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Hot enough for you? A new NASA study has found that global temperatures are nearing their hottest level in more than 12,000 years - since the last glaciers covered large portions of the planet. In fact, global temperatures have been going up approximately 0.2° Celsius (.36° Fahrenheit) per decade for the past 30 years. In fact, global temperatures are now within one degree Celsius of the hottest temperatures measured in the last million years.
Responsible NASA Official: James E. Hansen
Originally posted by Muaddib
I wonder why is it that some scientists are claiming this when anyone who has done some research on this topic knows that 800 years ago, during the Medieval warming period, temperatures were much higher than they are now...
Originally posted by TaupeDragon
Hey Muaddib
But the magnesium science in the shells gives a reliable record for temperatures, doesn't it?
TD
X-ray diffraction analysis of Recent calcareous specimens of Foraminifera indicates that the mineralogic nature of tests is a generic characteristic, with the few genera that have aragonite tests being related at the family level. Environment appears to have no influence on the presence of calcite or aragonite and the two minerals do not occur together in the Foraminifera.
In modern seas, coralline algae produce skeletons of high-Mg calcite (>4 mol % MgCO3). We grew three species of these algae in artificial seawaters having three different Mg/Ca ratios. All of the species incorporated amounts of Mg into their skeletons in proportion to the ambient Mg/Ca ratio, mimicking the pattern for nonskeletal precipitation. Thus, the algae calcified as if they were simply inducing precipitation from seawater through their consumption of CO2 for photosynthesis; presumably organic templates specify the calcite crystal structure of their skeletons. In artificial seawater with the low Mg/Ca ratio of Late Cretaceous seas, the algae in our experiments produced low-Mg calcite (
Originally posted by TaupeDragon
.......
Edit 2 - the aragonite link you gave. It's a bit over my head - how does an article about CaCO3 relate to the Mg/Ca ratio claims of the UCSB guy? I'm not being stroppy, I just don't get the thrust of it, so if you could spell it out slowly I'd be grateful.
Originally posted by TaupeDragon
Edit 3 - From your last link. 'Thus, at past times when the Mg/Ca ratio of seawater was relatively low, these taxa may also have incorporated less magnesium into their skeletons than they do today.' I wonder if they *have* taken that into account in their data.
Thanks for the links Muaddib, fascinating!