During the last ice age (and others before it) temperatures across the Northern Hemisphere would abruptly swing up and down by a hefty 3 – 6°C every 1,500 years or so. A new study using isotopes on the sea floor rather provocatively suggests that the Atlantic ocean circulation was to blame. Apparently it slowed almost to halt, and before the surface water cooled. It seems that when the Atlantic currents slow too far they stop bringing warmer water north from the equator and Southern Hemisphere, and thus the north ices over. During these super-cold periods the ice sheets spread down and cover much of North America, (and real estate in Australia costs a motza). Massive icebergs break off and drift, but apparently things took a lot longer to get cold in the Southern Hemisphere, and the north and south possibly got a bit out of whack cooling and warming in opposite phases. The researcher used the word “bipolar”.
The $64 trillion dollar question is if ocean currents cause climate change, what causes the ocean currents? The researchers don’t know. (Seems kind of important). Things stabilized out in the last 10,000 warm years. It looks like the wild swings don’t occur […]
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