20th century sea level rise was fastest in 2,000 years along much of the U.S. east coast

Flooding at Forsythe National Nature Reserve

Sea level rise is causing increased flooding at the Edwin B. Forsythe National Wildlife Refuge in New Jersey. The photos show roughly the same view in October (left) and September 2016. Both photos show the same round hill in the upper left corner. Credit: Jennifer S. Walker, Rutgers University

A global increase in melting ice and warming oceans is the most significant change since the 1800s.

The rate of sea level rise in the 20th century along much of the U.S. Atlantic coast was the fastest in 2,000 years, and southern New Jersey had the fastest rates, according to a study led by Rutgers.

The global rise in sea level of melting ice and warming oceans from 1900 to 2000 caused a rate more than double the average during the years 0 to 1800 – the most significant change, according to the study in the journal Natural Communications.

The study first looked at the phenomena that have contributed to sea level change over 2,000 years at six locations along the coast (in Connecticut, New York, New Jersey and North Carolina), on a sea level budget. Budgeting improves understanding of the processes that cause a change in sea level. The processes are global, regional (including geological, such as land reclamation) and local, such as groundwater flow.

“Having a thorough understanding of sea level change at locations in the long run is essential for regional and local planning and responding to future sea level rise,” said lead author Jennifer S. Walker, a postdoctoral associate in the Department of Land. and Planetary Sciences at the School of Arts and Sciences at Rutgers University – New Brunswick. “By learning how various processes vary over time and contribute to sea level change, we can more accurately assess future contributions at specific locations.”

Sea Level Budget for North NJ

Sea level budget for northern New Jersey for the last 2000 years. The contribution to sea level change is divided into four components over time: global, local and regional (geological and other). Since the 20th century, the global contribution due to ice melting and warming of oceans is equal to the regional geological contribution, for a total sea level rise rate of 3.1 mm per year, which is the fastest rate in the last 2000 years. Credit: Rutgers University / Singapore Earth Observatory

Sea level rise stemming from climate change threatens to permanently flood low-lying islands, cities and countries. It also increases their vulnerability to floods and damage from coastal and other storms.

Most sea level budget studies are global and limited to the 20th and 21st centuries. Researchers led by Rutgers have estimated sea level budgets for longer time frames over 2,000 years. The goal was to better understand how the processes driving sea level have changed and could form a future change, and this sea level budgeting method could be applied to other websites around the world.

Using a statistical model, scientists developed sea level budgets for six locations, dividing sea level records into global, regional, and local items. They found that regional landslides – the sinking of the earth since the Laurentide ice retreated thousands of years ago – have dominated the budget of every site for the past 2,000 years. Other regional factors, such as ocean dynamics, and site-specific local processes, such as groundwater retreat that helps make land sink, contribute much less to each budget and vary in time and location.

The overall rate of sea level rise for each of the six sites in the 20th century (ranging from 2.6 to 3.6 millimeters per year, or about 1 to 1.4 inches per decade) was the fastest in 2,000 years. South New Jersey had the fastest rates over the 2,000-year period: 1.6 millimeters per year (about 0.63 inches per decade) at Edwin Forsythe National Nature Reserve, Leeds Point, in Atlantic County and 1.5 millimeters per year ( about 0.6 inches per decade) at Cape May Courthouse, Cape May County. Other sites included East River Marsh in Guilford, Connecticut; Pelham Bay, Bronx, New York; Cheesequake State Park in Old Bridge, New Jersey; and Roanoke Island in North Carolina.

Reference: “Common Era Sea Level Budgets Along the U.S. Atlantic Coast” by Jennifer S. Walker, Robert E. Kopp, Timothy A. Shaw, Niamh Cahill, Nicole S. Khan, Donald C. Barber, Erica L. Ashe, Matthew J. Brain, Jennifer L. Clear, D. Reide Corbett and Benjamin P. Horton, March 23, 2021, Natural Communications.
DOI: 10.1038 / s41467-021-22079-2

Rutgers co-authors include Robert E. Kopp, professor in the Department of Earth and Planetary Sciences at the School of Arts and Sciences at Rutgers University – New Brunswick and director of the Rutgers Institute of Earth, Ocean, and Atmospheric Sciences; and Erica L. Ashe, a postdoctoral scientist in the Department of Earth and Planetary Sciences. Scientists from Nanyang University of Technology, Maynooth University, University of Hong Kong, Bryn Mawr College, Durham University, Liverpool Hope University and University of East Carolina contributed to the study.

Funding: David and Arleen McGlade Foundation, Cushman Foundation for Foraminiferal Research, United States National Science Foundation, Singapore Ministry of Education Academic Research Foundation, Singapore National Research Foundation, Singapore Ministry of Education