Over the past decade, the role of green bonds has shifted from the edge of the financial market to the center of the global capital market. Green bonds, which were previously regarded as an experimental tool of financial product, have become one of the most significant tools leading private capital to climate solutions. Green bonds provide financing to extensive projects, such as renewable energy, sustainable housing, clean transportation and water infrastructure. Green bonds also help investors build a quantitative bridge between capital and environmental benefits.
By December 2024, the accumulated issuance scale of the labeled sustainable bonds market had achieved 6.2 trillion US dollars. Green bonds, which account for 57% of total issuance scale as of December 2024, played a leading role in labeled sustainable bonds. This trend reflects that environmental finance has deeply integrated into main investment strategies, whose driving power includes investors’ high demand for climate-aligned assets, corporations’ enhanced promises of sustainable development, and regulatory institutions’ increasing attention to the ESG topic.
While the green bonds market is developing around the world, the U.S. remains one of the major issuers of green bonds. Recently, the U.S.’s green bonds market has extended from traditional renewable energy to other new fields such as energy-saving residences, urban resilience plans, and water management systems. Fannie Mae reflects this trend of diversification through its Green Mortgage-Backed Securities (MBS) program, which will apply bond returns to enhance building performance and housing affordability. This action not only brought environmental benefits, but also increased the appeal of green bonds to investors.
Amundi predicted that the issuance of green, social, sustainability, and sustainability-linked (GSSS) would keep developing in the next few years. The decline in the cost of renewable energy and power storage would further motivate the increase in GSSS issuance. At the same time, the huge demand for refinancing provides additional impetus: the scale due in 2024 was less than 50 billion US dollars, while it will reach 100 billion US dollars in 2025 and 120 billion US dollars in 2026. This tendency shows that green bonds have become a popular financial product to fill the infrastructure gap and address climate vulnerability. However, the final success of green bonds depends on whether the market has sound financial design, strong governance and transparent reporting, which will ensure genuine environmental and social impact.
Scholars and policy makers have started to pay more attention to quality over quantity in the issuance of green bonds. Analysts have found that although the expansion of the green bonds issuance scale is usually associated with the strengthening of national climate policies, the correlation between green bond funds and actual emission reduction effects remains unstable. Some green bonds projects have achieved remarkable achievements, while the actual effectiveness of others is difficult to verify. This inconsistency has intensified concerns over “green washing”: bonds issued under the guise of environmental protection but lacking evidence of their validity.
Legal scholars have also paid more attention to the credibility of green bonds, with a particular focus on the reporting mechanism for the use of funds after issuance. Studies in a Columbia Business Law Review article revealed that nearly 10% of U.S. corporate green bonds failed to fulfill post-issuance reporting obligations, about one-third lacked third-party verification, and only 20% of the bonds had project-level certification. Investors face difficulties in verifying whether those funds are used for green purposes.
Going forward, the U.S. could consider building a more standardized and legally binding reporting mechanism, such as the European Union’s Sustainable Finance Disclosure Regulation. This new mechanism will significantly enhance market transparency and integrity, and strengthen the effectiveness of green bonds in achieving tangible environmental benefits.