Picture this:

You and a group of four friends share a magical pack of gum. In this magical pack, there are 10 sticks of gum. The pack can hold no more than 10 sticks, but however many sticks are left at the end of the day is doubled overnight. So you and your friends each take one stick per day, and the next day there is always still enough for everyone to have one.

Let’s say you have a really bad day. Maybe you ate garlic for lunch, and you really need a stick of gum to take care of your bad breath. You already took your stick for the day, but, hey, there are 5 left in the pack. It’ll be fine! So you take an extra stick.

The next day, there are only 8 sticks of gum in the pack. Still enough for everyone to have one, but people start to get nervous. A few of your friends decide to take an extra piece. The next day, there are only two sticks. Pretty soon, all the gum is gone.

In 1833, British economist William Forster Lloyd published a lecture on population control in which he outlined the abuse of common goods by individuals and how it affects the greater good.

Over 100 years later in America, ecologist Garrett Hardin developed that idea in a publication of his own and named it “the Tragedy of the Commons.”

What could be so important about these findings that it connected two men from different countries in different professions living in different centuries?

The accumulation of selfishness and the consequences we all face because of it.

Let’s revisit about the gum example. I know what you’re probably thinking.

“I would never take the extra stick! I can do basic math!”

But, how long are your showers? How often do you purchase products in plastic bottles? Drive a car? Use unnecessary energy?

We act selfishly all the time without thinking, and we never consider how our actions effect everyone. It's difficult to conceive, but there is only so much our earth can take. When we're all using more than our fair share, it can pack a serious punch.

In a TED Talk about the Tragedy of the Commons, Nicholas Amendolare said it this way: “Optimizing for the self in the short term, isn't optimal for anyone in the long term.”

Our 30 minute showers and daily paper coffee cup do not come without consequences. Fourteen billion pounds of garbage are dumped into the ocean every year. There are about 5.25 trillion pieces of plastic in the ocean. There are 500 million cars in the world, and that number is rising every day.

We may not always feel like our personal actions make a difference, but collectively our actions determine the course of the entire population.

Take shorter showers. Carpool. Better yet, walk or bike if you’re able. Invest in reusable water bottles, thermoses, silverware and grocery bags.

This is our earth, and we all live here.