The OECD DAC measures and monitors aid to the environment through a dedicated policy marker introduced in 1997, predating the Rio markers. Reporting on ODA flows has been mandatory since 1998. Reporting on non-credit OOF flows was introduced in 2010 on a voluntary basis.

Online database and Statistical Analysis
‌ Online database: Aid activities targeting Global Environmental Objectives (CRS). Statistical Analysis: Aid in Support of Environment 2023 (July 2023) - Includes tables and charts summarising statistics on aid focused on environment extended by each DAC member.