I am not the biggest "treehugger" in the world but I do have a healthy realisation that humans as a race are well on our way to destroy the very thing that is sustaining all life that we know of.

caring for our one and only planet earth

So I try what I can to minimise my carbon footprint. I recycle, I shop locally, buy mostly unpackaged food, we live in a energy efficient apartment and only use LED lighting.
But I have to admit I am still a creature of these modern times and buy things I do not need or fly on holiday occasionally (a big contributor) and drive a car to work. I guess cutting out a car or going electric and not flying might make a big difference and would be worth thinking about.
So even with someone like me that is at least making an effort there is still the need for 1.8 earths every year. So how much would it be for those that do not even make an effort???

There are a lot more interesting facts and figures on the site

https://www.footprintnetwork.org/

But I would recommend you to try out the footprintcalculator to see how you are doing
http://www.footprintcalculator.org/