It is pretty common knowledge, these days, that Earth’s oceans are the most important depository for atmospheric carbon dioxide in terms of a time scale from decades to millennia. However, this process of locking away greenhouse gases from the air gets weaker, over time, due to activity in the Southern Ocean. As such, increased activity in the Southern Ocean might explain what has been noted as a mysterious warming period, which has lasted for 11,000 years (or since the beginning of the Holocene).
According to an international team of researchers, the warming of this period stabilized from a gradual rise in global levels of carbon dioxide. Furthermore, Princeton University Dusenbury Professor of Geological and Geophysical Sciences, Daniel Sigman, admits that understanding the reason for such a rise is of great interest to the scientific community.
Of course, scientists have posed many theories about the increase of carbon dioxide; but none have been able to determine the ultimate cause of the rise.
Sigman goes on to say, “We think we may have found the answer. Increased circulation in the Southern Ocean allowed carbon dioxide to leak into the atmosphere, working to warm the planet.”
These findings regarding ocean changes might have further implications for predicting how overall global warming could affect future ocean circulation. It could also help determine how global warming might further increase the rate of atmospheric carbon dioxide rising as the result of burning fossil fuels.
Researchers have long known that the growth and sinking of phytoplankton regularly pump more carbon dioxide into the ocean. This is a process commonly known as “the biological pump” and is mostly driven by low altitude oceans which are undone as the water approaches the poles, at a point where CO2 is vented back to the surface.
According to Sigman, the Holocene is different from previous interglacial periods in many ways. First of all, the climate was unusually stable during this time, characterized by a lack of the major cooling trend attributed to most interglacial periods. Secondly, atmospheric CO2 concentration during this time rose 20ppm, which is larger than usual.
The research and study appear in the current issue of the journal Nature Geoscience.