The first step to pushing for change is to start speaking directly with colleagues. Are they aware of the issue? Do they feel strongly about it? Do they agree with your proposed solution? Test your ideas and arguments, be prepared to re-evaluate your stance in response to new information. Encourage them to get active and start talking to others.
Look if there are existing employee bodies that are working on the issue or related ones: green teams, employee resource groups, staff committees, groups or individuals that run volunteer activities or donation activities. Also seek out staff whose jobs directly overlap with what you’re trying to achieve and those with jobs focused on corporate impact. This should improve your awareness of what the company is already doing, its plans, barriers to more ambitious actions, how you can help.
While you might want to start with the already converted, broaden your reach as much as possible to get colleagues from different parts of the organisation on board. You don’t want to be dismissed as an unrepresentative minority of employees.
Bringing colleagues on board should be an ongoing step. The more colleagues you have on your side, the more credible and powerful you all will be.