Here is my understanding to this Art @velimir
Due to hazardous activities of human beings including huge usage of chlorofluorocarbons and nitrogenous gases the depletion of ozone layer occurred. Cosmic rays killed the greenery of Earth and look at those barren trees that are leaves-less how painful and horrible outcomes advancement of technology gave us.
Look at the grey sky which is also feeling sad on the horrible condition of the human land THE EARTH, yes Humans are responsible for all this.
Lets' go back to the days of childhood with less technological advancement, lets spend time together, lets work together, lets live in Peace again.
P.S: Thanks a lot Veli you brought something very close to my heart this time, Love your art <3
Stay Blessed, Steem On!