On February 9, the World Meteorological Organization (WMO) announced that in January 2023, the combined sea ice extent of the Arctic and Antarctic reached an all-time low.

More specifically, Antarctic sea ice was the lowest on record and Arctic sea ice was the third lowest on record, marking the lowest level ever recorded in the Southern and Northern Hemispheres combined. However, according to experts, this record does not necessarily indicate a trend in sea ice reduction, and it is possible that it is within the range of weather-related variability.

In any case, sea ice extent is an important indicator of climate change, along with temperature, which has been at an all-time high for the past eight years. January was the seventh warmest month on record and the third warmest month on record for Europe, which experienced unusually high temperatures in the New Year. In particular, the Arctic is said to be warming at twice the rate of the global average, and satellite observations over the past 44 years have shown that the Arctic sea ice has been rapidly receding in recent years.

Whether such sea ice melting immediately leads to sea level rise is also influenced by sea ice, ocean, and atmospheric feedbacks. A paper published in Nature Communications, uses a model analysis that takes these variables into account, and showed that if warming exceeds 1.8°C relative to pre-industrial times, significant sea level rise could accelerate due to sea ice loss.

In discussions on climate change, it is believed that the earth is gradually reaching a tipping point (a phenomenon in which changes such as greenhouse gases gradually accumulate and cause dramatic changes after a certain point), which is accompanied by large-scale changes that are irreversible, due to anthropogenic activities. Ice sheet melting, along with deforestation in the Amazon, is one of the large-scale subsystems that are likely to exceed the tipping point, especially due to global warming caused by human-induced economic activities. In order to avoid the tipping point of the Earth system, political and economic actions to reduce greenhouse gas emissions are required.

Contributor: IIYAMA Miyuki (Information Program)