The waters of two main rivers in Alaska are usually frozen at this time of the year, flow smoothly after a much earlier melting due to a high temperature rise during winter and spring.
In the city of Ninna, Alaska, the ice layer was broken over the Tanana River shortly after midnight on Sunday. This is the earliest date for the ice break so far in the 102-year history of the famous Ninna Ice Classic, where a contest is being held in which participants try to predict when a melted wooden structure will collapse due to melting.
Another early meltdown occurred on Friday at the Kaskokwim River in Bethel, southwest Alaska. This melting was the earliest in this part of the river since 92 years of records maintained by the National Meteorological Authority.
Records of the two rivers show that the ice break has been occurring an average of one week on average since the 1960s, without taking into account the early record of melting this year.
Brian Pritschneider, a climate researcher at the International Arctic Research Center at Fairbanks of the University of Alaska, said the continued melting earlier than expected reflected the long-term change in climate in the state.
Early melting this year was a reflection of the warmth of large areas of Alaska, from mountain peaks to the ocean, he said.
For people living in rural Alaska, in communities with no access roads, changes in river ice may have serious consequences, as rural people as well as indigenous people use frozen rivers to travel by snowmobiles or other vehicles.