Unexpected consequence of climate change? Rivers in Alaska are turning ORANGE. Here’s why

The crisis of climate change continues to affect the world, be it the record-breaking heatwaves in Asia or the heavy rains and floods in Latin America.

In another unusual phenomenon, rivers and streams in Alaska are turning from a clear blue to a rusty orange colour, primarily due to the toxic metals released by thawing permafrost, according to a new study. The new findings were discovered by the National Park Service, the University of California at Davis and the US Geological Survey.

The surprising revelation came after conducting tests at 75 locations in the waterways of Alaska’s Brooks Range, CNN reported. The rivers and streams in the range appeared to rust and became cloudy and orange over the past five to 10 years, according to the study published in the journal Communications: Earth and Environment. Researchers said these degraded rivers and streams could have significant implications for drinking water and fisheries in Arctic watersheds.

The discolouration and cloudiness of the water in Alaska’s streams are being caused by metals such as iron, zinc, copper, nickel and lead, some of which are toxic to river and stream ecosystems. Permafrost, which refer to permanently frozen grounds, exposes the waterways to minerals locked away underground for thousands of years.

Jon O’Donnell, an ecologist and lead author of the study, said, “The more we flew around, we started noticing more and more orange rivers and streams. There are certain sites that look almost like a milky orange juice… Those orange streams can be problematic both in terms of being toxic but might also prevent migration of fish to spawning areas.’

Why is this a worrying phenomenon?

“We’re used to seeing this in parts of California, parts of Appalachia where we have mining history. This is a classic process that happens in rivers here in the continental US that have been impacted for over 100 years since some of the mining rushes in the 1850s,” said Brett Poulin, a co-author of the study and a professor of environmental toxicology at UC Davis. “But it’s very startling to see it when you’re on some of the most remote wilderness and you’re far from a mine source.”

The researchers found that impaired waters have a pH of 2.3 as compared to average pH of 8 for these rivers, meaning that the weathering of sulfide minerals and is resulting in highly acidic and corrosive conditions that release additional metals. The water risks affecting the habitat, water quality and other ecological systems, turning healthy areas into degraded habitats with fewer fish, according to the study.

Previous studies have cast light on the rising temperatures in the Arctic, which is warming four times faster than the rest of the world. Since it contain organic carbon, nutrients and metals, such as mercury, high temperatures have caused these minerals and the water sources around them to meet as permafrost melts.

There are a variety of fish in Alaska’s Arctic rivers that are “critical for subsistence, sport, and commercial fisheries,” researchers wrote. “What we believe we’re seeing is this thawing of soil that’s happening faster there than it would happen elsewhere,” Poulin said. “It’s really an unexpected consequence of climate change.” Furthermore, the orange colour of these rivers have now become visible from space.

Is this happening anywhere else?

Yes, Alaska is not the only state whose rivers are experiencing discolouration and degradation. Another study, published just a month before researchers in Alaska made their findings public, details how Colorado’s Rocky Mountains are seeing similar effects from, among other things, a warming climate. A similar increase of metal concentrations like sulfate, zinc and copper was found by researchers.

The Water Resources Research published the study highlighting how 22 of Colorado’s mountain rivers have experienced degradation in the past 30 years. Researchers found a reduced streamflow accounted for half of the increase, while the other half, they say, is from the thawing of frozen ground that allows for minerals to leach out of the bedrock.

Similar research on increases in metal and rare earth element concentrations in mountain rivers and streams has been done in the Chilean Andes, the European Alps and the Pyrenees in northern Spain. These studies have raised questions on how climate change is affecting mountain water sources and by extension, normal human life.