Seasonal change in Antarctic ice sheet movement noticed for the primary time

The Conchie, Hubert, Saturn, Venus and Uranus glaciers drain into a George VI ice shelf laden with meltwater.

The Conchie, Hubert, Saturn, Venus and Uranus glaciers drain into a George VI ice shelf laden with meltwater.

Some estimates of Antarctica’s complete contribution to sea degree rise could also be overestimated or underestimated, after researchers detected a beforehand unknown supply of variability in ice loss.

The researchers, from the College of Cambridge and Austrian engineering agency ENVEO, have recognized distinct seasonal patterns within the movement of land ice flowing into the George VI Ice Shelf – a floating ice shelf of ice the dimensions of Wales – on the Antarctic Peninsula.

Utilizing pictures from the Copernicus/European Area Company Sentinel-1 satellites, the researchers discovered that the glaciers feeding the ocean ice speed up by round 15% through the Antarctic summer time. That is the primary time that such seasonal cycles have been detected on land ice flowing into the Antarctic ice cabinets. The outcomes are printed within the journal The Cryosphere.

Though it isn’t uncommon for the movement of ice in Arctic and Alpine areas to speed up through the summer time, scientists had beforehand assumed that Antarctic ice was not topic to the identical seasonal actions. , particularly the place it flows in giant ice cabinets and temperatures are beneath freezing. for a lot of the 12 months.

This speculation was additionally, partially, fueled by a scarcity of images collected from the icy continent prior to now. “In contrast to the Greenland Ice Sheet, the place a considerable amount of knowledge allowed us to grasp how the ice strikes from season to season and 12 months to 12 months, we had no protection of comparable knowledge to seek for such modifications over Antarctica till just lately,” stated Karla Boxall of the Scott Polar Analysis Institute (SPRI) in Cambridge, the examine’s first writer.

“Observations of ice velocity change on the Antarctic Peninsula have usually been measured over successive years, so we missed loads of the finer particulars of how the movement varies from month to month all through. of the 12 months,” stated co-author Dr. Frazer. Christie, additionally from SPRI.

Previous to the detailed data of ice velocity made potential by the Sentinel-1 satellites, scientists wishing to review short-term variations in Antarctic-scale ice movement needed to depend on data collected by optical satellites reminiscent of NASA’s Landsat 8.

“Optical measurements can solely observe the Earth’s floor on cloudless days through the summer time months,” stated co-author Dr. Thomas Nagler, CEO of ENVEO. “However utilizing Sentinel-1 radar imagery, we had been capable of uncover seasonal modifications in ice movement because of the power of those satellites to observe year-round and in all climate circumstances.”

At present, the causes of this seasonal change are unsure. This may very well be attributable to floor soften water reaching the bottom of the ice and appearing as a lubricant, as is the case in arctic and alpine areas, or it may very well be because of comparatively heat ocean water that melts ice from beneath, thinning floating ice and permitting glaciers upstream to maneuver sooner.

“These seasonal cycles may very well be because of both mechanism, or a mix of the 2,” Christie stated. “Detailed ocean and floor measurements will probably be wanted to totally perceive why this seasonal change is happening.”

The outcomes suggest that related seasonal variability might exist at different extra susceptible websites in Antarctica, such because the Pine Island and Thwaites Glaciers in West Antarctica. “If true, these seasonal signatures will not be captured in some measures of Antarctic ice mass loss, with probably necessary implications for estimates of world sea degree rise,” Boxall stated.

“That is the primary time this seasonal sign has been discovered on the Antarctic ice sheet, so the questions it raises concerning the potential presence and causes of seasonality elsewhere in Antarctica are actually fascinating,” stated the co-author Professor Ian Willis, additionally from SPRI. “We look ahead to taking a better look and shedding gentle on these necessary questions.”

The analysis was supported partially by the Pure Surroundings Analysis Council (NERC), a part of UK Analysis & Innovation (UKRI), the Prince Albert II of Monaco Basis and the European Area Company. Karla Boxall is a PhD scholar at Newnham Faculty, Cambridge. Frazer Christie is a Fellow of Jesus Faculty, Cambridge. Ian Willis is a Fellow of St Catharine’s Faculty, Cambridge.