Has the Earth's sixth mass extinction already arrived? A. D. Barnosky, N. Matzke, S. Tomiya, G. O. U. Wogan, B. Swartz, T. B. Quental, C. Marshall, J. L. McGuire, E. L. Lindsey, K. C. Maguire, B. Mersey, E. A. Ferrer

This article suggests that the current rate of species extinction is higher than what has been expected in the past (compared against fossil records). The authors propose that this elevated rate of extinction may possibly be the beginning of the 6th known mass extinction event on earth.

This extinction would drastically lower biodiversity by killing off many species that would otherwise function as carbon sinks. The release of such massive amounts of carbon might have dramatic effects upon the environment.

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Past and present of sediment and carbon biogeochemical cycling models By:Mackenzie, FT (Mackenzie, FT); Lerman, A (Lerman, A); Andersson, AJ (Andersson, AJ) This is a secondary study of the history of the carbon cycle, with particular respect to the onset of industrialization as well as the dynamic role the ocean plays in carbon storage. Prior to industrialization, the ocean was a net source of CO2 emissions due to the net carbon differences between photosynthesis and respiration. However, the massive CO2 releases from the burning of fossil fuels have made the ocean into a net carbon sink.

This citation is referring to the storage of carbon within calcium carbonate (CaCO3), or limescale within the ocean. This limescale comprises most of the 'rocks' in reference.

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