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William Nordhaus和其他人的开创性工作的基础上，该项目（与Per Krusell共同工作）将构建一个以福利为基础的世界经济定量动态宏观经济模型，其中包括经济活动和全球气候系统之间的现实相互作用。该项目将利用PI和其他人开发的最先进的计算方法来研究消费者和企业之间具有实质性异质性的宏观经济模型，这些模型以前从未用于分析所谓的“综合评估”模型。这些方法将使该项目能够纳入现有气候-经济相互作用模型中基本上不存在的许多重要特征，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福利分析;技术、气候、气象和其他可能干扰的不确定性;大量区域（整个地球仪以千计）;关于全球气候变化造成的经济损失的性质和规模的重要区域具体细节;以及地区之间丰富的经济互动，包括贸易、保险和移民，从而使地区能够适应，通过标准的经济市场机制，应对全球变暖造成的变化。借助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布效果。这些政策包括对碳排放征税和要求公司获得排放温室气体许可证的"总量管制与交易"制度。这一政策分析将通过报告各种政策可能结果的概率分布，考虑经济和全球气候如何相互作用的不确定性。此外，它将使用不确定性下的决策工具来计算政策参数的最佳设置。最后，它将解决气候政策的政治问题，对区域集团的激励措施进行定量评估（例如，为了实现这些目标，该项目将分三个阶段进行：第一，开发一个适当的全球经济理论模型，沿着分析该模型的计算工具;第二，使用具有高度地理分辨率的经济、人口、气候和气象数据校准模型参数;第三，对气候相关政策的福利效应进行详细的逐区域定量分析。 因此，拟议研究的智力价值是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，来推进“综合评估”模型的最新发展。 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，并提高其设计和评估政府政策的能力，这些政策试图减少全球变暖并减轻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