Scientists baffled by declining oxygen levels in the atmosphere explore possible causes.
The level of oxygen on the earth’s atmosphere has been on a decline for the past 8000 centuries. While the rate of decline (0.7 percent) has had very minimal effect on the earth’s inhabitants, experts remain baffled by this phenomena.
According to “Science” journal, a team from Princeton University studied air bubbles in polar ice found in the world’s two main ice sheets – Antarctica and Greenland. By calculating the oxygen-nitrogen ratio in these bubbles, the team came up with the atmospheric pressure of oxygen on earth in prehistoric times.
Life on earth will not thrive in the absence of oxygen. This important element is also vital for various chemical processes to take place on earth. On the surface, a 0.7 percent decrease may be insignificant at the moment but its effect on the earth on a much longer period might later present some issues.
Many experts have been researching on the possible reasons for decline in the earth’s oxygen supply.
One possibility was raised by geochemist Daniel Stolper. He said that the rates of global erosion have gone up compared with those many million years ago. The growth of glaciers aggravate erosion which eventually expose the subsoil. Elements present underneath layers of soil like iron when combined with oxygen produce rust. It is a process that draws in oxygen. The mineral pyrite when bonded with organic carbon also affect the oxygen concentration in the atmosphere.
Others raised that the cooling of the earth’s oceans heightens oxygen’s solubility and at very low temperatures, oceans tend to retain more oxygen. Microbes become more active and consume more oxygen.
Research also revealed another unexplained occurrence. When oxygen declines, carbon dioxide levels typically rise. But for one reason or another, carbon dioxide levels did not change much.
Another expert in geological systems explained that the seemingly constant level of carbon dioxide (despite a diminished oxygen level) may be due to silicate weathering thermostat. The earth over hundreds of years controls carbon dioxide in the atmosphere. This concept however has yet to be reviewed and tested over time.
