This ecologist thinks coastal wetlands can outrun rising seas. Not everyone’s convinced
By Gabriel Popkin
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Saltwater is forecast to slosh into places it hasn’t been since long before humans arrived. In the continental United States alone, just 1 meter of relative sea level rise could allow high tides to submerge as much as 49,000 square kilometers of now dry land—an area the size of Vermont and New Hampshire combined. Other countries have it worse. Egypt and Bangladesh could lose almost one-fifth of their habitable land. More than 200 million people could face flooding risk by 2050, studies suggest.
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Kirwan, however, has argued that such forecasts are needlessly bleak. Studies that he and colleagues have conducted—many around the Chesapeake Bay—have shown that in the right conditions, tidal marshes can build themselves up to keep pace with rising seas, while also migrating inland as water creeps up coastlines. Some coastal wetlands could even expand as seas rise, the studies suggest—if people don’t block their paths with seawalls, levees, and other infrastructure designed to hold back the flood.
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But many researchers are skeptical, and some are challenging Kirwan’s results. Models suggesting wetlands can keep pace with high rates of sea level rise are “seriously flawed,” says ecologist Neil Saintilan of Macquarie University. “This idea of wetlands expanding under accelerated sea level rise, it basically violates some of the most basic geologic theory,” says Torbjörn Törnqvist, a geologist at Tulane University. “It’s just not going to happen.”
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