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1. Ten New Insights in Climate Science 2023/2024

Author

Bustamante, Mercedes, Roy, Joyashree, Ospina, Daniel, Achakulwisut, Ploy, Aggarwal, Anubha, Bastos, Ana, Broadgate, Wendy, Canadell, Josep G, Carr, Edward R, Chen, Deliang, Cleugh, Helen A, Ebi, Kristie L, Edwards, Clea, Farbotko, Carol, Fernández-Martínez, Marcos, Frölicher, Thomas L, Fuss, Sabine, Geden, Oliver, Gruber, Nicolas, Harrington, Luke J, Hauck, Judith, Hausfather, Zeke, Hebden, Sophie, Hebinck, Aniek, Huq, Saleemul, Huss, Matthias, Jamero, M Laurice P, Juhola, Sirkku, Kumarasinghe, Nilushi, Lwasa, Shuaib, Mallick, Bishawjit, Martin, Maria, McGreevy, Steven, Mirazo, Paula, Mukherji, Aditi, Muttitt, Greg, Nemet, Gregory F, Obura, David, Okereke, Chukwumerije, Oliver, Tom, Orlove, Ben, Ouedraogo, Nadia S, Patra, Prabir K, Pelling, Mark, Pereira, Laura M, Persson, Åsa, Pongratz, Julia, Prakash, Anjal, Rammig, Anja, Raymond, Colin, Redman, Aaron, Reveco, Cristobal, Rockström, Johan, Rodrigues, Regina, Rounce, David R, Schipper, E Lisa F, Schlosser, Peter, Selomane, Odirilwe, Semieniuk, Gregor, Shin, Yunne-Jai, Siddiqui, Tasneem A, Singh, Vartika, Sioen, Giles B, Sokona, Youba, Stammer, Detlef, Steinert, Norman J, Suk, Sunhee, Sutton, Rowan, Thalheimer, Lisa, Thompson, Vikki, Trencher, Gregory, van der Geest, Kees, Werners, Saskia E, Wübbelmann, Thea, Wunderling, Nico, Yin, Jiabo, Zickfeld, Kirsten, and Zscheischler, Jakob

Subjects
Development Studies, Climate Change Impacts and Adaptation, Environmental Sciences, Human Society, Climate change impacts and adaptation, Development studies
Abstract

Non-technical summary: We identify a set of essential recent advances in climate change research with high policy relevance, across natural and social sciences: (1) looming inevitability and implications of overshooting the 1.5°C warming limit, (2) urgent need for a rapid and managed fossil fuel phase-out, (3) challenges for scaling carbon dioxide removal, (4) uncertainties regarding the future contribution of natural carbon sinks, (5) intertwinedness of the crises of biodiversity loss and climate change, (6) compound events, (7) mountain glacier loss, (8) human immobility in the face of climate risks, (9) adaptation justice, and (10) just transitions in food systems. Technical summary The IPCC Assessment Reports offer the scientific foundation for international climate negotiations and constitute an unmatched resource for climate change researchers. However, the assessment cycles take multiple years. As a contribution to cross- and interdisciplinary understanding across diverse climate change research communities, we have streamlined an annual process to identify and synthesise essential research advances. We collected input from experts on different fields using an online questionnaire and prioritised a set of ten key research insights with high policy relevance. This year we focus on: (1) looming overshoot of the 1.5°C warming limit, (2) urgency of phasing-out fossil fuels, (3) challenges for scaling carbon dioxide removal, (4) uncertainties regarding the future of natural carbon sinks, (5) need for join governance of biodiversity loss and climate change, (6) advances in the science of compound events, (7) mountain glacier loss, (8) human immobility in the face of climate risks, (9) adaptation justice, and (10) just transitions in food systems. We first present a succinct account of these Insights, reflect on their policy implications, and offer an integrated set of policy relevant messages. This science synthesis and science communication effort is also the basis for a report targeted to policymakers as a contribution to elevate climate science every year, in time for the UNFCCC COP. Social media summary We highlight recent and policy-relevant advances in climate change research - with input from more than 200 experts 1.

Published
2023

3. Projected land ice contributions to twenty-first-century sea level rise

Author

Edwards, Tamsin L, Nowicki, Sophie, Marzeion, Ben, Hock, Regine, Goelzer, Heiko, Seroussi, Hélène, Jourdain, Nicolas C, Slater, Donald A, Turner, Fiona E, Smith, Christopher J, McKenna, Christine M, Simon, Erika, Abe-Ouchi, Ayako, Gregory, Jonathan M, Larour, Eric, Lipscomb, William H, Payne, Antony J, Shepherd, Andrew, Agosta, Cécile, Alexander, Patrick, Albrecht, Torsten, Anderson, Brian, Asay-Davis, Xylar, Aschwanden, Andy, Barthel, Alice, Bliss, Andrew, Calov, Reinhard, Chambers, Christopher, Champollion, Nicolas, Choi, Youngmin, Cullather, Richard, Cuzzone, Joshua, Dumas, Christophe, Felikson, Denis, Fettweis, Xavier, Fujita, Koji, Galton-Fenzi, Benjamin K, Gladstone, Rupert, Golledge, Nicholas R, Greve, Ralf, Hattermann, Tore, Hoffman, Matthew J, Humbert, Angelika, Huss, Matthias, Huybrechts, Philippe, Immerzeel, Walter, Kleiner, Thomas, Kraaijenbrink, Philip, Le clec’h, Sébastien, Lee, Victoria, Leguy, Gunter R, Little, Christopher M, Lowry, Daniel P, Malles, Jan-Hendrik, Martin, Daniel F, Maussion, Fabien, Morlighem, Mathieu, O’Neill, James F, Nias, Isabel, Pattyn, Frank, Pelle, Tyler, Price, Stephen F, Quiquet, Aurélien, Radić, Valentina, Reese, Ronja, Rounce, David R, Rückamp, Martin, Sakai, Akiko, Shafer, Courtney, Schlegel, Nicole-Jeanne, Shannon, Sarah, Smith, Robin S, Straneo, Fiammetta, Sun, Sainan, Tarasov, Lev, Trusel, Luke D, Van Breedam, Jonas, van de Wal, Roderik, van den Broeke, Michiel, Winkelmann, Ricarda, Zekollari, Harry, Zhao, Chen, Zhang, Tong, and Zwinger, Thomas

Subjects
Earth Sciences, Physical Geography and Environmental Geoscience, Climate Action, General Science & Technology
Abstract

The land ice contribution to global mean sea level rise has not yet been predicted1 using ice sheet and glacier models for the latest set of socio-economic scenarios, nor using coordinated exploration of uncertainties arising from the various computer models involved. Two recent international projects generated a large suite of projections using multiple models2-8, but primarily used previous-generation scenarios9 and climate models10, and could not fully explore known uncertainties. Here we estimate probability distributions for these projections under the new scenarios11,12 using statistical emulation of the ice sheet and glacier models. We find that limiting global warming to 1.5 degrees Celsius would halve the land ice contribution to twenty-first-century sea level rise, relative to current emissions pledges. The median decreases from 25 to 13 centimetres sea level equivalent (SLE) by 2100, with glaciers responsible for half the sea level contribution. The projected Antarctic contribution does not show a clear response to the emissions scenario, owing to uncertainties in the competing processes of increasing ice loss and snowfall accumulation in a warming climate. However, under risk-averse (pessimistic) assumptions, Antarctic ice loss could be five times higher, increasing the median land ice contribution to 42 centimetres SLE under current policies and pledges, with the 95th percentile projection exceeding half a metre even under 1.5 degrees Celsius warming. This would severely limit the possibility of mitigating future coastal flooding. Given this large range (between 13 centimetres SLE using the main projections under 1.5 degrees Celsius warming and 42 centimetres SLE using risk-averse projections under current pledges), adaptation planning for twenty-first-century sea level rise must account for a factor-of-three uncertainty in the land ice contribution until climate policies and the Antarctic response are further constrained.

Published
2021

5. Understanding of Contemporary Regional Sea‐Level Change and the Implications for the Future

Author

Hamlington, Benjamin D, Gardner, Alex S, Ivins, Erik, Lenaerts, Jan TM, Reager, JT, Trossman, David S, Zaron, Edward D, Adhikari, Surendra, Arendt, Anthony, Aschwanden, Andy, Beckley, Brian D, Bekaert, David PS, Blewitt, Geoffrey, Caron, Lambert, Chambers, Don P, Chandanpurkar, Hrishikesh A, Christianson, Knut, Csatho, Beata, Cullather, Richard I, DeConto, Robert M, Fasullo, John T, Frederikse, Thomas, Freymueller, Jeffrey T, Gilford, Daniel M, Girotto, Manuela, Hammond, William C, Hock, Regine, Holschuh, Nicholas, Kopp, Robert E, Landerer, Felix, Larour, Eric, Menemenlis, Dimitris, Merrifield, Mark, Mitrovica, Jerry X, Nerem, R Steven, Nias, Isabel J, Nieves, Veronica, Nowicki, Sophie, Pangaluru, Kishore, Piecuch, Christopher G, Ray, Richard D, Rounce, David R, Schlegel, Nicole‐Jeanne, Seroussi, Hélène, Shirzaei, Manoochehr, Sweet, William V, Velicogna, Isabella, Vinogradova, Nadya, Wahl, Thomas, Wiese, David N, and Willis, Michael J

Subjects
Climate Action, sea level, satellite observations, remote sensing, Physical Sciences, Earth Sciences, Engineering, Meteorology & Atmospheric Sciences
Abstract

Global sea level provides an important indicator of the state of the warming climate, but changes in regional sea level are most relevant for coastal communities around the world. With improvements to the sea-level observing system, the knowledge of regional sea-level change has advanced dramatically in recent years. Satellite measurements coupled with in situ observations have allowed for comprehensive study and improved understanding of the diverse set of drivers that lead to variations in sea level in space and time. Despite the advances, gaps in the understanding of contemporary sea-level change remain and inhibit the ability to predict how the relevant processes may lead to future change. These gaps arise in part due to the complexity of the linkages between the drivers of sea-level change. Here we review the individual processes which lead to sea-level change and then describe how they combine and vary regionally. The intent of the paper is to provide an overview of the current state of understanding of the processes that cause regional sea-level change and to identify and discuss limitations and uncertainty in our understanding of these processes. Areas where the lack of understanding or gaps in knowledge inhibit the ability to provide the needed information for comprehensive planning efforts are of particular focus. Finally, a goal of this paper is to highlight the role of the expanded sea-level observation network-particularly as related to satellite observations-in the improved scientific understanding of the contributors to regional sea-level change.

Published
2020

9. Global glacier change in the 21st century: Every increase in temperature matters

Author

Rounce, David R., Hock, Regine, Maussion, Fabien, Hugonnet, Romain, Kochtitzky, William, Huss, Matthias, Berthier, Etienne, Brinkerhoff, Douglas, Compagno, Loris, Copland, Luke, Farinotti, Daniel, Menounos, Brian, and McNabb, Robert W.

Subjects
Multidisciplinary
Abstract

Glacier mass loss affects sea level rise, water resources, and natural hazards. We present global glacier projections, excluding the ice sheets, for shared socioeconomic pathways calibrated with data for each glacier. Glaciers are projected to lose 26 ± 6% (+1.5°C) to 41 ± 11% (+4°C) of their mass by 2100, relative to 2015, for global temperature change scenarios. This corresponds to 90 ± 26 to 154 ± 44 millimeters sea level equivalent and will cause 49 ± 9 to 83 ± 7% of glaciers to disappear. Mass loss is linearly related to temperature increase and thus reductions in temperature increase reduce mass loss. Based on climate pledges from the Conference of the Parties (COP26), global mean temperature is projected to increase by +2.7°C, which would lead to a sea level contribution of 115 ± 40 millimeters and cause widespread deglaciation in most mid-latitude regions by 2100. ISSN:0036-8075 ISSN:1095-9203

Published
2023
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10. 10 New Insights in Climate Science 2023/2024

Author

Bustamante, Mercedes, Roy, Joyashree, Ospina, Daniel, Achakulwisut, Ploy, Aggarwal, Anubha, Bastos, Ana, Broadgate, Wendy, Canadell, Josep G., Carr, Edward R., Chen, Deliang, Cleugh, Helen A., Ebi, Kristie L., Edwards, Clea, Farbotko, Carol, Fernández-Martínez, Marcos, Frölicher, Thomas L., Fuss, Sabine, Geden, Oliver, Gruber, Nicolas, Harrington, Luke J., Hauck, Judith, Hausfather, Zeke, Hebden, Sophie, Hebinck, Aniek, Huq, Saleemul, Huss, Matthias, Jamero, Laurice P., Juhola, Sirkku, Kumarasinghe, Nilushi, Lwasa, Shuaib, Mallick, Bishawjit, Martin, Maria, McGreevy, Steven, Mirazo, Paula, Mukherji, Aditi, Muttitt, Greg, Nemet, Gregory F., Obura, David, Okereke, Chukwumerije, Oliver, Tom, Orlove, Ben, Ouedraogo, Nadia S., Patra, Prabir K., Pelling, Mark, Pereira, Laura M., Persson, Åsa, Pongratz, Julia, Prakash, Anjal, Rammig, Anja, Raymond, Colin, Redman, Aaron, Reveco, Cristobal, Rockström, Johan, Rodrigues, Regina, Rounce, David R., Schipper, Lisa F., Schlosser, Peter, Selomane, Odirilwe, Semieniuk, Gregor, Shin, Yunne Jai, Siddiqui, Tasneem A., Singh, Vartika, Sioen, Giles B., Sokona, Youba, Stammer, Detlef, Steinert, Norman J., Suk, Sunhee, Sutton, Rowan, Thalheimer, Lisa, Thompson, Vikki, Trencher, Gregory, Van Der Geest, Kees, Werners, Saskia E., Wübbelmann, Thea, Wunderling, Nico, Yin, Jiabo, Zickfeld, Kirsten, Zscheischler, Jakob, Blome, Tanja, Wolff, Maria, Bustamante, Mercedes, Roy, Joyashree, Ospina, Daniel, Achakulwisut, Ploy, Aggarwal, Anubha, Bastos, Ana, Broadgate, Wendy, Canadell, Josep G., Carr, Edward R., Chen, Deliang, Cleugh, Helen A., Ebi, Kristie L., Edwards, Clea, Farbotko, Carol, Fernández-Martínez, Marcos, Frölicher, Thomas L., Fuss, Sabine, Geden, Oliver, Gruber, Nicolas, Harrington, Luke J., Hauck, Judith, Hausfather, Zeke, Hebden, Sophie, Hebinck, Aniek, Huq, Saleemul, Huss, Matthias, Jamero, Laurice P., Juhola, Sirkku, Kumarasinghe, Nilushi, Lwasa, Shuaib, Mallick, Bishawjit, Martin, Maria, McGreevy, Steven, Mirazo, Paula, Mukherji, Aditi, Muttitt, Greg, Nemet, Gregory F., Obura, David, Okereke, Chukwumerije, Oliver, Tom, Orlove, Ben, Ouedraogo, Nadia S., Patra, Prabir K., Pelling, Mark, Pereira, Laura M., Persson, Åsa, Pongratz, Julia, Prakash, Anjal, Rammig, Anja, Raymond, Colin, Redman, Aaron, Reveco, Cristobal, Rockström, Johan, Rodrigues, Regina, Rounce, David R., Schipper, Lisa F., Schlosser, Peter, Selomane, Odirilwe, Semieniuk, Gregor, Shin, Yunne Jai, Siddiqui, Tasneem A., Singh, Vartika, Sioen, Giles B., Sokona, Youba, Stammer, Detlef, Steinert, Norman J., Suk, Sunhee, Sutton, Rowan, Thalheimer, Lisa, Thompson, Vikki, Trencher, Gregory, Van Der Geest, Kees, Werners, Saskia E., Wübbelmann, Thea, Wunderling, Nico, Yin, Jiabo, Zickfeld, Kirsten, Zscheischler, Jakob, Blome, Tanja, and Wolff, Maria

Abstract

Each year, Future Earth, the Earth League and the World Climate Research Programme gather leading scholars from around the world to review the most pressing findings in climate research. The result is the 10 New Insights in Climate Science, delivered as two self-standing products: a peer-reviewed scientific article and this policy report providing a rich and valuable synthesis for policymakers and society at large. The scientific evidence underpinning this year’s report was published between January 2022–June 2023. For policymakers responding to the urgent challenge of the climate crisis, the 10 New Insights in Climate Science 2023/2024 offers credible guidance through 2024 and beyond.

Published
2023

11. Progress toward globally complete frontal ablation estimates of marine-terminating glaciers.

Author

Kochtitzky, William, Copland, Luke, Van Wychen, Wesley, Hock, Regine, Rounce, David R., Jiskoot, Hester, Scambos, Ted A., Morlighem, Mathieu, King, Michalea, Cha, Leo, Gould, Luke, Merrill, Paige-Marie, Glazovsky, Andrey, Hugonnet, Romain, Strozzi, Tazio, Noël, Brice, Navarro, Francisco, Millan, Romain, Dowdeswell, Julian A., and Cook, Alison

Subjects
GLACIERS, ICE calving, ICE sheets
Abstract

Knowledge of frontal ablation from marine-terminating glaciers (i.e., mass lost at the calving face) is critical for constraining glacier mass balance, improving projections of mass change, and identifying the processes that govern frontal mass loss. Here, we discuss the challenges involved in computing frontal ablation and the unique issues pertaining to both glaciers and ice sheets. Frontal ablation estimates require numerous datasets, including glacier terminus area change, thickness, surface velocity, density, and climatic mass balance. Observations and models of these variables have improved over the past decade, but significant gaps and regional discrepancies remain, and better quantification of temporal variability in frontal ablation is needed. Despite major advances in satellite-derived large-scale datasets, large uncertainties remain with respect to ice thickness, depth-averaged velocities, and the bulk density of glacier ice close to calving termini or grounding lines. We suggest ways in which we can move toward globally complete frontal ablation estimates, highlighting areas where we need improved datasets and increased collaboration. [ABSTRACT FROM AUTHOR]

Published
2023
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12. Progress toward globally complete frontal ablation estimates of marine-terminating glaciers

Author

Kochtitzky, William, primary, Copland, Luke, additional, Van Wychen, Wesley, additional, Hock, Regine, additional, Rounce, David R., additional, Jiskoot, Hester, additional, Scambos, Ted A., additional, Morlighem, Mathieu, additional, King, Michalea, additional, Cha, Leo, additional, Gould, Luke, additional, Merrill, Paige-Marie, additional, Glazovsky, Andrey, additional, Hugonnet, Romain, additional, Strozzi, Tazio, additional, Noël, Brice, additional, Navarro, Francisco, additional, Millan, Romain, additional, Dowdeswell, Julian A., additional, Cook, Alison, additional, Dalton, Abigail, additional, Khan, Shfaqat, additional, and Jania, Jacek, additional

Published
2022
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13. Progress toward globally complete frontal ablation estimates of marine-terminating glaciers

Author

Kochtitzky, William, Copland, Luke, Van Wychen, Wesley, Hock, Regine, Rounce, David R., Jiskoot, Hester, Scambos, Ted A., Morlighem, Mathieu, King, Michalea, Cha, Leo, Gould, Luke, Merrill, Paige Marie, Glazovsky, Andrey, Hugonnet, Romain, Strozzi, Tazio, Noël, Brice, Navarro, Francisco, Millan, Romain, Dowdeswell, Julian A., Cook, Alison, Dalton, Abigail, Khan, Shfaqat, Jania, Jacek, Kochtitzky, William, Copland, Luke, Van Wychen, Wesley, Hock, Regine, Rounce, David R., Jiskoot, Hester, Scambos, Ted A., Morlighem, Mathieu, King, Michalea, Cha, Leo, Gould, Luke, Merrill, Paige Marie, Glazovsky, Andrey, Hugonnet, Romain, Strozzi, Tazio, Noël, Brice, Navarro, Francisco, Millan, Romain, Dowdeswell, Julian A., Cook, Alison, Dalton, Abigail, Khan, Shfaqat, and Jania, Jacek

Abstract

Knowledge of frontal ablation from marine-terminating glaciers (i.e., mass lost at the calving face) is critical for constraining glacier mass balance, improving projections of mass change, and identifying the processes that govern frontal mass loss. Here, we discuss the challenges involved in computing frontal ablation and the unique issues pertaining to both glaciers and ice sheets. Frontal ablation estimates require numerous datasets, including glacier terminus area change, thickness, surface velocity, density, and climatic mass balance. Observations and models of these variables have improved over the past decade, but significant gaps and regional discrepancies remain, and better quantification of temporal variability in frontal ablation is needed. Despite major advances in satellite-derived large-scale datasets, large uncertainties remain with respect to ice thickness, depth-averaged velocities, and the bulk density of glacier ice close to calving termini or grounding lines. We suggest ways in which we can move toward globally complete frontal ablation estimates, highlighting areas where we need improved datasets and increased collaboration.

Published
2022

15. Grand Challenges of Hydrologic Modeling for Food-Energy-Water Nexus Security in High Mountain Asia

Author

Mishra, Shruti K., primary, Rupper, Summer, additional, Kapnick, Sarah, additional, Casey, Kimberly, additional, Chan, Hoi Ga, additional, Ciraci', Enrico, additional, Haritashya, Umesh, additional, Hayse, John, additional, Kargel, Jeffrey S., additional, Kayastha, Rijan B., additional, Krakauer, Nir Y., additional, Kumar, Sujay V., additional, Lammers, Richard B., additional, Maggioni, Viviana, additional, Margulis, Steven A., additional, Olson, Mathew, additional, Osmanoglu, Batuhan, additional, Qian, Yun, additional, McLarty, Sasha, additional, Rittger, Karl, additional, Rounce, David R., additional, Shean, David, additional, Velicogna, Isabella, additional, Veselka, Thomas D., additional, and Arendt, Anthony, additional

Published
2021
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16. Projected land ice contributions to twenty-first-century sea level rise

Author

Edwards, Tamsin L., Nowicki, Sophie, Marzeion, Ben, Hock, Regine, Goelzer, Heiko, Seroussi, Hélène, Jourdain, Nicolas C., Slater, Donald A., Turner, Fiona E., Smith, Christopher J., McKenna, Christine M., Simon, Erika, Abe-Ouchi, Ayako, Gregory, Jonathan M., Larour, Eric, Lipscomb, William H., Payne, Antony J., Shepherd, Andrew, Agosta, Cécile, Alexander, Patrick, Albrecht, Torsten, Anderson, Brian, Asay-Davis, Xylar, Aschwanden, Andy, Barthel, Alice, Bliss, Andrew, Calov, Reinhard, Chambers, Christopher, Champollion, Nicolas, Choi, Youngmin, Cullather, Richard, Cuzzone, Joshua, Dumas, Christophe, Felikson, Denis, Fettweis, Xavier, Fujita, Koji, Galton-Fenzi, Benjamin K., Gladstone, Rupert, Golledge, Nicholas R., Greve, Ralf, Hattermann, Tore, Hoffman, Matthew J., Humbert, Angelika, Huss, Matthias, Huybrechts, Philippe, Immerzeel, Walter, Kleiner, Thomas, Kraaijenbrink, Philip, Le clec’h, Sébastien, Lee, Victoria, Leguy, Gunter R., Little, Christopher M., Lowry, Daniel P., Malles, Jan-Hendrik, Martin, Daniel F., Maussion, Fabien, Morlighem, Mathieu, O’Neill, James F., Nias, Isabel, Pattyn, Frank, Pelle, Tyler, Price, Stephen F., Quiquet, Aurélien, Radić, Valentina, Reese, Ronja, Rounce, David R., Rückamp, Martin, Sakai, Akiko, Shafer, Courtney, Schlegel, Nicole-Jeanne, Shannon, Sarah, Smith, Robin S., Straneo, Fiammetta, Sun, Sainan, Tarasov, Lev, Trusel, Luke D., Van Breedam, Jonas, van de Wal, Roderik, van den Broeke, Michiel, Winkelmann, Ricarda, Zekollari, Harry, Zhao, Chen, Zhang, Tong, Zwinger, Thomas, Edwards, Tamsin L., Nowicki, Sophie, Marzeion, Ben, Hock, Regine, Goelzer, Heiko, Seroussi, Hélène, Jourdain, Nicolas C., Slater, Donald A., Turner, Fiona E., Smith, Christopher J., McKenna, Christine M., Simon, Erika, Abe-Ouchi, Ayako, Gregory, Jonathan M., Larour, Eric, Lipscomb, William H., Payne, Antony J., Shepherd, Andrew, Agosta, Cécile, Alexander, Patrick, Albrecht, Torsten, Anderson, Brian, Asay-Davis, Xylar, Aschwanden, Andy, Barthel, Alice, Bliss, Andrew, Calov, Reinhard, Chambers, Christopher, Champollion, Nicolas, Choi, Youngmin, Cullather, Richard, Cuzzone, Joshua, Dumas, Christophe, Felikson, Denis, Fettweis, Xavier, Fujita, Koji, Galton-Fenzi, Benjamin K., Gladstone, Rupert, Golledge, Nicholas R., Greve, Ralf, Hattermann, Tore, Hoffman, Matthew J., Humbert, Angelika, Huss, Matthias, Huybrechts, Philippe, Immerzeel, Walter, Kleiner, Thomas, Kraaijenbrink, Philip, Le clec’h, Sébastien, Lee, Victoria, Leguy, Gunter R., Little, Christopher M., Lowry, Daniel P., Malles, Jan-Hendrik, Martin, Daniel F., Maussion, Fabien, Morlighem, Mathieu, O’Neill, James F., Nias, Isabel, Pattyn, Frank, Pelle, Tyler, Price, Stephen F., Quiquet, Aurélien, Radić, Valentina, Reese, Ronja, Rounce, David R., Rückamp, Martin, Sakai, Akiko, Shafer, Courtney, Schlegel, Nicole-Jeanne, Shannon, Sarah, Smith, Robin S., Straneo, Fiammetta, Sun, Sainan, Tarasov, Lev, Trusel, Luke D., Van Breedam, Jonas, van de Wal, Roderik, van den Broeke, Michiel, Winkelmann, Ricarda, Zekollari, Harry, Zhao, Chen, Zhang, Tong, and Zwinger, Thomas

Abstract

The land ice contribution to global mean sea level rise has not yet been predicted1 using ice sheet and glacier models for the latest set of socio-economic scenarios, nor using coordinated exploration of uncertainties arising from the various computer models involved. Two recent international projects generated a large suite of projections using multiple models2,3,4,5,6,7,8, but primarily used previous-generation scenarios9 and climate models10, and could not fully explore known uncertainties. Here we estimate probability distributions for these projections under the new scenarios11,12 using statistical emulation of the ice sheet and glacier models. We find that limiting global warming to 1.5 degrees Celsius would halve the land ice contribution to twenty-first-century sea level rise, relative to current emissions pledges. The median decreases from 25 to 13 centimetres sea level equivalent (SLE) by 2100, with glaciers responsible for half the sea level contribution. The projected Antarctic contribution does not show a clear response to the emissions scenario, owing to uncertainties in the competing processes of increasing ice loss and snowfall accumulation in a warming climate. However, under risk-averse (pessimistic) assumptions, Antarctic ice loss could be five times higher, increasing the median land ice contribution to 42 centimetres SLE under current policies and pledges, with the 95th percentile projection exceeding half a metre even under 1.5 degrees Celsius warming. This would severely limit the possibility of mitigating future coastal flooding. Given this large range (between 13 centimetres SLE using the main projections under 1.5 degrees Celsius warming and 42 centimetres SLE using risk-averse projections under current pledges), adaptation planning for twenty-first-century sea level rise must account for a factor-of-three uncertainty in the land ice contribution until climate policies and the Antarctic response are further constrained.

Published
2021
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17. Projected land ice contributions to twenty-first-century sea level rise

Author

Sub Dynamics Meteorology, Hydrologie, Landscape functioning, Geocomputation and Hydrology, Proceskunde, Sub Algemeen Marine & Atmospheric Res, Edwards, Tamsin L, Nowicki, Sophie, Marzeion, Ben, Hock, Regine, Goelzer, Heiko, Seroussi, Hélène, Jourdain, Nicolas C, Slater, Donald A, Turner, Fiona E, Smith, Christopher J, McKenna, Christine M, Simon, Erika, Abe-Ouchi, Ayako, Gregory, Jonathan M, Larour, Eric, Lipscomb, William H, Payne, Antony J, Shepherd, Andrew, Agosta, Cécile, Alexander, Patrick, Albrecht, Torsten, Anderson, Brian, Asay-Davis, Xylar, Aschwanden, Andy, Barthel, Alice, Bliss, Andrew, Calov, Reinhard, Chambers, Christopher, Champollion, Nicolas, Choi, Youngmin, Cullather, Richard, Cuzzone, Joshua, Dumas, Christophe, Felikson, Denis, Fettweis, Xavier, Fujita, Koji, Galton-Fenzi, Benjamin K, Gladstone, Rupert, Golledge, Nicholas R, Greve, Ralf, Hattermann, Tore, Hoffman, Matthew J, Humbert, Angelika, Huss, Matthias, Huybrechts, Philippe, Immerzeel, Walter, Kleiner, Thomas, Kraaijenbrink, Philip, Le Clec'h, Sébastien, Lee, Victoria, Leguy, Gunter R, Little, Christopher M, Lowry, Daniel P, Malles, Jan-Hendrik, Martin, Daniel F, Maussion, Fabien, Morlighem, Mathieu, O'Neill, James F, Nias, Isabel, Pattyn, Frank, Pelle, Tyler, Price, Stephen F, Quiquet, Aurélien, Radić, Valentina, Reese, Ronja, Rounce, David R, Rückamp, Martin, Sakai, Akiko, Shafer, Courtney, Schlegel, Nicole-Jeanne, Shannon, Sarah, Smith, Robin S, Straneo, Fiammetta, Sun, Sainan, Tarasov, Lev, Trusel, Luke D, Van Breedam, Jonas, van de Wal, Roderik, van den Broeke, Michiel, Winkelmann, Ricarda, Zekollari, Harry, Zhao, Chen, Zhang, Tong, Zwinger, Thomas, Sub Dynamics Meteorology, Hydrologie, Landscape functioning, Geocomputation and Hydrology, Proceskunde, Sub Algemeen Marine & Atmospheric Res, Edwards, Tamsin L, Nowicki, Sophie, Marzeion, Ben, Hock, Regine, Goelzer, Heiko, Seroussi, Hélène, Jourdain, Nicolas C, Slater, Donald A, Turner, Fiona E, Smith, Christopher J, McKenna, Christine M, Simon, Erika, Abe-Ouchi, Ayako, Gregory, Jonathan M, Larour, Eric, Lipscomb, William H, Payne, Antony J, Shepherd, Andrew, Agosta, Cécile, Alexander, Patrick, Albrecht, Torsten, Anderson, Brian, Asay-Davis, Xylar, Aschwanden, Andy, Barthel, Alice, Bliss, Andrew, Calov, Reinhard, Chambers, Christopher, Champollion, Nicolas, Choi, Youngmin, Cullather, Richard, Cuzzone, Joshua, Dumas, Christophe, Felikson, Denis, Fettweis, Xavier, Fujita, Koji, Galton-Fenzi, Benjamin K, Gladstone, Rupert, Golledge, Nicholas R, Greve, Ralf, Hattermann, Tore, Hoffman, Matthew J, Humbert, Angelika, Huss, Matthias, Huybrechts, Philippe, Immerzeel, Walter, Kleiner, Thomas, Kraaijenbrink, Philip, Le Clec'h, Sébastien, Lee, Victoria, Leguy, Gunter R, Little, Christopher M, Lowry, Daniel P, Malles, Jan-Hendrik, Martin, Daniel F, Maussion, Fabien, Morlighem, Mathieu, O'Neill, James F, Nias, Isabel, Pattyn, Frank, Pelle, Tyler, Price, Stephen F, Quiquet, Aurélien, Radić, Valentina, Reese, Ronja, Rounce, David R, Rückamp, Martin, Sakai, Akiko, Shafer, Courtney, Schlegel, Nicole-Jeanne, Shannon, Sarah, Smith, Robin S, Straneo, Fiammetta, Sun, Sainan, Tarasov, Lev, Trusel, Luke D, Van Breedam, Jonas, van de Wal, Roderik, van den Broeke, Michiel, Winkelmann, Ricarda, Zekollari, Harry, Zhao, Chen, Zhang, Tong, and Zwinger, Thomas

Published
2021

18. Partitioning the Uncertainty of Ensemble Projections of Global Glacier Mass Change

Author

Marzeion, Ben, Hock, Regine, Anderson, Brian, Bliss, Andrew, Champollion, Nicolas, Fujita, Koji, Huss, Matthias, Immerzeel, Walter W., Kraaijenbrink, Philip, Malles, Jan Hendrik, Maussion, Fabien, Radić, Valentina, Rounce, David R., Sakai, Akiko, Shannon, Sarah, van de Wal, Roderik, Zekollari, Harry, Hydrologie, Landscape functioning, Geocomputation and Hydrology, Landdegradatie en aardobservatie, Proceskunde, Sub Algemeen Marine & Atmospheric Res, and Marine and Atmospheric Research

Subjects
projections, glacier, Environmental Science(all), sea level rise, Earth and Planetary Sciences (miscellaneous), modeling, uncertainties
Abstract

Glacier mass loss is recognized as a major contributor to current sea level rise. However, large uncertainties remain in projections of glacier mass loss on global and regional scales. We present an ensemble of 288 glacier mass and area change projections for the 21st century based on 11 glacier models using up to 10 general circulation models and four Representative Concentration Pathways (RCPs) as boundary conditions. We partition the total uncertainty into the individual contributions caused by glacier models, general circulation models, RCPs, and natural variability. We find that emission scenario uncertainty is growing throughout the 21st century and is the largest source of uncertainty by 2100. The relative importance of glacier model uncertainty decreases over time, but it is the greatest source of uncertainty until the middle of this century. The projection uncertainty associated with natural variability is small on the global scale but can be large on regional scales. The projected global mass loss by 2100 relative to 2015 (79 ± 56 mm sea level equivalent for RCP2.6, 159 ± 86 mm sea level equivalent for RCP8.5) is lower than, but well within, the uncertainty range of previous projections.

Published
2020

19. Partitioning the Uncertainty of Ensemble Projections of Global Glacier Mass Change

Author

Hydrologie, Landscape functioning, Geocomputation and Hydrology, Landdegradatie en aardobservatie, Proceskunde, Sub Algemeen Marine & Atmospheric Res, Marine and Atmospheric Research, Marzeion, Ben, Hock, Regine, Anderson, Brian, Bliss, Andrew, Champollion, Nicolas, Fujita, Koji, Huss, Matthias, Immerzeel, Walter W., Kraaijenbrink, Philip, Malles, Jan Hendrik, Maussion, Fabien, Radić, Valentina, Rounce, David R., Sakai, Akiko, Shannon, Sarah, van de Wal, Roderik, Zekollari, Harry, Hydrologie, Landscape functioning, Geocomputation and Hydrology, Landdegradatie en aardobservatie, Proceskunde, Sub Algemeen Marine & Atmospheric Res, Marine and Atmospheric Research, Marzeion, Ben, Hock, Regine, Anderson, Brian, Bliss, Andrew, Champollion, Nicolas, Fujita, Koji, Huss, Matthias, Immerzeel, Walter W., Kraaijenbrink, Philip, Malles, Jan Hendrik, Maussion, Fabien, Radić, Valentina, Rounce, David R., Sakai, Akiko, Shannon, Sarah, van de Wal, Roderik, and Zekollari, Harry

Published
2020

20. Understanding of contemporary regional sea-level change and the implications for the future

Author

Hamlington, Benjamin D., Gardner, Alex S., Ivins, Erik, Lenaerts, Jan T. M., Reager, John T., Trossman, David S., Zaron, Edward D., Adhikari, Surendra, Arendt, Anthony, Aschwanden, Andy, Beckley, Brian D., Bekaert, David P. S., Blewitt, Geoffrey, Caron, Lambert, Chambers, Don P., Chandanpurkar, Hrishikesh A., Christianson, Knut, Csatho, Beata, Cullather, Richard I., DeConto, Robert M., Fasullo, John T., Frederikse, Thomas, Freymueller, Jeffrey T., Gilford, Daniel M., Girotto, Manuela, Hammond, William C., Hock, Regine, Holschuh, Nicholas, Kopp, Robert E., Landerer, Felix, Larour, Eric, Menemenlis, Dimitris, Merrifield, Mark, Mitrovica, Jerry X., Nerem, R. Steven, Nias, Isabel J., Nieves, Veronica, Nowicki, Sophie, Pangaluru, Kishore, Piecuch, Christopher G., Ray, Richard D., Rounce, David R., Schlegel, Nicole‐Jeanne, Seroussi, Helene, Shirzaei, Manoochehr, Sweet, William V., Velicogna, Isabella, Vinogradova, Nadya, Wahl, Thomas, Wiese, David N., Willis, Michael J., Hamlington, Benjamin D., Gardner, Alex S., Ivins, Erik, Lenaerts, Jan T. M., Reager, John T., Trossman, David S., Zaron, Edward D., Adhikari, Surendra, Arendt, Anthony, Aschwanden, Andy, Beckley, Brian D., Bekaert, David P. S., Blewitt, Geoffrey, Caron, Lambert, Chambers, Don P., Chandanpurkar, Hrishikesh A., Christianson, Knut, Csatho, Beata, Cullather, Richard I., DeConto, Robert M., Fasullo, John T., Frederikse, Thomas, Freymueller, Jeffrey T., Gilford, Daniel M., Girotto, Manuela, Hammond, William C., Hock, Regine, Holschuh, Nicholas, Kopp, Robert E., Landerer, Felix, Larour, Eric, Menemenlis, Dimitris, Merrifield, Mark, Mitrovica, Jerry X., Nerem, R. Steven, Nias, Isabel J., Nieves, Veronica, Nowicki, Sophie, Pangaluru, Kishore, Piecuch, Christopher G., Ray, Richard D., Rounce, David R., Schlegel, Nicole‐Jeanne, Seroussi, Helene, Shirzaei, Manoochehr, Sweet, William V., Velicogna, Isabella, Vinogradova, Nadya, Wahl, Thomas, Wiese, David N., and Willis, Michael J.

Abstract

Author Posting. © American Geophysical Union, 2020. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Reviews of Geophysics 58(3), (2020): e2019RG000672, doi:10.1029/2019RG000672., Global sea level provides an important indicator of the state of the warming climate, but changes in regional sea level are most relevant for coastal communities around the world. With improvements to the sea‐level observing system, the knowledge of regional sea‐level change has advanced dramatically in recent years. Satellite measurements coupled with in situ observations have allowed for comprehensive study and improved understanding of the diverse set of drivers that lead to variations in sea level in space and time. Despite the advances, gaps in the understanding of contemporary sea‐level change remain and inhibit the ability to predict how the relevant processes may lead to future change. These gaps arise in part due to the complexity of the linkages between the drivers of sea‐level change. Here we review the individual processes which lead to sea‐level change and then describe how they combine and vary regionally. The intent of the paper is to provide an overview of the current state of understanding of the processes that cause regional sea‐level change and to identify and discuss limitations and uncertainty in our understanding of these processes. Areas where the lack of understanding or gaps in knowledge inhibit the ability to provide the needed information for comprehensive planning efforts are of particular focus. Finally, a goal of this paper is to highlight the role of the expanded sea‐level observation network—particularly as related to satellite observations—in the improved scientific understanding of the contributors to regional sea‐level change., The research was carried out in part at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration. The authors acknowledge support from the National Aeronautics and Space Administration under Grants 80NSSC17K0565, 80NSSC170567, 80NSSC17K0566, 80NSSC17K0564, and NNX17AB27G. A. A. acknowledges support under GRACE/GRACEFO Science Team Grant (NNH15ZDA001N‐GRACE). T. W. acknowledges support by the National Aeronautics and Space Administration (NASA) under the New (Early Career) Investigator Program in Earth Science (Grant: 80NSSC18K0743). C. G. P was supported by the J. Lamar Worzel Assistant Scientist Fund and the Penzance Endowed Fund in Support of Assistant Scientists at the Woods Hole Oceanographic Institution.

Published
2020

21. Understanding of Contemporary Regional Sea‐Level Change and the Implications for the Future

Author

Agencia Estatal de Investigación (España), Hamlington, Benjamin D., Gardner, Alex S., Ivins, Erik, Lenaerts, Jan T.M., Reager, J.T., Trossman, David S., Zaron, Edward, Adhikari, Jan T.M., Arendt, Anthony, Aschwanden, Andy, Beckley, Brian D., Bekaert, David P.S., Blewitt, Geoffrey, Caron, Lambert, Chambers, Don, Chandanpurka, Hrishikesh A., Christianson, Knut, Csatho, Beata, Cullather, Richard I., Deconto, Robert M., Fasullo, John T., Frederikse, Thomas, Freymueller, Jeffrey T., Gilford, Daniel M., Girotto, Manuela, Hammond, William C., Hock, Regine, Holschuh, Nicholas, Kopp, Robert E., Landerer, Felix, Larour, Eric, Menemenlis, Dimitris, Merrifield, Mark, Mitrovica, Jerry X., Nerem, R. Steven, Nias, Isabel J., Nieves, Verònica, Nowicki, Sophie, Pangaluru, Kishore, Piecuch, Christopher G., Ray, Richard D., Rounce, David R., Schlegel, Nicole‐Jeanne, Seroussi, Helene, Shirzaei, Manoochehr, Sweet, W., Velicogna, Isabella, Vinogradova, N., Wahl, Thomas, Wiese, David N., Willis, Michael J., Agencia Estatal de Investigación (España), Hamlington, Benjamin D., Gardner, Alex S., Ivins, Erik, Lenaerts, Jan T.M., Reager, J.T., Trossman, David S., Zaron, Edward, Adhikari, Jan T.M., Arendt, Anthony, Aschwanden, Andy, Beckley, Brian D., Bekaert, David P.S., Blewitt, Geoffrey, Caron, Lambert, Chambers, Don, Chandanpurka, Hrishikesh A., Christianson, Knut, Csatho, Beata, Cullather, Richard I., Deconto, Robert M., Fasullo, John T., Frederikse, Thomas, Freymueller, Jeffrey T., Gilford, Daniel M., Girotto, Manuela, Hammond, William C., Hock, Regine, Holschuh, Nicholas, Kopp, Robert E., Landerer, Felix, Larour, Eric, Menemenlis, Dimitris, Merrifield, Mark, Mitrovica, Jerry X., Nerem, R. Steven, Nias, Isabel J., Nieves, Verònica, Nowicki, Sophie, Pangaluru, Kishore, Piecuch, Christopher G., Ray, Richard D., Rounce, David R., Schlegel, Nicole‐Jeanne, Seroussi, Helene, Shirzaei, Manoochehr, Sweet, W., Velicogna, Isabella, Vinogradova, N., Wahl, Thomas, Wiese, David N., and Willis, Michael J.

Abstract

Global sea level provides an important indicator of the state of the warming climate, but changes in regional sea level are most relevant for coastal communities around the world. With improvements to the sea‐level observing system, the knowledge of regional sea‐level change has advanced dramatically in recent years. Satellite measurements coupled with in situ observations have allowed for comprehensive study and improved understanding of the diverse set of drivers that lead to variations in sea level in space and time. Despite the advances, gaps in the understanding of contemporary sea‐level change remain and inhibit the ability to predict how the relevant processes may lead to future change. These gaps arise in part due to the complexity of the linkages between the drivers of sea‐level change. Here we review the individual processes which lead to sea‐level change and then describe how they combine and vary regionally. The intent of the paper is to provide an overview of the current state of understanding of the processes that cause regional sea‐level change and to identify and discuss limitations and uncertainty in our understanding of these processes. Areas where the lack of understanding or gaps in knowledge inhibit the ability to provide the needed information for comprehensive planning efforts are of particular focus. Finally, a goal of this paper is to highlight the role of the expanded sea‐level observation network—particularly as related to satellite observations—in the improved scientific understanding of the contributors to regional sea‐level change

Published
2020

22. Seasonally stable temperature gradients through supraglacial debris in the Everest region of Nepal, Central Himalaya

Author

Rowan, Ann V., primary, Nicholson, Lindsey I., additional, Quincey, Duncan J., additional, Gibson, Morgan J., additional, Irvine-Fynn, Tristram D.L., additional, Watson, C. Scott, additional, Wagnon, Patrick, additional, Rounce, David R., additional, Thompson, Sarah S., additional, Porter, Philip R., additional, and Glasser, Neil F., additional

Published
2020
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30. Quantifying Debris Thickness of Debris-Covered Glaciers in the Everest Region of Nepal Through Inversion of a Subdebris Melt Model

Author

Rounce, David R., King, Owen, McCarthy, Michael, Shean, David E., Salerno, Franco, Rounce, David R., King, Owen, McCarthy, Michael, Shean, David E., and Salerno, Franco

Abstract

Debris‐covered glaciers are ubiquitous in the Himalaya, and supraglacial debris significantly alters how glaciers respond to climate forcing. Estimating debris thickness at the glacier scale, however, remains a challenge. This study inverts a subdebris melt model to estimate debris thickness for three glaciers in the Everest region from digital elevation model difference‐derived elevation change. Flux divergences are estimated from ice thickness and surface velocity data. Monte Carlo simulations are used to incorporate the uncertainties associated with debris properties, flux divergence, and elevation change. On Ngozumpa Glacier, surface lowering data from 2010 to 2012 and 2012 to 2014 are used to calibrate and validate the method, respectively. The debris thickness estimates are consistent with existing in situ measurements. The method performs well over both actively flowing and stagnant parts of the glacier and is able to accurately estimate thicker debris (>0.5 m). Uncertainties associated with the thermal conductivity and elevation change contribute the most to uncertainties of the debris thickness estimates. The surface lowering associated with ice cliffs and supraglacial ponds was found to significantly reduce debris thickness, especially for thicker debris. The method is also applied to Khumbu and Imja‐Lhotse Shar Glaciers to highlight its potential for regional application.

Published
2018

31. Seasonally stable temperature gradients through supraglacial debris in the Everest region of Nepal, Central Himalaya.

Author

Rowan, Ann V., Nicholson, Lindsey I., Quincey, Duncan J., Gibson, Morgan J., Irvine-Fynn, Tristram D.L., Watson, C. Scott, Wagnon, Patrick, Rounce, David R., Thompson, Sarah S., Porter, Philip R., and Glasser, Neil F.

Subjects
ABLATION (Glaciology), WEATHER, TEMPERATURE, THERMAL properties, CLIMATE change, GLACIERS
Abstract

Rock debris covers ~30% of glacier ablation areas in the Central Himalaya and modifies the impact of atmospheric conditions on mass balance. The thermal properties of supraglacial debris are diurnally variable but remain poorly constrained for monsoon-influenced glaciers over the timescale of the ablation season. We measured vertical debris profile temperatures at 12 sites on four glaciers in the Everest region with debris thickness ranging from 0.08 to 2.8 m. Typically, the length of the ice ablation season beneath supraglacial debris was 160 days (15 May to 22 October)—a month longer than the monsoon season. Debris temperature gradients were approximately linear (r2 > 0.83), measured as −40°C m–1 where debris was up to 0.1 m thick, −20°C m–1 for debris 0.1–0.5 m thick, and −4°C m–1 for debris greater than 0.5 m thick. Our results demonstrate that the influence of supraglacial debris on the temperature of the underlying ice surface, and therefore melt, is stable at a seasonal timescale and can be estimated from near-surface temperature. These results have the potential to greatly improve the representation of ablation in calculations of debris-covered glacier mass balance and projections of their response to climate change. [ABSTRACT FROM AUTHOR]

Published
2021
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35. A Field-based Study of Impacts of the 2015 Earthquake on Potentially Dangerous Glacial Lakes in Nepal

Author

Byers, Alton C., III, Byers, Elizabeth A, McKinney, Daene C, Rounce, David R, Byers, Alton C., III, Byers, Elizabeth A, McKinney, Daene C, and Rounce, David R

Abstract

Following the earthquake that occurred on April 25, 2015 in Nepal, and the second major earthquake that occurred on May 12, 2015, we conducted field-based studies of five potentially dangerous glacial lakes in Nepal— Imja Tsho, Tsho Rolpa, Dig Tsho, Panga Dinga, and Thulagi. This research was undertaken in an effort to better understand what impacts the earthquake may have had on lake stability, flood potential as well as local perceptions of the dangers that post-earthquake outburst floods pose. Although only one relatively small, earthquakerelated glacial lake outburst flood (GLOF) was found to have occurred, the presence of new cracks, slumps, shifted or displaced boulders, and landslide activity within the already deteriorating terminal and lateral moraines of the lakes suggests that they may have been further de-stabilized by the earthquake and its aftershock. Downstream communities feared the increased likelihood of aftershocks and GLOFs, and at least two downstream regions experienced panic when rumors of imminent floods started spreading. In all our visits to these downstream villages, we encountered inadequate awareness of: early flood warning systems, lake risk reduction methods, and disaster management planning. In order to eliminate the potential impacts of future glacial lake outburst floods to downstream communities, agricultural land, and infrastructure, the authors recommend the development: of standardized glacial lake risk assessment methods, Himalayan-specific lake lowering and risk reduction approaches, user friendly early warning systems, and disaster preparedness training.

Published
2017

37. Multiannual observations and modelling of seasonal thermal profiles through supraglacial debris in the Central Himalaya

Author

Rowan, Ann V., primary, Nicholson, Lindsey, additional, Collier, Emily, additional, Quincey, Duncan J., additional, Gibson, Morgan J., additional, Wagnon, Patrick, additional, Rounce, David R., additional, Thompson, Sarah S., additional, King, Owen, additional, Watson, C. Scott, additional, Irvine-Fynn, Tristram D. L., additional, and Glasser, Neil F., additional

Published
2017
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41. Modeling the Glacial Lake Outburst Flood Process Chain in the Nepal Himalaya: Reassessing Imja Tsho's Hazard.

Author

Lala, Jonathan M., Rounce, David R., and McKinney, Daene C.

Abstract

The Himalayas of South Asia are home to many glaciers that are retreating due to climate change and causing the formation of large glacial lakes in their absence. These lakes are held in place by naturally deposited moraine dams that are potentially unstable. Specifically, an impulse wave generated by an avalanche or landslide entering the lake can destabilize the moraine dam, thereby causing a catastrophic failure of the moraine and a glacial lake outburst flood (GLOF). Imja-Lhotse Shar glacier is amongst the glaciers experiencing the highest rate of mass loss in the Mount Everest region, which has contributed to the expansion of Imja Tsho. A GLOF from this lake may have the potential to cause catastrophic damage to downstream villages, threatening both property and human life. Therefore, it is essential to understand the processes that could trigger a flood and quantify the potential downstream impacts. The avalanche-induced GLOF process chain was modeled using the output of one component of the chain as input to the next. First, the volume and momentum of various avalanches entering the lake were calculated using RAMMS. Next, the avalanche-induced waves were simulated using BASEMENT and validated with empirical equations to ensure the proper transfer of momentum from the avalanche to the lake. With BASEMENT, the ensuing moraine erosion and downstream flooding was modeled, which was used to generate hazard maps downstream. Moraine erosion was calculated for two geomorphologic models: one site-specific using field data and another worst-case based on past literature that is applicable to lakes in the greater region. Neither case resulted in flooding outside the river channel at downstream villages. The worst-case model resulted in some moraine erosion and increased channelization of the lake outlet, which yielded greater discharge downstream but no catastrophic collapse. The site-specific model generated similar results, but with very little erosion and a smaller downstream discharge. These results indicated that Imja Tsho is unlikely to produce a catastrophic GLOF due to an avalanche in the near future, although some hazard exists within the downstream river channel, necessitating continued monitoring of the lake. Furthermore, these models were designed for ease and flexibility so that they can be adopted by a wide range of stakeholders and appropriated for other lakes in the region. [ABSTRACT FROM AUTHOR]

Published
2017
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42. Identification of Hazard and Risk for Glacial Lakes in the Nepal Himalaya Using Satellite Imagery from 2000-2015.

Author

Rounce, David R., Watson, C. Scott, and McKinney, Daene C.

Subjects
*GLACIAL lakes, *ROCKFALL, *MORAINES, *AVALANCHES, *REMOTE-sensing images
Abstract

Glacial lakes in the Nepal Himalaya can threaten downstream communities and have large socio-economic consequences if an outburst flood occurs. This study identified 131 glacial lakes in Nepal in 2015 that are greater than 0.1 km2 and performed a first-pass hazard and risk assessment for each lake. The hazard assessment included mass entering the lake, the moraine stability, and how lake expansion will alter the lake's hazard in the next 15-30 years. A geometric flood model was used to quantify potential hydropower systems, buildings, agricultural land, and bridges that could be affected by a glacial lake outburst flood. The hazard and downstream impacts were combined to classify the risk associated with each lake. 11 lakes were classified as very high risk and 31 as high risk. The potential flood volume was also estimated and used to prioritize the glacial lakes that are the highest risk, which included Phoksundo Tal, Tsho Rolpa, Chamlang North Tsho, Chamlang South Tsho, and Lumding Tsho. These results are intended to assist stakeholders and decision makers in making well-informed decisions with respect to the glacial lakes that should be the focus of future field studies, modeling efforts, and risk-mitigation actions. [ABSTRACT FROM AUTHOR]

Published
2017
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45. Partitioning the Uncertainty of Ensemble Projections of Global Glacier Mass Change

Author

Marzeion, Ben, Hock, Regine, Anderson, Brian, Bliss, Andrew, Champollion, Nicolas, Fujita, Koji, Huss, Matthias, Immerzeel, Walter W., Kraaijenbrink, Philip, Malles, Jan-Hendrik, Maussion, Fabien, Radi?, Valentina, Rounce, David R., Sakai, Akiko, Shannon, Sarah, Van De Wal, Roderik, and Zekollari, Harry

Subjects
13. Climate action
Abstract

Glacier mass loss is recognized as a major contributor to current sea level rise. However, large uncertainties remain in projections of glacier mass loss on global and regional scales. We present an ensemble of 288 glacier mass and area change projections for the 21st century based on 11 glacier models using up to 10 general circulation models and four Representative Concentration Pathways (RCPs) as boundary conditions. We partition the total uncertainty into the individual contributions caused by glacier models, general circulation models, RCPs, and natural variability. We find that emission scenario uncertainty is growing throughout the 21st century and is the largest source of uncertainty by 2100. The relative importance of glacier model uncertainty decreases over time, but it is the greatest source of uncertainty until the middle of this century. The projection uncertainty associated with natural variability is small on the global scale but can be large on regional scales. The projected global mass loss by 2100 relative to 2015 (79 ± 56 mm sea level equivalent for RCP2.6, 159 ± 86 mm sea level equivalent for RCP8.5) is lower than, but well within, the uncertainty range of previous projections.

46. Partitioning the Uncertainty of Ensemble Projections of Global Glacier Mass Change

Author

Marzeion, Ben, Hock, Regine, Anderson, Brian, Bliss, Andrew, Champollion, Nicolas, Fujita, Koji, Huss, Matthias, Immerzeel, Walter W., Kraaijenbrink, Philip, Malles, Jan-Hendrik, Maussion, Fabien, Radic, Valentina, Rounce, David R., Sakai, Akiko, Shannon, Sarah, van de Wal, Roderik, and Zekollari, Harry

Subjects
13. Climate action
Abstract

Glacier mass loss is recognized as a major contributor to current sea level rise. However, large uncertainties remain in projections of glacier mass loss on global and regional scales. We present an ensemble of 288 glacier mass and area change projections for the 21st century based on 11 glacier models using up to 10 general circulation models and four Representative Concentration Pathways (RCPs) as boundary conditions. We partition the total uncertainty into the individual contributions caused by glacier models, general circulation models, RCPs, and natural variability. We find that emission scenario uncertainty is growing throughout the 21st century and is the largest source of uncertainty by 2100. The relative importance of glacier model uncertainty decreases over time, but it is the greatest source of uncertainty until the middle of this century. The projection uncertainty associated with natural variability is small on the global scale but can be large on regional scales. The projected global mass loss by 2100 relative to 2015 (79 ± 56 mm sea level equivalent for RCP2.6, 159 ± 86 mm sea level equivalent for RCP8.5) is lower than, but well within, the uncertainty range of previous projections., Earth's Future, 8 (7), ISSN:2328-4277

47. Partitioning the Uncertainty of Ensemble Projections of Global Glacier Mass Change

Author

Marzeion, Ben, Hock, Regine, Anderson, Brian, Bliss, Andrew, Champollion, Nicolas, Fujita, Koji, Huss, Matthias, Immerzeel, Walter W., Kraaijenbrink, Philip, Malles, Jan‐Hendrik, Maussion, Fabien, Radić, Valentina, Rounce, David R., Sakai, Akiko, Shannon, Sarah, Wal, Roderik, Zekollari, Harry, Hydrologie, Landscape functioning, Geocomputation and Hydrology, Landdegradatie en aardobservatie, Proceskunde, Sub Algemeen Marine & Atmospheric Res, and Marine and Atmospheric Research

Subjects
lcsh:GE1-350, projections, glacier, Environmental Science(all), sea level rise, lcsh:QH540-549.5, Earth and Planetary Sciences (miscellaneous), modeling, lcsh:Ecology, uncertainties, lcsh:Environmental sciences, Sciences exactes et naturelles
Abstract

Glacier mass loss is recognized as a major contributor to current sea level rise. However, large uncertainties remain in projections of glacier mass loss on global and regional scales. We present an ensemble of 288 glacier mass and area change projections for the 21st century based on 11 glacier models using up to 10 general circulation models and four Representative Concentration Pathways (RCPs) as boundary conditions. We partition the total uncertainty into the individual contributions caused by glacier models, general circulation models, RCPs, and natural variability. We find that emission scenario uncertainty is growing throughout the 21st century and is the largest source of uncertainty by 2100. The relative importance of glacier model uncertainty decreases over time, but it is the greatest source of uncertainty until the middle of this century. The projection uncertainty associated with natural variability is small on the global scale but can be large on regional scales. The projected global mass loss by 2100 relative to 2015 (79 ± 56 mm sea level equivalent for RCP2.6, 159 ± 86 mm sea level equivalent for RCP8.5) is lower than, but well within, the uncertainty range of previous projections. ISSN:2328-4277

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48. Partitioning the uncertainty of ensemble projections of global glacier mass change

Author

Marzeion, Ben, Hock, Regine, Anderson, Brian, Bliss, Andrew, Champollion, Nicolas, Fujita, Koji, Huss, Matthias, Immerzeel, Walter W., Kraaijenbrink, Philip, Malles, Jan‐Hendrik, Maussion, Fabien, Radić, Valentina, Rounce, David R., Sakai, Akiko, Shannon, Sarah, Wal, Roderik, Zekollari, Harry, Marzeion, Ben, Hock, Regine, Anderson, Brian, Bliss, Andrew, Champollion, Nicolas, Fujita, Koji, Huss, Matthias, Immerzeel, Walter W., Kraaijenbrink, Philip, Malles, Jan‐Hendrik, Maussion, Fabien, Radić, Valentina, Rounce, David R., Sakai, Akiko, Shannon, Sarah, Wal, Roderik, and Zekollari, Harry

Abstract

Glacier mass loss is recognized as a major contributor to current sea level rise. However, large uncertainties remain in projections of glacier mass loss on global and regional scales. We present an ensemble of 288 glacier mass and area change projections for the 21st century based on 11 glacier models using up to 10 general circulation models and four Representative Concentration Pathways (RCPs) as boundary conditions. We partition the total uncertainty into the individual contributions caused by glacier models, general circulation models, RCPs, and natural variability. We find that emission scenario uncertainty is growing throughout the 21st century and is the largest source of uncertainty by 2100. The relative importance of glacier model uncertainty decreases over time, but it is the greatest source of uncertainty until the middle of this century. The projection uncertainty associated with natural variability is small on the global scale but can be large on regional scales. The projected global mass loss by 2100 relative to 2015 (79 ± 56 mm sea level equivalent for RCP2.6, 159 ± 86 mm sea level equivalent for RCP8.5) is lower than, but well within, the uncertainty range of previous projections.

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