In the 9 October Science magazine, H. Cheng et al. make some big connections between glacier melt in the North Atlantic, Asian monsoons, and the ends of ice ages. There's no simple explanation. Jeffrey Severinghaus gives a nice summary in that issue of the magazine, but it's also hard to cut down in length. The last paragraph gives a flavor of the intertwined feedbacks.
Cheng et al. thus confirm the astronomical theory of the ice ages, but with a twist: The shutoff of the MOC [Atlantic meridional overturning circulation] and its associated southward shift of tropical rian belts, warming of the Southern Hemisphere..., and rise in atmospheric CO2 plays an integral role in the meltdown of the great ice sheets. Using monsoons to improve dating precision across the whole suite of paleodata, Cheng et al. show the way to the first coherent narrative that truly explains terminations and the inseparable question of what causes the ice age cycles.In the 16 October Science, archaea and bacteria are reported to have been found in ocean-floor cold seeps that fix nitrogen. There have recently been some problems in modeling the nitrogen balance of oceans. This discovery may help to fix that.
It's frustrating that Science keeps their articles behind a subscription wall. I probably should sign up for the on-line version instead of depending on the dead-tree one.
Bonus: you can use the quote above as a Friday Dinner Party Conversation Stopper™.