In the summer of 2014 the city of Toledo and surrounding areas (pop. 500,000) were forced to cut off their own drinking water supply due to a massive a toxic algae bloom in Lake Erie. For two days, residents were told not to cook with or drink tap water.
While not quite as bleak as the lake's 1970s pollution heyday of actual burning water, images of supernaturally green sludge lapping at the city's shores were about the next best/worst thing. And, according to research presented Wednesday at the annual American Geophysical Union meeting in San Francisco, they're also likely to be a new normal, with the number of severe Lake Erie algae blooms expected to double this century.
The increasing severity of Lake Erie blooms over the past few decades traces back to the vast farmlands spread across the Midwestern Great Lakes states and Ontario. As farmers apply nutrients to benefit crops, often in extreme excess, all of the leftovers wind up being flushed into creeks and rivers and, eventually, lakes. Here, instead of soybeans and wheat, the rogue phosphorous and nitrogen kickstart marine life. In the case of cyanobacteria like blue-green algae, that invigorated life goes on to produce dangerous toxins.
The new prediction, which comes courtesy of engineers and ecologists at Ohio State University, is the result of combining runoff and climate change models, which together offer a considerably more dire prediction than runoff-only models. While regional governments in Ohio, Michigan, and Ontario have together pledged to reduce phosphorous runoff by 40 percent, it may not be enough to prevent toxic blooms from becoming even more commonplace.
The takeaway, according to OSU ecologist Jay Martin, is that historical records are insufficient to predict future algae blooms and are thus insufficient as the basis for public policy. As warming waters lead to friendlier and friendlier conditions for algae, it's safe to assume that we will be seeing more and more algae corresponding to the same amounts of fertilizer runoff. In fact, it may not be possible at all to curb Lake Erie's algae blooms through only nutrient reductions, according to the new study.
"Our assessment of climate in the region reveals less winter snow, more heavy spring rains, and hotter summers," postdoctoral researcher Noel Aloysius explained in his group's presentation. "Those are perfect growing conditions for algae. We can reduce phosphorus by 40 percent, but the algae won't suffer as much as you might hope."
As Aloysius noted in a press briefing, algae blooms are a global problem, just as climate change is a global problem. Water will become warmer everywhere, which means increasingly favorable conditions for cyanobacteria to grow and thrive. Everywhere. The effect is particularly extreme in areas with worse pollution controls and rapidly increasing urbanization, such as China. Here, algae get a boost from not just fertilizer runoff, but human wastewater.
Dark, neon-green days ahead.