Climate Science

High and Dry

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Science  09 Jan 2004:
Vol. 303, Issue 5655, pp. 146
DOI: 10.1126/science.303.5655.146c

Venice is being swallowed by the sea. The combination of land subsidence due to groundwater pumping and sea level rise due to global warming has increased the water level in the city by 23 cm in the past 100 years, and a further rise of about 50 cm is projected to occur over the next century. The frequency of the floods known as “acqua alta” has increased; these events submerge large areas of the city by as much as a meter in extreme cases. Various measures have been proposed to safeguard the islands from the high waters, such as the construction of a set of movable gates across the three entrances to the lagoon in which Venice resides, but none have convinced all of the critics.

In a departure from the idea that the solution is to control the sea, Comerlati et al. offer a fundamentally different proposal: raise Venice by pumping CO2 or seawater into the brackish aquifer that lies 600 to 800 m beneath the city. They estimate that the city could be raised by as much as 30 cm in 10 years if seawater were used, and up to 24 cm if CO2 were used, which would have the added benefit of reducing Italy's net greenhouse gas emissions. This strategy could avoid the potentially harmful side effects that repeatedly restricting water flow into the lagoon would precipitate and could eliminate all but the severest of the acqua alta episodes, which would make raising the gates an infrequent necessity. — HJS

Eos 84, 546 (2003).

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