If foreign official holdings of Treasuries were the source of the decline in their yields, then we would expect to observe increased spreads between yields on Treasury securities and the returns to other types of debt less favored by foreign official holders.
The Network of Central Banks and Supervisors for Greening the Financial System (NGFS) has been playing a major role in such cooperation, and the Bank of Japan has been a member of this network. The NGFS has released climatechange scenarios, compiled guides for measuring risks using these scenarios, and identified future research issues.