It is known why the rivers are running orange. It is because the permafrost is thawing.
Sure, the exact, specific process causing the oxidation is being debated by scientists, but … the reason is because the permafrost is thawing.
Anyway, what this nearly certainly means is that the artic has already blown past the feared warming tipping point and is now releasing methane, which is a much more potent greenhouse gas than CO2.
This article should be focusing on how this likely indicates that climate change will intensify faster than commonly understood by the general public.