Warming at 140 ka: Causality Problem for Milankovitch?

Sediment cores that contain records of both temperature and global ice volume indicate a major warming at about 140 ka. This is a potential causality problem for Milankovitch theory, because summertime, high-latitude, northern hemisphere insolation is at a low point at 140 ka, and does not peak until 127 ka. Such "early warming" is observed in the North Atlantic, Equatorial Atlantic, East Pacific, and West Pacific. Thus the phenomenon is more widespread than previously appreciated. Because it is observed at sites around the world, and because the warming is of a scale similar to that of deglaciation - itself the largest amplitude climate change of the Quaternary - its failure to be explained by Milankovitch forcing is a serious shortcoming for the theory.