Oxygen and water...the two most critical elements for human survival. In this story, they are inextricably linked. The story of the threat to the air we breathe is deceptively simple. It's based on 3 scientifically proven facts (well 4, actually, by implication).
First, depending on whose numbers you trust, between 1/3 and 1/2 of the world's atmospheric oxygen is supplied by ocean-borne algae. See Phyto Plankton - The Most Valuable Species on Earth
Second, the phytoplankton, much of which is algae, in the world's oceans are decreasing. A number of theories have been proposed.
- The oceans are becoming warmer, which reduces the nutrients that phytoplankton need. See Rising Sea Temperatures Killing Vital Algae.
- Chemicals, especially herbicides and pesticides, are showing up in the oceans at increasing concentrations, perhaps enough to be lethal for the smallest organisms. See Pollution Wreaks Havoc on the Oceans, Animals and Plants.
Third, the ocean's top fish predators, such as bluefin tuna and sharks are being harvested into extinction. By implication, the population of small bait fish will explode and the bait fish eat phytoplankton, including algae. Absent other factors, this will cause a well known boom-and-bust cycle. Phytoplankton populations drop partly because of high bait fish consumption. With less food, bait fish populations drop. Phytoplankton populations resurge. Then, bait fish populations resurge. And the cycle starts over. During these cycles, atmospheric oxygen and carbon dioxide levels could wax and wane significantly.
So, two seemingly unrelated controversies are interconnected and potentially the cause of lowering the oxygen concentration in our atmosphere by killing off the algae that provide it.
If the atmospheric oxygen concentration drops 33%, the more conservative estimate, as a result of an algae collapse, living at sea level will be the equivalent of 12,000 feet today. 12,000 feet! Very few people can function at that altitude, certainly not the average, overweight, out of shape American. Are we all going to walk around with a tank and cannula and pay for oxygen to breathe? And you thought buying drinking water was bad.
Even if global warming isn't real, as many argue, business as usual with regard to carbon emissions and fishing will guarantee the loss of a substantial amount of the oxygen we breathe. The irrefutable facts are in. We know tuna populations are collapsing. We know the increased ocean acidity is killing phytoplankton blooms and it's inevitable that exploding bait fish populations, in the absence of predation, will consume vast quantities of phytoplankton.
What's to be done? The easy one is to halt the taking of the large predatory fish such as the bluefin tuna. The harder one is to reduce carbon dioxide levels in the atmosphere. Not slow down the emissions. That won't work. It will require ceasing emissions or sequestering the carbon dioxide so that atmospheric concentration is below the levels that they were before the industrial revolution.
It's a tough assignment. But, do we want to wear oxygen tanks the rest of our lives and pay and pay and pay just to be able to breathe? Have you seen an emphysema patient tied to an oxygen bottle 24x7? Is that how we want to live?