Earth Southern Ocean – Earth’s Southern Ocean (the ocean around Antarctica) has long served as a heat reservoir, absorbing most of the excess heat from greenhouse gas pollution. New research indicates that if greenhouse gas levels are eventually cut and even reversed, the ocean could one day release much of the stored heat back into the atmosphere. GEOMAR researchers say such a sudden “thermal burp” of heat could increase warming by up to a century.

Southern Ocean: A Huge Heat Reservoir According to a GEOMAR Helmholtz Center modeling study, the Southern Ocean has absorbed about 90% of the extra heat from greenhouse emissions. In the model scenario, CO₂ levels double, then fall to net-negative; As the world cools and sea ice grows, the very cold, dense surface water eventually sinks, causing deep ocean convection.

This causes a sudden ‘heat belch’ as ​​pent-up heat is released into the atmosphere. Ivy Franzer, a co-author of the study, compares the ocean to an “exit valve” that allows pent-up heat to escape. Models suggest this warming could continue at roughly the current rate for decades or even a century.

Implications and uncertainties The scenario is highly idealized. This assumes a dramatic change in net-negative CO₂ that is currently unrealistic and excludes processes such as ice sheet melting. Fränger emphasizes that cutting emissions is still important: “The most important step right now is to reduce current CO₂ emissions to zero, to avoid further disruption to the climate system”.

This shows that the Southern Ocean’s vast heat reservoir could influence the climate for generations, reinforcing the need for urgent emissions cuts.