Global Sea Ice is Lost at an Astonishing Rate of 13500 Square Miles Per Year

It turns out that global sea ice is decreasing globally. While it's increasing in Antarctica, scientists have found that this doesn't make up for the accelerated Arctic sea ice loss in the last decades and that this ice is being lost at an astonishing rate of 13,500 square miles per year.

"Even though Antarctic sea ice reached a new record maximum this past September, global sea ice is still decreasing," said Claire Parkinson, one of the researchers, in a news release. "That's because the decreases in the Arctic sea ice far exceed the increases in Antarctic sea ice."

In order to better understand sea ice extent, the researchers used microwave data collected by NASA and Department of Defense satellites. They examined Arctic and Antarctic sea ice extents month by month from November 1978 to December 2013 to determine the global ice extent for each month.

What did they find? It turns out that global sea ice decrease has accelerated. In the first half of the record from 1979 to 1996, the sea ice loss was about 8,300 square miles per year. Then the rate more than doubled for the second half of the period when there was an average loss of 19,500 square miles per year. That's an average yearly loss larger than the states of Vermont and New Hampshire combined.

That doesn't mean that the sea ice loss will continue to accelerate. However, it does show that sea ice has diminished in almost all regions of the Arctic. While there have been increases in the Antarctic, though, the total sea ice loss is far more globally.

"One of the reasons people care about sea ice decreases is that sea ice is highly reflective whereas the liquid ocean is very absorptive," said Parkinson. "So when the area of sea ice coverage is reduced, there is a smaller sea ice area reflecting the sun's radiation back to space. This means more retention of the sun's radiation within the Earth system and further heating. I think that the expectation is that, if anything, in the long-term the Antarctic sea ice growth is more likely to slow down or even reverse."

The findings reveal that sea ice extent is declining across the globe. Understanding this decline is crucial for examining global sea level rise and potential warming in the future.

The findings are published in the Journal of Climate.

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