The ice shelves aren’t losing their mass in the way we typically would envision. Commonly pictured to be losing mass as a result of calving, or chunks of ice melting and falling off the above glaciers. Rather a study has shown that warm oceans are the major culprit behind the melting of the Antarctic ice shelves, causing the melting to occur from below the water level.
Also referred to as basal melt, the melting of the under side of the massive ice shelves in the Antarctic is a growing problem facing our world today. A study was conducted to explore the melting of all the Antarctic ice shelves from 2003 to 2008, finding that 55 percent of the melting occurred at the basal level, a figure far higher than anyone had previously imagined. An ice shelf is the floating extension of a glacier into the sea, for those of you who may have been wondering.
Professor of Earth System Science at UC Irvine Eric Rignot summarized the results found by saying, “We find that iceberg calving is not the dominant process of ice removal. Ice shelves melt mostly from the bottom before they even form icebergs.”
The importance of this research lies in the fact that Antarctica possesses nearly 60 percent of the world’s fresh water supply in the massive ice sheets that make up the continent. Ice shelves serve the purpose of reinforcing the massive glacier structures behind them, as well as controlling the speed that the melted water from above enters the oceans.
If scientists are able to grasp a better understanding of how the melting of the ice shelves in Antarctica occurs, and now they know that the majority of it occurs from below, there is a possibility that we can better project how the world will react to further melting as a result of the warming ocean temperatures.
An understanding of sea level rise as a result of the melting of ice sheets, as well as a more accurate estimate of the amount of fresh water entering the oceans can be obtained through this information.
Conducted over six years by NASA’s Operation Ice Bridge program, the results found that the Antarctic ice shelves were losing 1,325 gigatons of ice every year as a result of basal melting, compared to just 1,089 gigatons from calving. Although these numbers sound incredibly high, they are not as high as you might think.
The amounts of ice in the Antarctic have not gone down despite the increased melting from below. Much of the Antarctic has maintained a near equal level of ice gained and ice lost, keeping its natural balance. Other spots were found to lose ice over the six year study, while some actually increased the amount of ice in the area.
Icebergs and ice shelves are able to continue to add mass by way of a combination of land ice flowing in from the sea and into Antarctica, as well as snow fall accumulating on the surface and compacting into ice.
The Majority of ice melts from below the surface in the Antarctic, also known as basal melting. This new information will change how scientists approach the problem of glacial melting in the continent, giving them new insight and a better understanding of the world around us.
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The Guardian Express
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