Bummer: Antarctic ocean currents allegedly fluctuated a bit starting around the time of the Warren G. Harding administration; CO2 blamed

Polar research: Trouble bares its claws : Nature News & Comment

Cold temperatures have kept crabs out of Antarctic seas for 30 million years. [Really?  How can we presume to know that?]
...
The temperature of this intruding water is only about 1.8 °C — but for an ocean region generally between 1 and −2 °C, the impact is substantial...On the basis of these measurements, Domack has deduced that the warm-water incursion “kicked in somewhere around the turn of the last century, 1920 or 1930”.