Interactions between financial and environmental networks in OECD countries

We analysed a multiplex of financial and environmental networks between OECD countries from 2002 to 2010. Foreign direct investments and portfolio investment showing the flows in equity securities, short-term, long-term and total debt, these securities represent the financial layers; emissions of NOX, PM10, SOX, CO2 equivalent and the water footprint associated with international trade represent the environmental layers. We present a new measure of cross-layer correlations between flows in different layers based on reciprocity. For the assessment of results, we implement a null model for this measure based on the exponential random graph theory. We find that short-term financial flows are more correlated with environmental flows than long-term investments. Moreover, the correlations between reverse financial and environmental flows (i.e. the flows of different layers going in opposite directions) are generally stronger than correlations between synergic flows (flows going in the same direction). This suggests a trade-off between financial and environmental layers, where, more financialised countries display higher correlations between outgoing financial flows and incoming environmental flows than from lower financialised countries. Five countries are identified as hubs in this finance-environment multiplex: The United States, France, Germany, Belgium-Luxembourg and United Kingdom.

本研究分析了2002年至2010年间经济合作与发展组织（Organisation for Economic Co-operation and Development，OECD）国家之间的金融与环境多层网络。金融层由对外直接投资与证券投资的流动数据构成，涵盖股权证券、短期、长期及总债务维度；环境层则包含氮氧化物（NOₓ）、可吸入颗粒物（PM10）、硫氧化物（SOₓ）、二氧化碳当量（CO₂ equivalent）排放，以及与国际贸易相关的水足迹（water footprint）数据。本研究提出了一种基于互惠性的跨层流动相关性全新测度方法。为评估该测度的结果，本研究基于指数随机图理论（exponential random graph theory）构建了对应的零模型。研究发现，相较于长期投资，短期金融流动与环境流动的相关性更强。此外，反向金融流动与环境流动（即不同层级的流动方向相反）之间的相关性，普遍强于同向协同流动（即不同层级的流动方向一致）之间的相关性。这表明金融层与环境层之间存在权衡关系：金融化程度更高的国家，其对外金融流动与外来环境流动之间的相关性，显著高于金融化程度较低的国家。本研究识别出该金融-环境多层网络中的5个核心枢纽：美国、法国、德国、比利时-卢森堡以及英国。