A global analysis of sea level over the past 2,000 years revealed a rapid rate of rise consistent with the industrial revolution.
In 1863, researchers found that the rate of sea level rise had clearly exceeded background variability. Unsurprisingly, it was at this time that the first evidence of ocean warming and glacier melting due to human activity also appeared in the research, and both are known to contribute to sea level rise.
For 1,700 years (from 0 CE), the current analysis found that global sea level has fluctuated between a 0.3 millimeter drop and a 0.2 mm rise.
Between 1700 and 1760, just before the Industrial Revolution and the beginning of widespread fossil fuel burning, sea level was falling by 0.1 millimeter per year.
But from 1940 to 2000, global sea level had reached an increase of 1.4 millimeters per year.
“Consistent with previous analyses, it is virtually certain that the global growth rate from the most recent 60-year interval, 1940–2000 CE, was faster than all previous 60-year intervals during the common era,” the authors write.
This is not the first analysis to attempt to put an “emergence” date on sea level rise, but it is one of the first to simultaneously compare individual sites in certain regions to a global signal.
According to a chronology of published instrumental and proxy data — things like foraminifera, diatoms, archaeological evidence, and sediment geochemistry — across the North Atlantic, some parts of this ocean have shown signs of significant sea level rise earlier than others.
In the Mid-Atlantic region, for example, sea level began to rise in the mid- to late-19th century. But based on data from the Atlantic coasts of Canada and Europe, the rate of sea-level rise only stands out in the mid-20th century.
“The fact that modern rates emerge at all of our study sites in the mid-20th century demonstrates the significant influence of global sea level rise on our planet over the past century,” says environmental scientist Jennifer Walker of Rutgers University.
“Further analysis of the spatial variability in the timing of emergence at different locations will continue to improve society’s understanding of the impact of regional and local processes on rates of sea level rise.”
Previous global estimates have also found significant acceleration in sea level from the 19th century onward. And the latest report from the Intergovernmental Panel on Climate Change (IPCC) shows a sustained rise between 1820 and 1860.
But the new research is disturbing because it reveals an unprecedented rise in sea level from one region to another across the Atlantic.
Sea levels are poised to rise faster than ever over the next century, and we need to know what’s headed for the world’s coasts so we can work to mitigate the effects as much as possible.
The study was published in Nature Communications.