The Great Ocean Conveyor Belt – blue = deep cold and saltier water current, red = shallower and warmer current
[credit: NWS / NOAA]
It’s known, or at least believed, that transit times of some ocean waters can be as long as 1,000 years. The researchers are well aware that this exceeds the time since some well-known warming and cooling periods in the Earth’s past, such as the Medieval Warm Period and Little Ice Age.
Whereas most of the ocean is responding to modern warming, the deep Pacific may be cooling, say researchers.
The ocean has a long memory. When the water in today’s deep Pacific Ocean last saw sunlight, Charlemagne was the Holy Roman Emperor, the Song Dynasty ruled China and Oxford University had just held its very first class.
During that time, between the 9th and 12th centuries, the earth’s climate was generally warmer before the…
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