attention to climate change, inturn associated with growing scientific evidence andpolitical attention.63

In the United States, the extent to which thepublic report they personally worry about climatechange has risen and fallen several times since thelate 1980s.20 As shown in Figure 3, the remarkablevolatility in this indicator of personal concern hasbeen particularly evident since the late 1990s; we also



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FIGURE 2 | Early trends in public perceptions in the United States. Data points show how serious U.S. public survey respondents consideredclimate change to be during the 1980s. Data obtained from Ref. 58 (n 1000 at each time-point).

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FIGURE 3 | Changing levels of worry about climate change in the United States. Data points show the extent to which U.S. public surveyrespondents reported personally worrying about climate change over a 25-year period. Data combined from Refs 20 and 64 (n 1000 at eachtime-point).

include here data showing continuing variation to thepresent time.20,64

Despite the temporal variability in this measure,a review of more than 40 U.S. surveys focused on theearly 2000s nevertheless concluded that the weightof public opinion in the period 20012004 strongly

favored U.S. participation in the Kyoto Protocol anddecisive action on climate change, in direct contrastto national policy at this time.31 In 2004, e.g., nearlythree-quarters (71%) of U.S. respondents supportedthe countrys participation in the Kyoto Protocol, withonly 19% opposing.31



By the year 2007, support for substantialaction to mitigate climate change was evident at theinternational level. Brechin32 has argued that datafrom several cross-national polls point to growingpublic concern about climate change worldwide inthe 2000s, as well as to strong public support at thistime for climate mitigation policies. Likewise, froma synthesis of eleven international polls conductedbetween 2003 and 2007, Kull et al.65 argued thatconcern about climate change cross-nationally was bynow widespread and growing, with large majoritiesacknowledging that human activities caused climatechange, and supporting policies aimed at emissionsreduction. For example, the proportion of publicsacross 14 countries viewing climate change as a veryserious problem increased between 2003 and 2006(with only two further countries for which repeatedmeasures data was available, India and Mexico,showing slight decreases in this measure over time).66

Similar comparisons between 2000 and 2006 alsoshow broad-based increase in international concern.67

Likewise, a poll of 10 European countries carried outin both 2005 and 2007 showed a sharp rise in thepercentage of respondents who considered it verylikely they would be personally affected by climatechangeincreasing from 36 to 55% over this timeperiod.68

Mid 2000s to Late 2000s: Increasing Skepticismand PolarizationIn general, the interpretation placed by researchersupon polls up to the mid-2000s affirms a widespreadincrease in awareness among the public, and theestablishment of a popular consensus for action onclimate change, albeit against a backdrop of varyingpersonal concern in some countries. Survey studiesfrom the latter part of the 2000s and early 2010shave, by contrast, often emphasized the proliferationof public doubts and skepticism about climate change.Perhaps most surprisingly, given the growing scientificconsensus on the basic reality and human contributionto climate change, have been indications in some partsof the world that publics have become less acceptingof these matters. Although trends at this time doappear to indicate growing skepticism about climatechange, it is nonetheless important to note that clearmajorities in many countries still expressed high levelsof concern and recognition of the problem throughoutthis period.30

Between the years 2006 and 2009, a declinewas observed in the proportion of U.S. citizensof the opinion that global temperatures were ris-ing, and that weather patterns in their localitieswere changingalthough a large majority did still

accept the former proposition.69 Separate data like-wise point to a sharp drop between 2008 and 2010in the proportion of U.S. citizens who accepted cli-mate change is happening, that it had an anthro-pogenic component, or that there was scientific con-sensus about its human causes.70 During the mid- tolate-2000s, related research found that the types ofimagery people spontaneously associate with climatechange moved progressively in a skeptical direction.Smith and Leiserowitz26 carried out an analysis ofresponses to open-ended survey items which askedparticipants to state the first thought or image thatcomes to mind in relation to climate change. Based onanswers provided over four time-points, these authorsshowed that through the 2000s in the United Statesthe extent to which climate change was associatedwith what they term naysayer imagery increased dra-matically. This imagery centered most prominentlyon associations with climate change as a conspiracytheory, together with denials of the existence of cli-mate change and assertions that it was a natural phe-nomenon. Whilst naysayer imagery accounted forless than 10% of responses in 2002, this rose to 23%in 2010.

Similar findings have been obtained elsewherein the developed world. Across Europe as a whole,over three surveys conducted during 2008 and 2009, adecline in the perceived seriousness of climate changewas observed.71 In Australia, an increasing tendencyfor survey respondents to view climate change as exag-gerated and/or to denigrate policy designed to addressit, was recorded across the 20082011 time period.72,c

Within Great Britain, too, survey findings from themid-2000s pointed to an increase in public doubtsabout the basic reality of climate change. Whereasonly 4% of people in 2005 were of the view that theworlds climate is not changing, this had risen to morethan one in seven people (15%) by 2010, with the per-ceived risk from climate change also decreasing overthis time period.73,74 Separate research in England byWhitmarsh25 drawing on survey data from 2003 and2008 drew the conclusion that the most significantelement of increasing public skepticism concerned theperception that the seriousness of climate change isexaggerated, with an almost doubling of this percep-tion over the 5-year period. Likewise, Ratter et al.75

point out the declines in several measures of publicperception of risk from climate change in Hamburg,Germany, around this time. These authors note, e.g.,that the proportion of respondents considering climatechange to be a serious threat dropped from 17% in2008 to 9% in 2011.

Whilst the research described above was notdesigned to directly attribute reasons for increases in



skepticism over time, both the Smith and Leiserowitz,and Whitmarsh studies25,26 argued that a process ofpoliticization of climate changewas likely to have beena significant contributing factor. The former authorssuggested that with the shift in political context in theUnited States following the election of Barak Obama,climate change came to constitute a litmus test, withconservative Republicans aligningwith climate skepticpositions as ameans of differentiating themselves fromDemocrats.

Other survey-based research would appear toempirically bear out the notion of growing polariza-tion, particularly in the latter 2000s. McCright andDunlap76 demonstrate a statistically significant inter-action between political orientation and survey yearover the 2000s in the United States. These authors alsopoint out that whilst political polarizationwith respectto peoples views on climate change had already begunin the early 2000s, the division is increasingly evidentbetween 2008 and 2010. Whereas in 2001 there wasan 18% difference between liberals (67%) and conser-vatives (49%) concerning whether climate change hadalready begun to happen, this develops into a muchlarger 45-point difference by 2010, at which time 75%of liberals and 30% of conservatives were of thisview.

Separate analyses affirm that polarization of theU.S. publics views on climate change gathered pace inthe late 2000s.7779 Brewer78 observes that increasingpartisan disparity occurred subsequent to Obamaselection in 2008 on a survey indicator examiningacceptance of the reality of climate change, althougha widening gap was less clear for other measuresexamined. Guber79 argues that U.S. citizens weremorepolarized on the topic of climate change in 2010 thanat any other point in time, or on any of the other social,economic, and foreign policy topics considered in heranalysis.

In addition to variability and polarizationobserved within the United States in particular, it isimportant to note that survey research also pointsto substantial heterogeneity in the ways public per-spectives have changed over time at an internationallevel.

The very broadest international trends acrossthe late 2000s are illustrated by polling across 111countries, carried out by Gallup in both 20072008and 2010.80 These data show that across this timeperiod there were wide regional and global varia-tions in public opinion trends, both with respect tothe perceived risk arising from climate change, andthe recognition of an anthropogenic component. Inboth the United States and Western Europe, sharpdeclines occurred between 2007/2008 and 2010 in the

proportion of respondents viewing climate change aseither a somewhat serious or very serious threat tothemselves or their family. By contrast, in Latin Amer-ica and sub-Saharan Africa increasing proportions ofpeople considered climate change to represent a threatin these termsalthough the differences over time forthese regions are relatively small and may be closeto the margins of error for these survey data. Con-cerning the extent to which respondents saw climatechange as being connected to human activities, again,declining proportions were of this view in the UnitedStates andWestern Europe, whereas in parts of Africa,developing Asia, and Latin America, the human com-ponent to climate change was increasingly coming tobe acknowledged.80

Divergences in public opinion are also obtainedon a country-by-country basis toward the end of the2000s. Table 3 shows broad regional trends basedon Gallup data between 2007/2008 and 2010 asdescribed above, as well as from nations selected toillustrate both rising and falling public risk perceptionworldwide. Whilst it cannot be stated with certaintythat the smaller changes shown in this Table aresignificant (e.g., a 2% change in risk perceptionfor the Commonwealth of Independent States) thesedata can nevertheless be considered illustrative of theheterogeneity of trends occurring worldwide over thistime period.

Separate research carried out by the PewResearch Centers 20072010 Global AttitudesProject81 has also concluded that there were pro-nounced variations cross-nationally at this time,with some nations reporting sharp increasesandothers sharp decreasesin the percentages of peopleconsidering climate change to be a very serious prob-lem. Reasons for such international variations anddiverging trends in opinion are little understood andcomplex, although clearly aspects of the surroundingphysical and social contexts are important, includ-ing levels of risk exposure, cultural values, politicalcontext, and the nature of media coverage. Withrespect to the growth in concern in Latin America inthe late 2000s,80 this may be related to a growth inclimate justice activism linked to left-wing politicalactivism at this time, as well as to the occurrenceof extreme weather events.82,83 Conversely, recentanalyses have argued that in the United States andother Anglophone countries, right-wing think tanksand media outlets have been key players in a con-servative counter-movement that has emerged tochallenge climate policy.8487 We consider studies thathave carried out empirical analyses of the influence ofsuch political factors on changing public opinion in asubsequent section of the review.



TABLE 3 Proportions of Survey Respondents Considering ClimateChange to be a Threat

% Considering Climate

Change to be a Threat

Region or Country 20072008 2010 Change

Latin America 67 73 +6Sub-Saharan Africa 29 34 +5Commonwealth of

Independent States42 44 +2

Developing Asia 31 31 0

Middle East & North Africa 42 37 5Developed Asia 79 74 5Eastern/Southern Europe 67 60 7USA 63 53 10Western Europe 66 56 10

World average 41 42 +1

Mongolia 30 54 +24Philippines 42 60 +18Ecuador 69 85 +16Uganda 30 45 +15Morocco 29 41 +12Haiti 35 18 17Sudan 42 26 16France 75 59 16Czech Republic 39 28 11United States 63 53 10

Data obtained from Ref 80.

Late 2000s to the Early 2010s: A New Phasefor Public Perceptions?Cross-national divergences in public opinion trendsappear to be continuing to the present time.Nevertheless, there are signs that in some partsof the world public concern about climate change isstabilizing and in some cases increasing.

Surveys undertaken across the 28 member statesof the EU between 2009 and 2013 suggest that therelative importance of climate change has remainedlargely consistent over this more recent time period.88

At each of three time-points (2009, 2011, and 2013)between 16 and 20% of respondents considered cli-mate change to be the single most serious problemfacing the world as a whole. When permitted to selectmore than one area of concern, around a half ofrespondents consistently considered climate change tobe among the most serious problems facing the worldin each of the 20092013 surveys.88

There have been less consistent trends at aninternational scale over this time period. Globescandata appear to show that at an aggregate, globallevel, concern has continued to decrease since 2009.89

Disaggregated by country, however, these data suggestthat whereas concern in many developed countries(UK, USA, Canada, and France) has stabilized duringthe 2010s, the trends for developing countries havebeen more mixed, with some countries (e.g., China,Mexico, and Kenya) seeing falls in public concern.90

Separate survey data from Britain available to 201391

suggest that the proportion of people expressing con-cern about climate change has continued to declineover this period, however. Compared to 82% express-ing concern in 2005, and 71% in 2010, only 60% didso by 2013. In Britain, doubts about the reality of cli-mate change have likewise continued to increase, withalmost one in five (19%) of respondents doubting itsexistence in 2013, compared to only 9% in 2005.91

Some U.S. polls appear to point to a halt inthe downward trend on a number of indicators, andsuggest that climate change may be returning to thepublic agenda. Data from the Pew Research Centershow that the proportion of the U.S. public of the viewthat there is solid evidence that the Earth is warm-ing has increased steadily from a low point of 57%around 2009 to 67% by October 2013.92 Similarly,the proportion of people stating that human activityis the main cause of climate change has risen from36 to 44% over the same period, a trend observedamong Republican as well as Democrat voters.92 Sepa-rate polling data to 2014 further show a steady growthin the proportion of Americans of the view that climatechange has a human cause from 2010 onward, whichis again observed among both Democrat and Repub-lican voters.93 This is accompanied by an increase inthe number of people worrying a great deal aboutglobal warming from 25% in 2011 to 34% in 2014(see Figure 3). Other research in the United States sug-gests more modest increases in acceptance and con-cern about climate change, however. The Yale Projecton Climate Change Communication reports that moreU.S. respondents accept that climate change is hap-pening in 2014 (64%) than in early 2010 (57%), adifference that is only slightly larger than the marginsof error of the surveys; furthermore this figure remainslower than that obtained by this project towardthe end of the 2000s.94 Similarly, the proportion ofrespondents who report being worried about climatechange, whilst largely stable over the 2010s to themost recent data point in 2014, is nevertheless lowerthan that obtained by this project in the late 2000s.94

It is unclear, and would be unwise to speculate,as to the likely direction of future trends in these



types of polling data. It may tentatively be concludedfrom the more recent evidence available, however, thatthe declines in some measures observed in the 2000sappear to have slowed in the United States and Europeas a whole, although this pattern is not observed inmany major developing countries. Research attentionis now required to examine prospective trends andpatterns in public perceptions across multiple regions,with a view to understanding how and why thesedevelop in the coming years.

Time Series Analyses and Studies ExaminingDrivers of Change (Study Type 3)The trends described above can plausibly be accountedfor by a range of factors. Particularly with respectto the declines in public concern observed duringthe second part of the 2000s, contributory factorsmay include cycles of media and political attention,deliberate attempts by some actors actively to under-mine climate science, and a wider politicization of cli-mate change with the associated public distrust thisbrings.30 One prominent theoretical explanation hasbeen that people only have a finite pool of worryavailable and that where other pressing concernssuch as the implications arising from the financial cri-sis of 2008dominate, then these may diminish theattention paid to climate change.95

Given the variety of possible explanations forchanging public perceptions, analyses which utilizelongitudinal data to directly examine the underlyingreasons for changes in public perceptions are partic-ularly valuable. Studies of this sort can be dividedinto three types, each of which we consider below:(1) measurement of public perceptions of climatechange before and after the occurrence of significantevents (five studies); (2) time-sensitive analyses of therelationships between meteorological data (e.g., tem-perature) and public perceptions (four studies); and(3) time series analyses that use data from severaltime-points to test the relationships between socioeco-nomic variables and attitudes toward climate change(three studies).

Public Opinion Before and AfterSignificant EventsDirectly prior to the Kyoto conference in 1997 and thesigning of the Kyoto Protocol to limit internationalgreenhouse gas emissions, a substantial effort wasmade by the Clinton administration in the UnitedStates to build public support for action on climatechange, leading to what Krosnick et al. describe as amajor national debate on the subject.96 In order toascertain whether the heightened media attention and

changed political landscape at the time had affectedAmericans beliefs and attitudes toward climatechange, these authors administered a survey in twowaves, the first in September/October 1997 and thesecond between December 1997 and February 1998.This study found that among the U.S. public as awhole, and indeed among those for whom climatechange was a personally salient topic, attitudes werelargely unaffected by the 1997 debate. However, evi-dence was obtained that the debate did have a polar-izing effect, whereby Democratic respondents movedin favor of action on climate change and on a rangeof other measures (in line with the Clinton admin-istrations position) at the same time as Republicanrespondents moved in the opposite direction. Thesefindings are in line with the longer-term polling studiesoutlined above showing polarization of opinion in theUnited States,7679 and furthermore underline howkey national events such as the attention in late 1997to climate change in the context of the Kyoto Pro-tocol can trigger shifts in public opinion in opposingdirections.

A rather different form of communicationaround climate change occurred with the release ofthe 2004 film The Day After Tomorrow, in which amajor environmental disaster occurs as a consequenceof climate change. As Leiserowitz et al.97 show, thisfilm generated more than 10 times the media cov-erage in the United States of the 2001 IPCC report.Because of these factors, as well as the large numberof people who viewed the film (around 30 millionin the United States), we include consideration ofthis study here as a national event which had thepotential to affect public opinion on a large scale.Using a quasi-experimental design, Leiserowitz et al.argued that for those who viewed the film, attitudestoward climate change had altered (e.g., they reportedmore concern about climate change, and morepro-environmental behavioral intentions). Based onnationally representative surveys undertaken immedi-ately before and after the release of the film, the studynevertheless concludes that The Day After Tomorrowwas not itself influential enough to have significantlyaltered U.S. public opinion at a national scale.

Another putative influence on public opinionwas the so-called Climategate affair of late 2009,in which emails obtained from the University ofEast Anglias Climate Research Unit (CRU) gener-ated extensive skeptical commentary about the sci-ence of climate change. This has been widely per-ceived as a particularly damaging episode for pub-lic trust in climate science.98,99 However, despitethere being extensive consideration in the researchliterature of the implications of Climategate for the



conduct and representation of climate science (e.g., seeGrundmann99), there has to our knowledge been onlyone published study which has directly examined theimpact of this episode on public opinion (althoughsee Anderegg and Goldsmith100 for a discussion of itsimpact on internet search terms as an indicator of issuesalience).

Drawing on data gathered in 2008 and thenin 2010, Leiserowitz et al.101 measured respondentsbelief in the reality and human causation of cli-mate change, degree of personal concern, and trustin information sources. The 2010 survey was car-ried out around 2months after the CRU e-mails werefirst posted online and 1month after the story hadappeared in mainstreammedia. In addition to replicat-ing items from the 2008 survey, this second survey alsoasked a series of questions about respondents recallof, and attitudes toward, the Climategate episode.Over this time period, these authors found there hadbeen sharp declines in several attitudinal measures,including trust in climate scientists. They argued fur-thermore that this could be directly connected to peo-ples degree of exposure to the story. In line withthe studies of opinion polarization described above,this effect was, however, largely confined to thosewho were already predisposed to skepticism about cli-mate change, whether measured by political orienta-tion (Republicans) or worldview (Individualists).

A limitation of the Climategate study describedabove is its reliance on self-report (respondents indi-cated the extent to which they were aware of thestory). As such, it is possible that those reporting atten-tion to this news story were also those already lesstrusting of climate science. The study authors indeedacknowledge that a perfect storm of other majorevents around this time (including the worldwide eco-nomic recession and shifts in the political landscape)may have contributed to a wider social attenuationof risk around climate change, and broader changesin public attitudes.101 It is also worth noting that aseparate UK poll commissioned for the BBC in early2010 showed that, among those who stated they hadheard news stories about flaws or weaknesses in thescience of climate change, there was no evidence thatthis media attention had led to more people reportingreduced levels of conviction about the risks of climatechange, than reported higher levels of conviction as aresult.102

Research examining public perceptions of cli-mate change has often been carried out in conjunctionwith that examining perceptions of other environmen-tal and technological risks as well as attitudes towardenergy policy, not least due to the fact that nuclearpower has in more recent years been presented as a

low-carbon technology able to contribute to climatechange mitigation.103 Following the disaster thatoccurred at the Fukushima nuclear power complexin Japan in March 2011, two separate studies haveexamined whether there were subsequent shifts inpublic attitudes toward climate change, as well astoward nuclear power. Bird et al.104 found that publicconcern about climate change in Australia reducedfollowing the accident, at the same time as pub-lic support for nuclear power declined. Poortingaet al.105 also observed changes in public attitudestoward climate change in the UK (this study drewon some of the same measures reported in Spenceet al.74). In Japan, however, public acceptance of thereality of climate change was as high after Fukushimaas beforesuggesting that, whilst the accident hadaffected Japanese attitudes to nuclear power, this didnot extend to attitudes to climate change.

The two studies described above showed thatUK and Australian attitudes toward climate changealtered in the wake of Fukushima, although neitherclaimed that this demonstrates that the accident wasthe direct cause of this. Bird et al. did suggest thatrelative risk perceptions (whether nuclear power wasseen as worse than climate change) may have beenaffected. However, as Poortinga et al. argued, thetrends observed in these studies were instead likelyto have been connected to other factors influencingpublic opinion at the time, such as structural economicconditions.

The Role of Weather Conditions and EventsAt the time of rising public skepticism in the late2000s, some commentators suggested that this couldbe connected to the unusually cold weather in Europeand the United States.106,107 Albeit that there areimportant distinctions between the two concepts,weather is strongly associated with climate bynonexperts37 and current temperature may be used(consciously or not) to draw conclusions about thevalidity of climate change. Peoples perceptions of tem-perature anomalies (e.g., whether they are of the viewthat recent weather has been warmer or colder thanusual) can also affect beliefs.108110 It is thus plausi-ble that changingmeteorological conditions may influ-ence aggregate public perceptions over time.

Here, we consider four studies that have exam-ined changes in public perceptions in light of varyingweather conditionseach of these was conducted inthe United States. For the purposes of this review, weonly consider studies that have collected public per-ceptions data at more than one time-point, and relatedthese to temperature and/or other weather data. Thesestudies represent a subset of a larger body of work



TABLE 4 Studies Considering Role of Weather in ChangingPerceptions

Study Citation Time Period Findings

Deryugina (2013)113 20032010 Short-term temperatureuctuations have noeffect; longer-term(1month to 1 year)changes predict climatechange beliefs amongconservative voters

Donner andMcDaniels(2013)112

19902010 Temperature anomaliesover previous 312months predict level ofconcern, and beliefsabout climate change

Egan and Mullin(2012)115

20062008 Weather anomalies predictclimate change beliefsalthough this effectdecays rapidly

Hamilton andStampone(2013)114

20102012 Recent temperatureanomalies predict beliefin human causation ofclimate change amongunaligned voters

Analyses for each of the four studies are based on U.S. data.

examining public perceptions of weather and weatherevents (e.g., see Reser111). The studies we consider aresummarized in Table 4.

Drawing on data from national weather sta-tion observations, Donner and McDaniels112 exam-ined the extent to which these corresponded with pub-lic opinion data over the period 19902010. Theseauthors found that attitudes toward the reality of cli-mate change, and degree of personal concern, wereboth strongly related to temperature anomalies overthe past 12 monthswith both attitudinal measuresbeing lower in the context of colder than usual tem-peratures, and higher for warmer periods.

Also utilizing weather station data, this timeover the period 20032010, Deryugina113 found thatwhere temperature deviates from the mean over ashort time period of up to 2weeks prior to survey com-pletion, this did not affect peoples beliefs. However,more sustained periods of anomalous warm weatherdid affect the likelihood that respondents would beof the opinion that climate change had already begunto happenwith colder weather having the oppo-site effect. Interestingly, Deryugina obtained this effectonly for Conservative voters, although did acknowl-edge that this may have been an artifact of the studydesign. Separate work by Hamilton and Stampone114

by contrast observed an effect of temperature anomalyon perceptions across political orientations, although

this effect was strongest for voters describing them-selves as Independent. Again in contrast to Deryug-inas study, which found that longer-term anoma-lies were more important in altering perceptions, thisresearch found that the effect of temperature anomalywas strongest the closer in time that this occurred tosurvey completion.

A finding that temperature anomalies can influ-ence perceptions but that this effect decays rapidly wasobtained by Egan and Mullin.115 These authors usedas their outcome variable responses to a statementasking whether or not there was solid evidence thatthe Earth was getting warmer. Again, these authorsobserved that deviations in local temperature affectedbelief in the reality of climate change. However, thiswas found to occur as a function of the absolute sizeof the deviation from mean temperaturein contrastto the finding by Deryugina113 that warmer and colderweather had contrasting effects on beliefs. Egan andMullin also argued that the effect of weather variationwas, in itself, particularly pronouncedcomparablein importance, they argued, to those identified inthe political science literature of boosts in campaignadvertising on voting intentions. Nevertheless, theyalso conclude that, under normal circumstances, theweathers effect on opinion is fleeting.

These results, taken together, suggest thatlong-term temperature anomalies have a robust effecton public perceptions of climate change. Because ofthe contrasting findings obtained with respect to thetimescale at which these effects occur, it neverthelessremains unclear whether the influence of the weatheron public opinion is most pronounced for immediateor for longer-term conditions. It also remains unclearwhether such effects are short-lived or have thepotential to endure over a sustained period. A furtherresearch need concerns assessment of the influence ofdiscrete extreme weather events on long-term publicopinion. Whilst there is a growing body of literaturethat examines individuals perceptions of climatechange in response to events such as flooding andhurricanes111,116119 it remains unclear the extent towhich this may have effects at the population level.

Sociopolitical, Economic, and EnvironmentalDrivers of ChangeAll the research considered in the review thus farhas offered insights into patterns and trends in pub-lic perceptions of climate change over time; and inthe previous sections we considered evidence of therole of one-off events in shaping public perceptions,as well as the role of changing meteorological con-ditions. Nevertheless, the question of which factorsare most important in driving the shifts in attitudes



identified has rarely been directly addressed in the lit-erature. This is problematic because, as we have sug-gested, there are a wide range of possible explanationsavailable for changing perceptions of climate change.Without direct assessment and comparison of socioe-conomic and other factors as influences on changingpublic opinion, there is a risk that such phenomenaas the widely documented increases in public skep-ticism in the late 2000s come to be associated withplausible-seeming, but untested rationalizations. Forexample, there has been a widespread tendency toattribute a major impact on public opinion to the Cli-mategate episode,120 but with the exception of thework we cite above101 there is very little evidenceavailable to support this.121 Indeed, public concernabout climate change in the United States and UKhad already begun to decline prior to the controversygenerated by this story, with multiple other factorsof potential relevance salient around this time. As wenote above, there has been a tendency in some quartersfor changes over time in polling data to be overin-terpreted or undue inferences made about the factorsbehind shifts in public opinion. Those studies whichhave attempted to empirically examine the causes ofchanging public perceptions of climate change are,therefore, of particular value.

One study by Scruggs and Benegal122 that setout to assess the reasons behind the increase in pub-lic doubts about climate change in the late 2000s,compared the influence on public opinion of skepticalmedia coverage, short-term weather anomalies, andeconomic circumstancesthese latter in the formof unemployment data and an index of consumerconfidence.

This study was able to analyze the effects of eachof these on aggregate public opinion in both the UnitedStates and Europe, as well as to look more closely atthe effects of unemployment and weather anomaliesat the subnational level in the United States throughmatching individual-level responses to locally relevantindicators. These authors analysis concluded that aneconomic accountcontextualized to the recessionsexperienced inmany countries in the late 2000smostconvincingly explained declines in public concern andacceptance of the reality of climate change, both in theUnited States and Europe, at national as well as locallevel. As part of these findings, they observed thatwithin Europe, there was a very strong associationbetween increases in employment rates and increasesin skeptical opinion on a country-by-country basis.Whilst the study obtained modest significant effectsfor temperature variations upon public opinion,these were much smaller in comparison to economiceffects.

A second study by Shum123 largely bears outthese findings in the European context. This researchdrew on the same European dataset as Scruggs andBenegal122 to gauge public attitudes concerning theperceived seriousness of climate change, althoughmade use of this in a different manner. Shums studyalso applied figures for economic growth as an eco-nomic indicator, together with mean temperatures inthe month of August preceding each of three surveywaves from 2007 to 2009. This study concluded thatchanges in quarterly GDP growth rates affected atti-tudes toward climate change at both national andEuropean levels. The effect of summer temperatureswas limited to an aggregate European level (i.e.,in warmer years, the European public as a wholeexpressed more concern), but the authors acknowl-edged the limitation of this inference and pointed outthat where analyzed at national level, temperatureswere not influential. A further important observationwas that, controlling for income levels, those countriesin the old Europe of the West showed decreased con-cern over time, in comparison to those countries inthe East where this effect was less pronounced. Fromthis, Shum makes the prediction that should incomesin the East of Europe continue to increase, they can beexpected to become among the more concerned coun-tries with respect to climate change.

From these two analyses, an economic explana-tion for declines in concern is most apposite. This isconsistent with the finite pool of worry hypothesis95

which predicts that concern about one issueclimatechangewill decrease as concern about anotherinthis case, economic circumstancesbecomes moresalient.

Although it would appear that the economicdownturn has played a part in changing public opin-ion, it is important to note that the studies consideredabove were only able to test this hypothesis againsta limited number of competing explanations (mediareporting and temperature variation). A further fac-tor argued to have been important in effecting publicskepticism has been the role of social factors involvedin promoting climate change denial, such as conser-vative think-tanks, media outlets and politicians, andsections of the media.8486 Conversely, it might beexpected that advocacy in favor of action on climatechange could raise public concern.

One of the most comprehensive analyses of themultiple possible influences on public opinion, whichincorporated an assessment of such political cues wascarried out by Brulle et al.124 in the United States.This study used a large number of measures designedto capture and distinguish between the effects ofextreme weather events, mass media coverage and



more direct media advocacy of pro/anti positions onclimate change, dissemination of scientific informa-tion, and elite cuesthe last of these being gauged byCongressional statements, voting patterns and hear-ings with respect to climate change.

Brulle et al. concluded from their analysis thatthree major factors affected levels of public concernabout climate change over the 20022010 period.They observed, first, that the quantity of mediacoverageitself an indirect measure of the importanceascribed to climate change as a topictranslated intopublic concern. Secondly, and in line with the studiesdescribed above concerning the influence of economicfactors on public opinion, they found that economicfactors (unemployment and economic growth) wereinfluentialand furthermore that U.S. war deaths inIraq and Afghanistan significantly decreased publicconcern. These influences they attribute to society hav-ing a limited amount of issue space, analogous ata societal scale to the idea of a finite pool of worrywhereby other issues compete with climate changefor the publics attention. The study found howeverthat the most important influence on public concernabout climate change was elite political cues, bothoriginating from Democratic and Republican sources,which led to heightening and diminishing of concernrespectively.

Whilst these results clearly demonstrate theimportance of political impetus both for constrain-ing and motivating public concern, it is important tonote that there are likely to be complex interrelationsbetween many of the social forces considered. Forexample, the publication of the Fourth IPCC Assess-ment Report may have galvanized support amongsome politicians for action; in addition, and as Brulleet al. point out, media reporting of climate change isitself affected by economic circumstances and atten-tion paid to climate change by prominent politicians.It should also be noted that there may be particulareffects at play in the United States that do not oper-ate the same way in other parts of the world. This isnot least because the U.S. debate on climate changeappears to be particularly politicized, with analysesshowing that media reporting and wider discussionof climate change occurs in a very different mannerelsewhere125127e.g., Billett128 concludes that thepress in India entirely endorses climate change as ascientific reality.

Qualitative Studies with a LongitudinalComponent (Study Type 4)As both Pidgeon30,129 and Wolf and Moser130 pointout, qualitative approaches provide the potential for

considerable added value over quantitative surveys,providing far greater depth of explanation and insightinto peoples perspectives on climate change, includ-ing the complexity of their cognitive and emotionalengagement with the issues involved. Much anthropo-logical research considering peoples understanding ofand responses to climate change entails engagementwith communities over a sustained period of time,and many such studies have noted that research par-ticipants assert the view that the weather and otherfactors in their locality have changed over time.131,132

However, despite the growing body of research uti-lizing qualitative methodologies to understand thehuman dimensions of climate change130,133,134 it isoften unclear from such studies how peoples percep-tions of climate change have, in themselves, changedover the years. Here we consider five studies whichhave included a focus on changing public perceptions,using qualitative data.

One exceptional study by Paerregaard135 consid-ered the development of climate change perceptionsover a 27-year period in a traditional community inthe Peruvian Andes. This research achieves such acomparison over time by drawing on long-term ethno-graphic field data dating back to repeated visits tosouthern Peru in 1986, 1990, and 1993as well asrecent comparative data obtained in 2011. In contrastto many of the studies considered in this review, Paer-regaard states that an explicit aim of this work is toexplore perceptions of climate change among peopleliving on the margins of the global world.

Among many socioeconomic and culturalchanges observed in this region of study, was the find-ing that changes in ritual practices were intimatelyconnected with changes in the ways in which envi-ronmental changeincluding climate changewasconceptualized. Whereas in the 1980s and early 1990sthe vast majority of villagers in the region continuedto participate in ritual practices, such as making offer-ings to mountain deities, in return fieldwork in 2011 agrowing number of people had grown doubtful aboutthe effectiveness of offerings and rituals. Such shifts inpractice and attitudes were in turn related to peoplesexperience of climate change as one of many externalforces impacting on their locality. In part because oftheir experience of changing temperature and wateravailability, however, Paerregaard notes that studyparticipants had by 2011 begun to employ a newterminology to observe and interpret environmentalchange and that they talked of the climate as aphenomenon posing serious threats to their lives.Notwithstanding the emergence of climate change asa meaningful concept for the people in this region,this author points out that the way in which it was



understood nevertheless remained distinct in manyways from a typical Western conceptualization.

The above study is pertinent for drawing atten-tion to the fact that shifts in understanding of climatechange do not happen in isolation but rather as partof a pattern of unfolding social changes in conjunctionwith changes to physical conditions. Lavrillier136 haslikewise observed that changes in values and attitudeshave occurred in concert with the manifestations ofclimate change among the Tungus of Siberia. As thisauthor notes, climate change has lead both to outlookswhich may be considered positive and adaptive, butalso to a fear of future impacts and challenges to tra-ditional beliefs and narratives (p. 269):

For the present time, they are expressing the strongconfidence they have in their ability to adapt. On thecontrary, for the future, their narratives and ritualsexpress a dread at the thought of being endangeredand a mutation in some perceptions of the environ-ment. Previously held to be eternally renewable, theenvironment is now seen as likely to disappear.

Crate137,138 has also reflected upon how the per-ceptions of another population in Siberiain thiscase the Viliui Sakha of northeastern Siberiahavechanged over time in the context of climate change.Having carried out research with these communitiessince 1991, writing in 2011 Crate137 commented thatit is only in the past few years that her research partic-ipants have started to express concern about changingweather patterns and the timing of seasons, as well aschanges to land formations such as permafrost.

A further study by Capstick139 carried out in theUK examined changing public perceptions of climatechange over the period 19972010 through com-parative analysis of six separate qualitative datasets(focus group and interview studies) obtained overthis time period. This research found substantialcontinuity over time in the ways in which publicparticipants expressed their viewpoints across a seriesof discourses encompassing the personal, social, andscientific aspects of climate change. Capstick arguedhowever that several key changes were evident overtime in how people understood climate change. Whilstearlier research participants tended to see the scientificaspects of climate change as undecided or yet-proven,there was an increasing tendency toward later yearsfor climate science to be characterized as representingopposing positions or sides indicative of scientificdispute. In the personal domain, peoples accountsof their own climate-relevant behavior displayed anincreasingly moralized character over time. This wasalso reflected in changing views about wider practicessuch as energy-saving and recycling, which were seen

as becoming increasingly routine and normalizedover the period of analysis. A further finding of thisstudy was that expressions of fatigue around climatechange appeared to be a recent development, withinstances of this found only in the 2010 data.

Whilst the studies described above have adopteddisparate methodologies to explore the perceptionsof very different research populations, they neverthe-less point to the possibility of developing insights intochanging public perceptions of climate change thattake into account peoples shifting values, practices,and wider cultural contexts. These findings are of adifferent character to those obtained from quantita-tive, usually survey-based, studies that for the mostpart dominate the present review. However, such workoffers some clues as to how changing perceptions ofclimate change may occur in concert with changingphysical and social conditions which are specific toparticular communities.

CONCLUSIONS

Understanding popular opinion on climate change andsupport for measures to address it is critically impor-tant given the need for profound societal changes asso-ciated with mitigation and adaptation. Our systematicreview has drawn on diverse quantitative and qual-itative evidence from a range of countries over thepast quarter century, to demonstrate the growthandsubsequent fluctuationsin climate change awarenessand concern since the issue emerged into the publicconsciousness in the 1980s. After a period of risingconcern to around 2007, polls show a sharp declinein belief and concern across many developed coun-tries, followed by stabilization in some parts of theworld since about 2010. While experiences of anoma-lous weather and other events (e.g., The Day afterTomorrow; Fukushima; Climategate) appear to haveexerted some influence on public perceptions (or, mostoften, perceptions of a sub-group of the population),time series analyses that take into account a range ofpossible explanatory factors (e.g., weather, socioeco-nomic factors, and political actions) indicate the eco-nomic downturn and political events have been par-ticularly influential.

Polling studies also reveal important variationsboth within and between countries in these longitudi-nal trends. Notably, there has been growing politicalpolarization in the United States, with right-of-centervoters growing increasingly skeptical, compared toleft-of-center voters. This is consistent with per-vasive confirmation bias (the propensity to seekout and believe information that confirms existingviews140) and interest-based efforts to shape public



opinion.84,86,87 Between countries, parts of Europesuch as the UK, and Australia and the United States,appear to have seen a much larger growth in skepti-cism than other regions, such as sub-Saharan Africaand South America, where concern about climatechange has tended to increase.

Recent analysis85 finds that media coverage con-tain

International Trends in Public Perceptions of Climate Change Over the Past Quarter Century

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