Can financial intermediation mitigate climate change?

1.气候变化对生态系统、人类和世界经济构成了重大威胁（Nordhaus，2019）。2015年的《巴黎协定》代表了一项全球努力，旨在“使资金流动与实现低温室气体排放和气候适应性发展的途径相兼容”。欧洲央行行长克莉丝汀·拉加德（2021）曾倡导低碳社会需要推动“绿色金融”。政府、企业和家庭都必须进行足够的投资，以促进低碳转型（Hong等人，2020年）。因此，各国政府面临越来越大的压力，要求减少碳排放，并在2050年前实现碳中和，以减缓气候变化。金融机构向污染企业提供大量资金。根据雨林行动网络（2019）的数据，自巴黎协定以来，全球顶级银行已向化石燃料公司注入了1.9万亿美元。还有证据表明，价格稳定，这是中央银行的主要任务，可能会受到气候变化的影响（Schnabel，2021）。因此，作为其任务的一部分，中央银行应该采取与政府一致的减缓气候变化的政策。本研究的目的是运用理论和实证的框架来研究政府政策如何通过融资渠道激励企业减少碳排放。企业是利润最大化者。因此，向公司收取与他们造成的社会和环境碳污染相关的成本，将抑制他们的高碳排放（Lagarde，2021）。银行信贷是企业的主要资金来源（Campiglio，2016）。因此，对污染企业而不是非污染企业征收更高的融资成本应鼓励降低碳排放。在这种情况下，政府有责任采取政策来规范银行对企业的融资行为，本文运用序贯博弈模型、系统动力学模型和面板数据方法，研究政府如何通过金融中介来减少企业的碳排放.研究设计序贯博弈模型广泛用于供应链管理和能源系统研究，以阐明具有冲突目标的利益相关者之间的相互作用（Tunca和Zhu，2017; Liu等人，2007; Dong and Rudi，2004）.本研究采用三阶段序贯博弈模型，涉及政府、银行和个体企业，将根据不同的目标和决策变量生成理论解决方案（图1）。绿色税和可再生能源补贴将构成政府的决策变量。政府首先在社会福利最大化目标下设定绿色税t和可再生能源补贴K。这种绿色税构成了污染公司的直接成本。碳交易计划所征收的碳价格和对污染燃料的税收都可以被视为一种绿色税。可再生能源补贴用于促进发电等部门采用可再生能源技术（Acemoglu等人，2012年; Popp，2002年）。意外的政策变化可能导致银行资产价值的重新定价，并造成重大损失（Batten等人，2016; ESRB，2016）。因此，银行需要在其决策过程中考虑环境政策。在该模型中，银行根据利润最大化原则，根据政府政策调整对企业的利率。最后，企业将考虑政府政策和融资成本对利润的约束，在利润最大化的原则下决定碳排放量q和产品价格p。

1. IntroductionClimate change poses a major threat to the ecosystem, mankind and the world economy (Nordhaus, 2019). The 2015 Paris Agreement represents a global effort to "make finance flows compatible with a pathway toward low greenhouse gas emissions and climate-resilient development". The president of the ECB, Christine Lagarde (2021), has advocated that a low carbon society requires boosting "green finance". Governments, corporations, and households must all make adequate investments to promote a low carbon transition (Hong et al., 2020). Thus, governments are increasingly under pressure to reduce carbon emission and achieve carbon neutrality by 2050 to mitigate climate change. Financial institutions allocate significant funding to polluting companies. According to Rainforest Action Network (2019), since the Paris Agreement, the world's top banks have injected $1.9 trillion into fossil fuel companies. There is also evidence that price stability, which is the primary mandate of the central bank, could become affected by climate change (Schnabel, 2021). Hence, as part of their mandate, central banks should adopt policies, which mitigate climate change in line with the government. The aim of this study is to use a theoretical and empirical frameworks to investigate how government policies could encourage firms to reduce carbon emission through the finance channel. Firms are profit maximizers. So, charging companies for the costs associated with the societal and environmental carbon pollution they cause, would disincentivize their high carbon emission (Lagarde, 2021). Banks' credit represents the main source of funding for firms (Campiglio, 2016). Thus, imposing higher financing costs to polluting as opposed to non-polluting firms should encourage lowering carbon emission. Within this scenario, it would be then the government responsibility to adopt policies which regulate banks financing of firms.Using sequential game model, system dynamics model, and panel data method, this study investigates how government could reduce firms carbon emissions through financial intermediation.2. Research DesignThe sequential game model is widely used in supply chain management and energy system research to elucidate interactions among stakeholders with conflicting objectives (Tunca and Zhu, 2017; Liu et al., 2007; Dong and Rudi, 2004). Using a three-stage sequential game model, involving the government, the bank, and the individual firm, the study will generate theoretical solutions based on the different objectives and decision variables (Figure l). Green tax and renewable energy subsidies will form the decision variables by the government. The government first sets the green tax t and renewable energy subsidy K under the objective of social welfare maximization. This green tax constitutes the direct cost for the polluting company. Both the carbon price imposed by the carbon trading scheme and the tax on the polluting fuels can be seen as a green tax. Renewable energy subsidy is used to promote the adoption of renewable energy technologies in sectors like electricity generation (Acemoglu et al., 2012; Popp, 2002).Unanticipated changes policies could result in repricing of bank's asset value and cause significant loss (Batten et al., 2016; ESRB, 2016). Thus, the bank needs to take into account environmental policies in its decision-making process. In this model, following the government policy, the bank adjusts the interest rate r to the firm, based on the principle of profit maximization. Finally, the firm will take into account the government policy and financing cost as a constrain on its profit and decides on its carbon emission q and product price p under the principle of profit maximization.