Start Date
25-2-2020 4:00 PM
End Date
25-2-2020 5:00 PM
Access Type
Open Access
Abstract
Sea-level history reflects the thermal and cryospheric evolution of the Earth, providing a history of ice- sheet behavior and operation of the climate systems under ice-free and glaciated conditions. I compare ice-volume and sea-level estimates obtained from deep Pacific δ18O and Mg/Ca records with those from the mid-Atlantic U.S. obtained by “backstripping”, progressively accounting for the effects of compaction, loading, and thermal subsidence. Peak warmth, sea levels, high CO2 (>1000 ppm), and mostly ice-free condition occurred in the Hothouse Late Cretaceous (ca. 100-66 Ma) and Early Eocene (55-47.9 Ma). During the cool greenhouse (Paleocene, Middle-Late Eocene) sea level was driven by ice growth and decay of small ice sheets. The Earth became a unipolar Icehouse world in the Oligocene-Pliocene (35-2.55 Ma) punctuated by the ice-free Miocene Climate Optimum (~17-15 Ma) and warmth of the Pliocene Climate Optimum, with partial loss of the East Antarctic ice sheet. Very large sea-level changes (60-130 m) were restricted to the past 2.7 Myr northern hemisphere “ice ages”. Following the last glacial sea-level lowering (~130 m), rates of sea-level exceeded 50 mm/yr, slowing to a Common Era “stillstand”, 20th century rise of 1-2 mm/yr, and a modern rise of 3 mm/yr. Projected sea-level rise in the 21st century is ~1 m under high emissions scenarios, with possible upper limit of over 2 m and rates exceeding 10 mm/yr.
Biography
Ken Miller studies sea-level and oceanographic changes over the past 200 million years. He is a Distinguished Professor with an A.B. from Rutgers College (1978) and a Ph.D. from the MIT/WHOI Joint Program (1982). He was awarded the Laurence L. Sloss Award, the Rosenstiel Award from the University of Miami and is a two-time JOI/USSAC Distinguished Lecturer, an AAPG Distinguished Lecturer, and a Fellow of AGU & GSA. He just sold his house in Waretown, NJ where he used to watch the inexorable rise in sea level from his deck 15 ft above Barnegat Bay.
An Overview of Climate & Sea-level Changes Over the Past 100 Million Years
Sea-level history reflects the thermal and cryospheric evolution of the Earth, providing a history of ice- sheet behavior and operation of the climate systems under ice-free and glaciated conditions. I compare ice-volume and sea-level estimates obtained from deep Pacific δ18O and Mg/Ca records with those from the mid-Atlantic U.S. obtained by “backstripping”, progressively accounting for the effects of compaction, loading, and thermal subsidence. Peak warmth, sea levels, high CO2 (>1000 ppm), and mostly ice-free condition occurred in the Hothouse Late Cretaceous (ca. 100-66 Ma) and Early Eocene (55-47.9 Ma). During the cool greenhouse (Paleocene, Middle-Late Eocene) sea level was driven by ice growth and decay of small ice sheets. The Earth became a unipolar Icehouse world in the Oligocene-Pliocene (35-2.55 Ma) punctuated by the ice-free Miocene Climate Optimum (~17-15 Ma) and warmth of the Pliocene Climate Optimum, with partial loss of the East Antarctic ice sheet. Very large sea-level changes (60-130 m) were restricted to the past 2.7 Myr northern hemisphere “ice ages”. Following the last glacial sea-level lowering (~130 m), rates of sea-level exceeded 50 mm/yr, slowing to a Common Era “stillstand”, 20th century rise of 1-2 mm/yr, and a modern rise of 3 mm/yr. Projected sea-level rise in the 21st century is ~1 m under high emissions scenarios, with possible upper limit of over 2 m and rates exceeding 10 mm/yr.