An interesting point I came across in preparing a Green ICT course is that who does the auditing of CO2 emission schemes is still up in the air (pun intended). The Australian Department of Climate Change issued a Draft National Carbon Offset Standard, 19 December 2008, along with a Discussion Paper and an External Audit Consultation Paper (October 2008). I have summarised these for the course on "compliance audit".
The audit paper points out that a multi-disciplinary team with individuals from different professions is likely to be needed and accreditation against ISO 14065:2007 is not directly suited. So neither financial auditors, nor environmental experts will have the field to themselves. The paper emphasises the people need to subscribe to a code of ethics and the like. So ACS members (and of comparable bodies) who are required to subscribe to a code of ethics, have their indemnity insurance up to date and have done a Green ICT course may be suitable for audit teams.