Record-setting temperatures and rainfall in the Arctic over the past year sped up the melting of permafrost and washed toxic minerals into more than 200 rivers across northern Alaska, threatening vital salmon runs, according to a report card issued by federal scientists.
The report, compiled by dozens of academic and government scientists and coordinated by the National Oceanic and Atmospheric Administration, documented rapid environmental changes from Norway’s Svalbard Island to the Greenland ice sheet and the tundra of northern Canada and Alaska.
Between October 2024 and September 2025, the period from when the ground begins to freeze until the end of summer, surface air temperatures were the warmest on record dating back 125 years, the report found.
“The Arctic region has a powerful influence on Earth’s ecosystem as a whole,” said Steve Thur, NOAA’s assistant administrator for research and acting chief scientist.
This year’s 153-page Arctic report card is coming out despite a shift at the agency, including a focus on commercial aspects of the ocean, such as deep-sea mining. In April, the Trump administration proposed eliminating NOAA’s research arm, a move that would hobble early warning systems for natural disasters, science education and the study of the Arctic. The Trump administration fired 1,000 NOAA employees earlier this year, but has since tried to rehire 450 of them, mostly in its National Weather Service branch.
Despite the proposed budget cuts, the report card was compiled by NOAA this year and was written by scientists from academic institutions in the United States, Canada and Europe, as well as researchers from NASA and several other federal science agencies. NOAA has been monitoring changes in the Arctic region for 20 years. Over this year’s study period, there was a record amount of precipitation, both snow and rain, averaged across the region.
“To see both of these historical records being set in the same year is quite remarkable,” said Matthew Druckenmiller, a senior scientist at the National Snow and Ice Data Center in Boulder, Colo., and a lead author of the report, which was released on Tuesday in New Orleans at the annual meeting of the American Geophysical Union, an association of earth and space scientists.
“Since 1980, the Arctic annual air temperatures have warmed nearly three times faster than the rest of the planet,” according to Dr. Druckenmiller. He said the warming is affecting the timing and amount of rain and snow in the Arctic, which affects fisheries, wildlife and the people who live there.
Permafrost, a mixture of soil, rocks and organic matter that remains frozen year-round, covers much of the Arctic’s land surface. That permafrost has been melting since the early 2000s, and researchers have now discovered toxic chemicals leaching into rivers in northern Alaska as the permafrost melts.
The troubling phenomenon was first noted in 2019 in several rivers, and has now been seen in more than 200 river basins north of Alaska’s Brooks Range mountains, according to Joshua Koch, a research hydrologist at the United States Geological Survey in Anchorage.
Since then, Dr. Koch and others have been conducting aerial and satellite surveys of the North Slope, an area of about 95,000 square miles that stretches from the Canadian border to the Arctic Ocean.
“We started to see some of these streams turning orange,” Dr. Koch said. “These are really pristine areas that don’t have impacts from mines or from human activity.”
The melting permafrost exposed naturally-occurring deposits of pyrite, an iron sulfide mineral, to air and water, causing a chemical reaction known as oxidation. As the climate warms and permafrost thaws, groundwater seeps into deep soil layers.
Once the researchers got on the ground, they discovered that the rust-colored water was coming from springs and hillsides rich in pyrite. They also detected toxic levels of naturally occurring aluminum, copper and zinc from the tundra soil that are leaching into waterways. “We could see places where there’s actually upwelling water just coming right out of the ground from these springs,” he said.
The acidic and toxic water is killing insects and other aquatic life relied on by salmon and other fish that are a key food source for the region’s 10,000 residents. During a 2024 ground survey in Kobuk Valley National Park, researchers found that the Akillik River rapidly changed from clear to orange in the summer, killing all the fish and aquatic life, according to the report.
So far, there is no evidence that the fish have been contaminated by the toxic chemicals, however the scientists are continuing to monitor the streams and salmon.
But if the rusting rivers phenomenon spreads to larger watersheds, such as the Yukon River, it could threaten Alaska’s $541 million salmon industry. Salmon are sensitive to chemicals in the water, according to Nicole Kimball, vice president of Alaskan operations for the Pacific Seafood Processors Association.
“It doesn’t take a lot to make salmon less reproductively successful if they are fighting off toxicity,” said Ms. Kimball, who is also a commissioner on the North Pacific Marine Fisheries Management Council, which regulates harvests of commercial fisheries. “They can become confused on where they go to spawn.”
The post Arctic Warming Turning Alaska’s Rivers Red With Toxic Runoff appeared first on New York Times.
