A study has found that over the past 30 years, a vast amount of Antarctic ice equal to 20 times the area of Seoul has melted away. Scientists plan further research, believing there may be causes beyond the continued battering of Antarctic ice by warm seawater.

Researchers at the University of California, Irvine (UC Irvine) and the National Aeronautics and Space Administration (NASA) said last week that by analyzing Earth surface imagery from instruments aboard satellites, they had determined that since 1996 a total of 12,820㎢ of Antarctic ice had been lost. The findings were published in the international journal ‘Proceedings of the National Academy of Sciences (PNAS)’.

The observation instrument used in this study is called ‘synthetic aperture radar (SAR)’. SAR uses radio waves to map surface morphology with high precision. Unlike cameras that rely on visible light, it can capture images on cloudy days and at night.

Using SAR, the team determined how much the point where the ocean meets the Antarctic ice, that is, the ‘grounding line’, has retreated toward the continent since 1996. The more the grounding line retreats, the more ice has melted.

The analysis found grounding line retreat across one quarter of all Antarctic ice over 30 years. The most pronounced retreat, meaning the most severe ice loss, occurred in southwestern Antarctica. Sixty-two percent of the lost Antarctic ice came from the southwest.

The researchers said, “The concentrated inflow of warm seawater into southwestern Antarctica is the cause”. Winds that changed direction decades ago drove relatively warm seawater toward southwestern Antarctica, ultimately causing massive ice loss. It is akin to pouring hot water over cold ice cream.

However, the team said the inflow of warm seawater alone does not fully explain Antarctic ice loss. Ten percent of the melted ice originated in the northwestern part of the continent, yet they could find no sign that warm seawater had approached this area. The researchers said, “There appears to be another cause, but it is not clear what that is”.

The team stated, “We will further survey Antarctic regions where glacier retreat is likely to accelerate or newly occur”.