sentences:  In fact, during periods of both eccentricity and precession minima, even small variations in total insolation might lead the control of climate to greenhouse gasses, in particular .In shallow-water environments, the development of several major reef systems (such as the Great Barrier Reef) accompanied increased reef carbonate production.Calcium carbonate production peaked in subpolar and subtropical oceans, reflecting a shift in plankton ecology from diatoms to calcareous plankton due to changes in seawater temperatures, which were apparently warmer at low latitudes.