Shortening ice season on Chistochina River

Observation by Wilson Justin

March 2024 - significance! The river was iced over for less then 6 weeks! As opposed to 5 months of ice 2 to 3 feet thick before climate change. Between 2005 and 2020 the open water gradually moved from thick ice status to a more thinner status while the open water status slowly moved from October through November then December. The years roughly from 2017 to 2020 had the Chistochina river freezing up around Christmas. Then in 2021 almost January 1. In 2022 it finally went into January when a cold snap iced up the River. The years 2022 and 2023 were heavy snowfall late winter into spring but the river kept a character of not freezing over later and later. I selected ice cover because in the 1960s and 1970s when the ice caved in in the spring break up it was easy to see the thickness of the river ice anywhere from two feet to 6 feet. It seems now the norm is 6 inches to a foot and a half.

LEO Says:

Wilson Justin has a life time of observations about the Chistochina River area, and is is holder of traditional ecological knowledge that goes back generations. For more from Wilson see link to his profile above and related articles. We reached out to the NWS River Forecast Center for their insights.

Comment by Bob Busey, Alaska/ Pacific River Forecast Center:

Local observations help to bridge that gap between large and small rivers. Changes in the timing and duration of the ice cover season is a pretty active topic in the academic research community. The Chistochina River Basin has quite a bit of permafrost. According to a commonly referenced 2008 map of permafrost distribution it is primarily discontinuous permafrost roughly, that means fifty to ninety percent of the land has frozen ground beneath it. In the side link is a story map and if you scroll down the page you’ll see the map I’m referencing.

A number of the larger Arctic rivers with permafrost within them have shown increases in winter time river discharge. In the links is a recent science story about that.

Increases in summer temperatures increase the thickness of the top part of the soil that freeze and thaws each year. Scientists call that part of the soil column the active layer. Here’s a nice quote about implications of that from the article: "A thicker active layer creates a bigger bucket for storing water," says Rawlins. "Our work shows that as precipitation intensifies, the water will be stored longer in thawed soils and released at a later time via subsurface pathways, instead of running off immediately into rivers and streams, as much of it does now."

This is a review paper about all kinds of things related to river ice: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2021JG006275

Something to ponder from that article which ties into observation is this snippet: " Ice timing and duration are shifting due to warming winter temperatures (Magnuson et al., 2000; Prowse et al., 2010; Yang et al., 2020) but how these trends are occurring in small versus large rivers is not well studied."

So, the trends aren’t well studied but it is an active area of interest. Some scientists look at discharge data to estimate changes in winter time discharge. Others look at changes over the satellite record like the post refers to.

The focus is on Arctic Rivers and the Copper River basin is definitely not Arctic. However, with the high permafrost content of the Chistochina river and it’s interior climate it qualifies as sub Arctic.