We have 148 million square kilometers of earth's land surface.

But out of that almost 50 million square kilometers are occupied by ice and desert.

16 million square kilometers is currently in use for cultivation of agricultural crops.

34 million square kilometers is currently in use for Grazing. Grasslands in the wider sense  are about 52 million square kilometres according to fao.org estimates.

So effectively we have less than 50 million square kilometers of land surface (including forested area) out of this 148 mskm.

But to sustain that human civilization about 70 million square kilometers of additional plantation requires; putting in balance the use of carbon dioxide emitted by human activities; which is equivalent to 1.5 of earth's land surface. 

Doing various performances on World Environment Day is not only a joke, then?