Climate change: Arctic rivers turn orange

In recent years, Arctic rivers have taken on striking orange hues. The phenomenon was first spotted by pilots flying over northern Alaska, noticing suddenly "rusty" rivers. This is not industrial pollution: the surrounding areas are wild and devoid of human activity, indicating a natural cause, linked to climate change.

The culprit is permafrost, the permanently frozen layer of soil that covers much of the Arctic. As temperatures rise, this ground gradually thaws. As the ice melts, water seeps deeper, exposing minerals such as pyrite, an iron sulfide that reacts with oxygen and water to release iron and sulfuric acid, thus colouring the rivers and altering their chemical composition.

Orange rivers contain not only iron, but other heavy metals such as aluminum, copper and zinc as well. This cocktail can seriously disrupt aquatic ecosystems, affecting the insects, fish and animals that depend on these waters. Salmon are particularly vulnerable: chemical alterations can interfere with their ability to orientate themselves and reproduce, with possible repercussions for local fishing and the economy, especially for Alaska's salmon industry.

The phenomenon of 'rusty' rivers is a clear sign of climate change in the Arctic, a region experiencing the most rapid warming on the planet. In addition to thawing permafrost, the Arctic is already suffering the effects of shrinking sea ice, rising sea levels and the penetration of warmer Atlantic waters into the Arctic Ocean, modifying marine ecosystems and influencing the climate at lower latitudes.

(MP/©Greenme.it/Translation and adaptation: The Global Nature/Pic: Unsplash)