SOURCE: Inside Climate News

DATE: June 26, 2019

SNIP: The historic rains that flooded millions of acres of Midwestern cropland this spring landed a blow to an already struggling farm economy.

They also delivered bad news for the climate.

Scientists project that all that water has flushed vast amounts of fertilizer and manure into waterways, triggering a potentially unprecedented season of algae blooms. The National Oceanic and Atmospheric Administration has predicted that the “dead zone” in the Gulf of Mexico—a massive overgrowth of algae—could become the size of Massachusetts this summer, coming close to a record set in 2017, and that an algae bloom in Lake Erie could also reach a record size.

“Every place in the Midwest is wet,” said John Downing, an aquatic ecologist and director of the Minnesota Sea Grant. “There will be a terrific amount of algae blooms.”

As rain washes nutrients—mostly fertilizers and manure—into streams, rivers and lakes, those nutrients stoke the growth of algae, a process known as eutrophication that depletes oxygen in the water. That algae can choke the waterways, killing aquatic life and making water unsafe to swim in or drink.

These algae-filled waterways also emit methane, a powerful climate pollutant. Atmospheric methane has shot up over the past 12 years, threatening global emissions-reduction goals. Downing and his colleagues have determined that algae blooms could accelerate methane emissions even more.

“We not only lose good water,” he said, “we also exacerbate climate change.”