Greenhouse gases escaping from thawing permafrost in the Arctic region have been worrying climatologists for years, and now it appears the same thing may be happening in Antarctica.

Over a series of three field campaigns in the southern summers of 2020, 2023 and 2025, Livio Ruggiero from Italy’s National Research Council and his colleagues collected hundreds of measurements across Antarctica’s Taylor valley – a freezing cold desert on the edge of the continent. The scientists drove a small canister into the ground at each selected site and monitored the gases that percolated up into the device to determine how fast carbon dioxide seeped through the frozen soils.

In 2020, the measurements showed an average of roughly 1.7 grams of CO2 creeping through 1 square metre of soil every day. “We were really surprised,” says Ruggiero. By 2025, that rate had grown five-and-a-half fold to 9.5 grams per day. “The increase was amazing,” he says, and entirely unexpected.

To confirm the findings, Ruggiero extracted a sample of the gas from the field instrument and ran it through a more sophisticated piece of equipment back in the lab at their research station. “And the concentrations were real,” he says.

Part of the surprise is that 9.5 grams of CO2 per day is roughly equivalent to the amount of CO2 Arctic soils emit in the summer. But unlike emissions in the Arctic, which most often come from long-frozen flora decomposing after they have thawed, Antarctic gases appear to be seeping from ancient stores of CO2 mobilised by underground processes as warming alters the hydrology of the continent.

“The findings are intriguing,” says Peter Morse at the Geological Survey of Canada. Permafrost can act as a frozen lid on reservoirs of oil and gas, and many who study permafrost expect seepage from these reservoirs to increase as soils thaw. But the CO2 leak doesn’t appear to be driven by permafrost thaw, says Morse. “What is driving the rise is unclear.”

Ruggiero and his colleagues speculate that perhaps subglacial lakes in Antarctica’s interior that have accumulated salt and carbon dioxide over aeons could be discharging their brines with quickening pace as the continent’s glaciers melt, and this salt water may be thawing the permafrost from the bottom up, allowing subterranean stores of carbon dioxide to escape. It’s a hypothesis they intend to investigate in a future expedition.

Ida Kubiszewski at University College London led an interdisciplinary paper on the global threats posed by Antarctic tipping points in 2024, and permafrost was one they identified. “But we don’t understand the processes enough,” she says, “so this study is an important piece of the puzzle.”

Ruggiero’s team argues that climate scientists must begin to account for these processes in their carbon budgets for the southern hemisphere. When the team scaled up the measurements to the total ice-free terrain in Antarctica, they found that the emissions could add up to 76.8 million tonnes of CO2 per year – comparable to Chile’s annual greenhouse gas emissions in 2024 of 78.7 million tonnes.

This estimate is by no means a rigorous inventory of Antarctica’s natural carbon emissions. But it reveals that there could be a significant source of carbon entering our atmosphere that no one has yet accounted for.