Accelerated Melting in Antarctica May Support Key Ocean Currents

The melting of Greenland’s ice sheet is predicted to hinder or disrupt the Atlantic current that helps keep Europe warm; however, meltwater from West Antarctica might help maintain this essential flow.

That said, it won’t be sufficient to prevent significant climate changes. The Atlantic Meridional Overturning Circulation (AMOC) is already down by 60% and could take up to 3,000 years to recover fully.

“I suggest caution in predicting an AMOC collapse,” states Sasha Sinnett from Utrecht University in the Netherlands. “However, my findings don’t alter what is forecasted for the next century. We may never see if West Antarctica successfully stabilizes the AMOC.”

The AMOC is a system of ocean currents that transports warm surface water from the tropics to northern Europe. Here, the water cools and sinks, then flows back south to Antarctica. This current carries an enormous amount of heat—1.2 petawatts—equivalent to the output of one million power plants, keeping Europe notably warmer than regions like Labrador or Siberia at similar latitudes. Lighter, fresher meltwater from Greenland is expected to obstruct the sinking of the denser, saltier AMOC water, thereby slowing its flow.

If the AMOC were to collapse, winter temperatures in Northern Europe could drop to almost -50℃ (-58°F). Recently, Iceland declared the closure of the AMOC as an “existing” security threat. Additionally, rising sea levels are threatening the U.S. East Coast, while Africa may face even more severe drought conditions.

A recent study indicates that even if we achieve net zero emissions by 2075 and begin reducing CO2 from the atmosphere, there is still a 25% risk of AMOC collapse. One study forecasts its closure in the coming decades, while another suggests that it will remain weakened due to Antarctic winds.

Currently, the melting of the West Antarctic ice sheet has accelerated, with some research indicating a probable complete collapse. However, the impact on AMOC remains uncertain.

The timing of the melting is crucial, according to simulations by Sinet and his team. If pulses of ancient Antarctic meltwater coincide with substantial meltwater from Greenland, the AMOC’s closure will be expedited.

Conversely, if the Antarctic water arrives about 1,000 years prior to the peak melting of Greenland, the AMOC may weaken for a few centuries but then recover over the next 3,000 years. While AMOC shows eventual recovery in all scenarios, early Antarctic melting prevents total collapse and accelerates its resurgence.

This phenomenon could be due to the relocation of the sinking, salty AMOC water moving south as lighter, fresher meltwater accumulates around Greenland, with the flow regaining strength as Antarctic melting decreases.

Though it’s improbable that West Antarctica melts at such a rapid pace while Greenland melts more slowly, these results illuminate a significant connection between AMOC and Antarctic ice melt, notes Louise Sim from the British Antarctic Survey.

“Prior to this study, the extent to which Antarctic changes could significantly influence the effects of Greenland’s ice sheet melting on the AMOC was largely unknown,” she remarks.

However, the study does not address potential feedback effects, such as shifts in wind patterns that might increase Antarctic sea ice, so this relationship needs to be explored in more complex models moving forward, she adds.

Even if rapid melting in West Antarctica prevents the AMOC from collapsing, it could still lead to sea-level rises of up to 3 meters, inundating coastal cities.

“Unfortunately, while one potential disaster may lessen the danger of another, this is little consolation,” concludes Stefan Rahmstorf from the University of Potsdam, Germany.