{"669058":{"#nid":"669058","#data":{"type":"news","title":"Thinning Ice Sheets May Drive Sharp Rise in Subglacial Waters","body":[{"value":"\u003Cp\u003ETwo \u003Ca href=\u0022https:\/\/research.gatech.edu\/\u0022\u003EGeorgia Tech\u003C\/a\u003E researchers, \u003Ca href=\u0022https:\/\/eas.gatech.edu\/people\/robel-dr-alexander\u0022\u003EAlex Robel\u003C\/a\u003E and \u003Ca href=\u0022https:\/\/eas.gatech.edu\/people\/sim-joyce-shi\u0022\u003EShi Joyce Sim\u003C\/a\u003E, have collaborated on a new model for how water moves under glaciers. The new theory shows that up to twice the amount of subglacial water that was originally predicted might be draining into the ocean \u2013 potentially increasing glacial melt, sea level rise, and biological disturbances.\u003C\/p\u003E\r\n\r\n\u003Cp\u003EThe paper, \u003Ca href=\u0022https:\/\/www.science.org\/doi\/10.1126\/sciadv.adh3693\u0022\u003Epublished in \u003C\/a\u003E\u003Cem\u003E\u003Ca href=\u0022https:\/\/www.science.org\/doi\/10.1126\/sciadv.adh3693\u0022\u003EScience Advances\u003C\/a\u003E,\u003C\/em\u003E \u201cContemporary Ice Sheet Thinning Drives Subglacial Groundwater Exfiltration with Potential Feedbacks on Glacier Flow,\u201d is co-authored by \u003Ca href=\u0022https:\/\/engineering.dartmouth.edu\/community\/faculty\/colin-meyer#\u0022\u003EColin Meyer\u003C\/a\u003E (\u003Ca href=\u0022https:\/\/home.dartmouth.edu\/\u0022\u003EDartmouth\u003C\/a\u003E), \u003Ca href=\u0022https:\/\/geophysics.mines.edu\/project\/siegfried-matthew\/\u0022\u003EMatthew Siegfried\u003C\/a\u003E (\u003Ca href=\u0022https:\/\/www.mines.edu\/\u0022\u003EColorado School of Mines\u003C\/a\u003E), and \u003Ca href=\u0022https:\/\/www.usgs.gov\/staff-profiles\/chloe-gustafson\u0022\u003EChloe Gustafson\u003C\/a\u003E (\u003Ca href=\u0022https:\/\/www.usgs.gov\/\u0022\u003EUSGS\u003C\/a\u003E).\u003C\/p\u003E\r\n\r\n\u003Cp\u003EWhile there are pre-existing methods to understand subglacial flow, these techniques involve time-consuming computations. In contrast, Robel and Sim developed a simple equation, which can predict how fast exfiltration, the discharge of groundwater from aquifers under ice sheets, using satellite measurements of Antarctica from the last two decades.\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u201cIn mathematical parlance, you would say we have a closed form solution,\u201d explains Robel, an assistant professor in the \u003Ca href=\u0022https:\/\/eas.gatech.edu\/\u0022\u003ESchool of Earth and Atmospheric Sciences\u003C\/a\u003E. \u201cPreviously, people would run a hydromechanical model, which would have to be applied at every point under Antarctica, and then run forward over a long time period.\u201d Since the researchers\u2019 new theory is a mathematically simple equation, rather than a model, \u201cthe entirety of our prediction can be done in a fraction of a second on a laptop,\u201d Robel says.\u003C\/p\u003E\r\n\r\n\u003Cp\u003ERobel adds that while there is precedence for developing these kinds of theories for similar kinds of models, this theory is specific in that it is for the particular boundary conditions and other conditions that exist underneath ice sheets. \u201cThis is, to our knowledge, the first mathematically simple theory which describes the exfiltration and infiltration underneath ice sheets.\u201d\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u201cIt\u0027s really nice whenever you can get a very simple model to describe a process \u2014 and then be able to predict what might happen, especially using the rich data that we have today. It\u2019s incredible\u201d adds Sim, a research scientist in the \u003Ca href=\u0022https:\/\/eas.gatech.edu\/\u0022\u003ESchool of Earth and Atmospheric Sciences\u003C\/a\u003E. \u201cSeeing the results was pretty surprising.\u201d\u003C\/p\u003E\r\n\r\n\u003Cp\u003EOne of the main arguments in the paper underscores the potentially large source of subglacial water \u2014 possibly up to double the amount previously thought \u2014 that could be affecting how quickly glacial ice flows and how quickly the ice melts at its base. Robel and Sim hope that the predictions made possible by this theory can be incorporated into ice sheet models that scientists use to predict future ice sheet change and sea level rise.\u003C\/p\u003E\r\n\r\n\u003Ch3\u003EA dangerous feedback cycle\u003C\/h3\u003E\r\n\r\n\u003Cp\u003EAquifers are underground areas of porous rock or sediment rich in groundwater. \u201cIf you take weight off aquifers like there are under large parts of Antarctica, water will start flowing out of the sediment,\u201d Robel explains, referencing a diagram Sim created. While this process, known as exfiltration, has been studied previously, focus has been on the long time scales of interglacial cycles, which cover tens of thousands of years.\u003C\/p\u003E\r\n\r\n\u003Cp\u003EThere has been less work on modern ice sheets, especially on how quickly exfiltration might be occurring under the thinning parts of the current-day Antarctic ice sheet. However, using recent satellite data and their new theory, the team has been able to predict what exfiltration might look like under those modern ice sheets.\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u201cThere\u0027s a wide range of possible predictions,\u201d Robel explains. \u201cBut within that range of predictions there is the very real possibility that groundwater may be flowing out of the aquifer at a speed that would make it a majority, or close to a majority of the water that is underneath the ice sheet.\u201d\u003C\/p\u003E\r\n\r\n\u003Cp\u003EIf those parameters are correct, that would mean there\u0027s twice as much water coming into the subglacial interface than previous estimates assumed.\u003C\/p\u003E\r\n\r\n\u003Cp\u003EIce sheets act like a blanket, sitting over the warm earth and trapping heat on the bottom, away from Antarctica\u2019s cold atmosphere \u2014 and this means that the warmest place in the Antarctic ice sheet is at the bottom of a sheet, not on the surface. As an ice sheet thins, the warmer underground water can exfiltrate more readily, and this heat gradient can accelerate the melting that an ice sheet experiences.\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u201cWhen the atmosphere warms up, it takes tens of thousands of years for that signal to diffuse through an ice sheet of the size, of the thickness, of the Antarctic ice sheet,\u201d Robel explains. \u201cBut this process of exfiltration is a response to the already-ongoing thinning of the ice sheet, and it\u0027s an immediate response right now.\u201d\u003C\/p\u003E\r\n\r\n\u003Ch3\u003EBroad implications\u003C\/h3\u003E\r\n\r\n\u003Cp\u003EBeyond sea level rise, this additional exfiltration and melt has other implications. Some of the places of richest marine productivity in the world occur off the coast of Antarctica, and being able to better predict exfiltration and melt could help marine biologists better understand where marine productivity is occurring, and how it might change in the future.\u003C\/p\u003E\r\n\r\n\u003Cp\u003ERobel also hopes this work will open the doorway to more collaborations with groundwater hydrologists who may be able to apply their expertise to ice sheet dynamics, while Sim underscores the need for more fieldwork.\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u201cGetting the experimentalists and observationalists interested in trying to help us better constrain some of the properties of these water-laden sediments \u2014 that would be very helpful,\u201d Sim says. \u201cThat\u0027s our largest unknown at this point, and it heavily influences the results.\u201d\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u201cIt\u0027s really interesting how there\u0027s a potential to draw heat from deeper in the system,\u201d she adds. \u201cThere\u0027s quite a lot of water that could be drawing more heat out, and I think that there\u0027s a heat budget there that could be interesting to look at.\u201d\u003C\/p\u003E\r\n\r\n\u003Cp\u003EMoving forward, collaboration will continue to be key. \u201cI really enjoyed talking to Joyce (Sim) about these problems,\u201d Rober says, \u201cbecause Joyce is an expert on heat flow and porous flow in the Earth\u0027s interior, and those are problems that I had not worked on before. That was kind of a nice aspect of this collaboration. We were able to bridge these two areas that she works on and that I work on.\u201d\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u003Cem\u003E\u003Cstrong\u003EDOI:\u003C\/strong\u003E \u003C\/em\u003E\u003Ca href=\u0022https:\/\/doi.org\/10.1126\/sciadv.adh3693\u0022\u003Edoi.org\/10.1126\/sciadv.adh3693 \u003C\/a\u003E\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u003Cem\u003E\u003Cstrong\u003EFunding: \u003C\/strong\u003EThis work was supported by startup funds from the Georgia Tech Research Corporation (A.A.R. and S.J.S.) and NASA grant 80NSSC21K0912 (M.R.S.). Alex Robel (A.A.R.) is also the recipient of a \u003Ca href=\u0022https:\/\/cos.gatech.edu\/news\/gauging-glaciers-alex-robel-awarded-nsf-career-grant-new-ice-melt-modeling-tool\u0022 target=\u0022_blank\u0022\u003ENational Science Foundation CAREER grant\u003C\/a\u003E. \u003C\/em\u003E\u003C\/p\u003E\r\n","summary":"","format":"limited_html"}],"field_subtitle":"","field_summary":[{"value":"\u003Cp\u003EAlex Robel and Shi Joyce Sim have a new model for how water moves under glaciers. Their theory shows that up to twice the amount of subglacial water that was originally predicted might be draining into the ocean \u2013 potentially increasing glacial melt, sea level rise, and biological disturbances.\u003C\/p\u003E\r\n","format":"limited_html"}],"field_summary_sentence":[{"value":"Up to twice the amount of subglacial water that was originally predicted might be draining into the ocean \u2013 potentially increasing glacial melt, sea level rise, and biological disturbances.  "}],"uid":"34528","created_gmt":"2023-08-21 13:58:52","changed_gmt":"2024-02-05 14:45:38","author":"jhunt7","boilerplate_text":"","field_publication":"","field_article_url":"","dateline":{"date":"2023-08-21T00:00:00-04:00","iso_date":"2023-08-21T00:00:00-04:00","tz":"America\/New_York"},"extras":[],"hg_media":{"671437":{"id":"671437","type":"image","title":"March 2, 2015: Image taken by the Operational Land Imager onboard Landsat 8. (NASA Earth Observatory) ","body":null,"created":"1692626968","gmt_created":"2023-08-21 14:09:28","changed":"1692626968","gmt_changed":"2023-08-21 14:09:28","alt":"Shrinking glaciers","file":{"fid":"254497","name":"glacier after.jpg","image_path":"\/sites\/default\/files\/2023\/08\/21\/glacier%20after.jpg","image_full_path":"http:\/\/hg.gatech.edu\/\/sites\/default\/files\/2023\/08\/21\/glacier%20after.jpg","mime":"image\/jpeg","size":632794,"path_740":"http:\/\/hg.gatech.edu\/sites\/default\/files\/styles\/740xx_scale\/public\/2023\/08\/21\/glacier%20after.jpg?itok=GwN4lG1u"}},"671438":{"id":"671438","type":"image","title":"February 18, 1975: Image taken by the Multispectral Scanner onboard Landsat 2. (NASA Earth Observatory)","body":null,"created":"1692626968","gmt_created":"2023-08-21 14:09:28","changed":"1692626968","gmt_changed":"2023-08-21 14:09:28","alt":"Shrinking glaciers","file":{"fid":"254498","name":"glacier before.jpg","image_path":"\/sites\/default\/files\/2023\/08\/21\/glacier%20before.jpg","image_full_path":"http:\/\/hg.gatech.edu\/\/sites\/default\/files\/2023\/08\/21\/glacier%20before.jpg","mime":"image\/jpeg","size":429173,"path_740":"http:\/\/hg.gatech.edu\/sites\/default\/files\/styles\/740xx_scale\/public\/2023\/08\/21\/glacier%20before.jpg?itok=FmCsY1qc"}},"658812":{"id":"658812","type":"image","title":"Alex Robel (Credit: Allison Carter)","body":null,"created":"1654895880","gmt_created":"2022-06-10 21:18:00","changed":"1687974677","gmt_changed":"2023-06-28 17:51:17","alt":"Alex Robel (Credit: Allison Carter)","file":{"fid":"249724","name":"robel headshot.jpg","image_path":"\/sites\/default\/files\/images\/robel%20headshot.jpg","image_full_path":"http:\/\/hg.gatech.edu\/\/sites\/default\/files\/images\/robel%20headshot.jpg","mime":"image\/jpeg","size":902540,"path_740":"http:\/\/hg.gatech.edu\/sites\/default\/files\/styles\/740xx_scale\/public\/images\/robel%20headshot.jpg?itok=lS4Q4Wyj"}},"671440":{"id":"671440","type":"image","title":"Shi Joyce Sim","body":"\u003Ch2\u003EShi Joyce Sim\u003C\/h2\u003E\r\n","created":"1692627598","gmt_created":"2023-08-21 14:19:58","changed":"1701454040","gmt_changed":"2023-12-01 18:07:20","alt":"Shi Joyce Sim","file":{"fid":"254501","name":"joyce sim.JPG","image_path":"\/sites\/default\/files\/2023\/08\/21\/joyce%20sim.JPG","image_full_path":"http:\/\/hg.gatech.edu\/\/sites\/default\/files\/2023\/08\/21\/joyce%20sim.JPG","mime":"image\/jpeg","size":317655,"path_740":"http:\/\/hg.gatech.edu\/sites\/default\/files\/styles\/740xx_scale\/public\/2023\/08\/21\/joyce%20sim.JPG?itok=51FKayKz"}},"671439":{"id":"671439","type":"image","title":"Exfiltration or infiltration of groundwater occurs due to unloading or loading of ice sheets over saturated subglacial sediment half-space. At the ice-sediment interface, z = 0 and z increases down into sediment. (Robel et al)","body":null,"created":"1692626968","gmt_created":"2023-08-21 14:09:28","changed":"1692626968","gmt_changed":"2023-08-21 14:09:28","alt":"Illustration of exfiltration, infiltration of groundwater","file":{"fid":"254499","name":"sciadv.adh3693-f1.jpg","image_path":"\/sites\/default\/files\/2023\/08\/21\/sciadv.adh3693-f1.jpg","image_full_path":"http:\/\/hg.gatech.edu\/\/sites\/default\/files\/2023\/08\/21\/sciadv.adh3693-f1.jpg","mime":"image\/jpeg","size":433826,"path_740":"http:\/\/hg.gatech.edu\/sites\/default\/files\/styles\/740xx_scale\/public\/2023\/08\/21\/sciadv.adh3693-f1.jpg?itok=j_9NIJoe"}},"671436":{"id":"671436","type":"image","title":"Before and After: Satellite images of shrinking glaciers along western Antarctica. At left, February 18, 1975 \u2014 and right, March 2, 2015. (NASA Earth Observatory) ","body":null,"created":"1692626968","gmt_created":"2023-08-21 14:09:28","changed":"1692626968","gmt_changed":"2023-08-21 14:09:28","alt":"Shrinking glaciers along western Antarctica.","file":{"fid":"254496","name":"glacier before and after - banner.jpg","image_path":"\/sites\/default\/files\/2023\/08\/21\/glacier%20before%20and%20after%20-%20banner.jpg","image_full_path":"http:\/\/hg.gatech.edu\/\/sites\/default\/files\/2023\/08\/21\/glacier%20before%20and%20after%20-%20banner.jpg","mime":"image\/jpeg","size":1831419,"path_740":"http:\/\/hg.gatech.edu\/sites\/default\/files\/styles\/740xx_scale\/public\/2023\/08\/21\/glacier%20before%20and%20after%20-%20banner.jpg?itok=p6EP2Ds7"}}},"media_ids":["671437","671438","658812","671440","671439","671436"],"related_links":[{"url":"https:\/\/cos.gatech.edu\/news\/gauging-glaciers-alex-robel-awarded-nsf-career-grant-new-ice-melt-modeling-tool","title":"Robel Awarded NSF CAREER Grant for New Ice Melt Modeling Tool "},{"url":"https:\/\/cos.gatech.edu\/news\/turning-tide-climate-change","title":"Turning the Tide on Climate Change"},{"url":"https:\/\/cos.gatech.edu\/news\/seawater-seep-may-be-speeding-glacier-melt-sea-level-rise","title":" Seawater Seep May Be Speeding Glacier Melt, Sea Level Rise "},{"url":"https:\/\/cos.gatech.edu\/news\/coastal-glacier-retreat-linked-climate-change","title":"Coastal Glacier Retreat Linked to Climate Change"},{"url":"https:\/\/cos.gatech.edu\/news\/exploring-reservoir-within-greenland-glacier-and-plumbing-uncertainties-sea-level-rise","title":"Exploring a Greenland Glacier Reservoir, Plumbing Sea Level Rise Uncertainties"}],"groups":[{"id":"1278","name":"College of Sciences"},{"id":"364801","name":"School of Earth and Atmospheric Sciences (EAS)"},{"id":"1316","name":"Green Buzz"}],"categories":[{"id":"154","name":"Environment"},{"id":"135","name":"Research"}],"keywords":[{"id":"192254","name":"cos-climate"},{"id":"187915","name":"go-researchnews"},{"id":"192258","name":"cos-data"}],"core_research_areas":[{"id":"39431","name":"Data Engineering and Science"},{"id":"39541","name":"Systems"}],"news_room_topics":[{"id":"71911","name":"Earth and Environment"}],"event_categories":[],"invited_audience":[],"affiliations":[],"classification":[],"areas_of_expertise":[],"news_and_recent_appearances":[],"phone":[],"contact":[{"value":"\u003Cp\u003EBy: Selena Langner\u003C\/p\u003E\r\n\r\n\u003Cp\u003EMedia Contact:\u003Cbr \/\u003E\r\n\u003Ca href=\u0022https:\/\/cos.gatech.edu\/news\/jess@cos.gatech.edu\u0022\u003EJess Hunt-Ralston\u003C\/a\u003E\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u003Cstrong\u003EAbout the photos: Images of Change\u003C\/strong\u003E\u003Cbr \/\u003E\r\n\u003Cem\u003EGlaciers are shrinking along western Antarctica, and NASA is documenting the melt. \u003Ca href=\u0022https:\/\/climate.nasa.gov\/images-of-change\/?id=577#577-shrinking-glaciers-along-western-antarctica\u0022\u003EExplore and toggle satellite images\u003C\/a\u003E with the NASA Earth Observatory.\u003C\/em\u003E\u003C\/p\u003E\r\n","format":"limited_html"}],"email":["jess@cos.gatech.edu"],"slides":[],"orientation":[],"userdata":""}}}