Definition and Certification Standards
A green bond is a fixed-income instrument whose proceeds are earmarked for projects that deliver environmental benefits - such as renewable energy, energy efficiency, pollution prevention, and sustainable water management. The International Capital Market Association (ICMA) established the Green Bond Principles (GBP), which require four core components: eligible use of proceeds, a process for project evaluation and selection, management of proceeds, and reporting.
Global green bond issuance reached approximately $575 billion (about 86 trillion yen) in 2023, growing roughly 14-fold from about $42 billion in 2015. In Japan, the Ministry of the Environment has published Green Bond Guidelines, and issuers include the Tokyo Metropolitan Government, the Development Bank of Japan, and Toyota Motor Corporation. The Japanese government also issued its first green sovereign bond (GX Economic Transition Bond) in 2024.
Benefits for Investors and Yield Considerations
Green bond yields are broadly comparable to those of conventional bonds with similar credit quality, though strong demand has led to a slight yield discount known as a 'greenium.' The greenium is typically 2-5 bp (0.02-0.05%), so the yield sacrifice for investors is minimal.
The key benefit for investors is the ability to combine environmental impact with financial returns. As ESG investing expands, institutional demand for green bonds is robust, and oversubscription rates at issuance often exceed those of conventional bonds. Green bonds also make an issuer's environmental commitments visible, contributing to improved ESG ratings. Retail investors can gain exposure through green bond funds and ETFs.
Greenwashing Concerns and Caveats
The biggest challenge facing the green bond market is 'greenwashing' - the risk that proceeds are not genuinely directed toward environmental improvement. Third-party verification is sometimes insufficient. The EU has responded with the EU Green Bond Standard (EU GBS), which imposes strict criteria based on the EU Taxonomy for environmentally sustainable economic activities. Books on sustainable investing trends are available on Amazon
Investors should remember that a green bond carries the same issuer credit risk as a conventional bond. Even if proceeds fund environmental projects, a bankrupt issuer means impaired principal. 'Green' describes the use of proceeds, not the creditworthiness of the issuer. Sound investment decisions require a holistic assessment of the issuer's credit rating, financial health, and the quality of its green bond framework.