Macroeconomics and Global Climate Change

拟议项目的总体目的是研究全球气候变化的宏观经济学。其具体和总体目标是对旨在减少导致全球变暖的温室气体（如二氧化碳）排放的政府政策进行定量评估。为此，在威廉·诺德豪斯和其他人的开创性工作的基础上，该项目（与佩尔·克鲁塞尔合作）将构建一个定量的、基于福利的动态宏观经济模型，该模型将经济活动与全球气候系统之间的现实相互作用结合起来。该项目将采用PI和其他机构开发的最先进的计算方法来研究消费者和企业之间存在巨大异质性的宏观经济模型，这些模型以前没有被用于分析所谓的“综合评估”模型。这些方法将使该项目纳入许多重要特征，这些特征在现有的气候-经济相互作用模型中基本上是不存在的，包括：一个完全微观基础的新古典模型，可以对政策进行标准的福利分析；技术、气候、气象和其他可能干扰的不确定性；非常多的地区（全球数千个地区）；关于全球气候变化造成的经济损失的性质和程度的重要区域具体细节；各地区之间丰富的经济互动，包括贸易、保险和移民，从而使各地区能够通过标准的经济市场机制适应全球变暖造成的变化。利用这一丰富的全球经济-气候相互作用模型，该项目将定量评估旨在减少温室气体排放的各种政策在世界不同地区的分配效应。这些政策包括对碳排放征税，以及要求企业获得温室气体排放许可的“总量管制与交易”制度。这项政策分析将通过报告各种政策可能结果的概率分布，考虑到经济和全球气候如何相互作用的不确定性。此外，还将利用不确定性下的决策工具来计算策略参数的最优设置。最后，它将通过对区域集团（例如，国家和其他经济和政治联盟，如欧盟）偏离国际气候变化政策协议的动机进行定量评估来解决气候政策的政治问题。为了实现这些目标，该项目将分三个阶段进行：首先，开发一个适当的全球经济理论模型，并使用计算工具进行分析；第二，以非常高的地理分辨率，利用经济、人口、气候和气象数据对模型参数进行校准；第三，对气候相关政策的福利效应进行了详细的逐地区定量分析。因此，所提议的研究的智力价值在于，通过将这些模型纳入现代宏观经济学的主流，并通过使用现代宏观经济学的工具来建立更丰富、更复杂、更现实的经济-气候相互作用模型，从而推动了“综合评估”模型的发展。拟议研究的更广泛影响是丰富社会对全球变暖的经济影响的理解，提高其设计和评估政府政策的能力，这些政策既试图减少全球变暖，又试图改善其对全球经济的影响

The overall purpose of the proposed project is to study the macroeconomics of global climate change. Its specific and overarching goal is to provide a quantitative evaluation of government policies designed to reduce emissions of greenhouse gases (such as carbon dioxide) that cause global warming. To this end, building on the pioneering work of William Nordhaus and others, this project (which is joint work with Per Krusell) will construct a quantitative, welfare-based dynamic macroeconomic model of the world economy which incorporates realistic interactions between economic activity and the global climate system. The project will bring to bear state-of-the-art computational methods developed by the PI and others to study macroeconomic models with substantial heterogeneity across both consumers and firms that have not previously been used to analyze so called "integrated assessment" models. These methods will allow the project to incorporate many important features that are largely absent from existing models of climate-economy interactions,including: a fully micro-founded neoclassical model with which standard welfare analysis of policy can be undertaken; uncertainty about technological, climatic, meteorological, and other possible disturbances; a very large number of regions (in the thousands across the entire globe); significant region-specific detail about the nature and magnitude of economic damages caused by changes in global climate; and rich economic interactions between regions, including trade, insurance, and migration, thereby allowing regions to adapt, through standard economic market mechanisms, to changes caused by global warming. Armed with this rich global model of economy-climate interactions, the project will evaluate quantitatively the distributional effects across different regions of the world of a variety of policies aimed at reducing greenhouse-gas emissions. These policies include taxes on carbon emissions and "cap-and-trade" systems that require firms to obtain permits to emit greenhouse gases. This policy analysis will take into account uncertainty about how the economy and the global climate interact by reporting probability distributions over the possible outcomes of various policies. In addition, it will use the tools of decision-making under uncertainty to calculate optimal settings for policy parameters. Finally, it will address the politics of climate policy by providing a quantitative assessment of the incentives for groups of regions (e.g., countries and other economic and political unions such as the European Union) to deviate from international agreements on limate-change policy.To achieve these goals, the project will proceed in three phases: first, development of an appropriate theoretical model of the global economy along with computational tools to analyze it; second, calibration of the model's parameters using economic, demographic, climatic, and meteorological data at a very high degree of geographic resolution; and third, detailed region-by-region quantitative analysis of the welfare effects of climate-related policies. The intellectual merit of the proposed research, then, is to advance the state of the art in "integrated assessment" modelling by bringing these models into the mainstream of modern macroeconomics and by using the tools of modern macroeconomics to build richer, more complex, and more realistic models of economy-climate interactions. The broader impact of the proposed research is to enrich society's understanding of the economic effects of global warming and to improve its ability to design and evaluate government policies that attempt both to reduce global warming and to ameliorate its effects on the global economy