Researchers analyzing sediment cores from the Arctic Ocean have found that extreme warming can trigger a dangerous feedback loop. During the Paleocene-Eocene Thermal Maximum, a shift in microbial activity caused the ocean to stop trapping methane in minerals and instead convert it into carbon dioxide, which then escaped into the atmosphere. This transition from anaerobic to aerobic methane oxidation suggests that once a certain warming threshold is hit, the Arctic Ocean can shift from a carbon sink to a prolonged source of greenhouse gases. This study provides a critical analog for understanding how modern Arctic warming could amplify global temperature increases.
