1
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Creel RC, Miesner F, Wilkenskjeld S, Austermann J, Overduin PP. Glacial isostatic adjustment reduces past and future Arctic subsea permafrost. Nat Commun 2024; 15:3232. [PMID: 38622113 PMCID: PMC11018745 DOI: 10.1038/s41467-024-45906-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2023] [Accepted: 02/06/2024] [Indexed: 04/17/2024] Open
Abstract
Sea-level rise submerges terrestrial permafrost in the Arctic, turning it into subsea permafrost. Subsea permafrost underlies ~ 1.8 million km2 of Arctic continental shelf, with thicknesses in places exceeding 700 m. Sea-level variations over glacial-interglacial cycles control subsea permafrost distribution and thickness, yet no permafrost model has accounted for glacial isostatic adjustment (GIA), which deviates local sea level from the global mean due to changes in ice and ocean loading. Here we incorporate GIA into a pan-Arctic model of subsea permafrost over the last 400,000 years. Including GIA significantly reduces present-day subsea permafrost thickness, chiefly because of hydro-isostatic effects as well as deformation related to Northern Hemisphere ice sheets. Additionally, we extend the simulation 1000 years into the future for emissions scenarios outlined in the Intergovernmental Panel on Climate Change's sixth assessment report. We find that subsea permafrost is preserved under a low emissions scenario but mostly disappears under a high emissions scenario.
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Affiliation(s)
- Roger C Creel
- Lamont-Doherty Earth Observatory, Columbia University, New York, NY, USA
- Department of Physical Oceanography, Woods Hole Oceanographic Institution, Woods Hole, MA, USA
| | - Frederieke Miesner
- Alfred Wegener Institute Helmholtz-Centre for Polar and Marine Research, Potsdam, Germany.
| | | | | | - Pier Paul Overduin
- Alfred Wegener Institute Helmholtz-Centre for Polar and Marine Research, Potsdam, Germany
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2
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Zhao G, Merder J, Ballard TC, Michalak AM. Warming may offset impact of precipitation changes on riverine nitrogen loading. Proc Natl Acad Sci U S A 2023; 120:e2220616120. [PMID: 37549260 PMCID: PMC10438841 DOI: 10.1073/pnas.2220616120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2022] [Accepted: 05/18/2023] [Indexed: 08/09/2023] Open
Abstract
Climate change, especially in the form of precipitation and temperature changes, can alter the transformation and delivery of nitrogen on the land surface and to aquatic systems, impacting the trophic states of downstream water bodies. While the expected impacts of changes in precipitation have been explored, a quantitative understanding of the impact of temperature on nitrogen loading is lacking at landscape scales. Here, using several decades of nitrogen loading observations, we quantify how individual and combined future changes in precipitation and temperature will affect riverine nitrogen loading. We find that, contrary to recent decades, rising temperatures are likely to offset or even reverse previously reported impacts of future increases in total and extreme precipitation on nitrogen runoff across the majority of the contiguous United States. These findings highlight the multifaceted impacts of climate change on the global nitrogen cycle.
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Affiliation(s)
- Gang Zhao
- Department of Global Ecology, Carnegie Institution for Science, Stanford, CA94305
- Key Laboratory of Water Cycle and Related Land Surface Processes, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing100101, China
| | - Julian Merder
- Department of Global Ecology, Carnegie Institution for Science, Stanford, CA94305
| | - Tristan C. Ballard
- Department of Global Ecology, Carnegie Institution for Science, Stanford, CA94305
- Department of Earth System Science, Stanford University, Stanford, CA94305
| | - Anna M. Michalak
- Department of Global Ecology, Carnegie Institution for Science, Stanford, CA94305
- Department of Earth System Science, Stanford University, Stanford, CA94305
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3
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Song J, Tong G, Chao J, Chung J, Zhang M, Lin W, Zhang T, Bentler PM, Zhu W. Data driven pathway analysis and forecast of global warming and sea level rise. Sci Rep 2023; 13:5536. [PMID: 37015939 PMCID: PMC10073234 DOI: 10.1038/s41598-023-30789-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2022] [Accepted: 03/01/2023] [Indexed: 04/06/2023] Open
Abstract
Climate change is a critical issue of our time, and its causes, pathways, and forecasts remain a topic of broader discussion. In this paper, we present a novel data driven pathway analysis framework to identify the key processes behind mean global temperature and sea level rise, and to forecast the magnitude of their increase from the present to 2100. Based on historical data and dynamic statistical modeling alone, we have established the causal pathways that connect increasing greenhouse gas emissions to increasing global mean temperature and sea level, with its intermediate links encompassing humidity, sea ice coverage, and glacier mass, but not for sunspot numbers. Our results indicate that if no action is taken to curb anthropogenic greenhouse gas emissions, the global average temperature would rise to an estimated 3.28 °C (2.46-4.10 °C) above its pre-industrial level while the global sea level would be an estimated 573 mm (474-671 mm) above its 2021 mean by 2100. However, if countries adhere to the greenhouse gas emission regulations outlined in the 2021 United Nations Conference on Climate Change (COP26), the rise in global temperature would lessen to an average increase of 1.88 °C (1.43-2.33 °C) above its pre-industrial level, albeit still higher than the targeted 1.5 °C, while the sea level increase would reduce to 449 mm (389-509 mm) above its 2021 mean by 2100.
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Affiliation(s)
- Jiecheng Song
- Department of Applied Mathematics and Statistics, State University of New York at Stony Brook, Stony Brook, NY, 11794-3600, USA.
| | - Guanchao Tong
- Department of Applied Mathematics and Statistics, State University of New York at Stony Brook, Stony Brook, NY, 11794-3600, USA
| | - Jiayou Chao
- Department of Applied Mathematics and Statistics, State University of New York at Stony Brook, Stony Brook, NY, 11794-3600, USA
| | - Jean Chung
- Duke University, 2080 Duke University Road, Durham, NC, 27708, USA
| | - Minghua Zhang
- School of Marine and Atmospheric Sciences, State University of New York at Stony Brook, Stony Brook, NY, 11794-5000, USA
| | - Wuyin Lin
- Environmental and Climate Sciences Department, Brookhaven National Laboratory, Upton, NY, 11973-5000, USA
| | - Tao Zhang
- Environmental and Climate Sciences Department, Brookhaven National Laboratory, Upton, NY, 11973-5000, USA
| | - Peter M Bentler
- Department of Statistics, University of California, Los Angeles, Los Angeles, CA, 90095-1554, USA
| | - Wei Zhu
- Department of Applied Mathematics and Statistics, State University of New York at Stony Brook, Stony Brook, NY, 11794-3600, USA.
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4
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Li D, DeConto RM, Pollard D. Climate model differences contribute deep uncertainty in future Antarctic ice loss. SCIENCE ADVANCES 2023; 9:eadd7082. [PMID: 36791186 PMCID: PMC9931235 DOI: 10.1126/sciadv.add7082] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/02/2022] [Accepted: 01/18/2023] [Indexed: 06/18/2023]
Abstract
Future projections of ice sheets in response to different climate scenarios and their associated contributions to sea level changes are subject to deep uncertainty due to ice sheet instability processes, hampering a proper risk assessment of sea level rise and enaction of mitigation/adaptation strategies. For a systematic evaluation of the uncertainty due to climate model fields used as input to the ice sheet models, we drive a three-dimensional model of the Antarctic Ice Sheet (AIS) with the output from 36 climate models to simulate past and future changes in the AIS. Simulations show that a few climate models result in partial collapse of the West AIS under modeled preindustrial climates, and the spread in future changes in the AIS's volume is comparable to the structural uncertainty originating from differing ice sheet models. These results highlight the need for improved representations of physical processes important for polar climate in climate models.
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Affiliation(s)
- Dawei Li
- School of Oceanography, Shanghai Jiao Tong University, Shanghai 200030, China
- Department of Geosciences, University of Massachusetts Amherst, Amherst, MA 01003, USA
- MNR Key Laboratory for Polar Science, Polar Research Institute of China, Shanghai 200136, China
- Shanghai Key Laboratory of Polar Life and Environment Sciences, Shanghai Jiao Tong University, Shanghai 200030, China
| | - Robert M. DeConto
- Department of Geosciences, University of Massachusetts Amherst, Amherst, MA 01003, USA
| | - David Pollard
- Department of Geosciences, University of Massachusetts Amherst, Amherst, MA 01003, USA
- Earth and Environmental Systems Institute, Pennsylvania State University, University Park, PA 16802, USA
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5
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Abrupt loss and uncertain recovery from fires of Amazon forests under low climate mitigation scenarios. Proc Natl Acad Sci U S A 2022; 119:e2203200119. [PMID: 36534807 PMCID: PMC9907153 DOI: 10.1073/pnas.2203200119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Tropical forests contribute a major sink for anthropogenic carbon emissions essential to slowing down the buildup of atmospheric CO2 and buffering climate change impacts. However, the response of tropical forests to more frequent weather extremes and long-recovery disturbances like fires remains uncertain. Analyses of field data and ecological theory raise concerns about the possibility of the Amazon crossing a tipping point leading to catastrophic tropical forest loss. In contrast, climate models consistently project an enhanced tropical sink. Here, we show a heterogeneous response of Amazonian carbon stocks in GFDL-ESM4.1, an Earth System Model (ESM) featuring dynamic disturbances and height-structured tree-grass competition. Enhanced productivity due to CO2 fertilization promotes increases in forest biomass that, under low emission scenarios, last until the end of the century. Under high emissions, positive trends reverse after 2060, when simulated fires prompt forest loss that results in a 40% decline in tropical forest biomass by 2100. Projected fires occur under dry conditions associated with El Niño Southern Oscillation and the Atlantic Multidecadal Oscillation, a response observed under current climate conditions, but exacerbated by an overall decline in precipitation. Following the initial disturbance, grassland dominance promotes recurrent fires and tree competitive exclusion, which prevents forest recovery. EC-Earth3-Veg, an ESM with a dynamic vegetation model of similar complexity, projected comparable wildfire forest loss under high emissions but faster postfire recovery rates. Our results reveal the importance of complex nonlinear responses to assessing climate change impacts and the urgent need to research postfire recovery and its representation in ESMs.
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Du T, Jing Z, Wu L, Wang H, Chen Z, Ma X, Gan B, Yang H. Growth of ocean thermal energy conversion resources under greenhouse warming regulated by oceanic eddies. Nat Commun 2022; 13:7249. [PMID: 36433956 PMCID: PMC9700850 DOI: 10.1038/s41467-022-34835-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2022] [Accepted: 11/09/2022] [Indexed: 11/27/2022] Open
Abstract
The concept of utilizing a large temperature difference (>20 °C) between the surface and deep seawater to generate electricity, known as the ocean thermal energy conversion (OTEC), provides a renewable solution to fueling our future. However, it remains poorly assessed how the OTEC resources will respond to future climate change. Here, we find that the global OTEC power potential is projected to increase by 46% around the end of this century under a high carbon emission scenario, compared to its present-day level. The augmented OTEC power potential due to the rising sea surface temperature is partially offset by the deep ocean warming. The offsetting effect is more evident in the Atlantic Ocean than Pacific and Indian Oceans. This is mainly attributed to the weakening of mesoscale eddy-induced upward heat transport, suggesting an important role of mesoscale eddies in regulating the response of thermal stratification and OTEC power potential to greenhouse warming.
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Affiliation(s)
- Tianshi Du
- grid.4422.00000 0001 2152 3263Frontiers Science Center for Deep Ocean Multispheres and Earth System and Key Laboratory of Physical Oceanography, Ocean University of China, Qingdao, China ,Laoshan Laboratory, Qingdao, China
| | - Zhao Jing
- grid.4422.00000 0001 2152 3263Frontiers Science Center for Deep Ocean Multispheres and Earth System and Key Laboratory of Physical Oceanography, Ocean University of China, Qingdao, China ,Laoshan Laboratory, Qingdao, China
| | - Lixin Wu
- grid.4422.00000 0001 2152 3263Frontiers Science Center for Deep Ocean Multispheres and Earth System and Key Laboratory of Physical Oceanography, Ocean University of China, Qingdao, China ,Laoshan Laboratory, Qingdao, China
| | - Hong Wang
- grid.4422.00000 0001 2152 3263Frontiers Science Center for Deep Ocean Multispheres and Earth System and Key Laboratory of Physical Oceanography, Ocean University of China, Qingdao, China ,Laoshan Laboratory, Qingdao, China
| | - Zhaohui Chen
- grid.4422.00000 0001 2152 3263Frontiers Science Center for Deep Ocean Multispheres and Earth System and Key Laboratory of Physical Oceanography, Ocean University of China, Qingdao, China ,Laoshan Laboratory, Qingdao, China
| | - Xiaohui Ma
- grid.4422.00000 0001 2152 3263Frontiers Science Center for Deep Ocean Multispheres and Earth System and Key Laboratory of Physical Oceanography, Ocean University of China, Qingdao, China ,Laoshan Laboratory, Qingdao, China
| | - Bolan Gan
- grid.4422.00000 0001 2152 3263Frontiers Science Center for Deep Ocean Multispheres and Earth System and Key Laboratory of Physical Oceanography, Ocean University of China, Qingdao, China ,Laoshan Laboratory, Qingdao, China
| | - Haiyuan Yang
- grid.4422.00000 0001 2152 3263Frontiers Science Center for Deep Ocean Multispheres and Earth System and Key Laboratory of Physical Oceanography, Ocean University of China, Qingdao, China ,Laoshan Laboratory, Qingdao, China
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7
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Balaji V, Couvreux F, Deshayes J, Gautrais J, Hourdin F, Rio C. Are general circulation models obsolete? Proc Natl Acad Sci U S A 2022; 119:e2202075119. [PMID: 36375059 PMCID: PMC9704743 DOI: 10.1073/pnas.2202075119] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/21/2023] Open
Abstract
Traditional general circulation models, or GCMs-that is, three-dimensional dynamical models with unresolved terms represented in equations with tunable parameters-have been a mainstay of climate research for several decades, and some of the pioneering studies have recently been recognized by a Nobel prize in Physics. Yet, there is considerable debate around their continuing role in the future. Frequently mentioned as limitations of GCMs are the structural error and uncertainty across models with different representations of unresolved scales and the fact that the models are tuned to reproduce certain aspects of the observed Earth. We consider these shortcomings in the context of a future generation of models that may address these issues through substantially higher resolution and detail, or through the use of machine learning techniques to match them better to observations, theory, and process models. It is our contention that calibration, far from being a weakness of models, is an essential element in the simulation of complex systems, and contributes to our understanding of their inner workings. Models can be calibrated to reveal both fine-scale detail and the global response to external perturbations. New methods enable us to articulate and improve the connections between the different levels of abstract representation of climate processes, and our understanding resides in an entire hierarchy of models where GCMs will continue to play a central role for the foreseeable future.
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Affiliation(s)
- V. Balaji
- Cooperative Institute for Modeling the Earth System, Princeton University, NJ 08544
- Laboratoire des Sciences du Climat et de l’Environnement, Le Commissariat à l’Énergie Atomique et aux Énergies Alternatives, 91191 Gif-sur-Yvette, France
| | - Fleur Couvreux
- Centre National de Recherches Météorologiques, University of Toulouse, Meteo-France, CNRS, 31057 Toulouse Cedex, France
| | - Julie Deshayes
- Sorbonne Universités-CNRS-Institut de recherche pour le développement (IRD) - Muséum National d’Histoire Naturelle (MNHN), Laboratory of Oceanography and Climate: Experiments and Numerical Approaches (LOCEAN), 75005 Paris, France
| | - Jacques Gautrais
- Centre de Recherches sur la Cognition Animale, Centre de Biologie Intégrative, Université de Toulouse, CNRS, Université Paul Sabatier (UPS), 31062 Toulouse, France
| | - Frédéric Hourdin
- Laboratoire de Météorologie Dynamique - Institut Pierre Simon Laplace (LMD-IPSL), Sorbonne University, CNRS, 75005 Paris, France
| | - Catherine Rio
- Centre National de Recherches Météorologiques, University of Toulouse, Meteo-France, CNRS, 31057 Toulouse Cedex, France
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8
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Deforestation intensifies daily temperature variability in the northern extratropics. Nat Commun 2022; 13:5955. [PMID: 36216833 PMCID: PMC9550804 DOI: 10.1038/s41467-022-33622-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2021] [Accepted: 09/27/2022] [Indexed: 11/08/2022] Open
Abstract
While the biogeophysical effects of deforestation on average and extreme temperatures are broadly documented, how deforestation influences temperature variability remains largely unknown. To fill this knowledge gap, we investigate the biogeophysical effects of idealized deforestation on daily temperature variability at the global scale based on multiple earth system models and in situ observations. Here, we show that deforestation can intensify daily temperature variability (by up to 20%) in the northern extratropics, particularly in winter, leading to more frequent rapid extreme warming and cooling events. The higher temperature variability can be attributed to the enhanced near-surface horizontal temperature advection and simultaneously is partly offset by the lower variability in surface sensible heat flux. We also show responses of daily temperature variability to historical deforestation and future potential afforestation. This study reveals the overlooked effects of deforestation or afforestation on temperature variability and has implications for large-scale afforestation in northern extratropic countries. A new study finds that deforestation in the northern extratropics can enhance horizontal temperature advection through biogeophysical processes, leading to higher local daily temperature variability, particularly in winter.
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9
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Grinsted A, Bamber J, Bingham R, Buzzard S, Nias I, Ng K, Weeks J. The Transient Sea Level Response to External Forcing in CMIP6 Models. EARTH'S FUTURE 2022; 10:e2022EF002696. [PMID: 36582516 PMCID: PMC9786795 DOI: 10.1029/2022ef002696] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/29/2022] [Revised: 07/05/2022] [Accepted: 08/01/2022] [Indexed: 06/17/2023]
Abstract
Earth is warming and sea levels are rising as land-based ice is lost to melt, and oceans expand due to accumulation of heat. The pace of ice loss and steric expansion is linked to the intensity of warming. How much faster sea level will rise as climate warms is, however, highly uncertain and difficult to model. Here, we quantify the transient sea level sensitivity of the sea level budget in both models and observations. Models show little change in sensitivity to warming between the first and second half of the twenty-first century for most contributors. The exception is glaciers and ice caps (GIC) that have a greater sensitivity pre-2050 (2.8 ± 0.4 mm/yr/K) compared to later (0.7 ± 0.1 mm/yr/K). We attribute this change to the short response time of glaciers and their changing area over time. Model sensitivities of steric expansion (1.5 ± 0.2 mm/yr/K), and Greenland Ice Sheet mass loss (0.8 ± 0.2 mm/yr/K) are greater than, but still compatible with, corresponding estimates from historical data (1.4 ± 0.5 and 0.4 ± 0.2 mm/yr/K). Antarctic Ice Sheet (AIS) models tends to show lower rates of sea level rise (SLR) with warming (-0.0 ± 0.3 mm/yr/K) in contrast to historical estimates (0.4 ± 0.2 mm/yr/K). This apparent low bias in AIS sensitivity is only partly able to account for a similar low bias identified in the sensitivity of global mean sea level excluding GIC (3.1 ± 0.4 vs. 2.3 ± 0.4 mm/yr/K). The balance temperature, where SLR is zero, lies close to the pre-industrial value, implying that SLR can only be mitigated by substantial global cooling.
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Affiliation(s)
- Aslak Grinsted
- Physics of Ice, Climate, and EarthNiels Bohr InstituteUniversity of CopenhagenCopenhagenDenmark
| | - Jonathan Bamber
- School of Geographical SciencesUniversity of BristolBristolUK
- Department of Aerospace and GeodesyData Science in Earth ObservationTechnical University of MunichMunichGermany
| | - Rory Bingham
- School of Geographical SciencesUniversity of BristolBristolUK
| | - Sammie Buzzard
- School of Earth and Environmental SciencesCardiff UniversityCardiffUK
| | - Isabel Nias
- School of Environmental SciencesUniversity of LiverpoolLiverpoolUK
| | - Kelvin Ng
- School of Geography, Earth and Environmental SciencesUniversity of BirminghamBirminghamUK
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10
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Drivers and distribution of global ocean heat uptake over the last half century. Nat Commun 2022; 13:4921. [PMID: 36071053 PMCID: PMC9452516 DOI: 10.1038/s41467-022-32540-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2022] [Accepted: 08/04/2022] [Indexed: 11/09/2022] Open
Abstract
Since the 1970s, the ocean has absorbed almost all of the additional energy in the Earth system due to greenhouse warming. However, sparse observations limit our knowledge of where ocean heat uptake (OHU) has occurred and where this heat is stored today. Here, we equilibrate a reanalysis-forced ocean-sea ice model, using a spin-up that improves on earlier approaches, to investigate recent OHU trends basin-by-basin and associated separately with surface wind trends, thermodynamic properties (temperature, humidity and radiation) or both. Wind and thermodynamic changes each explain ~ 50% of global OHU, while Southern Ocean forcing trends can account for almost all of the global OHU. This OHU is enabled by cool sea surface temperatures and sensible heat gain when atmospheric thermodynamic properties are held fixed, while downward longwave radiation dominates when winds are fixed. These results address long-standing limitations in multidecadal ocean-sea ice model simulations to reconcile estimates of OHU, transport and storage.
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11
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Thompson V, Kennedy-Asser AT, Vosper E, Lo YTE, Huntingford C, Andrews O, Collins M, Hegerl GC, Mitchell D. The 2021 western North America heat wave among the most extreme events ever recorded globally. SCIENCE ADVANCES 2022; 8:eabm6860. [PMID: 35507648 PMCID: PMC9067932 DOI: 10.1126/sciadv.abm6860] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/05/2021] [Accepted: 03/16/2022] [Indexed: 05/28/2023]
Abstract
In June 2021, western North America experienced a record-breaking heat wave outside the distribution of previously observed temperatures. While it is clear that the event was extreme, it is not obvious whether other areas in the world have also experienced events so far outside their natural variability. Using a novel assessment of heat extremes, we investigate how extreme this event was in the global context. Characterizing the relative intensity of an event as the number of standard deviations from the mean, the western North America heat wave is remarkable, coming in at over four standard deviations. Throughout the globe, where we have reliable data, only five other heat waves were found to be more extreme since 1960. We find that in both reanalyses and climate projections, the statistical distribution of extremes increases through time, in line with the distribution mean shift due to climate change. Regions that, by chance, have not had a recent extreme heat wave may be less prepared for potentially imminent events.
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Affiliation(s)
- Vikki Thompson
- School of Geographical Sciences, University of Bristol, Bristol, UK
| | | | - Emily Vosper
- School of Geographical Sciences, University of Bristol, Bristol, UK
| | - Y. T. Eunice Lo
- School of Geographical Sciences, University of Bristol, Bristol, UK
| | | | - Oliver Andrews
- School of Geographical Sciences, University of Bristol, Bristol, UK
| | - Matthew Collins
- College of Engineering, Mathematics, and Physical Sciences, University of Exeter, Exeter, UK
| | | | - Dann Mitchell
- School of Geographical Sciences, University of Bristol, Bristol, UK
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12
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Samset BH, Zhou C, Fuglestvedt JS, Lund MT, Marotzke J, Zelinka MD. Earlier emergence of a temperature response to mitigation by filtering annual variability. Nat Commun 2022; 13:1578. [PMID: 35332146 PMCID: PMC8948247 DOI: 10.1038/s41467-022-29247-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2021] [Accepted: 02/28/2022] [Indexed: 11/23/2022] Open
Abstract
The rate of global surface warming is crucial for tracking progress towards global climate targets, but is strongly influenced by interannual-to-decadal variability, which precludes rapid detection of the temperature response to emission mitigation. Here we use a physics based Green’s function approach to filter out modulations to global mean surface temperature from sea-surface temperature (SST) patterns, and show that it results in an earlier emergence of a response to strong emissions mitigation. For observed temperatures, we find a filtered 2011–2020 surface warming rate of 0.24 °C per decade, consistent with long-term trends. Unfiltered observations show 0.35 °C per decade, partly due to the El Nino of 2015–2016. Pattern filtered warming rates can become a strong tool for the climate community to inform policy makers and stakeholder communities about the ongoing and expected climate responses to emission reductions, provided an effort is made to improve and validate standardized Green’s functions. The pattern of sea surface temperatures affects global mean temperatures from year to year. By filtering out parts of this natural variability, researchers show that they can more rapidly detect the influence of mitigation of CO2 emissions on the climate
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Affiliation(s)
- B H Samset
- CICERO Center for International Climate Research, Oslo, Norway.
| | - C Zhou
- Nanjing University, Nanjing, China
| | - J S Fuglestvedt
- CICERO Center for International Climate Research, Oslo, Norway
| | - M T Lund
- CICERO Center for International Climate Research, Oslo, Norway
| | - J Marotzke
- Max Planck Institute for Meteorology, Hamburg, Germany and Center for Earth System Research and Sustainability, Universität Hamburg, Hamburg, Germany
| | - M D Zelinka
- Lawrence Livermore National Laboratory, Livermore, USA
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Abstract
How will increasing wildfire activity affect water resources in the water-limited western United States (WUS)? Among basins where >20% of forest burned, postfire streamflow is significantly enhanced by an average of approximately 30% for 6 y. Over 2015 to 2020, several large WUS basins experienced >10% of forest burned. Climate projections and an exponential forest fire response to climate-induced drying suggest the next 3 decades will see repeated years when WUS forest fire area exceeds that of 2020, which set a modern record for forest area burned. If so, entire regions will likely experience more streamflow than expected, potentially enhancing human access to water but posing hazard management challenges. Projections of water supply and runoff-related hazards must account for wildfire. Streamflow often increases after fire, but the persistence of this effect and its importance to present and future regional water resources are unclear. This paper addresses these knowledge gaps for the western United States (WUS), where annual forest fire area increased by more than 1,100% during 1984 to 2020. Among 72 forested basins across the WUS that burned between 1984 and 2019, the multibasin mean streamflow was significantly elevated by 0.19 SDs (P < 0.01) for an average of 6 water years postfire, compared to the range of results expected from climate alone. Significance is assessed by comparing prefire and postfire streamflow responses to climate and also to streamflow among 107 control basins that experienced little to no wildfire during the study period. The streamflow response scales with fire extent: among the 29 basins where >20% of forest area burned in a year, streamflow over the first 6 water years postfire increased by a multibasin average of 0.38 SDs, or 30%. Postfire streamflow increases were significant in all four seasons. Historical fire–climate relationships combined with climate model projections suggest that 2021 to 2050 will see repeated years when climate is more fire-conducive than in 2020, the year currently holding the modern record for WUS forest area burned. These findings center on relatively small, minimally managed basins, but our results suggest that burned areas will grow enough over the next 3 decades to enhance streamflow at regional scales. Wildfire is an emerging driver of runoff change that will increasingly alter climate impacts on water supplies and runoff-related risks.
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14
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Dong B, Sutton RT, Shaffrey L, Harvey B. Recent decadal weakening of the summer Eurasian westerly jet attributable to anthropogenic aerosol emissions. Nat Commun 2022; 13:1148. [PMID: 35241666 PMCID: PMC8894405 DOI: 10.1038/s41467-022-28816-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2021] [Accepted: 02/03/2022] [Indexed: 11/09/2022] Open
Abstract
The Eurasian subtropical westerly jet (ESWJ) is a major feature of the summertime atmospheric circulation in the Northern Hemisphere. Here, we demonstrate a robust weakening trend in the summer ESWJ over the last four decades, linked to significant impacts on extreme weather. Analysis of climate model simulations from the Coupled Model Intercomparison Project Phase 6 (CMIP6) suggests that anthropogenic aerosols were likely the primary driver of the weakening ESWJ. Warming over mid-high latitudes due to aerosol reductions in Europe, and cooling in the tropics and subtropics due to aerosol increases over South and East Asia acted to reduce the meridional temperature gradient at the surface and in the lower and middle troposphere, leading to reduced vertical shear of the zonal wind and a weaker ESWJ in the upper troposphere. If, as expected, Asian anthropogenic aerosol precursor emissions decline in future, our results imply a renewed strengthening of the summer ESWJ. This study presents evidence that a major feature of the northern hemisphere summertime circulation, the Eurasian subtropical westerly jet (ESWJ), weakened significantly in recent decades, and that this weakening was caused by changes in anthropogenic aerosols.
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Affiliation(s)
- Buwen Dong
- National Centre for Atmospheric Science, Department of Meteorology, University of Reading, Berkshire, United Kingdom.
| | - Rowan T Sutton
- National Centre for Atmospheric Science, Department of Meteorology, University of Reading, Berkshire, United Kingdom
| | - Len Shaffrey
- National Centre for Atmospheric Science, Department of Meteorology, University of Reading, Berkshire, United Kingdom
| | - Ben Harvey
- National Centre for Atmospheric Science, Department of Meteorology, University of Reading, Berkshire, United Kingdom
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15
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Muntjewerf L, Sacks WJ, Lofverstrom M, Fyke J, Lipscomb WH, Ernani da Silva C, Vizcaino M, Thayer‐Calder K, Lenaerts JTM, Sellevold R. Description and Demonstration of the Coupled Community Earth System Model v2 - Community Ice Sheet Model v2 (CESM2-CISM2). JOURNAL OF ADVANCES IN MODELING EARTH SYSTEMS 2021; 13:e2020MS002356. [PMID: 34434489 PMCID: PMC8365656 DOI: 10.1029/2020ms002356] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/06/2020] [Revised: 05/06/2021] [Accepted: 05/21/2021] [Indexed: 06/13/2023]
Abstract
Earth system/ice-sheet coupling is an area of recent, major Earth System Model (ESM) development. This work occurs at the intersection of glaciology and climate science and is motivated by a need for robust projections of sea-level rise. The Community Ice Sheet Model version 2 (CISM2) is the newest component model of the Community Earth System Model version 2 (CESM2). This study describes the coupling and novel capabilities of the model, including: (1) an advanced energy-balance-based surface mass balance calculation in the land component with downscaling via elevation classes; (2) a closed freshwater budget from ice sheet to the ocean from surface runoff, basal melting, and ice discharge; (3) dynamic land surface types; and (4) dynamic atmospheric topography. The Earth system/ice-sheet coupling is demonstrated in a simulation with an evolving Greenland Ice Sheet (GrIS) under an idealized high CO2 scenario. The model simulates a large expansion of ablation areas (where surface ablation exceeds snow accumulation) and a large increase in surface runoff. This results in an elevated freshwater flux to the ocean, as well as thinning of the ice sheet and area retreat. These GrIS changes result in reduced Greenland surface albedo, changes in the sign and magnitude of sensible and latent heat fluxes, and modified surface roughness and overall ice sheet topography. Representation of these couplings between climate and ice sheets is key for the simulation of ice and climate interactions.
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Affiliation(s)
- Laura Muntjewerf
- Department of Geoscience and Remote SensingDelft University of TechnologyDelftThe Netherlands
| | - William J. Sacks
- Climate and Global Dynamics LaboratoryNational Center for Atmospheric ResearchBoulderCOUSA
| | | | - Jeremy Fyke
- Associated Engineering Group LtdCalgaryABCanada
| | - William H. Lipscomb
- Climate and Global Dynamics LaboratoryNational Center for Atmospheric ResearchBoulderCOUSA
| | | | - Miren Vizcaino
- Department of Geoscience and Remote SensingDelft University of TechnologyDelftThe Netherlands
| | | | - Jan T. M. Lenaerts
- Department of Atmospheric and Oceanic SciencesUniversity of Colorado BoulderBoulderCOUSA
| | - Raymond Sellevold
- Department of Geoscience and Remote SensingDelft University of TechnologyDelftThe Netherlands
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16
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Projected land ice contributions to twenty-first-century sea level rise. Nature 2021; 593:74-82. [PMID: 33953415 DOI: 10.1038/s41586-021-03302-y] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2019] [Accepted: 01/27/2021] [Indexed: 02/03/2023]
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.
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17
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Briner JP, Cuzzone JK, Badgeley JA, Young NE, Steig EJ, Morlighem M, Schlegel NJ, Hakim GJ, Schaefer JM, Johnson JV, Lesnek AJ, Thomas EK, Allan E, Bennike O, Cluett AA, Csatho B, de Vernal A, Downs J, Larour E, Nowicki S. Rate of mass loss from the Greenland Ice Sheet will exceed Holocene values this century. Nature 2020; 586:70-74. [PMID: 32999481 DOI: 10.1038/s41586-020-2742-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2019] [Accepted: 07/27/2020] [Indexed: 11/09/2022]
Abstract
The Greenland Ice Sheet (GIS) is losing mass at a high rate1. Given the short-term nature of the observational record, it is difficult to assess the historical importance of this mass-loss trend. Unlike records of greenhouse gas concentrations and global temperature, in which observations have been merged with palaeoclimate datasets, there are no comparably long records for rates of GIS mass change. Here we reveal unprecedented mass loss from the GIS this century, by placing contemporary and future rates of GIS mass loss within the context of the natural variability over the past 12,000 years. We force a high-resolution ice-sheet model with an ensemble of climate histories constrained by ice-core data2. Our simulation domain covers southwestern Greenland, the mass change of which is dominated by surface mass balance. The results agree favourably with an independent chronology of the history of the GIS margin3,4. The largest pre-industrial rates of mass loss (up to 6,000 billion tonnes per century) occurred in the early Holocene, and were similar to the contemporary (AD 2000-2018) rate of around 6,100 billion tonnes per century5. Simulations of future mass loss from southwestern GIS, based on Representative Concentration Pathway (RCP) scenarios corresponding to low (RCP2.6) and high (RCP8.5) greenhouse gas concentration trajectories6, predict mass loss of between 8,800 and 35,900 billion tonnes over the twenty-first century. These rates of GIS mass loss exceed the maximum rates over the past 12,000 years. Because rates of mass loss from the southwestern GIS scale linearly5 with the GIS as a whole, our results indicate, with high confidence, that the rate of mass loss from the GIS will exceed Holocene rates this century.
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Affiliation(s)
- Jason P Briner
- Department of Geology, University at Buffalo, Buffalo, NY, USA.
| | - Joshua K Cuzzone
- Department of Earth System Science, University of California Irvine, Irvine, CA, USA.,Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA
| | - Jessica A Badgeley
- Department of Earth and Space Sciences, University of Washington, Seattle, WA, USA
| | - Nicolás E Young
- Lamont-Doherty Earth Observatory, Geochemistry, Palisades, NY, USA
| | - Eric J Steig
- Department of Earth and Space Sciences, University of Washington, Seattle, WA, USA.,Department of Atmospheric Sciences, University of Washington, Seattle, WA, USA
| | - Mathieu Morlighem
- Department of Earth System Science, University of California Irvine, Irvine, CA, USA
| | | | - Gregory J Hakim
- Department of Atmospheric Sciences, University of Washington, Seattle, WA, USA
| | - Joerg M Schaefer
- Lamont-Doherty Earth Observatory, Geochemistry, Palisades, NY, USA.,Department of Earth and Environmental Sciences, Columbia University, New York, NY, USA
| | - Jesse V Johnson
- Department of Computer Science, University of Montana, Missoula, MT, USA
| | - Alia J Lesnek
- Department of Geology, University at Buffalo, Buffalo, NY, USA
| | | | - Estelle Allan
- Geotop, Université du Québec à Montréal, Montréal, Quebec, Canada
| | - Ole Bennike
- Geological Survey of Denmark and Greenland, Copenhagen, Denmark
| | | | - Beata Csatho
- Department of Geology, University at Buffalo, Buffalo, NY, USA
| | - Anne de Vernal
- Geotop, Université du Québec à Montréal, Montréal, Quebec, Canada
| | - Jacob Downs
- Department of Computer Science, University of Montana, Missoula, MT, USA
| | - Eric Larour
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA
| | - Sophie Nowicki
- Cryospheric Sciences Laboratory, Goddard Space Flight Center, NASA, Greenbelt, MD, USA
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18
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Hamlington BD, Gardner AS, Ivins E, Lenaerts JTM, Reager JT, Trossman DS, Zaron ED, Adhikari S, Arendt A, Aschwanden A, Beckley BD, Bekaert DPS, Blewitt G, Caron L, Chambers DP, Chandanpurkar HA, Christianson K, Csatho B, Cullather RI, DeConto RM, Fasullo JT, Frederikse T, Freymueller JT, Gilford DM, Girotto M, Hammond WC, Hock R, Holschuh N, Kopp RE, Landerer F, Larour E, Menemenlis D, Merrifield M, Mitrovica JX, Nerem RS, Nias IJ, Nieves V, Nowicki S, Pangaluru K, Piecuch CG, Ray RD, Rounce DR, Schlegel N, Seroussi H, Shirzaei M, Sweet WV, Velicogna I, Vinogradova N, Wahl T, Wiese DN, Willis MJ. Understanding of Contemporary Regional Sea-Level Change and the Implications for the Future. REVIEWS OF GEOPHYSICS (WASHINGTON, D.C. : 1985) 2020; 58:e2019RG000672. [PMID: 32879921 PMCID: PMC7375165 DOI: 10.1029/2019rg000672] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/01/2019] [Revised: 03/17/2020] [Accepted: 03/19/2020] [Indexed: 06/11/2023]
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.
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19
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Lofverstrom M, Fyke JG, Thayer‐Calder K, Muntjewerf L, Vizcaino M, Sacks WJ, Lipscomb WH, Otto‐Bliesner BL, Bradley SL. An Efficient Ice Sheet/Earth System Model Spin-up Procedure for CESM2-CISM2: Description, Evaluation, and Broader Applicability. JOURNAL OF ADVANCES IN MODELING EARTH SYSTEMS 2020; 12:e2019MS001984. [PMID: 32999702 PMCID: PMC7507768 DOI: 10.1029/2019ms001984] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/06/2019] [Revised: 07/02/2020] [Accepted: 07/17/2020] [Indexed: 06/11/2023]
Abstract
Spinning up a highly complex, coupled Earth system model (ESM) is a time consuming and computationally demanding exercise. For models with interactive ice sheet components, this becomes a major challenge, as ice sheets are sensitive to bidirectional feedback processes and equilibrate over glacial timescales of up to many millennia. This work describes and demonstrates a computationally tractable, iterative procedure for spinning up a contemporary, highly complex ESM that includes an interactive ice sheet component. The procedure alternates between a computationally expensive coupled configuration and a computationally cheaper configuration where the atmospheric component is replaced by a data model. By periodically regenerating atmospheric forcing consistent with the coupled system, the data atmosphere remains adequately constrained to ensure that the broader model state evolves realistically. The applicability of the method is demonstrated by spinning up the preindustrial climate in the Community Earth System Model Version 2 (CESM2), coupled to the Community Ice Sheet Model Version 2 (CISM2) over Greenland. The equilibrium climate state is similar to the control climate from a coupled simulation with a prescribed Greenland ice sheet, indicating that the iterative procedure is consistent with a traditional spin-up approach without interactive ice sheets. These results suggest that the iterative method presented here provides a faster and computationally cheaper method for spinning up a highly complex ESM, with or without interactive ice sheet components. The method described here has been used to develop the climate/ice sheet initial conditions for transient, ice sheet-enabled simulations with CESM2-CISM2 in the Coupled Model Intercomparison Project Phase 6 (CMIP6).
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Affiliation(s)
- Marcus Lofverstrom
- Department of GeosciencesUniversity of ArizonaTucsonAZUSA
- Climate and Global Dynamics LaboratoryNational Center for Atmospheric ResearchBoulderCOUSA
| | - Jeremy G. Fyke
- Associated Engineering Group Ltd.CalgaryAlbertaCanada
- Department of Atmospheric and Oceanic SciencesUniversity of Colorado BoulderBoulderCOUSA
| | | | - Laura Muntjewerf
- Department of Geoscience and Remote SensingDelft University of TechnologyDelftNetherlands
| | - Miren Vizcaino
- Department of Geoscience and Remote SensingDelft University of TechnologyDelftNetherlands
| | - William J. Sacks
- Climate and Global Dynamics LaboratoryNational Center for Atmospheric ResearchBoulderCOUSA
| | - William H. Lipscomb
- Climate and Global Dynamics LaboratoryNational Center for Atmospheric ResearchBoulderCOUSA
| | - Bette L. Otto‐Bliesner
- Climate and Global Dynamics LaboratoryNational Center for Atmospheric ResearchBoulderCOUSA
| | - Sarah L. Bradley
- Department of Geoscience and Remote SensingDelft University of TechnologyDelftNetherlands
- Department of GeographyUniversity of SheffieldSheffieldUK
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20
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Abstract
The Antarctic Ice Sheet is losing mass at an accelerating pace, and ice loss will likely continue over the coming decades and centuries. Some regions of the ice sheet may reach a tipping point, potentially leading to rates of sea level rise at least an order of magnitude larger than those observed now, owing to strong positive feedbacks in the ice-climate system. How fast and how much Antarctica will contribute to sea level remains uncertain, but multimeter sea level rise is likely for a mean global temperature increase of around 2°C above preindustrial levels on multicentennial time scales, or sooner for unmitigated scenarios.
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Affiliation(s)
- Frank Pattyn
- Laboratoire de Glaciologie, Université Libre de Bruxelles, Brussels, Belgium.
| | - Mathieu Morlighem
- Department of Earth System Science, University of California, Irvine, CA, USA
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21
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Kennicutt MC, Bromwich D, Liggett D, Njåstad B, Peck L, Rintoul SR, Ritz C, Siegert MJ, Aitken A, Brooks CM, Cassano J, Chaturvedi S, Chen D, Dodds K, Golledge NR, Le Bohec C, Leppe M, Murray A, Nath PC, Raphael MN, Rogan-Finnemore M, Schroeder DM, Talley L, Travouillon T, Vaughan DG, Wang L, Weatherwax AT, Yang H, Chown SL. Sustained Antarctic Research: A 21st Century Imperative. ACTA ACUST UNITED AC 2019. [DOI: 10.1016/j.oneear.2019.08.014] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
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22
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Larour E, Seroussi H, Adhikari S, Ivins E, Caron L, Morlighem M, Schlegel N. Slowdown in Antarctic mass loss from solid Earth and sea-level feedbacks. Science 2019; 364:science.aav7908. [PMID: 31023893 DOI: 10.1126/science.aav7908] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2018] [Accepted: 04/12/2019] [Indexed: 11/02/2022]
Abstract
Geodetic investigations of crustal motions in the Amundsen Sea sector of West Antarctica and models of ice-sheet evolution in the past 10,000 years have recently highlighted the stabilizing role of solid-Earth uplift on polar ice sheets. One critical aspect, however, that has not been assessed is the impact of short-wavelength uplift generated by the solid-Earth response to unloading over short time scales close to ice-sheet grounding lines (areas where the ice becomes afloat). Here, we present a new global simulation of Antarctic evolution at high spatiotemporal resolution that captures all solid Earth processes that affect ice sheets and show a projected negative feedback in grounding line migration of 38% for Thwaites Glacier 350 years in the future, or 26.8% reduction in corresponding sea-level contribution.
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Affiliation(s)
- E Larour
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA. .,Joint Institute for Regional Earth System Science and Engineering, University of California, Los Angeles, Los Angeles, CA, USA
| | - H Seroussi
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA
| | - S Adhikari
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA
| | - E Ivins
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA
| | - L Caron
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA
| | - M Morlighem
- Department of Earth System Science, University of California, Irvine, Croul Hall, Irvine, CA, USA
| | - N Schlegel
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA
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23
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Goelzer H, Nowicki S, Edwards T, Beckley M, Abe-Ouchi A, Aschwanden A, Calov R, Gagliardini O, Gillet-Chaulet F, Golledge NR, Gregory J, Greve R, Humbert A, Huybrechts P, Kennedy JH, Larour E, Lipscomb WH, clećh SL, Lee V, Morlighem M, Pattyn F, Payne AJ, Rodehacke C, Rückamp M, Saito F, Schlegel N, Seroussi H, Shepherd A, Sun S, van de Wal R, Ziemen FA. Design and results of the ice sheet model initialisation experiments initMIP-Greenland: an ISMIP6 intercomparison. THE CRYOSPHERE 2019; 12:1433-1460. [PMID: 32676174 PMCID: PMC7365265 DOI: 10.5194/tc-12-1433-2018] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Earlier large-scale Greenland ice sheet sea-level projections (e.g., those run during the ice2sea and SeaRISE initiatives) have shown that ice sheet initial conditions have a large effect on the projections and give rise to important uncertainties. The goal of the initMIP-Greenland intercomparison exercise is to compare, evaluate and improve the initialisation techniques used in the ice sheet modelling community and to estimate the associated uncertainties in modelled mass changes. initMIP-Greenland is the first in a series of ice sheet model intercomparison activities within ISMIP6 (the Ice Sheet Model Intercomparison Project for CMIP6), which is the primary activity within the Coupled Model Intercomparison Project - phase 6 (CMIP6) focusing on the ice sheets. Two experiments for the large-scale Greenland ice sheet have been designed to allow intercomparison between participating models of 1) the initial present-day state of the ice sheet and 2) the response in two idealised forward experiments. The forward experiments serve to evaluate the initialisation in terms of model drift (forward run without additional forcing) and in response to a large perturbation (prescribed surface mass balance anomaly), and should not be interpreted as sea-level projections. We present and discuss results that highlight the diversity of data sets, boundary conditions and initialisation techniques used in the community to generate initial states of the Greenland ice sheet. We find good agreement across the ensemble for the dynamic response to surface mass balance changes in areas where the simulated ice sheets overlap, but differences arising from the initial size of the ice sheet. The model drift in the control experiment is reduced for models that participated in earlier intercomparison exercises.
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Affiliation(s)
- Heiko Goelzer
- Utrecht University, Institute for Marine and Atmospheric Research (IMAU), Utrecht, Netherlands
- Laboratoire de Glaciologie, Université Libre de Bruxelles, Brussels, Belgium
| | | | - Tamsin Edwards
- School of Environment, Earth & Ecosystem Sciences, The Open University, Milton Keynes, United Kingdom
| | | | - Ayako Abe-Ouchi
- Atmosphere Ocean Research Institute, University of Tokyo, Kashiwa, Japan
| | | | - Reinhard Calov
- Potsdam Institute for Climate Impact Research, Potsdam, Germany
| | - Olivier Gagliardini
- Univ. Grenoble Alpes, CNRS, IRD, Grenoble INP, IGE, F-38000 Grenoble, France
| | | | - Nicholas R. Golledge
- Antarctic Research Centre, Victoria University of Wellington, Wellington, New Zealand
| | - Jonathan Gregory
- Department of Meteorology, University of Reading, Reading, United Kingdom
- Met Office Hadley Center, Exeter, United Kingdom
| | - Ralf Greve
- Institute of Low Temperature Science, Hokkaido University, Sapporo, Japan
| | - Angelika Humbert
- Alfred Wegener Institute for Polar and Marine Research, Bremerhaven, Germany
- University of Bremen, Bremen, Germany
| | | | - Joseph H. Kennedy
- Climate Change Science Institute, Oak Ridge National Laboratory, Oak Ridge, USA
- Computational Sciences and Engineering Division, Oak Ridge National Laboratory, Oak Ridge, USA
| | - Eric Larour
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, USA
| | - William H. Lipscomb
- Los Alamos National Laboratory, Los Alamos, USA
- National Center for Atmospheric Research, Boulder, USA
| | - Sébastien Le clećh
- LSCE/IPSL, Laboratoire des Sciences du Climat et de l’Environnement, CEA-CNRS-UVSQ, Gif-sur-Yvette, France
| | | | | | - Frank Pattyn
- Laboratoire de Glaciologie, Université Libre de Bruxelles, Brussels, Belgium
| | | | - Christian Rodehacke
- Alfred Wegener Institute for Polar and Marine Research, Bremerhaven, Germany
- Danish Meteorological Institute, Copenhagen, Denmark
| | - Martin Rückamp
- Alfred Wegener Institute for Polar and Marine Research, Bremerhaven, Germany
| | - Fuyuki Saito
- Japan Agency for Marine-Earth Science and Technology, Yokohama, Japan
| | - Nicole Schlegel
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, USA
| | - Helene Seroussi
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, USA
| | - Andrew Shepherd
- School of Earth and Environment, University of Leeds, United Kingdom
| | - Sainan Sun
- Laboratoire de Glaciologie, Université Libre de Bruxelles, Brussels, Belgium
| | - Roderik van de Wal
- Utrecht University, Institute for Marine and Atmospheric Research (IMAU), Utrecht, Netherlands
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24
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Revisiting Antarctic ice loss due to marine ice-cliff instability. Nature 2019; 566:58-64. [PMID: 30728522 DOI: 10.1038/s41586-019-0901-4] [Citation(s) in RCA: 162] [Impact Index Per Article: 32.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2017] [Accepted: 01/04/2019] [Indexed: 11/08/2022]
Abstract
Predictions for sea-level rise this century due to melt from Antarctica range from zero to more than one metre. The highest predictions are driven by the controversial marine ice-cliff instability (MICI) hypothesis, which assumes that coastal ice cliffs can rapidly collapse after ice shelves disintegrate, as a result of surface and sub-shelf melting caused by global warming. But MICI has not been observed in the modern era and it remains unclear whether it is required to reproduce sea-level variations in the geological past. Here we quantify ice-sheet modelling uncertainties for the original MICI study and show that the probability distributions are skewed towards lower values (under very high greenhouse gas concentrations, the most likely value is 45 centimetres). However, MICI is not required to reproduce sea-level changes due to Antarctic ice loss in the mid-Pliocene epoch, the last interglacial period or 1992-2017; without it we find that the projections agree with previous studies (all 95th percentiles are less than 43 centimetres). We conclude that previous interpretations of these MICI projections over-estimate sea-level rise this century; because the MICI hypothesis is not well constrained, confidence in projections with MICI would require a greater range of observationally constrained models of ice-shelf vulnerability and ice-cliff collapse.
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25
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High-Resolution Mass Trends of the Antarctic Ice Sheet through a Spectral Combination of Satellite Gravimetry and Radar Altimetry Observations. REMOTE SENSING 2019. [DOI: 10.3390/rs11020144] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Time-variable gravity measurements from the Gravity Recovery and Climate Experiment (GRACE) and GRACE-Follow On (GRACE-FO) missions and satellite altimetry measurements from CryoSat-2 enable independent mass balance estimates of the Earth’s glaciers and ice sheets. Both approaches vary in terms of their retrieval principles and signal-to-noise characteristics. GRACE/GRACE-FO recovers the gravity disturbance caused by changes in the mass of the entire ice sheet with a spatial resolution of 300 to 400 km. In contrast, CryoSat-2measures travel times of a radar signal reflected close to the ice sheet surface, allowing changes of the surface topography to be determined with about 5 km spatial resolution. Here, we present a method to combine observations from the both sensors, taking into account the different signal and noise characteristics of each satellite observation that are dependent on the spatial wavelength. We include uncertainties introduced by the processing and corrections, such as the choice of the re-tracking algorithm and the snow/ice volume density model for CryoSat-2, or the filtering of correlated errors and the correction for glacial-isostatic adjustment (GIA) for GRACE. We apply our method to the Antarctic ice sheet and the time period 2011–2017, in which GRACE and CryoSat-2 were simultaneously operational, obtaining a total ice mass loss of 178 ± 23 Gt yr−1. We present a map of the rate of mass change with a spatial resolution of 40 km that is evaluable across all spatial scales, and more precise than estimates based on a single satellite mission.
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Moon T, Ahlstrøm A, Goelzer H, Lipscomb W, Nowicki S. Rising Oceans Guaranteed: Arctic Land Ice Loss and Sea Level Rise. CURRENT CLIMATE CHANGE REPORTS 2018; 4:211-222. [PMID: 30956936 PMCID: PMC6428231 DOI: 10.1007/s40641-018-0107-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
PURPOSE OF REVIEW This paper reviews sea level contributions from land ice across the Arctic, including Greenland. We summarize ice loss measurement methods, ice loss mechanisms, and recent observations and projections, and highlight research advances over the last 3-5 years and remaining scientific challenges. RECENT FINDINGS Mass loss across the Arctic began to accelerate during the late twentieth century, with projections of continued loss across all future greenhouse gas emission scenarios. Recent research has improved knowledge of ice hydrology and surface processes, influences of atmospheric and oceanic changes on land ice, and boundary conditions such as subglacial topography. New computer models can also more accurately simulate glacier and ice sheet evolution. SUMMARY Rapid Arctic ice loss is underway, and future ice loss and sea level rise are guaranteed. Research continues to better understand and model physical processes and to improve projections of ice loss rates, especially after 2050.
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Affiliation(s)
- Twila Moon
- National Snow and Ice Data Center (NSIDC), Cooperative Institute for Research in Environmental Sciences (CIRES), 449 UCB, University of Colorado, Boulder, CO 80309-0449 USA
| | - Andreas Ahlstrøm
- Department of Glaciology and Climate, Geological Survey of Denmark and Greenland, Copenhagen, Denmark
| | - Heiko Goelzer
- Institute for Marine and Atmospheric Research Utrecht (IMAU), Utrecht University, Princetonplein 5, 3584 CC Utrecht, The Netherlands
- Laboratoire de Glaciologie, Université Libre de Bruxelles, Brussels, Belgium
| | - William Lipscomb
- National Center for Atmospheric Research (NCAR), Boulder, CO USA
| | - Sophie Nowicki
- NASA Goddard Space Flight Center, Greenbelt, MD 20771 USA
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Colleoni F, De Santis L, Siddoway CS, Bergamasco A, Golledge NR, Lohmann G, Passchier S, Siegert MJ. Spatio-temporal variability of processes across Antarctic ice-bed-ocean interfaces. Nat Commun 2018; 9:2289. [PMID: 29915266 PMCID: PMC6006349 DOI: 10.1038/s41467-018-04583-0] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2017] [Accepted: 05/11/2018] [Indexed: 11/23/2022] Open
Abstract
Understanding how the Antarctic ice sheet will respond to global warming relies on knowledge of how it has behaved in the past. The use of numerical models, the only means to quantitatively predict the future, is hindered by limitations to topographic data both now and in the past, and in knowledge of how subsurface oceanic, glaciological and hydrological processes interact. Incorporating the variety and interplay of such processes, operating at multiple spatio-temporal scales, is critical to modeling the Antarctic's system evolution and requires direct observations in challenging locations. As these processes do not observe disciplinary boundaries neither should our future research.
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Affiliation(s)
- Florence Colleoni
- Fondazione Centro Euro-Mediterraneo sui Cambiamenti Climatici, 40129, Bologna, Italy.
| | - Laura De Santis
- Istituto Nazionale di Oceanografia Sperimentale, 34010, Sgonico, Italy
| | | | - Andrea Bergamasco
- Centro Nazionale delle Ricerche - Istituto di Scienze Marine, 30122, Venice, Italy
| | - Nicholas R Golledge
- Antarctic Research Centre, Victoria University of Wellington, Wellington, 6140, New Zealand
- GNS Science, Avalon, Lower Hutt, 5010, New Zealand
| | - Gerrit Lohmann
- Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, 27570, Bremerhaven, Germany
- University of Bremen, 28359, Bremen, Germany
| | - Sandra Passchier
- Department of Earth and Environmental Studies, Center for Environmental and Life Sciences, Montclair State University, Montclair, NY, 07043, USA
| | - Martin J Siegert
- Grantham Institute and Department of Earth Science and Engineering, Imperial College of London, London, SW7 2AZ, UK
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Goelzer H, Robinson A, Seroussi H, van de Wal RSW. Recent Progress in Greenland Ice Sheet Modelling. CURRENT CLIMATE CHANGE REPORTS 2017; 3:291-302. [PMID: 32010550 PMCID: PMC6959375 DOI: 10.1007/s40641-017-0073-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
PURPOSE OF REVIEW This paper reviews the recent literature on numerical modelling of the dynamics of the Greenland ice sheet with the goal of providing an overview of advancements and to highlight important directions of future research. In particular, the review is focused on large-scale modelling of the ice sheet, including future projections, model parameterisations, paleo applications and coupling with models of other components of the Earth system. RECENT FINDINGS Data assimilation techniques have been used to improve the reliability of model simulations of the Greenland ice sheet dynamics, including more accurate initial states, more comprehensive use of remote sensing as well as paleo observations and inclusion of additional physical processes. SUMMARY Modellers now leverage the increasing number of high-resolution satellite and air-borne data products to initialise ice sheet models for centennial time-scale simulations, needed for policy relevant sea-level projections. Modelling long-term past and future ice sheet evolution, which requires simplified but adequate representations of the interactions with the other components of the Earth system, has seen a steady improvement. Important developments are underway to include ice sheets in climate models that may lead to routine simulation of the fully coupled Greenland ice sheet-climate system in the coming years.
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Affiliation(s)
- Heiko Goelzer
- 1Institute for Marine and Atmospheric Research Utrecht (IMAU), Utrecht University, Princetonplein 5, 3584 CC Utrecht, The Netherlands
- 2Laboratoire de Glaciologie, Université Libre de Bruxelles, Brussels, Belgium
| | - Alexander Robinson
- 3Faculty of Geology and Geoenvironment, University of Athens, 15784 Athens, Greece
- 4Universidad Complutense de Madrid, 28040 Madrid, Spain
- 5Instituto de Geociencias, UCM-CSIC, 28040 Madrid, Spain
| | - Helene Seroussi
- 6Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA USA
| | - Roderik S W van de Wal
- 1Institute for Marine and Atmospheric Research Utrecht (IMAU), Utrecht University, Princetonplein 5, 3584 CC Utrecht, The Netherlands
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