SCIENCE: Study reveals year of actual acceleration in sea level rise.

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.

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