The sea level in Venice may level off by about 2035, giving the city a brief respite from constantly rising water. It turns out that changes in the surface temperature of the Atlantic Ocean are linked to how high the water gets in Venice, and as the North Atlantic enters a cooler phase, it should slow the rise of water in the Mediterranean.
A combination of subsidence and sea level rise has left Venice about . Continuing sea level rise, caused by global warming, is expected to push waters up further by the end of the century, by between 30cm and 120cm, which would leave much of the iconic Italian city permanently flooded under the most pessimistic warming scenarios.
Rising global temperatures have resulted in sea level rise across the Mediterranean, but it hasn鈥檛 climbed smoothly. Historic tide gauge and satellite data show a climbing pattern punctuated by periods of two decades or more when sea level rise has slowed or even plateaued.
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To better understand these fluctuations, at Ca鈥� Foscari University of Venice and his colleagues have compared 150 years鈥� worth of sea level data from Venice with data on sea surface temperature variations from the North Atlantic Ocean.
The researchers found a correlation between average winter sea level in Venice and naturally occurring sea surface temperature variations in the North Atlantic, which happen over a 60 to 80-year time period, known as Atlantic multi-decadal oscillation or Atlantic multi-decadal variability (AMV).
During cooler phases of the oscillation, sea level rise in Venice slowed down, whereas during warmer phases, it accelerated. The link between the two is complex, but it seems that changes in sea surface temperature in the Atlantic propagate into the Mediterranean, where they influence circulation patterns in the water and the atmosphere, says Zanchettin.
Some studies suggest , he says. 鈥淚f it does, then our calculations indicate that between now and 2035, the sea level in Venice may level off, with the cold AMV phase temporarily compensating for the sea level rise due to ongoing global heating.鈥�
鈥淭he findings may partially explain the sea level fall that we鈥檝e observed across the Mediterranean basin between 1960 and 1989 and the rise since the 1990s, but there are many other influences like ice sheet melt and thermal expansion of water due to global warming,鈥� says at the National Oceanography Centre in Liverpool, UK.
Having a better understanding of sea level change means we can plan better and avoid wasting money on building infrastructure bigger than it needs to be, he says.
Earth and Space Science
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