展望净零：代理人的期望和政策选择如何在气候情景中推动经济成果

About the National Institute of Economic and Social ResearchThe National Institute of Economic and Social Research is Britain's longest establishedindependent researchinstitute, founded in 1938. The vision of our founders was to carry outresearch to improve understanding of the economic and social forces that affect people’s lives,and the ways in which policy can bring about change. Over eighty years later, this remainscentral to NIESR’s ethos. We continue to apply our expertise in both quantitative and qualitativemethods and our understanding of economic and social issues to current debates and toinfluence policy. The Institute is independent of all party-politicalinterests.National Institute of Economic and Social Research2 Dean Trench StLondon SW1P 3HET: +44 (0)20 7222 7665E:enquiries@niesr.ac.ukwww.niesr.ac.ukRegistered charity no. 306083This paper was first published inMay2025Competing Interest Statement: The views expressed in this paper are based on research andare not attributed to the organizations to which the researchers are affiliated. There are noconflicts of interest. The usual disclaimer applies.© National Institute of Economic and Social Research 2025 Looking-Forward to Net Zero:How Agent’sExpectations andPolicyChoicesDriveEconomicOutcomes inClimateScenariosEd Cornforth, LeaDe Greef andPatricia Sánchez Juanino.1AbstractThis paper explores the sensitivity of the macroeconomic impacts of climate change scenariosto underlying assumptions about the policy environment and agentresponses.Using theNational Institute Global Econometric Model (NiGEM), we analyse the Net Zero long-termscenario developed by the Network for Greening the Financial System (NGFS)modifying thedifferent assumptionsrelated toagent expectations, monetary policy reactions, and fiscalrecyclingmechanisms. We assesshow these options influence the economic outcomes of thetransition to net zero.Keywords:NiGEM, macroeconomic model, expectations, net zero scenario, NGFS, monetarypolicy, fiscal policy.JELclassification :E70, E17, Q541The authors would like to thankIan Hurst and Stephen Millardfor their valuable comments and support. Contents1.Introduction......................................................................................................................................................32.The Role of Expectations..............................................................................................................................52.1. Sensitivity to Adaptive Expectations....................................................................................................62.2. Sensitivity to Forward-Looking Consumers.......................................................................................82.3 Sensitivity to Forward-Looking Financial Markets........................................................................123.The Role of Monetary Policy....................................................................................................................164.The Role of Fiscal Policy.............................................................................................................................205.Conclusion......................................................................................................................................................246.References......................................................................................................................................................25 1.IntroductionClimate change has emerged as one of the most pressing challenges of the decade, with itsburden becoming more evident every year.Understanding the economic risks associated withclimate change is essential for informed decision-making and effective mitigation strategies.However, assessing these risks is complex and involves a significant level of uncertainty.To address this challenge,the Network forGreening theFinancialSystem (NGFS)has beendesigning,since 2020,hypothetical climate scenariosonhow physical and transition risks couldunfold in different futuresandimpact the global economy and financial systems.Figure 1. NGFS scenarios frameworkin Phase V.Source: NGFS climate scenarios for central banks and supervisors.The NGFS hasdeveloped seven scenarios2based on different sets of assumptions regarding thesmoothness, ambition, and coordination of policy responses, as well as how emissions andtemperatures evolve across regions(see Figure 1). The creation of these scenarios relies onIntegrated Assessment Models (IAMs), which use a cost-effective approach to identify theoptimal mitigation pathways and decarbonization strategies, setting a carbon budget to meetclimate targets.On top of that,the National Institute Global Econometric Model (NiGEM) isused to convert the IAM’s output into macroeconomic impacts,providinga more detailedanalysis of the potentialeconomicimpacts of climate policieswithinthe NGFSscenarios.2To ensure relevance and stay aligned with evolving data