Orange waters of Alaska’s rivers – is climate change to blame?

Pomarańczowe wody rzek Alaski

In remote, economically undeveloped regions of Arctic Alaska, where streams and rivers usually offer crystal clear drinking water, scientists have observed a disturbing phenomenon. For some time now, waters in the northern part of North America have been changing their color and becoming increasingly turbid. Initially, it might have been thought that acidic mining waste was responsible for the orange waters of Alaska’s rivers, but a recent report by Scientific American points to a different culprit.

Orange waters of Alaskan rivers – areas affected by change

The orange water phenomenon in Alaska, which has drawn the attention of scientists and environmentalists, covers many remote areas of the Arctic part of the state. The change affects several key regions that are not only ecologically important, but also part of Alaska’s natural heritage.

  • Arctic National Wildlife Refuge: a vast nature reserve, one of the largest in the world, is home to a variety of wildlife. Changing the color of the water in this park could have a significant impact on local ecosystems, including habitat for water and land birds.
  • Gates of the Arctic National Park and Preserve: this national park, known for its rugged, undisturbed beauty, also hides color-changing waters. Its streams and rivers, which were previously crystal clear, now take on a disturbingly orange hue.
  • Kobuk Valley National Park: the Kobuk River, which flows through the park for some 451 kilometers, is one of the most visible examples of this phenomenon. Its waters, which were previously clear and transparent, are now turning orange.
  • Selawik Wildlife Refuge: this wildlife refuge, an important site for many waterfowl species, has also seen changes in water color. Streams and smaller rivers are also changing their color.
The orange waters of Alaska's rivers
Jon O’Donnell/National Park Service

Inter-institutional research

Responding to these alarming developments, the U.S. Geological Survey (USGS), along with the National Park Service, the University of California at Davis, the University of Alaska-Anchorage and the University of Alaska Pacific, have collaborated. The goal of the research is to map the extent of orange waterways, understand their impact on the broader ecosystem, and determine the clear causes of this unusual phenomenon.

So far, studies have shown that orange streams have higher iron concentrations and lower dissolved oxygen compared to neighboring clean streams. What’s more, according to Scientific American, the water in these streams is more acidic – the pH of some of them has dropped to 3.5, which is more acidic than orange juice has. This indicates significant chemical changes in the aquatic environment. So what is the reason for this?

River scientists agree that climate change is the ultimate cause. Kobuk Valley National Park has seen a significant increase in temperature (by 2.4°C since 2006), and forecasts for 2100 indicate the possibility of further changes in this range (an increase of up to 10.2°C). The Arctic is warming almost four times faster than the rest of the world, making Alaska’s northern areas particularly vulnerable. Such a rise in temperature can lead to melting of as much as 40 percent. permafrost in the park, that is, a layer of soil that is usually frozen all year round will be exposed. This process can release iron that was previously trapped in the frozen soil.

However, the mechanism causing the permafrost thaw to turn rivers orange is still a mystery. Scientists are considering various theories. One hypothesis is that the acid from the minerals leaches iron from the bedrock, which was exposed to water for the first time in thousands of years. Another theory suggests that the process of thawing wetlands allows bacteria to mobilize iron from the soil. Both of these processes can contribute to changing the color of the waters.

Orange waters of Alaskan rivers – consequences

Changing the color and chemical composition of rivers can have far-reaching effects on local ecosystems. Increased acidity and the presence of iron can disrupt biological life in the water, affecting a range of organisms found in this environment. In addition, these changes could affect the quality of drinking water and fish stocks, which are crucial to the lives and economies of Alaska’s indigenous communities. However, how long this phenomenon will last and what its effects will be remains unknown. Scientists stress the need for further research to better understand the impact of climate change on Arctic ecosystems and prepare for future challenges.

The phenomenon of waters taking on unusual colors is becoming increasingly common. About a similar case, we wrote in our article“The pink waters of Kealia Pond in Hawaii – a miracle of nature or a warning signal?“.

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