COMMON ERA CONSTRAINTS ON FUTURE SEA-LEVEL RISE (Invited Presentation)

Common Era (CE) sea-level reconstructions capture climate and sea-level variability over a wide range of spatial and temporal scales. Our database reveals multiple phases of coherent regional and global change, indicative of both natural and forced variability that provide a pre-anthropogenic background against which to compare recent trends. These records offer a unique opportunity to evaluate the representation of climate and sea-level variability in climate models from the last millennium through the 21st century.

We have developed CE sea-level reconstructions from Newfoundland, Canada to Tampa Bay, Florida. These reconstructions from the Atlantic and Gulf coasts of North America reveal two distinct patterns in sea-level variability during the CE. Firstly, south of Cape Hatteras, North Carolina, to Florida, sea-level rise is essentially flat, with the record dominated by long-term geological processes until the onset of historic rates of rise in the late 19th century. Secondly, north of Cape Hatteras to Connecticut, sea level rises to a maximum around 1000 CE, falls to a sea-level minimum around 1500 CE, before further long-term sea-level rise through the second half of the second millennium prior to the late 19th century acceleration. The northern-intensified sea-level fall beginning ~1000 is coincident with shifts toward persistent positive NAO-like atmospheric state inferred from other proxy records.

To reveal global mean sea-level variability, we collate high resolution proxies from coasts of the northern and southern hemispheres that are tectonically stable. We apply a spatio-temporal modeling framework, which identifies a long-term falling global mean sea level during the last millennia. The trend was interrupted in the middle of the 19th century by an acceleration, which yielded a 20th century rate of rise that was faster (probability P = 0:95) than any previous century in the CE.