Record temperatures and precipitation in the Arctic over the past year have accelerated the melting of permafrost and washed toxic minerals into more than 200 northern Alaska rivers, threatening salmon habitat, according to a report released by U.S. government scientists.
The survey, compiled by dozens of researchers and coordinated by the National Oceanic and Atmospheric Administration (Noaa), documented rapid environmental changes from the Svalbard archipelago, Norway, to the Greenland ice sheet and the tundra of northern Canada and Alaska.
From October 2024 to September 2025, when the ground begins to freeze until the end of summer, surface air temperatures were the warmest on record in 125 years, the study found.
“The Arctic region has a powerful influence on the Earth’s ecosystem as a whole,” said Steve Thur, NOAA deputy administrator for research and acting chief scientist.
This year’s 153-page Arctic report comes despite a shift within the agency, including a focus on commercial aspects of the ocean, such as deep-sea mining.
In April, Donald Trump’s administration proposed eliminating NOAA’s research arm, a move that would harm early warning systems for natural disasters, science education and study of the Arctic. The Trump administration laid off 1,000 NOAA employees earlier this year but has since attempted to rehire 450, mostly in its National Weather Service division.
Despite proposed budget cuts, the report card was compiled by the agency this year and written by scientists from academic institutions in the United States, Canada and Europe, as well as researchers from NASA and several other federal science entities.
NOAA has been monitoring changes in the Arctic region for 20 years. During this year’s study period, there was an average of a record amount of precipitation, both snow and rain, across the region.
“To see these two historic records set in the same year is quite remarkable,” said Matthew Druckenmiller, senior scientist at the National Snow and Ice Data Center in Boulder, Colo., and one of the lead authors of the report, released Tuesday in New Orleans at the annual meeting of the American Geophysical Union, an association of Earth and space scientists.
“Since 1980, the annual air temperature in the Arctic has warmed nearly three times faster than the rest of the planet,” Druckenmiller said. He said warming affects 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, rock and organic matter that remains frozen year-round, covers much of the Arctic land surface. This permafrost has been melting since the early 2000s, and researchers have found toxic chemicals seeping into northern Alaska’s rivers as the ice breaks up.
The disturbing phenomenon was first observed in 2019 in several rivers and has now been observed in more than 200 watersheds north of Alaska’s Brooks Range mountains, according to Joshua Koch, a research hydrologist at the U.S. Geological Survey in Anchorage.
Since then, Koch and others have conducted aerial and satellite surveys of the North Slope, an area of about 246,000 square kilometers that stretches from the Canadian border to the Arctic Ocean.
“We started to see some of these streams turn orange,” Koch said. “These are truly pristine areas that are unaffected by mining or human activity.”
Melting permafrost exposed natural deposits of pyrite, an iron sulfide mineral, to air and water, causing a chemical reaction known as oxidation. As the climate warms and permafrost melts, groundwater seeps into deeper layers of the soil.
When researchers arrived at the site, they discovered that the rust-colored water came from springs and hillsides rich in pyrite. They also detected toxic levels of aluminum, copper and zinc, naturally present in tundra soil, seeping into waterways.
“We were able to see places where water comes straight out of the ground from these springs,” Koch said.
The acidic, toxic water kills insects and other aquatic organisms that depend on the salmon and other fish that provide a vital food source for the area’s 10,000 residents.
In a 2024 ground survey in Kobuk Valley National Park, researchers found that the Akillik River quickly turned from clear to orange in summer, killing all fish and aquatic life, according to the report.
So far, there is no evidence that the fish were contaminated with toxic chemicals. However, scientists continue to monitor rivers and salmon.
But if the Orange River phenomenon spreads to larger watersheds like the Yukon River, it could threaten Alaska’s $541 million salmon industry.
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