According to the Science Council, “A Professional Body is an organisation with individual members practicing a profession or occupation in which the organisation maintains an oversight of the knowledge, skills, conduct and practice of that profession or occupation.”
There are numerous professional bodies that contribute to the green agenda, both in the UK and internationally, many of which are licensed by the Society for the Environment (SocEnv). You could explore the option of gaining Chartered Environmentalist status, which reflects a high level of skill and experience for environmental professionals.
Furthermore, there are professional bodies across all sectors, such as construction, and finance, which may be more relevant to your role.