There is a lot of relevant work within other ISO Technical Committees and here are several standards already published that are of relevance to sustainable finance.
ISO 14007 Guidelines for determining environmental costs and benefits- see ISO news item
ISO 14008 Monetary valuation of environmental impacts and related environmental aspects
ISO 14000 series on environmental management (including ISO 14001 Environmental Management Systems)
ISO 14090 Adaptation to climate change — Principles, requirements and guidelines - see ISO news item
ISO 14097 Framework including principles and requirements for assessing and reporting investments and financing activities relating to climate change
ISO 26000 Guidance on social responsibility - find out more
ISO 37000 Guidance for the governance of organizations
ISO 55001 Asset management — Management systems — Requirements - find out more
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