Forget rising temperatures and bigger storms, this is the big problem that neither side of the mainstream debate over environmental destruction is talking about. Peter Tatchell reported for the Guardian back in 2008:
The rise in carbon dioxide emissions is big news. It is prompting action to reverse global warming. But little or no attention is being paid to the long-term fall in oxygen concentrations and its knock-on effects.
Compared to prehistoric times, the level of oxygen in the earth’s atmosphere has declined by over a third and in polluted cities the decline may be more than 50%. This change in the makeup of the air we breathe has potentially serious implications for our health. Indeed, it could ultimately threaten the survival of human life on earth, according to Roddy Newman, who is drafting a new book, The Oxygen Crisis.
I am not a scientist, but this seems a reasonable concern.