To me, the one most important thing for most professionals to do for the environment is to ensure their superannuation and other major investments go into aggressively ethical funds with an environmental emphasis.
The reality is that our investments are used to fund activities such as construction of infrastructure, provision of capital to growing businesses, and so on.
That money either builds the capacity of business to achieve greater environmental impacts, or to reduce environmental impacts or even enhance environmental outcomes.
Investing in businesses whose business it is to improve environmental outcomes has a much greater impact than just investing in personal positive environmental choices.
Your money is increasing the capacity of environmentally positive businesses, who can then use that capacity to produce ongoing benefits. For example, supporting development and production of a high efficiency refrigerator allows a manufacturer to produce hundreds of thousands of units each year.
And they will influence other manufacturers by their actions.
Such investment action also helps to change the priorities of the broader investment sector, by showing a community preference for values-based investment.
And, in many cases, ethical investment offers very good returns!