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The Gulf Stream in the Ice Age

17 September 2014

At http://phys.org/print330072076.html … an article in the journal Geology claims the Gulf Stream still flowed into the Nordic seas during the coldest parts of the Ice Age. Is this possible?

The Ice Ages, it informs us, were a generally cold period (stadials) interrupted by a number of warm periods (interstadials). These are not to be confused with interglacials which are supposed to have occurred at roughly 100,000 year intervals. In the consensus view the warm Gulf Stream was thought to have ceased to reach Norwegian waters – but bottom water temperatures seem to have been fairly similar to those of today. In other words, the bottom waters appear to be opposite to the consensus view in respect of the atmosphere and the air – which is that an ice sheet covered most of the northern hemisphere which meant it must have been very cold outside.

So, how did the researchers get around that? The explanation involves fresh melt water from ice bergs stopped the oceans from achieving the required density to sink – a process linked to salinity. The warm Atlantic water was saltier and therefore heavier and subducted at depth – as far as the ocean bottom. It wamred the ocean beneath a lid of ice and melt water and this in turn prevented the release of heat to the atmosphere.

The evidence of warmth in bottom waters comes from sediments on the sea floor, namely the shells of benthic foraminifera, a form of plankton. The chemistry of the shells is telling them that it was warmer – but they still insist the Ice Age was cold. Full stop. Another assumption of course is that the shells are mini thermometers – are they?

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