Could We Ever Run Out of Breathable Oxygen?

We all know that humans, animals and insects need oxygen to breathe, and that we expel carbon dioxide through exhalation. Similarly, we all know that the reverse of this process occurs through the photosynthesis which allows plant life to grow. As such, we have a perfect, mutually-beneficial relationship with our coniferous and deciduous friends.

However, the exponential boom of human, animal and insect populations, coupled with the wanton deforestation of the planet’s green areas, could pose a threat to our idyllic relationship. Indeed, it could theoretically pose a threat to our very existence. What happens if we run out of oxygen? Is a scenario even conceivable?

The Keeling Curve

Professor Ralph Keeling of Scripps Institute is one of the most respected thinkers at the forefront of the oxygen issue. In fact, he’s so well respected that the famous Keeling Curve – a diagram which charts the amount of oxygen in our atmosphere over the millennia – was named after him. Keeling’s diagram illustrates a gradual dwindling in our oxygen supplies… which is accelerating all of the time.

Meanwhile, Keeling’s colleague from Yale University, Robert Berner, believes that levels of oxygen in our atmosphere today are significantly less than they were some 300 million years ago. His predictions place levels of that time at 30% - a good 10% or 11% above today’s levels. The figures have been affected by dramatic events (such as the meteor strike which ultimately caused the extinction of the dinosaurs) and by gradual degrees. Either way, Berner and Keeling agree that oxygen supplies have been dwindling ever more rapidly over the last century or so – in large part due to man’s industrialisation and increasing need for energy.

Carbon emissions, deforestation and damage to the environment have all contributed to less and less oxygen available for us to breathe. Whilst a complete lack of oxygen isn’t feasible within the next few centuries or perhaps even millennia, it is certainly conceivable at some stage.

How Would We Know?

Aside from asphyxiation, there would be a few tell-tale warning signs that our oxygen supplies were getting low… and we can already observe two of three, already.

1)Oceanic “Dead Zones”

There are parts of the ocean where oxygen is so non-existent that life forms cannot be supported. Those which used to live there have either died out or moved onto a new habitat… and the problem appears to be spreading inland into reservoirs and lakes, too. 

2)Forest Fire Charcoal

In areas of high oxygen concentration, forest fires burn rapidly and thoroughly, leaving behind little carbon trace of their combustion. However, where oxygen is scarcer, they burn less efficiently, leaving behind charcoal. More charcoal means less oxygen… a phenomenon we have been witnessing more and more, over recent years.

3)Natural Gas, Unnatural Atmosphere

Gregory Ryskin, a researcher at North-western University, came up with the theorem of mass extinction via methane-driven oceanic eruptions. Too much methane would signal too little oxygen… thus sealing our doom.

What Would Survive?

Cockroaches are often cited as the hardiest critters on Earth, capable of braving a nuclear war and still living to tell the tale. However, even they would struggle to survive without a steady oxygen supply.

Moss, on the other hand, might just make it. Recently, researchers from Reading University and the British Antarctic Survey successfully brought moss back to life after being frozen in ice for 1,500 years. If it can survey a millennium and a half while being frozen, a little absence of oxygen surely won’t hurt.