Antarctic sea ice, the frozen seawater that surrounds the Antarctic continent, has been shrinking rapidly since 2016 due to warmer ocean temperatures and changing wind patterns. This winter, it has reached a new record low, which is currently 2.2 million km2 below the long-term average. This means that an area of sea ice larger than Saudi Arabia is effectively “missing”. 

We cannot yet say whether this dramatic decline is the result of natural variability or human-induced climate change because satellite observations only go back four decades. However, this trend is consistent with what climate models project for a warmer world. 

Although Antarctica may seem like a faraway and isolated place, what happens there has serious implications for the whole world. Antarctic sea ice acts as a buffer zone for the continent’s ice sheet, keeping it cool and its ice shelves stable. Without this protection, the ice sheet would melt faster and the rate of sea level rise would increase, threatening coastal communities and infrastructure around the globe. 

The sea ice also plays a crucial role in the ocean currents that distribute heat and nutrients around the world. When the seawater freezes, it pushes out some of its salt, making the water more dense. This increased density causes the water to sink to the depths of the ocean and drive the currents that regulate the Earth’s climate. With less sea ice, these cold currents would weaken. As a result, not only would this allow warmer water to reach the ice sheet and further accelerate its melt, but also it would have far-reaching effects on the world’s weather patterns, and increase the risk of extreme weather, such as droughts, floods and storms.