Earth Overshoot Day

In the year 1987 the Earth Overshoot Day on December was on November 19th, 1995 already on 21st November and in the year 2017 already on August 2nd. Why the Earth Overshoot Day comes out every year and what this day means in detail, explained by Sustainability Illustrated in  collaboration with Global Footprint Network and Earth Overshoot Day:

They also offer a lesson plan to the subject – ‘LESSON: What day is Earth Overshootday 2017?‘