The graphic shows the water temperatures around the Antarctic. On the western side of Antarctica, water temperature level at the sea floor is approaching 2 degrees C– which is warm enough to melt the ice that is flowing on top of it. Sea temperatures on the eastern flank are chillier. Credit: Dr. Benjamin Davison/University of Leeds.
Over 40 percent of Antarcticas ice racks lowered in volume over 25 years.
Thinning ice racks release a huge amount of freshwater into the oceans
Ice shelves on the western side of Antarctica most impacted
Human-induced worldwide warming a likely cause
71 of the 162 ice racks that surround Antarctica have decreased in volume over 25 years from 1997 to 2021, with a net release of 7.5 trillion tonnes of meltwater into the oceans, state researchers.
They found that nearly all the ice racks on the western side of Antarctica experienced ice loss. On the other hand, the majority of the ice shelves on the eastern side remained the exact same or increased in volume.
Over the 25 years, the scientists determined practically 67 trillion tonnes of ice was exported to the ocean, which was balanced out by 59 trillion tonnes of ice being contributed to the ice racks, providing a bottom line of 7.5 trillion tonnes.
The video animation reveals what has actually occurred to ice around the Antarctic over the last 25 years– and summarizes the findings of this research study project. Credit: Planetary Visions/European Space Agency
Dr. Benjamin Davison, a research fellow at the University of Leeds who led the study, stated: “There is a blended image of ice-shelf deterioration, and this is to do with the ocean temperature and ocean currents around Antarctica.
” The western half is exposed to warm water, which can rapidly erode the ice racks from below, whereas much of East Antarctica is presently safeguarded from nearby warm water by a band of cold water at the coast.”
Geographical and Climate Differences
Antarctica is a large continent– 50 times the size of the UK– and the seas on the western side experience various currents and winds than on the east, and this is driving warmer water beneath the ice racks on the western flank.
Dr. Davison, an expert in Earth Observation of polar areas in the School of Earth and Environment, stated: “We anticipated many ice shelves to go through cycles of rapid, but short-term shrinking, then to grow back gradually. Instead, we see that practically half of them are shrinking with no indication of healing.”
It is completely covered by a layer of ice that averages more than one mile in thickness, but is almost three miles thick in places. This ice accumulated over millions of years through snowfall. Currently, the Antarctic ice sheet includes 90% of the ice on Earth and would raise sea levels worldwide by over 200 feet were it to melt.
He thinks human-induced international warming is likely to be a crucial element in the loss of the ice. If it was because of natural variation in environment patterns, there would have been some signs of ice regrowth on the western ice shelves.
Ice shelves float on the seas surrounding Antarctica and are extensions to the ice sheet that covers much of the continent. The ice shelves act as huge “plugs” at the end of glaciers, decreasing the circulation of ice draining pipes into the oceans.
When the ice shelves thin or lower in size, these plugs weaken with the result that the rate of ice lost from the glaciers boosts.
Getz Ice Shelf
Some of the greatest ice losses were observed on the Getz Ice Shelf, where 1.9 trillion tonnes of ice were lost over the 25-year research study duration. Simply 5 % of that was because of calving, where large portions of ice break away from the shelf and move into the ocean. The rest was due to melting at the base of the ice shelf.
A satellite image revealing the Getz ice shelf. Getz lost 1.9 trillion tonnes of ice over the 25-year research study period.
Likewise, on the Pine Island Ice Shelf, 1.3 trillion tonnes of ice were lost. Around a 3rd of that loss– 450 billion tonnes– was due to calving. The rest is due to melting from the underside of the ice shelf.
On the other hand, the Amery Ice Shelf– on the other side of Antarctica– gained 1.2 trillion tonnes of ice. It is surrounded by much cooler waters.
Major Assessment of Antarctica
The scientists examined over 100,000 satellite radar images to produce this significant assessment of the “state of the health” of the ice racks.
If the ice shelves vanish or perhaps lessen, there will be significant ripple effects for the ice system on Antarctica and for international ocean circulation, the giant “conveyor belt” which moves nutrients as well as heat and carbon from this sensitive polar environment.
Prospective Disruption to Ocean Circulation
Water launched into the ocean from the ice racks and from the glaciers is freshwater. Over the 25-year research study period, the researchers approximated that 66.9 trillion tonnes of freshwater went into the Southern Ocean around Antarctica from the ice shelves alone.
In the Southern Ocean, thick salted water sinks to the ocean floor as part of the worldwide ocean conveyor belt. This sinking of water serves as one of the engines that drive the ocean conveyor belt.
Freshwater from Antarctica dilutes the salted ocean water, making it fresher and lighter, which takes longer to sink and this can compromise the ocean flow system
A different study, published in the journal Nature Climate Change, reveals that this procedure may currently be underway.
Steady Attrition
Teacher Anna Hogg, also from the University of Leeds and a co-author of the research study, said: “The research study has actually created important findings. We tend to think of ice racks as going through cyclical advances and retreats. Rather, we are seeing a stable attrition due to melting and calving.
” Many of the ice racks have weakened a lot: 48 lost more than 30% of their preliminary mass over simply 25 years.
” This is more evidence that Antarctica is altering due to the fact that the climate is warming.
” The study provides a standard procedure from which we can see additional changes that might emerge as the climate gets warmer.”
Satellite Monitoring
Information about what is occurring in Antarctica recently has largely come from the CryoSat-2 and Sentinel-1 satellites, which can keep track of Antarctica even when it is cloudy and through the long polar nights.
CryoSat-2, introduced in 2010, was the first European Space Agency Explorer objective and the first devoted to keeping an eye on the Earths polar ice sheets and glaciers.
Professor Noel Gourmelen, from the University of Edinburgh and Earthwave and co-author of the study, said: “CryoSat-2 has actually been an extraordinary tool for monitoring the polar environment. Its capability to specifically map the disintegration of ice shelves by the ocean listed below enabled this accurate metrology and partitioning of ice shelf loss, however also revealed fascinating details on how this erosion takes place.”
Information recorded by these satellite sensors are so terrific scientists have been able to track year-by-year modifications in Antarctica.
Dr. Mark Drinkwater, Head of Earth and Mission Science at the European Space Agency (ESA), said: “Monitoring and tracking climate change across the huge Antarctic continent requires a satellite system that records information consistently throughout the year.
” The European Copernicus Programmes Sentinel-1 satellite objective has satisfied this need. Together with the historic information acquired by its ESA predecessors ERS-1, -2, and Envisat, Sentinel-1 has actually reinvented our capability to analyze floating ice racks, as a bellwether for mass balance and the health of the Antarctic ice sheet.
” In the near future, we will even more enhance Antarctic monitoring with 3 new polar-focused missions CRISTAL, CIMR, and ROSE-L.
Recommendation: “Annual mass spending plan of Antarctic ice shelves from 1997 to 2021” by Benjamin J. Davison, Anna E. Hogg, Noel Gourmelen, Livia Jakob, Jan Wuite, Thomas Nagler, Chad A. Greene, Julia Andreasen and Marcus E. Engdahl, 12 October 2023, Science Advances.DOI: 10.1126/ sciadv.adi0186.
Currently, the Antarctic ice sheet contains 90% of the ice on Earth and would raise sea levels worldwide by over 200 feet were it to melt. Some of the greatest ice losses were observed on the Getz Ice Shelf, where 1.9 trillion tonnes of ice were lost over the 25-year research study duration. Simply 5 % of that was due to calving, where big chunks of ice break away from the shelf and move into the ocean. A satellite image showing the Getz ice rack. On the Pine Island Ice Shelf, 1.3 trillion tonnes of ice were lost.