Sea ranges are rising quickest in 2000 years (or not!)


JUNE 14, 2021

By Paul Homewood

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

The global rise in sea levels from melting ice and ocean warming from 1900 to 2000 resulted in a rate more than double the average from 0 to 1800 – the most significant change, according to the

Study in the journal Nature Communications.

The study first examined the phenomena that contributed to sea level change over 2,000 years at six locations along the coast (in Connecticut, New York City, New Jersey, and North Carolina) using a sea level budget. A budget improves understanding of the processes that drive sea level change. The processes are global, regional (including geological, such as land subsidence), and local, such as water abstraction.

“A thorough understanding of long-term sea level changes at locations is essential for regional and local planning and for responding to future sea level rise,” said lead author

Jennifer S. Walker, postdoctoral fellow in the Department of Earth and Planetary Sciences at the School of Arts and Sciences at Rutgers University-New Brunswick. “By learning how various processes change over time and contribute to changing sea levels, we can more accurately estimate future contributions at specific locations.”

The rise in sea levels caused by climate change threatens to permanently flood low-lying islands, cities and rural areas. It also increases their vulnerability to flooding and damage from coastal and other storms.

Most studies of the sea level budget are global and limited to the 20th and 21st centuries. Rutgers-led researchers estimated sea level budgets for extended periods of time over 2,000 years. The aim was to better understand how the processes that drive sea level have changed and could affect future changes, and this method of sea level budgeting could be applied to other locations around the world.

Using a statistical model, the scientists developed sea level budgets for six locations and divided the sea level records into global, regional and local components. They found that regional subsidence – the subsidence of land since the Laurentide Ice Sheet retreated thousands of years ago – has dominated any site’s budget for the past 2,000 years. Other regional factors such as ocean dynamics and site-specific local processes such as groundwater abstraction, which contributes to subsidence of land, add much less to any budget and vary over time and by location.

As current data shows, New Jersey sea level rise has been fairly constant since 1910, suggesting that overall carbon emissions have had little impact. What we see is the result of natural global warming since the end of the Little Ice Age:

The study claims that the sea level rise in the 20th century is double what it was in 0-1800. But its modeling does not take into account changing century or decade trends over the period. We know for sure that the glaciers advanced massively between the 17th and 19th centuries. So there must have been a significant decrease in sea level rise at that time, maybe even a fall in sea level, as HH Lamm believed.

Lamb also believed that in the previous cold epoch, around AD 450 to 850, the glaciers were almost as large as the LIA. Hence there will have been fluctuations in the long-term trend, with sea levels rising sometimes faster and sometimes slower.

What we do know is that many of the world’s glaciers are larger today than they were in the Middle Ages and before.

As with all climate studies, the aim is to prove that climate change is “getting worse than ever”. Therefore, one speaks of an accelerated rise in sea level. The intent is to make people afraid of something that is too small to affect them.

NOAA kindly provides this table that compares actual sea level rise with official forecasts:

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