Arctic tundra becoming a source of carbon dioxide emissions, NOAA warns

Foreboding environmental milestones abounded again this year in the Arctic, where experts say dramatic climate shifts are fundamentally altering the ecosystem and how it operates. One recent turning point for the region involves its carbon footprint: Where conditions in the Arctic historically worked to reduce global emissions, they're now actively contributing to them.

That's a major transition that could reap consequences on human, plant and animal life far beyond Earth's northernmost arena, warned a cohort of scientists whose research appears in the National Oceanic and Atmospheric Administration's 2024 Arctic Report Card, published Tuesday. The report is an annual assessment of the polar environment, which in recent years has become a stark alert signal marked by unprecedented and ominous observations all linked to rising temperatures from human-caused climate change.

A focus of the latest Arctic evaluation was the effects of warmer weather and wildfires on the tundra, a far-northern biome that's typically known for extreme cold, little precipitation and a layer of permanently frozen soil, called permafrost, covering the land. Those traits collectively made the Arctic an important carbon sink for millennia, meaning the region essentially helped reduce carbon dioxide emissions worldwide by absorbing more carbon than it emitted into the atmosphere.