Cenomanian-Turonian Extinction Events Case Study

To have a better indication of what actually happens during anoxic events, the Cenomanian-Turonian boundary event will be discussed as a case study. During this time period, two anoxic extinction events happened. The earth’s oceans lacked oxygen for nearly half a million years, causing the extinction of approximately 27 percent of the marine invertebrates (Turgeon, 2008 p. 16). As expected, the global environmental disturbance increased atmospheric and oceanic temperatures. A possible cause was the sub-oceanic volcanism that occurred 500.000 years earlier. Hot mantle plumes under the oceans melted at the base of the lithosphere, resulting in the thickening of the oceanic crust. It produced large quantities of carbon dioxide in atmosphere,
First, there is the temperature rise itself. ‘Altitudinal limits of plant and animal communities will shift upward and amphibians must either move with them or acclimate until adaption occurs’ (Wake, 2008 p. 11471). Another cause that might have led to today’s mass extinction is the magnitude of human population. It has increased dramatically since industrialization and caused habitat modification and destruction, often accompanied by the use of pesticides and fertilizers. Moreover, with the expansion of human populations in new habitats, new diseases have emerged that could have consequences for many taxa (Wake, 2008 p. 11472). Coming back to the anoxic events, the likelihood of them causing the current mass extinction is small, as anoxic events have not yet been verified to be the main cause of a mass extinction event. Furthermore, the effects of anoxic events are relatively smaller than the effects of a global temperature rise at the pace that is happening now. On the other hand, all the conditions for anoxia are present and therefore it would not be surprising if anoxic events would be the main cause after
Mass extinctions are periods of time in Earth’s history when extremely large numbers of species die out simultaneously. This mass extinction could be explained by oceanic anoxic events as the present environmental state of the planet meets all the conditions for anoxia. As researchers find more and more evidence every day, it is assumed that there is indeed a mass extinction happening on our planet today. As the carbon dioxide levels are increasing, oceanic anoxic events are just the earth’s response to excess carbon dioxide into the atmosphere and hydrosphere. In extreme cases, anoxic events can lead to mass extinctions of marine organisms because there is less oxygen in the oceans. During the Cenomanian-Turonian boundary event, the earth’s oceans lacked oxygen for nearly half a million years, causing the extinction of approximately 27 percent of the marine invertebrates. In the Permian-Triassic mass extinction event, anoxia might even have led to the most severe mass extinction event the world has ever known. The aim of the research was to determine whether oceanic anoxic events can be the cause of today’s mass extinction. With the knowledge gained, it is safe to say that this mass extinction has, just like all others, more causes. Combined they caused todays mass extinction, and anoxic events can definitely be one of the causes. Human activity, however, is the