When the Olympics almost lost their bet against climate change

Paris Olympics organizers took a gamble on swimming in the Seine River, despite climate change's extreme weather challenges.

With plans for athletes to swim the Seine River through the heart of Paris, Olympic organizers essentially bet against climate change’s extreme weather. For several days it appeared they would lose — by ditching the swimming portion of triathlon races.

It wasn’t until early Wednesday, after the men’s race had been postponed a day and test events called off, that organizers announced the most recent tests showed the water met standards to allow swimming.

Some scientists and engineers said organizers were taking a huge gamble at a time when heavy rains have increased with human-caused climate change, especially in Europe. The rains run off from the urban environment and contribute to higher bacteria levels in the city’s famed river.

“They just gambled, flipped the coin and hope for a dry season and it turned out to be the rainiest in the last 30 years,” said Metin Duran, a professor of civil and environmental engineering at Villanova University who has researched stormwater management.

Organizers “had worked through most of the scenarios related to computer hacking and physical threats without fully assessing the implications of extreme events associated with climate,” said University of Arizona climate scientist Kathy Jacobs, who directs the Center for Climate Adaptation Science and Solutions. “It’s definitely time to take climate threats seriously.”

If any city could be expected to be mindful of the challenges of climate change, it’s Paris. It’s where the most significant climate agreement in history was struck almost a decade ago — to try to limit Earth’s warming to 1.5 degrees C above pre-industrial levels. And the Paris games aspire to have half the carbon footprint of earlier games held in London and Rio de Janeiro.

Paris, like many older cities around the world, has a combined sewer system, which means that the city’s wastewater and stormwater flow through the same pipes. With heavy or prolonged periods of rain, the pipes’ capacity is reached, sending raw wastewater into the river instead of a treatment plant.