The findings are not yet a cause for alarm, says Gersberg. At Lido, where tourists are allowed to swim, the pathogen levels were much lower and met European health standards. Those who stick to the city will be safe with only minimal precautions—not dipping their hands in the lagoon from the side of a gondola, for example.
The situation would likely worsen over time, though, if MOSE's gates remained closed for long periods. "Taking sewage when it floods and having people walk around in it—to not expect a health problem, you would have to be an eternal optimist," Gersberg says.
So far, and somewhat ironically, climate change's biggest impact on Venice has been that sea level forecasts might have spurred the government to move ahead with MOSE after years of sitting on the plans. Construction is 30 percent complete, says Campostrini, and few other options exist. In one scenario still being investigated, officials would pump water below the city surface, raising it as much as a foot.
Filmmakers Marylou and Jerome Bongiorno recently gathered several scientists, including Carrera, to discuss MOSE and alternative defenses against rising sea levels, as part of their research for a documentary and feature film focusing on climate change in Venice. The problems, they say, are not as far away as they seem.
"You have to look at Venice and say, 'It's already happening,'" says Marylou, whose parents are native Venetians. "'Global warming' has become this fashionable term, but we don't want everybody to say, 'It's going to be hot this summer,' and think that's global warming."
The researchers kicked around several ideas, says Jerome, from planting boats in various regions of the lagoon that would divert incoming sea water, to building a wall around the entire city.
"At a certain point, MOSE is not going to work anymore," he says. "Why not build a pretty wall now that becomes part of the city's culture?"
To satisfy Gersberg's fears, building a "Great Wall of Venice" would require retrofitting the city's classic buildings with modern sewage—a daunting task. Such an enclosure could still impact marine life and create economic problems by cutting off access to shipping harbors. Not to mention the facelift it would give a city known to value tradition. An attraction of MOSE, says Campostrini, is that it preserves the current look of the lagoon.
Lagoon or not, Venice might cease being operational without a more drastic plan, says Carrera. Though MOSE will do some good, he says, it's a bit like building a dome around Boston to keep away occasional snowstorms: A passable solution, yes. But probably not the best use of resources.
"If global warming's worst predictions come true in 100 years," says Carrera, "the real issue is preserving Venice as a liveable place—not stopping the occasional tide from coming in."