"What do you think is one of the biggest contributors to our individual carbon footprints?" she asked.

I like to consider myself to be living a fairly low-impact life when it comes to the environment. I take my own bags to the shops.

I walk or ride my bike whenever I can.

I even ask for my drinks at the pub to come without straws in them.

Answering this would be easy. I scrolled through a mental list.

Airplane flights. Having children. Driving cars. Surely it would have to be one of those three.

But my friend shook her head.

Certainly, those things were among the activities with high environmental impacts, but how an individual chooses to invest their superannuation can account for a colossal proportion of carbon emissions over a lifetime.

Hearing this, I almost fell off my bar stool. It was so obvious! Many conventional super funds generate the money we live off in our retirements via long-term investment in things like fossil fuel extraction industries (or banks that finance such extraction), logging and companies producing environmentally and socially harmful products (think tobacco, weapons).

That means, unless you have actively invested your superannuation in an ethical fund - which takes both positive action to make environmentally ethical investments, as well as "negative screening" for options that are do not meet ethical criteria - your superannuation is undoing all that good work you're doing as you sort your recycling, ride your bike and eat locally grown produce.

In fact, more than this, your superannuation is doing harm to the planet and your community.

Fortunately, it's easy to do something about this.

Set aside an afternoon when it's too hot to be outside and do some searches for "ethical superannuation" online.

Superannuation funds provide helpful detail as to their screening processes and what types of industries, activities and companies they will or will not invest your hard-earned cash in.

From there, you'll need to fill out a few forms to switch funds (if you already have one), and then it's time for a drink.

Actually, it sounds like I might owe my friend one...