THE PHANEROZOIC RECORD OF GLOBAL SEA-LEVEL CHANGE

Sea-level changes have occurred throughout the Phanerozoic (past 543 my) on various geological time scales and with distinctive causes. On the 10⁸ y scale, sea-level changes of 100's m are controlled by the assembly and dispersal of supercontinents. On the 10⁷ y scale, changes of 100-300 m have been attributed to variations in ocean crust production, although new data question this long-held tenet. Ice-volume variations controlled sea-level changes of ~30-80 m on the 10⁶ y scale over at least the past 100 my and changes of 30-120+ m on the 10⁴-10⁵ y scale for the past 2.5 my. The last deglaciation (18-6 ka) caused a rapid rise punctuated by 10³ y perturbations, with global sea level rising slowly (1 mm/y) over the past 6 ky. Here, we review sea-level changes over the past 543 my and present a new sea-level record for the last 100 my. 10⁷ y scale sea-level changes were smaller than previously inferred, with a Late Cretaceous peak of 100±50 m, implying smaller changes in seafloor spreading rates. Sea-level change has influenced evolutionary trends in phytoplankton, ocean chemistry, and the loci of carbonate, organic carbon, and siliciclastic sediment burial. It reflects global climate change through a covariance with CO₂ on the 10⁷ y scale and ice volume and CO₂ on the scales of 10⁴-10⁶ y. Over the past 100 my, sea-level changes reflect global climate evolution from a time of ephemeral Antarctic ice sheets (100-33 Ma) through a world in which Antarctic ice sheets were large and variable (33-2.5 Ma) to a world in which both Antarctic and Northern Hemisphere ice sheets were large and variable (2.5-0 Ma).