Permafrost Thaw Is Turning Alaska's Brooks Range Streams Orange
NASA Earth Observatory imagery is revealing a striking change in Alaska's remote Brooks Range: streams that were once clear are now running rusty orange. This discoloration has been documented in hundreds of watersheds throughout the region, and researchers trace the cause to thawing permafrost.
Permafrost—ground that remains frozen year-round—acts as a frozen reservoir for minerals and sediments. As rising temperatures cause permafrost to thaw, previously locked-away iron-rich sediments become exposed to oxygen and water. When this iron oxidizes, it produces the characteristic orange-brown color that is now visible across these remote watersheds.
The phenomenon highlights a cascading effect of climate change in Arctic and sub-Arctic regions. Beyond the visual change, these iron releases can affect water chemistry, aquatic ecosystems, and downstream water quality. Scientists continue to monitor the spread and intensity of these orange streams as permafrost degradation accelerates across northern latitudes.