This week, the world witnessed the calving (or breaking off) of an iceberg so enormous even scientists, not prone to exaggeration, are proclaiming it rare. The Larsen C ice shelf in Antarctica had a growing rift for years and it finally completed its path to the ocean, breaking off as a huge chunk of free floating ice. The iceberg weighs 1 trillion tons and is roughly the size of Delaware (and other reference points are shown to the right for comparison).

This calving event, and the melting of the iceberg yet to come, will not directly raise sea levels, since the ice was already in the sea; however, it could cause near-term destabilization of surrounding glaciers and facilitate faster land-based ice melt which would raise sea levels. Scientists say that it will take months or years to understand how much this calving event will have affected the remainder of the ice shelf.

The calving event was not directly caused by climate change, however it may have been affected by warming temperatures, particularly as oceans absorb the large majority of global warming heat. It is estimated that more than 90 percent of global warming over the past 50 years is held in the world’s oceans  and the rate of ocean warming in recent years is double what it was in 1960. In additional to warm oceans hastening sea ice melt, they also expand from the heat, which has been the primary cause of sea level rise historically.

On top of the ocean warming, West Antarctica specifically has experienced some of the fastest surface warming on earth. Combined with ocean warming, this is great cause for concern as Antarctica holds a vast volume of land-based ice that, when melted into to sea, could raise sea levels substantially. Antarctic ice melt has previously been considered a long term trend spanning centuries, however newer research finds that Antarctic ice melt could contribute several feet of sea level rise over the course of this century.

The Larsen C ice shelf event serves as a critical reminder of the need to mitigate greenhouse gas emissions to curb and then reverse global warming.