Scientists have speculated for some time that the Earth's carbon cycle extends deep into the planet's interior, but until now there has been no direct evidence. The mantle–Earth's thickest layer –is largely inaccessible...Analysis [of lower mantle diamonds] shows compositions consistent with the mineralogy of oceanic crust. This finding is the first direct evidence that slabs of oceanic crust sank or subducted into the lower mantle and that material, including carbon, is cycled between Earth's surface and depths of hundreds of miles.
The research is published in the September 15, 2011, online Science Express.__Physorg
Climate models have been unable to account for all the "missing carbon," the carbon being released into the atmosphere that seems to "disappear," from view in unaccountable fashion. But is it possible that the oceans are taking this carbon and turning it into carbonaceous rock which is being transformed by Earth's mantle into diamond?
The oceans are voracious consumers of atmospheric carbon. Dissolved CO2 immediately turns into bicarbonate ion almost in entirety. Oceanic sea life rapidly turns this bicarbonate into both biomass and calcium carbonate shells. This organic and inorganic carbon sinks to the seafloor, which over time is subducted into the Earth's mantle.
After the heat and pressure of the mantle have transformed carbons within the subducted oceanic crust into other forms -- including diamond -- some of the transformed carbon is returned to the crust in upwelling mantle plumes.
The lesson for scientists, in all of this, is not to jump to conclusions before all the facts are in. When it comes to the carbon cycle and global climate, the facts have just begun to come in. But we are nowhere close to being justified in coming to conclusions. Stop treating computer models as if they were the actual physical phenomenon being studied! Models are not reality. Stop treating them as such.