Impact of surface melt and ponding on ice shelf dynamics and stability

Lead Research Organisation: Swansea University
Department Name: College of Science

Abstract

Ice shelves fringe around half of the Antarctic coastline and exert a fundamental control on the discharge of ice from the Antarctic ice sheets. They can gain and lose mass through interactions with both the ocean and the atmosphere. In the long term their evolution and impact on the ice sheets is controlled by the ocean, but the effect of a warming atmosphere may dominate in the shorter term by providing the conditions and mechanisms for abrupt ice shelf collapse. The atmosphere on the Antarctic Peninsula, where ice shelves have recently undergone most change, is warming faster than anywhere else on Earth.

Atmospheric warming leading to surface melt and ponding has already been implicated in the collapse of ice shelves of the Antarctic Peninsula - the loss of the Larsen B ice shelf in 2002 led to significant and ongoing glacier acceleration, draw-down of grounded ice from the interior, and contribution to sea level rise. There is no doubt that climate warming will lead to more ice shelves being subject to temperatures above freezing for significant periods. The much larger southerly neighbour of the Larsen B ice shelf, Larsen C, annually experiences periods of surface melt and ponding, and appears in parts to be approaching the level of firn densification that preceded the Larsen B collapse. Very little is known, however, about the spatial and temporal pattern of melt and firn densification, the distribution and size of ponds, or the impact of these factors on flow and fracture. A key control on ice sheet mass balance is therefore inadequately understood.

Our project will address this issue through a combined program of fieldwork, remote sensing and numerical modelling. We will focus on the Larsen C Ice Shelf as an ideal example of a large ice shelf experiencing a wide variety of surface melt and ponding conditions, and which is readily accessible for field measurements. Using borehole camera survey and monitoring instrumentation, and surface geophysics, we will acquire much needed new data about the density and temperature across the ice shelf in the upper half of the ice column. We will probe layers of ice going back hundreds of years to understand the history of melt and ponding on Larsen C Ice Shelf. To understand the impact on the ice shelf of past and future melt and ponding, we will develop a coupled simulation which will use a regional climate model to predict surface melt and ponding and an ice shelf numerical model to test the impact of this meltwater on flow and fracture. These models will be optimised by data from fieldwork and remote sensing that we will collect. The outcome will be the most accurate model of an ice shelf to date which will allow us fully understand impact of melt and ponding on ice shelves and to predict the future evolution of Larsen C Ice Shelf over the next century.

Planned Impact

We focus our impact efforts on education and outreach, aiming for a better public understanding of processes and risks associated with ice shelves. The general public and policy makers will benefit from this project through a better understanding of the impact of climate change on ice shelves, a key part of the cryosphere which encompasses potential climate tipping points.

Our impact activities will include a daily blog from our fieldwork location designed to engage school age children and students from our home departments, a website dedicated to ice shelf research and featuring project progress and Google Earth downloads, and general outreach activities at venues such as the National Eisteddfod.

We recognise that the most effective public message is one that originates from an agreed view of an appropriate section of the academic community, rather than simply the outcomes of one project. Consequently, as a means of seeking common ground in related international research, we include a science workshop in the pathways to impact as a step on the critical path to better public understanding of ice shelf issues.
 
Description (1) Cabinet Inlet on Larsen C Ice Shelf contains a body of refrozen meltwater 45m thick
(2) Temperatures at depth in the ice shelf are up to 10 degrees warmer than previously thought
(3) A rift, 175km long, is extending rapidly and will eventually calve an iceberg of 5,000 sq. km. The Ice shelf will probably less stable when this happens. (4) Iceberg A-68 calved from the Larsen C Ice shelf on 12th July 2017. (5) A significant amount - up to 40% - of surface melt occurs on Larsne C Ice Shelf during the winter-time.
Exploitation Route Models of Larsen C Ice Shelf will be much improved by our new findings
Sectors Education,Environment

URL http://www.projectmidas.org/
 
Description Global media interest in the calving of iceberg A-68 from the Larsen C Ice shelf, as demonstrated by our online survey, has impacted awareness and understanding of ice shelf issues.
First Year Of Impact 2017
Sector Education,Environment
Impact Types Societal

 
Title Annual melt onset, duration and end dates for the Antarctic Peninsula derived from Quikscat and ASCAT scatterometer Enhanced Resolution data, 1999-2017 
Description Surface melt onset, duration and end date for the Antarctic Peninsula from 1999/2000 to 2016/2017 at a spatial resolution of 2 km, derived from scatterometer data. Years 1999/2000 to 2008/09 are based on QSCAT data and 2009/10 to 2016/17 on ASCAT data. 
Type Of Material Database/Collection of data 
Year Produced 2018 
Provided To Others? Yes  
 
Title Dataset from iWS 18 in Cabinet Inlet, Larsen C Ice Shelf, Antarctica, 2014-2017 
Description The data consists of 30 minute observations recorded by an automatic weather station (iWS 18) in Cabinet Inlet on Larsen C Ice Shelf on the Antarctic Peninsula. The iWS consists of a custom-built weather station unit, assembled at the Institute of Marine and Atmospheric research Utrecht (IMAU). There are sensors for air temperature, surface air pressure, relative humidity, as well as a gps, an acoustic snow height sensor, an ARGOS communication antenna, and three Lithium batteries that fuel the unit when solar radiation is absent. The unit is complemented by a propeller-vane Young anemometer measuring wind direction and speed. Additionally, all radiation fluxes are measured with a Kipp and Zonen CNR4 radiometer. This dataset runs from November 2014 to January 2017. 
Type Of Material Database/Collection of data 
Year Produced 2018 
Provided To Others? Yes  
 
Title Ground penetrating radar data from the Larsen C Ice Shelf, 2014 and 2015 
Description This archive is a suite of ground penetrating radar (GPR) data acquired by Project MIDAS during field campaigns on Larsen C, in 2014 and 2015. All data were acquired with a Sensors & Software pulsEKKO PRO GPR system, fitted with antennas of 200 MHz centre-frequency. The system was towed behind a snowmobile, with distances recorded with GPS. These data are part of the NERC-funded MIDAS ('Impact of surface melt and ponding on ice shelf dynamics and stability') research project, with grant references NE/L006707/1 and NE/L005409/1. Other MIDAS data are available. 
Type Of Material Database/Collection of data 
Year Produced 2018 
Provided To Others? Yes  
 
Title Seismic refraction data, Antarctic Peninsula, Larsen C Ice Shelf, Cabinet Inlet, November-December 2014 
Description Seismic refraction experiments were conducted in eight locations along a flowline originating in the Cabinet Inlet, Larsen C Ice Shelf, with the main purpose of estimating firn density profiles. The data were collected as part of NERC Project MIDAS. Funding was provided by NERC Standard Grant 'Impact of surface melt and ponding on ice shelf dynamics and stability', 2014-2017, NERC Reference NE/L005409/1. 
Type Of Material Database/Collection of data 
Year Produced 2019 
Provided To Others? Yes  
 
Title Seismic refraction data, Antarctic Peninsula, Larsen C Ice Shelf, Whirlwind Inlet, November-December 2015 
Description Seismic refraction experiments were conducted in four locations in the Whirlwind Inlet, Larsen C Ice Shelf, with the main purpose of estimating firn density profiles. The data were collected as part of NERC Project MIDAS. The locations, procedures and raw data files produced along with quality descriptions are all summarised in the observer's log provided along with the datasets. Funding was provided by NERC Standard Grant 'Impact of surface melt and ponding on ice shelf dynamics and stability', 2014-2017, NERC Reference NE/L005409/1. 
Type Of Material Database/Collection of data 
Year Produced 2019 
Provided To Others? Yes  
 
Description Engagement with the Press regarding the Larsen C rift/iceberg story 
Form Of Engagement Activity A press release, press conference or response to a media enquiry/interview
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Media (as a channel to the public)
Results and Impact Using Twitter, our own web-page, and Swansea University press release, we gained huge media attention for our monitoring of a rift on Larsen C Ice Shelf which threatens to calve an iceberg one quarter the size of Wales. This story was reported by all major UK newspapers and TV channels, and made it to thousands of international outlets including the New York Times, Washington Post, and USA Public Service Radio.
Year(s) Of Engagement Activity 2017
URL http://www.projectmidas.org/
 
Description Multiple, sustained engagement with the Worlds Press 
Form Of Engagement Activity A press release, press conference or response to a media enquiry/interview
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Media (as a channel to the public)
Results and Impact During 2017 the MIDAS project engaged with the global media regarding the calving of iceberg A-68 from Larsen C Ice Shelf. This resulted in the most far-reaching news story Swansea University has ever generated. We also launched an online survey which demonstrated significant improvements in the understanding of ice shelves in the general public.
Year(s) Of Engagement Activity 2017