About Marvin Gaye - Mercy Mercy Me (the ecology)?

Question

does anyone know the historic relative background for this song about the harmful things we do to hurt the environment?

are there any important issues during the time this song was written that might have resulted to this song (1971)?

here are the lyrics:
Ah, mercy, mercy me,Ah, things ain't what they used to
be, no, no.Where did all the blue skies go?Poison is
the wind that blows from the north and south andeast.Mercy, mercy me,Ah, things ain't what they used to
be, no, no.Oil wasted on the ocean and uponour seas
fish full of mercury,Oh, mercy, mercy me.Ah,
things ain't what they used to be, no, no, no.Radiation underground and in the sky;animals and birds
who live near by are dying.Oh, mercy, mercy me.Ah, things ain't what they used to be.What about
this over crowded land?How much more abuse from man can
she stand?

Answer 1

Several events happened during the time of this song:

Love Canal (NY) - the revelation of industrial pollution in a residential area, the formation of the Environmental Protection Agency (EPA), and a few years before that, the Occupational Safety and Health Administration (OSHA). Up until those times citizens and employees and the environment were not protected against the adverse effects of industrial pollution.