The oxygen crisis
Could the decline of oxygen in the atmosphere undermine our health and threaten human survival?
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. It is a possibility that we should examine and assess. So, what's the evidence?
Around 10,000 years ago, the planet's
forest cover was at least twice what it is today, which means that forests are now emitting only half the amount of oxygen.
Desertification and deforestation are rapidly accelerating this long-term loss of oxygen sources.
The story at sea is much the same. Nasa reports that in the north Pacific ocean oxygen-producing
phytoplankton concentrations are 30% lower today, compared to the 1980s. This is a huge drop in just three decades.
Moreover, the UN environment programme confirmed in 2004 that there were nearly 150 "
dead zones" in the world's oceans where discharged sewage and industrial waste, farm fertiliser run-off and other pollutants have reduced oxygen levels to such an extent that most or all sea creatures can no longer live there. This oxygen starvation is reducing regional fish stocks and diminishing the food supplies of populations that are dependent on fishing. It also causes genetic mutations and hormonal changes that can affect the reproductive capacity of sea life, which could further diminish global fish supplies.
Professor
Robert Berner of Yale University has researched oxygen levels in prehistoric times by chemically analysing air bubbles trapped in fossilised tree amber. He suggests that humans breathed a much more oxygen-rich air 10,000 years ago.
http://www.theguardian.com/commentisfree/2008/aug/13/carbonemissions.climatechange