Positive tipping points in a rapidly warming world

Positive

tipping

points

in

a

rapidly

warming

world

J

David

Ta`bara

,

Niki

Frantzeskaki

,

Katharina

Ho¨lscher

,

Simona

Pedde

,

Kasper

Kok

,

Francesco

Lamperti

,

Jens

H

Christensen

,

Jill

Ja¨ger

and

Pam

Berry

ThechallengeofmeetingtheUNFCCCCoP21goalofkeeping globalwarming‘wellbelow2Candtopursueeffortstowards 1.5C’(‘the2–1.5Ctarget’)callsforresearcheffortstobetter understandtheopportunitiesandconstraintsforfundamental transformationsinglobalsystemsdynamicswhichcurrently drivetheunsustainableandinequitableuseoftheEarth’s resources.Tothisend,thisresearchreviewsandintroduces thenotionofpositivetippingpointsasemergentpropertiesof systems–includingbothhumancapacitiesandstructural conditions—whichwouldallowthefastdeploymentof evolutionary-liketransformativesolutionstosuccessfullytackle thepresentsocio-climatequandary.Ourresearchprovidesa simpleproceduralsynthesistohelpidentifyandcoordinatethe requiredagents’capacitiestoimplementtransformative solutionsalignedwithsuchclimategoalindifferentcontexts. Ourresearchshowshowtoidentifytherequiredcapacities, conditionsandpotentialpolicyinterventionswhichcould eventuallyleadtotheemergenceofpositivetippingpointsin varioussocial–ecologicalsystemstoaddressthe2–1.5C policytarget.Ourinsightsarebasedontheparticipatory downscalingofglobalSharedSocio-economicPathways (SSPs)toEurope,theformulationofpathwaysofsolutions withinthesescenariosandtheresultsfromanagent-based economicmodelling.

Addresses

1_{InstituteofEnvironmentalSciencesandTechnology,Autonomous} UniversityofBarcelona,CampusUAB,08193CerdanyoladelValle`s (Barcelona),Catalonia,Spain

2

DutchResearchInstituteforTransitions,FacultyofSocialSciences, ErasmusUniversityRotterdam,TheNetherlands

3_{SoilGeographyandLandscapeGroup,WageningenUniversity,P.O.} Box47,6700AAWageningen,TheNetherlands

4

InstituteofEconomics,ScuolaSuperioreSant’AnnaPiazzaMartiridella Liberta` 33,56127Pisa,Italy

5_{FondazioneEniEnricoMattei,CorsoMagenta63,20123Milan,Italy} 6_{DanishMeteorologicalInstitute,Lyngbyvej100,DK-2100Copenhagen} O,Denmark

7_{NielsBohrInstitute,UniversityofCopenhagen,JulianeMariesVej30,} DK-2100CopenhagenO,Denmark

8_{Independent,Vienna,Austria}

9_{EnvironmentalChangeInstitute,UniversityofOxford,SouthParks} Road,Oxford,OX13QY,UnitedKingdom

Correspondingauthor:DavidTa`bara,J(joandavid.tabara@uab.cat)

CurrentOpinioninEnvironmentalSustainability2018,31:120–129 ThisreviewcomesfromathemedissueonSustainabilitygovernance andtransformation

EditedbyBronwynHaywardandLindaSygna

Received01June2017;Revised24November2017;Accepted31 January2018

https://doi.org/10.1016/j.cosust.2018.01.012

1877-3435/ã2018TheAuthors.PublishedbyElsevierB.V.Thisisan openaccessarticleundertheCCBYlicense(http://creativecommons. org/licenses/by/4.0/).

Introduction

ThechallengeofmeetingtheUNFCCCCoP21 goalof

keepingglobalwarming‘wellbelow2Cand topursue

effortstowards1.5C’(‘the 2–1.5C Paristarget’)calls

fortheaccelerateddevelopmentof humancapacitiesto

implementtransformativesolutionsinmultiplecontexts

ofaction[1,2,3].Inthepresentsituation,itisessential

notjust to considercommand-and-controlpolicies for a

‘rapiddecarbonisation’[4] whichwouldlikely keepthe

rootsocialcauses,individualmotivesandincentive

struc-turesofexcessiveGHGemissionsintact,butmore

impor-tantly,andintermsofsocietaltransformations,toidentify

the systemic conditions for a ‘rapid sustainabilisation’.

This questinvolves first of all, finding out more about

whicharethekeydynamicsthatwouldeventuallyallowa

fundamentallyreversionofthecurrentunsustainableand

inequitabletrendsintheuseoftheEarth’sresources[5,6]

andsecond,toexplorethepossibilitiesforindividualand

collectiveinterventionsinsuchdynamicsgiventhe

lim-itationsof existinggovernancearrangements.

Thisresearch hastwo main goals. On the one hand, it

reviews theliterature ontipping points froma

sustain-abilityscienceperspectiveandcallsforresearcheffortsto

bettercharacterizetheiruseinpolicymaking.Givenour

research focus,we concentrate onthenotion of positive

tippingpoints,understoodasemergentpropertiesderived

fromcomplex systems dynamicsthat allow rapid

trans-formationsinindividualandcollectivepracticessoas to

reach evolutionary-like solutions to the present

socio-climate quandary. In this regard, we provide a simple

and supporting the building of agent capacities and

systemconditionsconducivetosuchpositive

transforma-tions [7]. Our approach is based on the

acknowledge-ment of the structural uncertainty about when, where,

how or even if such new fundamentally new system

conditions,orpositivetippingpoints,willemerge.Italso

recognizesthatsocial–ecologicaldynamicsaresubjectto

multiple non-linear, irreversible and cumulative

pro-cesses that cannot be anticipated. However, it is also

based onthe assumption that social–ecological systems

cansomehowbenavigatedintentionallytoachieve

cer-tain desirablegoals,targets ormore broadlyvisions.

Assessing

positive

tipping

points

in

a

high-end

climate

World

Positivetippingpointsinsocial–ecologicalsystems

Most research in sustainability science and integrated

assessment has focused on examining the catastrophic,

abruptnatureoftippingpointsinbiophysicalsystemsor

the implications of the realization of such crises or of

crossingsuchnegativethresholdsforpolicyandaction[8–

10,11,12,13,14]. However, and with few exceptions

[15,16], little attention has been paid so far to trying

to identify and characterize the possible emergence of

positivetippingpointsinsocial–ecologicalsystems

dynam-ics. In the context of climate change ‘beneficial social

tippingpoints’havebeenalreadyreferredtothosewhich

‘increase societalresilience and reduce climate change

damages via mitigation or adaptation, whereas harmful

socialtippingpointsaremorelikelytooccurwherethere

arelowlevelsofsocietalresilience,underwhichsocietal

risks increase because of failure to effectivelyadapt or

mitigate’[17].Suchbeneficialsystemicchangesmaybe

derivedfromthesynergetic,multiplicativelearning

feed-backeffectsofdeliberateimplementationof

transforma-tive solutions developed in multiple contexts of action

[18]. Inthis way, thearticulationof learning feedbacks

between multiple deliberate transformations at small

system scales maybe neededto achieve thelong-term

resilienceathigherlevels[19].Addressingthequestion

on how to achievethe Paristargetpreciselyfallsunder

these concerns[20].Itisneitherpossibleto predictthe

exactmoment,shape,dynamicsorconsequencesofsuch

required far-reaching changes in the configuration of

global social–ecological systems nor if they will ever

happen.However,andusinganintegratedresearch

per-spective, it may be possible to provide an operational

frameworktorecognizethevariousconditions,capacities

andconcretepathwaysofsolutions,aswellasthe

incen-tives [21],which couldeventuallyleadin concrete

con-textsofactionorsubsystemstotheemergenceofpositive

tippingpoints.Thelaterwouldincreaseourlikelihoodof

successfullymeetingthe2–1.5CParistarget.

Tippingpointsfundamentallyandirreversiblychangethe

structureandtheintrinsicfunctioningofagivensystemof

reference. Some authors argue that early warnings and

exceedingathresholdofconcernabouttheacceptabilityof

imminent occurrence of a tipping point may lead to

‘adaptationturningpoints’inclimateaction[22]although

thismaybehardtoputinpractice.Sometippingpointsin

certain systems may be unintentional and unexpected,

others the resultof deliberate actions.Tryingdeliberate

or activetransformationstoachieveafundamentally

dif-ferentkindsofsystemsmaybenecessarywhenthepresent

institutions or systems’ goals become unattainable

[19,23,24]. However,global social–ecologicalsystems—

for which global warming is but only a symptom and

amplifier of its unsustainable dynamics, are constituted

by many‘systems of systems’ [25] each of whichbeing

determined by its own logics, complex dynamics and

effectsonothersystems.Forinstance,atippingpointin

the way that global communication systems operated

occurred with the introduction of the internet, rather

suddenly and unexpectedly and the ultimate effects of

this transformation cannot yet be forecast; governance

systemsalsofollowtheirownrationales,mainlystillunder

the nation-state interests and constraints and thus are

largelyresistanttochange;thestructureandthe

function-ing of global energy and resource property systems are

determinedbypriceandmarketcompetitionruleswhich

in turnmay bein conflictwithothermoretraditionalor

localculturalsystemsintheuse ofnaturalresources;the

building of institutionalsystems hasalsoundergone

tip-pingpointsinhistory,forexample,whencertaincivilrights

havebeenachieved,includingtheendofslavery,theend

ofchildlabour,therightofwomentovoteortohaveaccess

to education.Theconsolidationof theIPPCcanbealso

seenasatippingpointinthedevelopmentofsciencefor

policytoaddresstheclimatequandary,albeitwithlimited

effectsonglobaltransformation[26].Hence,both

collec-tiveandindividualsocialactionsoperateinmultiple

socio-cultural, technological, governance, bio-physical and

knowledgesystems whichinteract with manyother

sys-temsatthesametimeandatmanylevels.Therefore,itis

hard tothink of the existence ofa singletransformative

solutionorasingletippingpointinonesinglesystemthat

would lead to the achievement of the 2–1.5C target.

Instead,multiplepositivetippingpointsinmultiplesystems

of actionwillbeneededtoachievethisaim.

Thereis littleknowledgeaboutwhichkindsof specific

changes or transformative solutions are to be needed.

Ultimately,suchtransformativesolutionsshouldbeable

tocreatenewkindsofsystemicconditionsthateliminate

theultimate causesofthepersistent problems.Forthis

reason,weunderstandpositivetippingpointsasemergent

properties of systems that would allow the reaching of

evolutionary-liketransformativesolutionstosuccessfully

tackle thepresent socio-climatequandary.

However,weadmitthatontheonehand,agentswillonly

beabletoactuponandapplytransformativesolutionstoa

operate—for example, recycling materials, preventing

food waste, mobility, civic and political representation,

etc. [27]. While on the other, particular transformative

solutionsthatworkinonecontextmaynotworkinother

contexts.Amorenuancednarrativeandinterpretationof

how different kindsof solutions can belinked or even

supported through deliberate action-research to create

multiplicative synergies and potentially induce positive

tippingpointstoaddresstheclimatequandaryisneeded.

Aproceduralsynthesis

Given the large complexity and non-linearity in the

dynamics of social–ecological systems, it is simply not

possibleto forecastthewholearrayof potentially

trans-formativesolutionsthatneedtobeimplementedglobally

andwhichmaycontributetotheachievementof the2–

1.5Cpolicytarget.Instead,amorepragmaticapproach

can be formulated which focuses on identifying and

characterizing the kinds of concrete and distributed

capacitiestoimplementthesesolutions.Required

capac-itieswill varyaccording to different people, needs and

interestsintheirown contextsofaction.

In this regard, a simple procedural framework can be

developed linking desirable visions of the world, the

buildingofagentcapacitiesandsystemsoftransformative

solutions.Our perspectiveis based onthepremisethat

transformations in social–ecological systems may be

accelerated and purposefully brought about by social

action.Wemakethecasethatinpolicymakingavision

isamaindriveroftransformation[28–30,31],ratherthan

theimpendingawarenessofacatastrophe [32],andthat

positivetippingpointsmaybeinducedbythecascading,

feedbackandcumulativeeffectsof multipleinterlinked

actions—or interlinkedsystemsof transformative

solu-tions—which eventuallypushasystem towardsa new

desiredconfiguration(Figure 1).10

Apositive tippingpointoccurswhentheoriginal

condi-tions ofasystem of reference aresubstantiallyand

irre-versiblytransformedinawaythatmatchesorexceedsa

particulardesired(normative),better-offconfigurationor

vision(Figure 2).This moment islikely to happen fast

only once agents have been able to build the required

capacitiestoimplementtransformativesolutionstodoso.

In this sense, tipping points will appear as emergent

propertiesderivedfromtheexistingcapacitieswhichhave

beenacquiredwhenagentsengageinapplyingtheirown

systems of solutions to solve their problems according

their own needs and priorities (often in trial-and-error

and learning mode) [33]. The implementation of

transformativesolutionsmayalsoleadtoshiftsin

percep-tion,thereconfigurationofsocialnetworksandof

institu-tional arrangements [19]. Visions serve as a cognitive,

emotional and normative reference for orienting and

qualifying radical system changes as positive

develop-mentsin agivensystemofreference.Theyalsohelpto

introducetheintersubjectivenatureofagents’motivations

incollectiveactionwhichlies atthebaseofsocial

trans-formations[34],transformativescience[35,36];andinthis

way, visions play an important role in identifying the

potentialagencycapacities to implement transformative

solutions. However, visionsare notstatic, and therefore

theyought tobereframed asnew conditionsand

ambi-tionschange.Avisiondoesnotprovideasingle‘end-point’

insystemstrajectories,butonlyanopen-endeddesirable

state that demands continuous improvement and

reframing.

Co-producingpathwaysoftransformativesolutionsin socio-economicscenarios

Itisbecoming increasingly commonto co-producein a

participatorywaypathwaysofsolutionsusingexploratory

scenarios to determine the opportunity spaces for

sys-tems’transformations[37–39].Pathwaysare progressive

courses of action for achieving strategic objectives, or

more broadly to attain transformative visions, where

short-term actions canpave theway for more medium

andlong-termactions.Thepathwaysapproachaids

mak-ingsenseofpatternsofchangeandthinkingofstrategies

andsolutionstocomplexproblemsfromanintegratedand

systemicperspective.Formulatingpathwaysinconcrete

contextshelpstounveilclimateactionsthatnotonlylink

adaptation and mitigation but also embrace broader to

transformativechange[40–43].

The co-production of pathways can therefore help to

identifyandarticulateintegratedsolutionsandhowthey

may unroll over time, for instance, in the context of

Figure1

Vision

Solutions & pathways

Capacities

Current Opinion in Environmental Sustainability

Linkingagentcapacities,pathwaysofsolutionsandvisionstosupport systems’transformations.

10

ThisproceduralsynthesisisbeingusedintheEUproject GREEN-WIN (www.green-win-project.eu) to articulate a ‘Global Dialogue’ aimedatidentifyingandassessingaseriesofongoing‘win-win’solutions (understoodasclassoftransformativesolutionswhichmeeteconomic, sustainabledevelopmentandclimategoals)alreadybeingimplemented aroundtheWorld.

different scenarios that provide opportunities and

con-straintsforachievingthedesiredvision.Recently,anew

setofglobalscenarioshasbeenputforwardbythe

model-ling community [44–48]. The set includes the Shared

Socioeconomic Pathways (SSPs) as five socio-economic

scenarios11 and the Representative Concentration

Path-ways (RCPs) which constitute emission scenarios that

defineglobalwarmingandthusclimatechange.Bydesign,

the developmentof theSSPs andRCPs wasdecoupled,

allowingthematchingofdifferentsocio-economiccontexts

with the same emission scenario. In particular SSPs are

definedaccordingtotwokeysocio-economicchallengesof

High/LowMitigationChallengestoHigh/LowAdaptation

Challenges,but excludeTransformationas societal

chal-lengeindependentfromclimate,whichmaybeneededto

addressbothmitigationandadaptation[36].SSPsoffersets

ofbaselineconditionsandhowtheyevolvedifferentlyover

time,but sinceSSPsareexploratorytheydonotprovide

solutions to particularproblems.Theyonlydescribe the

contextsfromwhichtheopportunityspacesforthe

devel-opmentofdifferentpathwaysofsolutionsmayunfold.

However,thereisstilllittleresearchspecificallyaimedas

downscaling these global scenarios and turn them into

actionablestrategiesinparticularcontextsofactionusing

participatory procedures. Within the EU project

IMPRESSIONS12,such an endeavour hasbeen carried

outatdifferentspatialscales:fromtwomunicipalitiesin

Figure2 NEW SYSTEM CONDITIONS NEW SYSTEM CONDITIONS ORIGINAL SYSTEM CONDITIONS PTP1 PTP2 Capacities Solutions & pathways Vision Capacities Solutions & pathways Vision

Current Opinion in Environmental Sustainability

Apositivetippingpoint(PTP)maybeinducedbyboostingagents’capacitiestoimplementpathwaysofsolutionstoachieveatransformative visionoftheworld.

11

Havingbeendefinedasfollows:SSP1lowchallengesforadaptation and mitigation,SSP3highchallenges formitigation andadaptation, SSP4 highfor challenges adaptation, low formitigation, SSP5high challengesformitigation,lowforadaptation;whileSSP2moderateor ‘middleoftheroad’challenges.

12_{www.impressions-project.eu;seeBerry,P.M.,Betts,R.A.,Harrison,} P.A.andSanchez-Arcilla,A.(Eds.)2017.High-EndClimateChangein Europe.Availableat:http://highendclimateresearch.eu/.

Hungary to case studies in Scotland, Iberia, EU and

Central Asia. The ultimate aim being to identify and

assesspotentialpathwaysofsolutionsthatcould

eventu-allybeabletoachieveadesiredtransformativevisionof

theworld;orfollowingtheframeworkpresentedabove,to

‘flip’currentsystemstructuresanddynamicsinto

config-urationsattunedwiththecurrentclimateand

sustainabil-itychallenges.

IntheEuropeancasestudy,fourSSPswereco-developed

based online and workshops interaction with

stake-holders.13 SSP2 was excluded from the participatory

processgiventhatthefocusoftheprojectwastoidentify

thepotentialopportunitiesfor transformationin a

high-endclimatechangeworld(beyond2Cofglobalwarming

attheendofthecentury).Inaddition,themain

discrimi-natoryaxesof‘challengestomitigation/adaptation’were

substituted by the axes of ‘degree of social inequality/

carbon intensity’, with the aim of better capturing the

essence of the key required changes in the

socio-eco-nomicsystemwhilemaintainingthelinkwithgreenhouse

gas emissions. The newly adapted SSPs in

IMPRES-SIONS offered ways to think about transformations in

varioussystemsincludingenergy,governance,

socio-cul-tural,technologicalandeconomicsystemsandinthisway

to explore which structural conditions and capacities,

could lead to positive fundamental systemic changes

according to a normative vision of the future. While

different SSPs tended to promote different kinds of

solutionsandpathwayswhichemergedfromthedifferent

availablestructuralconditions,itwaspossibletoidentify

some cross-scenario robust actions across all scenarios

includingconcretetransformative solutions which

parti-cipants believed to be ‘game-changers’ for moving

towards the vision. In particular, and according to the

stakeholdersconsulted thepotentialemergence of new

systems’configurationsorpositivetippingpointswillbe

dependent on deploying transformative capacities of

agentsin systemssuchas:

 Energysystems:fullswitchto renewableenergiesanda

movetowards energy self-sufficient Europe in away

thatmakesfulluseofitscontext-dependentpotential

(e.g.solarenergy inSouthernEurope).

 Governance:civicparticipationiffullydeveloped,with

fairmulti-levelcoordinationandinternational

cooper-ation in line with shared, integrated and long-term

sustainabilityorientation.

 Socio-cultural:theEuropeansocietywidelyadoptsand

normalisessustainabilitybehavioursandisengagedin

continuouslearningandreflexivity.



Technological systems: Green high-tech and low-tech

infrastructuresystems are fully integrated in Europe

(e.g. household rainwatercollection, integratedwater

sensitiveinfrastructure, greenbiodiversitycorridors).

 Resourcesystems: fullmovetowardsacirculareconomy

andtowardsorganicagriculture.

 Economy:integratingecosystemservices,andafocuson

qualityoflifeandsocialwellbeingisintegratedintothe

coreeconomicactivity.

In short, trying to deliberately achieve positive tipping

pointsalignedwiththe2–1.5Ctargetandsustainability

challengeswouldrequirethefastdeploymentofamixof

differenttypesoftransformativecapacitiestoinducethe

synergetic,non-linearandcumulativeeffectswhichcould

be derived from the implementation of fundamental

changesintheabovesystems.Inaddition,thearticulation

oflearningfeedbacksderivedfromtheimplementationof

differentactionsandsolutionsislikelytobeacorepartof

the required dynamics to build agents’ capacities that

wouldleadtoapositivetippingpoint.Thislist,however,

is not exhaustive and is only for illustrative purposes.

Differentcontextsmayyieldalternativeproposalsoreven

consider otherkinds of systemscategorisation.14 Inthe

scenario exercise, negative events and constraints for

solution pathways werealso identified, which included

mostly the growing inequality,political de-stabilization

matchedwithrampantenvironmentaldegradationwhich

could make such positive transformation (in some

sys-tems)unattainable.Henceourresultshereonlyserveas

anexampleofhowthedevisingofabroadstrategy,based

on identifying feasible transformative solutions in

con-creteplaces couldultimately leadto apositive tipping

pointalignedwiththepressingclimateandsustainability

goals.

Tippingpointsintheeconomy

Agoodpart ofthe mostpromisingand recent

develop-mentsintheanalysisof tippingpointscomesfrom

eco-nomics [17,49]—although markedly concentrated on

negative tipping points which damage socio-economic

and/orenvironmentalconditionsandgeneralequilibrium

effects(e.g.[50])undersinglerationalagentassumptions.

Furthermore,standardcost-and-benefitanalysisislikely

tofailwhenuncertainregime-switchesdrivethe

behav-iourofthesystem[51].The effectsand implications of

negative tipping points are substantial when explored

13

ThisinteractionstartedwithafirstexpertworkshopinJanuary2015, andtwostakeholdersworkshopsinFebruary2016(23stakeholders)and January2017(17stakeholders)complementedwithonlineinteractionin theformofaquestionnairebothbefore andbetweentheworkshops whichfocusedonthedesignofthevision.

14

Forinstance,thereareothermoreradicaltransformationsarebeing proposedinothercircles,suchasturningthefunctioningoftheglobal economy and innovation systems from being based on ecosystems exploitationtobebasedonecosystemsrestorationandreconnectitto the biosphere [21], creating a single global citizenship with equal citizensrightsandresponsibilities,applyingfullykeypolicyprinciples suchasthepolluter-paysandprecautionaryprinciplesorsimplyphase outglobalfossilfuelextraction,thefeasibilityandacceptabilityofwhich andtheircontributiontoflippingglobalsystemsdynamicstoadifferent configurationalignedwiththe2–1.5Ccouldalsobeexploredusingthis approach.

through models that do not endogenously account for

threshold effects and tend to underestimate

climate-related damages[52].

Instead,arelativelynovelstrandworkfocuseson

model-lingtheeconomy,theenvironment,theclimateandtheir

multiple interactionsas alargecomplexsystem[53,54],

wherebothnegativeandpositivetippingpointsarefound

as emergent properties [55,56]. This allows exploring

agents’ capacities to reach evolutionary-like solutions

tothe1.5Cchallenge.Agent-basedcomputational

eco-nomicsabandonsdictatesofagents’rationalityand

mar-ketequilibriuminfavourofmorerealistic,yet

computa-tionallyintense,representationsofhumanbehavioursand

interactions [57] based on heterogeneous and bounded

rational agents and networks. In such a context, both

negative and positive tipping points emerge

endoge-nously [58]. In IMPRESSIONS, Lamperti et al. [59]

introduced the first agent-based integrated assessment

DSK modeland analyzedtheimpactof heterogeneous,

individual-levelclimatedamagesoneconomicdynamics

in line with the recent climate econometrics literature

[60].Inanutshell,themodeliscomposedoftwo

indus-trial sectors exchanging capital goods, an energy sector

endowed withdifferentenergy technologies,afinancial

systemprovidingcreditto theeconomyandhouseholds

thatconsume andprovidelabourforce.Further,a

dedi-catedclimatemoduleisaddedtothepictureinorderto

track the dynamics of climate and environmental

vari-ables. A remarkable feature of the model is that it

accountsforanecosystemofheterogeneousagents(firms,

households, energy plants and banks) that interact and

realistically behave according to evolutionary routines.

ThemodeliscalibratedinitsbaselinetoaRCP8.5

sce-nariorelyingondatafromtheWorldBankandtheRCP

Database (version2.0.5).

Largescalecomputationalexperimentsshowthat

cumu-lativeclimatedamagesmight shiftthesystemdynamics

andtraptheeconomyinastagnantstatecharacterizedby

absenteconomicgrowthandhighunemployment,which

cannot be exitedevenwhen emissionsare dramatically

reduced (Figure3).Theresultemergesfromthe

perco-lationofclimateshocksinthenetworkofagentsthat,ata

certain point,are notable to react.In particular, firms’

innovation-drivenproductivitygainsaremorethan

com-pensatedbynegativeshocks,whichincreasedefaultsand

exacerbatelackdemandduetoincreasedunemployment.

Overall, these effects prevent economic recovery and

switchesoftheengineofgrowth.Positivetippingpoints

are also found: technological change and competition

among differentenergytechnologies producesdifferent

equilibria,characterized byenergy mixes. Eventhough

thesystemstartsfromarelativelyhighshareof

fossil-fuel-related energy production, a rapid transition towards a

greener growth pattern, producing substantially higher

growthandemployment,ispossibleandsynergeticwith

the effects of a large green Keynesian multiplier [61],

derivedfromanactivepolicy intervention.Thismaybe

exploited to construct pathways of solutions leading to

positivetippingpoints(Figure4).Inourperspective,an

endogenous and rapid transition to renewable energy

sourcesconstituteanexampleofpositivetippingpoints,

whereeconomicagentsautonomouslymovesawayfrom

carbon-intensetechnologiesandself-organizein

sustain-able production systems. In particular, research and

development(R&D)effortsarefoundtofastmoveaway

from fossil-fuel shocksdue to increasing profitabilityof

renewable technologies, whose development allows to

slowemissiongrowthandreducesfutureclimatedamage;

such an effectfurther increases aggregate demand and

sustaininvestment in greenenergytechnologiesthanks

to the relatively lowerunitary costsof production.The

tippingelementconsistshereintherelative

competive-nessofgreentechnologies,whichself-sustainitsgrowth

patternthanks tothe aforementionedprocess, andhelp

the economy rapidly abandon fossil-fuel-related R&D.

However,ourmodellingresultsfindthatthelikelihoodof

suchtippingpointsisremarkablylowandsuggeststhat,

timely and strong policy interventions are needed to

increase the, otherwise extremely low, likelihood of

crossingsuchpositivethresholds[62].

Last but not least, multiple tipping points cannot be

treatedinisolation,astheyarenotindependent:crossing

one point deeply affects the likelihood of crossing

another, creating either catastrophic or beneficial

cas-cades.Regimeshiftschangingthetrajectoryofthe

econ-omyalsomodifytheselectionofstatisticalequilibriathe

systemmightbeattractedtointhefuture.Thisopensa

widerangeofrisks,as theroutefromoneregimetothe

other might not be smooth as mainstream neoclassical

economicspredicts.Copingwiththeserisksalsocalls,at

thevery least,for timelyandsharppolicy interventions

[63–65]andactionsatmultiplescalesinvolvingavariety

of state and non-state actors, whose non-trivial

gover-nancerequiresappropriatetoolsaccountingforthe

multi-layernetworkslinkingdifferentinstitutions.

Conclusion

The UNFCCC Paris goal of keeping global warming

‘well below 2C and to pursue efforts towards 1.5C’

cannotbeconsideredapositivetippingpoint.Nordoesit

necessarily contain a transformative vision that could

triggerthebuildingofthenecessarycapacitiesto

funda-mentally changethe currentunsustainable dynamicsof

global systemsaccordingly [66].Only when: (1) such a

policy target can be aligned with a series of multiple

visions, knowledge networks and sustainable practices

already beingdeveloped aroundtheWorld,and (2) the

required capacities of agents have been effectively

boostedsoastoapplytransformativesolutionsthatmeet

theirneedsinconcreteandmanydifferentcontexts,may

tippingpointincollectiveactionwherebypresentglobal

dynamics are fundamentally modified and address the

climatechallengein anequitableandsustainableway.

Certainly, in a world constituted by aclosely

intercon-nected ‘systems of systems’, multiple positive tipping

points are needed to address the 2–1.5C target. At

present,andgiventheirnon-linear,cumulativeand

com-plexdynamicsitisnotpossibletoanticipatewhen,how,

whereorevenifsuchpositivetippingpointswilloccur.

However, what is possible, at least from an integrated

assessment perspective, is to identify and appraise the

kindsofspecificcapacitieswhichcouldhelptoimplement

concretetransformativesolutionsinmanydifferentsystems

ofactionandtodosoaccordingtotheneedsandpriorities

ofdifferentkindsofgroupsand people.

Inparticular,therequired capacitiesthatwouldlead to

positive tipping points in system dynamics will vary

accordingtofuturesocial–ecologicalconditionsinwhich

humanswilllive inthefuture.Suchconditions,andthe

potentialpolicyinterventionstoalterthem,canbe

repre-sentedandassessedusingvarioustoolsandmethods.In

thisresearch,we usedtheresults ofthedownscaling of

theSharedSocio-economicPathways(SSPs)andthe

co-productionofstrategicpathwaysinEuropetogetherwith

the outputs from an agent-based modelling exercise.

Theseresultsshowedthatsomepathwaysof

transforma-tivesolutionswhichmayoccuratcertainmomentsintime

maydrive certainsystems closer(or furtheraway)from

their desired positive systemic transformation. That is,

thereisnotonesinglesolutionorpathwayofsolutionsto

the 2–1.5C target: but thousands of them of very

Figure3 Emissions Output 2000 2025 2050 2075 2100 13 14 15 16 17 2.2 2.3 2.4 2.5 2.6 Year

Output (logs) in real quantities and emissions in GtC

Current Opinion in Environmental Sustainability

ExampleofnegativeeconomictippingpointfromtheDSKmodel.Itrepresentstheeconomy’sshifttowardsastagnatinggrowthpatternwhichis notexitedwhenemissionsarereduced.

differentkinds.Theultimateshapeandcontentofthese

solutionswilldependonthemanysystemsofreferencein

which agentsoperatearoundtheworld;and iftheseare

alignedwiththeirowntransformativevisionsforabetter

life,there maybeagreaterchance todevelop

multipli-cativesynergiesandmultiplelearningfeedbacksamongst

them,ultimatelyleadingtoglobalpositivetippingpoint

in wayglobalsystemsoperate.

Conflict

of

interest

statement

Nothing declared.

Acknowledgements

TheresearchhasreceivedfundingfromtheEUprojects IMPRESSIONS-ImpactsandRisksfromHigh-EndScenarios:StrategiesforInnovative Solutions(www.impressions-project.eu;ECFP7/2007-2013grantno. 603416)andGREEN-WIN–GreenGrowthandWin-WinStrategiesfor SustainableClimateAction(http://green-win-project.eu/;ECHorizongrant

no.642018).WewouldliketothankAndreaRoventiniandDiana Mangalagiufortheirinputandtheveryinsightfulcommentsreceivedfrom threeanonymousreviewerstoanearliermanuscript.

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