In Alaska, River Water Turns Orange Due to Climate Change

In Alaska, the water of over 200 streams and rivers has turned a rusty orange color, according to an annual report from the National Oceanic and Atmospheric Administration (NOAA). While the image may appear beautiful, it actually hides a potential environmental disaster and illustrates one of the harmful effects of climate change.

The culprit is the melting permafrost caused by climate change. This Arctic region of North America is warming four times faster than the rest of the world and experienced its hottest year on record in 2025. As temperatures rise, the theoretically permanently frozen soils are melting at an increasing rate, releasing trapped components that have been locked away for thousands of years.

But how does this crystalline water acquire its orange hue? The answer lies in the composition of Arctic soils, which contain significant amounts of organic carbon, nutrients, mercury, and various metals and minerals. Among these is pyrite, a golden-looking iron disulfide, as explained by NOAA scientists.

When the permafrost melts, water can come into contact with the minerals that were previously trapped. This leads to various chemical reactions, including oxidation. In simple terms, the alteration of pyrite results in this rusty color by releasing ferrous ions.

In other words, sediments rich in iron oxidize and take on the rusty hue. These groundwater sources then gradually rise to the surface waters, transforming the crystalline blue into orange.