In order to assist policymakers in responding to such challenges, ESCAP's activity on green growth has been developed to focus on five paths: sustainable infrastructure development, investment in natural capital, green tax and budget reform, sustainable consumption and production, and the greening of business and markets. Natural capital provides both "direct" ecosystem services such as the provision of food and raw materials, and “indirect" ecosystem services such as carbon sequestration, watershed protection, aquifer recharge and biodiversity habitat provision (see box 1). They are usually irreplaceable, or can only be substituted for, at great cost.