Scientists Identify Causes of Antarctic Sea Ice Decline Since 2015

Antarctic sea ice expanded for decades while the Arctic experienced rapid ice loss. That pattern shifted in 2015 when sea ice around Antarctica stopped growing and entered a period of steep decline. A study published in the journal Science Advances on May 2, 2026, identifies a sequence of three interconnected processes that produced the change.

Stronger westerly winds around Antarctica began decades earlier, driven in part by increased emissions from fossil fuels and the ozone hole over the continent. The winds initially cooled the surface ocean. Over time a slower, deeper ocean response developed, and from around 2015 the winds began pulling relatively warm, salty water from deeper layers to the surface.

The warmer water contributed to sea ice melt. The additional salt at the surface increased water density, which altered ocean mixing and allowed still more heat to reach upper layers. By around 2018 a third phase had begun in which reduced sea ice left surface waters persistently warmer and saltier, which in turn limited new ice formation.

The study reports differences between East and West Antarctica. In the east, heat rising from deeper ocean layers has been the main driver of sea ice retreat. In the west, atmospheric factors including clouds carried by warmer air have played a larger role by trapping heat near the ocean surface.

The authors described the sequence as a set of linked processes triggered by long-term changes. Less sea ice has left coastal ice sheets and glaciers more exposed to waves and warmer ocean water. Sea ice also reflects sunlight; its reduction allows the darker ocean to absorb more solar energy, which contributes to further warming.