UNIVERSITY OF CAMBRIDGE
CREDIT: COPERNICUS/EUROPEAN SPACE AGENCY/KARLA BOXALL
Some estimates of Antarctica’s complete contribution to sea-level rise could also be over- or underestimated, after researchers detected a beforehand unknown supply of ice loss variability.
The researchers, from the College of Cambridge and Austrian engineering firm ENVEO, recognized distinct, seasonal actions within the circulate of land-based ice draining into George VI Ice Shelf – a floating platform of ice roughly the dimensions of Wales – on the Antarctic Peninsula.
Utilizing imagery from the Copernicus/European House Company Sentinel-1 satellites, the researchers discovered that the glaciers feeding the ice shelf velocity up by roughly 15% through the Antarctic summer time. That is the primary time that such seasonal cycles have been detected on land ice flowing into ice cabinets in Antarctica. The outcomes are reported within the journal The Cryosphere.
Whereas it’s not uncommon for ice circulate in Arctic and Alpine areas to hurry up throughout summer time, scientists had beforehand assumed that ice in Antarctica was not topic to the identical seasonal actions, particularly the place it flows into massive ice cabinets and the place temperatures are under freezing for many of the 12 months.
This assumption was additionally, partly, fuelled by a scarcity of images collected over the icy continent prior to now. “In contrast to the Greenland Ice Sheet, the place a excessive amount of information has allowed us to grasp how the ice strikes from season to season and 12 months to 12 months, we haven’t had comparable knowledge protection to search for such modifications over Antarctica till lately,” stated Karla Boxall from Cambridge’s Scott Polar Analysis Institute (SPRI), the examine’s first creator.
“Observations of ice-speed change within the Antarctic Peninsula have usually been measured over successive years, so we’ve been lacking loads of the finer element about how circulate varies from month to month all year long,” stated co-author Dr Frazer Christie, additionally from SPRI.
Previous to the detailed data of ice velocity made doable by the Sentinel-1 satellites, scientists wanting to check short-term variations in Antarctic-wide ice circulate needed to depend on info collected by optical satellites comparable to NASA’s Landsat 8.
“Optical measurements can solely observe the Earth’s floor on cloud-free days throughout summer time months,” stated co-author Dr Thomas Nagler, ENVEO’s CEO. “However through the use of Sentinel-1 radar imagery, we had been in a position to uncover seasonal ice-flow change due to the power of those satellites to watch year-round and in all-weather circumstances.”
At present, the causes of this seasonal change are unsure. It might be attributable to floor meltwater reaching the bottom of the ice and appearing like a lubricant, as is the case in Arctic and Alpine areas, or it might be because of comparatively heat ocean water melting the ice from under, thinning the floating ice and permitting upstream glaciers to maneuver quicker.
“These seasonal cycles might be because of both mechanism, or a mix of the 2,” stated Christie. “Detailed ocean and floor measurements will likely be required to grasp absolutely why this seasonal change is happening.”
The outcomes suggest that comparable 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 could also be uncaptured in some measurements of Antarctic ice-mass loss, with probably necessary implications for international sea-level rise estimates,” stated Boxall.
“It’s the primary time this seasonal sign has been discovered on the Antarctic Ice Sheet, so the questions it raises concerning the doable presence and causes of seasonality elsewhere in Antarctica are actually fascinating,” stated co-author Professor Ian Willis, additionally from SPRI. “We stay up for taking a more in-depth take a look at, and shedding mild on, these necessary questions.”
The analysis was supported partly by the Pure Surroundings Analysis Council (NERC), a part of UK Analysis & Innovation (UKRI), the Prince Albert II of Monaco Basis and the European House Company. Karla Boxall is a PhD scholar at Newnham Faculty, Cambridge. Frazer Christie is an Affiliate of Jesus Faculty, Cambridge. Ian Willis is a Fellow of St Catharine’s Faculty, Cambridge.
JOURNAL
The Cryosphere
DOI
ARTICLE TITLE
Seasonal land-ice-flow variability within the Antarctic Peninsula
ARTICLE PUBLICATION DATE
6-Oct-2022
