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重大威胁（诺德豪斯，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型发展的途径相适应”。欧洲央行行长克里斯蒂娜•拉加德（Christine Lagarde）（2021年）主张，低碳社会需要推动“绿色金融”。政府、企业和家庭都必须做出足够的投资来促进低碳转型（Hong et al., 2020）。因此，各国政府面临着越来越大的压力，需要在2050年之前减少碳排放，实现碳中和，以减缓气候变化。金融机构为污染企业提供了大量资金。根据热带雨林行动网络（2019）的数据，自《巴黎协定》签署以来，世界顶级银行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，作为其职责的一部分，央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框架来探讨政府政策如何通过融资渠道鼓励企业减少碳排放。企业是利润最大化者。因此，向企业收取与它们造成的社会和环境碳污染相关的成本，将抑制它们的高碳排放（拉加德，2021）。银行信贷是企业的主要资金来源（Campiglio, 2016）。因此，对污染企业施加比非污染企业更高的融资成本应该会鼓励降低碳排放。在这种情况下，政府将有责任采取政策来规范银行对企业的融资。本文运用序贯博弈模型、系统动力学模型和面板数据方法，探讨了政府如何通过金融中介减少企业碳排放。序列博弈模型被广泛应用于供应链管理和能源系统研究中，以阐明具有冲突目标的利益相关者之间的相互作用（Tunca and Zhu, 2017; Liu et al., 2007; Dong and Rudi, 2004）。使用一个涉及政府、银行和个体企业的三阶段顺序博弈模型，该研究将基于不同的目标和决策变量产生理论解决方案（图1）。绿色税收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的目标下设定绿色税t和可再生能源补贴K。这种环保税构成了污染企业的直接成本。碳交易计划征收的碳价和对污染燃料征收的税都可以被视为一种环保税。可再生能源补贴用于促进可再生能源技术在发电等部门的采用（Acemoglu et al., 2012; Popp, 2002）。政策的意外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 et al., 2016； ESRB, 2016）。因此，世行需要在其决策过程中考虑环境政策。在该模型中，银行根据政府的政策，根据利润最大化原则，向企业调整利率r。最后，考虑政府政策和融资成本对企业利润的约束，在利润最大化的原则下决定企业的碳排放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.