First number is three: three billion people. It’s the number of people joining the global middle class by 2030, coming out of poverty. Maybe it’s great for many family .but we have got two billion people in global middle class today.
Second number is six: This is six degrees, we have been having the last few years, much of that is due to just one degree warming, and we need CO2 emissions to peak by the end of this decade globally and then come down. It's not inevitable, but we need to act decisively.
Third number is twelve: That is the number of cities in the world that had a million or more people. But now there are 500cities ,nearly, with a million people or more in them.
So sustainability has gone from a nice- to-do, to much do. It's about what we do right here, right now.