Alaska's Pristine Rivers Turning Rusty

pristine /prĭs′tēn″, prĭ-stēn′/

adjective

1. Remaining in a pure state, without human alteration.
   "a pristine stream."
2. Remaining free from dirt or decay; clean.
   "pristine mountain snow."

3. Of, relating to, or typical of the earliest time or condition; primitive or original.

 

 Emily C. Dooley, of the University of California, Davis, brings to our attention the phenomenon of rusty-colored water that seems to indicate that anthropogenic climate change is melting the Alaskan permafrost, allowing the water produced to mingle with minerals, which then flow into existing streams and discolor them, to the disgust of aircraft passengers flying by. Gee, whiz.

 

The reality is that of the large portions of Alaska where permafrost is found only those areas with an overlay of aggregate are significant. Frozen, solid rock isn't much different, geologically, from unfrozen solid rock. In order for there to be meaningful permafrost the ground in question must have been unfrozen for many thousands of years, the minerals that make up that ground will need to have been ground up from larger rocks to make the sands, gravels and clays that are associated with the frozen water they hold.

 

For permafrost to exist to any extent it's generally accepted that a mean annual temperature of 28F must exist in the area for several years.

 

Just as there is an element of ambiguity in the term pristine, so too is there in the word permafrost. It doesn't mean ground that is frozen forever, simply ground that is frozen for more than a couple of years in succession. The surface of most, perhaps all, permafrost, thaws during the summer. This is the "active layer". The frozen ground beneath it may be only a few feet or hundreds of feet thick. The permafrost on Alaska's North Slope extends to a depth of about 1400 feet.

Rusty colored water from small creeks running downhill into larger streams is nothing new. It's always been the case, as any local can verify. And there's nothing pristine about Alaska's rivers or any other rivers anywhere. These streams scour the land they run through carrying immense loads of silt downstream and eventually to the sea, regardless of the climate at any given time.