Algae blooms are expected to devastate lakes in the next decades, as a direct result of global warming, according to a recent study presented at the 2015 fall meeting of the American Geophysical Union, which took place in San Francisco between December 14 and 18.
Research was commissioned by the National Science Foundation and by the National Aeronautics and Space Administration, and was carried out by dozens of experts, led by Catherine O’Reilly, hydrogeology graduate program coordinator at Illinois State University.
After reviewing samples collected from 235 lakes across the world, which store half of our planet’s fresh surface water supply, it was determined that these reservoirs had experienced a rise in temperatures amounting to 0.61 degrees Fahrenheit (0.34 degrees Celsius) every decade.
This may sound like an almost undetectable change, but it’s actually a much more significant upsurge than the one reported in average air temperatures, or in sea surface temperatures.
John Lenters, expert at the water science consulting company LimnoTech, points out that bodies of water which have been experiencing the most significant warming were those with higher depths, situated in colder regions.
Four of the Great Lakes of North America fell into this category: Superior, Ontario, Huron and Michigan. The only one which suffered a less obvious escalation in temperatures was Lake Erie, which was already the warmest of them all.
The phenomenon, which was three times as rapid in Lake Superior compared to figures reported worldwide, was also encountered in other lakes across the world, such as Fracksjon, Tahoe and Baikal.
As study authors explain, this alarming trend, caused by increased air temperatures, coupled with dwindling cloud cover and rapid ice loss, is bound to negatively impact the aquatic flora and fauna, as toxic algae blooms will become much more extensive.
It is expected that the amount of algae will soar by a fifth across the next century, with red tides expanding by around 5% and even doubling in some already severely affected areas, such as Lake Erie.
Aside from the fact that this phytoplankton depletes water of oxygen, causing rapid declines in the fish population, it also leads to higher concentrations of methane, whose contribution to the greenhouse gas effect is 25 times higher than that of carbon dioxide.
Such transformations will also negatively impact humans as well, because fresh water derived from lakes is essential to provide private households with daily supplies for drinking, cooking, cleaning and other chores.
One such crisis unfolded in August 2014, when over 500,000 people in southeast Michigan and northwest Ohio were deprived of drinking water, because supplies had been contaminated with Microcystin, a toxin produced by blue-green algae.
In addition, freshwater sources such as lakes are indispensable for thermoelectric power plants and for irrigation, so as to ensure that agricultural crops yield enough food to support the growing population. Therefore, even these sectors are bound to be severely disrupted by this unprecedented rise in lake temperatures.
More details regarding this study have been included in the online edition of the journal Geophysical Research Letters, published on December 16.
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