Arctic Ocean methane 'switch' that helped drive rapid global warming discovered

Icebergs floating near face of Sveabreen Glacier in Nordfjorden.

The Arctic Ocean was once an important source of greenhouse gases to the atmosphere — and it could become one again, researchers warn.

Methane (CH₄) is second only to carbon dioxide (CO₂) in trapping heat in Earth's atmosphere. Since 2020, human-driven greenhouse gas emissions have increased atmospheric methane by about 10 parts per billion per year, more than twice as much as CO₂. However, scientists don't yet know how the methane cycle will respond as our planet continues to warm.