scholarly journals Insensitivity of mass loss of Icelandic Vatnajökull ice cap to solar geoengineering

2021 ◽  
Author(s):  
Chao Yue ◽  
Louise Steffensen Schmidt ◽  
Liyun Zhao ◽  
Michael Wolovick ◽  
John C. Moore
Keyword(s):  
Heat Flow ◽  
Mass Loss ◽  
Mass Balance ◽  
Stratospheric Aerosol ◽  
Model Intercomparison ◽  
Geothermal Heat ◽  
Ice Dynamics ◽  
Local Climate ◽  
Ice Cap ◽  
Intercomparison Project

Abstract. Geoengineering by stratospheric aerosol injection (SAI) may reduce the mass loss from Vatnajökull ice cap (VIC), Iceland, by slowing surface temperature rise, despite relative increases in ocean heat flux brought by the Atlantic Meridional Circulation (AMOC). Although surface mass balance (SMB) is affected by the local climate, the sea level contribution is also dependent on ice dynamics. We use the Parallel Ice Sheet Model (PISM) to estimate the VIC mass balance under the CMIP5 (Coupled Model Intercomparison Project Phase 5) RCP4.5, 8.5 and GeoMIP (Geoengineering Model Intercomparison Project) G4 SAI scenarios during the period 1982–2089. The G4 scenario is based on the RCP4.5, but with additional 5 Tg yr−1 of SO2 injection to the lower stratosphere. By 2089, G4 reduces VIC mass loss from 16 % lost under RCP4.5, to 12 %. Ice dynamics are important for ice cap loss rates, increasing mass loss for RCP4.5 and G4 by 1/4 to 1/3 compared with excluding ice dynamics, but making no difference to mass loss difference under the scenarios. We find that VIC dynamics are remarkably insensitive to climate forcing partly because of AMOC compensation to SMB and low rates of iceberg calving making ocean forcing close to negligible. But the exceptionally high geothermal heat flow under parts of the ice cap which produces correspondingly high basal melt rates means that surface forcing changes are relatively less important than for glaciers with lower geothermal heat flow.

scholarly journals GlacierMIP – A model intercomparison of global-scale glacier mass-balance models and projections

2019 ◽  
Vol 65 (251) ◽  
pp. 453-467 ◽  
Author(s):  
REGINE HOCK ◽  
ANDREW BLISS ◽  
BEN MARZEION ◽  
RIANNE H. GIESEN ◽  
YUKIKO HIRABAYASHI ◽  
...  
Keyword(s):  
Mass Loss ◽  
Mass Balance ◽  
General Circulation ◽  
General Circulation Models ◽  
Global Scale ◽  
Relative Mass ◽  
Glacier Mass Balance ◽  
Model Intercomparison ◽  
Mass Balance Models ◽  
Intercomparison Project

ABSTRACTGlobal-scale 21st-century glacier mass change projections from six published global glacier models are systematically compared as part of the Glacier Model Intercomparison Project. In total 214 projections of annual glacier mass and area forced by 25 General Circulation Models (GCMs) and four Representative Concentration Pathways (RCP) emission scenarios and aggregated into 19 glacier regions are considered. Global mass loss of all glaciers (outside the Antarctic and Greenland ice sheets) by 2100 relative to 2015 averaged over all model runs varies from 18 ± 7% (RCP2.6) to 36 ± 11% (RCP8.5) corresponding to 94 ± 25 and 200 ± 44 mm sea-level equivalent (SLE), respectively. Regional relative mass changes by 2100 correlate linearly with relative area changes. For RCP8.5 three models project global rates of mass loss (multi-GCM means) of >3 mm SLE per year towards the end of the century. Projections vary considerably between regions, and also among the glacier models. Global glacier mass changes per degree global air temperature rise tend to increase with more pronounced warming indicating that mass-balance sensitivities to temperature change are not constant. Differences in glacier mass projections among the models are attributed to differences in model physics, calibration and downscaling procedures, initial ice volumes and varying ensembles of forcing GCMs.

scholarly journals The Model Intercomparison Project on the climatic response to Volcanic forcing (VolMIP): Experimental design and forcing input data

2016 ◽  
Author(s):  
Davide Zanchettin ◽  
Myriam Khodri ◽  
Claudia Timmreck ◽  
Matthew Toohey ◽  
Anja Schmidt ◽  
...  
Keyword(s):  
Climate Models ◽  
Climate Model ◽  
Initial Conditions ◽  
Volcanic Eruptions ◽  
Stratospheric Aerosol ◽  
Aerosol Layer ◽  
Model Intercomparison ◽  
Climatic Response ◽  
Volcanic Forcing ◽  
Intercomparison Project

Abstract. The enhancement of the stratospheric aerosol layer by volcanic eruptions induces a complex set of responses causing global and regional climate effects on a broad range of timescales. Uncertainties exist regarding the climatic response to strong volcanic forcing identified in coupled climate simulations that contributed to the fifth phase of the Climate Model Intercomparison Project (CMIP5). In order to better understand the sources of these model diversities, the model intercomparison project on the climate response to volcanic forcing (VolMIP) has defined a coordinated set of idealized volcanic perturbation experiments to be carried out in alignment with the CMIP6 protocol. VolMIP provides a common stratospheric aerosol dataset for each experiment to eliminate differences in the applied volcanic forcing, and defines a set of initial conditions to determine how internal climate variability contributes to determining the response. VolMIP will assess to what extent volcanically-forced responses of the coupled ocean-atmosphere system are robustly simulated by state-of-the-art coupled climate models and identify the causes that limit robust simulated behavior, especially differences in the treatment of physical processes. This paper illustrates the design of the idealized volcanic perturbation experiments in the VolMIP protocol and describes the common aerosol forcing input datasets to be used.

scholarly journals A new Geoengineering Model Intercomparison Project (GeoMIP) experiment designed for climate and chemistry models

2014 ◽  
Vol 7 (4) ◽  
pp. 5447-5464 ◽  
Author(s):  
S. Tilmes ◽  
M. J. Mills ◽  
U. Niemeier ◽  
H. Schmidt ◽  
A. Robock ◽  
...  
Keyword(s):  
Model Comparison ◽  
Stratospheric Aerosol ◽  
Atmospheric Composition ◽  
Model Intercomparison ◽  
Data Set ◽  
Aerosol Forcing ◽  
Input Dataset ◽  
Intercomparison Project ◽  
Total Burden ◽  
The Impact

Abstract. A new Geoengineering Model Intercomparison Project (GeoMIP) experiment "G4 specified stratospheric aerosols" (short name: G4SSA) is proposed to investigate the impact of stratospheric aerosol geoengineering on atmospheric composition, climate, and the environment. In contrast to the earlier G4 GeoMIP experiment, which requires an emission of sulphur dioxide (SO2) into the model, a prescribed aerosol forcing file is provided to the community, to be consistently applied to future model experiments between 2020 and 2100. This stratospheric aerosol distribution, with a total burden of about 2 Tg S has been derived using the ECHAM5-HAM microphysical model, based on a continuous annual tropical emission of 8 Tg SO2 year−1. A ramp-up of geoengineering in 2020 and a ramp-down in 2070 over a period of two years are included in the distribution, while a background aerosol burden should be used for the last 3 decades of the experiment. The performance of this experiment using climate and chemistry models in a multi-model comparison framework will allow us to better understand the significance of the impact of geoengineering and the abrupt termination after 50 years on climate and composition of the atmosphere in a changing environment. The zonal and monthly mean stratospheric aerosol input dataset is available at https://www2.acd.ucar.edu/gcm/geomip-g4-specified-stratospheric-aerosol-data-set.

scholarly journals Global streamflow and flood response to stratospheric aerosol geoengineering

2018 ◽  
Author(s):  
Liren Wei ◽  
Duoying Ji ◽  
Chiyuan Miao ◽  
John C. Moore
Keyword(s):  
Return Period ◽  
Flood Risk ◽  
Large Scale ◽  
Hydrological Cycle ◽  
Stratospheric Aerosol ◽  
Model Intercomparison ◽  
Geographic Pattern ◽  
Solar Geoengineering ◽  
Intercomparison Project ◽  
Future Warming

Abstract. Flood risk is projected to increase under projections of future warming climates due to an enhanced hydrological cycle. Solar geoengineering is known to reduce precipitation and slowdown the hydrological cycle, and may be therefore be expected to offset increased flood risk. We examine this hypothesis using streamflow and river discharge responses to the representative concentration pathway RCP4.5 and Geoengineering Model Intercomparison Project (GeoMIP) G4 experiments. We also calculate changes in 30, 50, 100-year flood return periods relative to the historical (1960–1999) period under the RCP4.5 and G4 scenarios. Similar spatial patterns are produced for each return period, although those under G4 are closer to historical values than under RCP4.5. Under G4 generally lower streamflows are produced on the western sides of Eurasia and North America, with higher flows on their eastern sides. In the southern hemisphere northern parts of the land masses have lower streamflow under G4, and southern parts increases relative to RCP4.5. So in general solar geoengineering does appear to reduce flood risk in most regions, but the relative effects are largely determined by this large scale geographic pattern. Both streamflow and return period show increased drying of the Amazon under both RCP4.5 and G4 scenarios, with more drying under G4.

scholarly journals Global streamflow and flood response to stratospheric aerosol geoengineering

2018 ◽  
Vol 18 (21) ◽  
pp. 16033-16050 ◽  
Author(s):  
Liren Wei ◽  
Duoying Ji ◽  
Chiyuan Miao ◽  
Helene Muri ◽  
John C. Moore
Keyword(s):  
Return Period ◽  
Flood Risk ◽  
Large Scale ◽  
Hydrological Cycle ◽  
Stratospheric Aerosol ◽  
Model Intercomparison ◽  
Geographic Pattern ◽  
Solar Geoengineering ◽  
Intercomparison Project ◽  
Future Warming

Abstract. Flood risk is projected to increase under future warming climates due to an enhanced hydrological cycle. Solar geoengineering is known to reduce precipitation and slow down the hydrological cycle and may therefore be expected to offset increased flood risk. We examine this hypothesis using streamflow and river discharge responses to Representative Concentration Pathway 4.5 (RCP4.5) and the Geoengineering Model Intercomparison Project (GeoMIP) G4 scenarios. Compared with RCP4.5, streamflow on the western sides of Eurasia and North America is increased under G4, while the eastern sides see a decrease. In the Southern Hemisphere, the northern parts of landmasses have lower streamflow under G4, and streamflow of southern parts increases relative to RCP4.5. We furthermore calculate changes in 30-, 50-, and 100-year flood return periods relative to the historical (1960–1999) period under the RCP4.5 and G4 scenarios. Similar spatial patterns are produced for each return period, although those under G4 are closer to historical values than under RCP4.5. Hence, in general, solar geoengineering does appear to reduce flood risk in most regions, but the overall effects are largely determined by this large-scale geographic pattern. Although G4 stratospheric aerosol geoengineering ameliorates the Amazon drying under RCP4.5, with a weak increase in soil moisture, the decreased runoff and streamflow leads to an increased flood return period under G4 compared with RCP4.5.

scholarly journals Temperature profiles for the barnes ice cap surge zone

1977 ◽  
Vol 18 (80) ◽  
pp. 391-405 ◽  
Author(s):  
D. F. Classen
Keyword(s):  
Heat Flow ◽  
Flow Line ◽  
Temperature Measurements ◽  
Temperature Profiles ◽  
Baffin Island ◽  
Geothermal Heat ◽  
Ice Cap ◽  
Marginal Areas ◽  
Thermal Drilling

AbstractThermal drilling and deep ice-temperature measurements along a flow line in a surge area of the Barnes Ice Cap, Baffin Island, N.W.T., Canada revealed a layer of basal temperate ice 30 m thick. Marginal areas were determined to be frozen to bedrock and geothermal heat flow estimated to be 1.02 μcal/cm2s (42 mW/m2).

scholarly journals The Interactive Stratospheric Aerosol Model Intercomparison Project (ISA-MIP): motivation and experimental design

2018 ◽  
Vol 11 (7) ◽  
pp. 2581-2608 ◽  
Author(s):  
Claudia Timmreck ◽  
Graham W. Mann ◽  
Valentina Aquila ◽  
Rene Hommel ◽  
Lindsay A. Lee ◽  
...  
Keyword(s):  
Radiative Forcing ◽  
Volcanic Eruptions ◽  
Stratospheric Aerosol ◽  
Transport Processes ◽  
Aerosol Layer ◽  
Model Intercomparison ◽  
Aerosol Model ◽  
Model Experiments ◽  
Aerosol Forcing ◽  
Intercomparison Project

Abstract. The Stratospheric Sulfur and its Role in Climate (SSiRC) Interactive Stratospheric Aerosol Model Intercomparison Project (ISA-MIP) explores uncertainties in the processes that connect volcanic emission of sulfur gas species and the radiative forcing associated with the resulting enhancement of the stratospheric aerosol layer. The central aim of ISA-MIP is to constrain and improve interactive stratospheric aerosol models and reduce uncertainties in the stratospheric aerosol forcing by comparing results of standardized model experiments with a range of observations. In this paper we present four co-ordinated inter-model experiments designed to investigate key processes which influence the formation and temporal development of stratospheric aerosol in different time periods of the observational record. The Background (BG) experiment will focus on microphysics and transport processes under volcanically quiescent conditions, when the stratospheric aerosol is controlled by the transport of aerosols and their precursors from the troposphere to the stratosphere. The Transient Aerosol Record (TAR) experiment will explore the role of small- to moderate-magnitude volcanic eruptions, anthropogenic sulfur emissions, and transport processes over the period 1998–2012 and their role in the warming hiatus. Two further experiments will investigate the stratospheric sulfate aerosol evolution after major volcanic eruptions. The Historical Eruptions SO2 Emission Assessment (HErSEA) experiment will focus on the uncertainty in the initial emission of recent large-magnitude volcanic eruptions, while the Pinatubo Emulation in Multiple models (PoEMS) experiment will provide a comprehensive uncertainty analysis of the radiative forcing from the 1991 Mt Pinatubo eruption.

scholarly journals Greenland high-elevation mass balance: inference and implication of reference period (1961–90) imbalance

2015 ◽  
Vol 56 (70) ◽  
pp. 105-117 ◽  
Author(s):  
William Colgan ◽  
Jason E. Box ◽  
Morten L. Andersen ◽  
Xavier Fettweis ◽  
Beáta Csathó ◽  
...  
Keyword(s):  
Mass Loss ◽  
Mass Balance ◽  
Greenland Ice Sheet ◽  
Mass Gain ◽  
High Elevation ◽  
Reference Period ◽  
Input Output ◽  
Specific Mass ◽  
Ice Dynamics ◽  
Dynamic Mass

AbstractWe revisit the input–output mass budget of the high-elevation region of the Greenland ice sheet evaluated by the Program for Arctic Regional Climate Assessment (PARCA). Our revised reference period (1961–90) mass balance of 54±48 Gt a–1 is substantially greater than the 0±21 Gt a–1 assessed by PARCA, but consistent with a recent, fully independent, input–output estimate of high-elevation mass balance (41±61 Gt a–1). Together these estimates infer a reference period high-elevation specific mass balance of 4.8±5.4 cm w.e. a–1. The probability density function (PDF) associated with this combined input–output estimate infers an 81% likelihood of high-elevation specific mass balance being positive (>0 cm w.e. a–1) during the reference period, and a 70% likelihood that specific balance was >2 cm w.e. a–1. Given that reference period accumulation is characteristic of centurial and millennial means, and that in situ mass-balance observations exhibit a dependence on surface slope rather than surface mass balance, we suggest that millennial-scale ice dynamics are the primary driver of subtle reference period high-elevation mass gain. Failure to acknowledge subtle reference period dynamic mass gain can result in underestimating recent dynamic mass loss by ~17%, and recent total Greenland mass loss by ~7%.

scholarly journals Response of the ice cap Hardangerjøkulen in southern Norway to the 20th and 21st century climates

2009 ◽  
Vol 3 (3) ◽  
pp. 947-993 ◽  
Author(s):  
R. H. Giesen ◽  
J. Oerlemans
Keyword(s):  
Mass Balance ◽  
21St Century ◽  
Meteorological Data ◽  
Coupled Model ◽  
Ice Dynamics ◽  
Change Models ◽  
Ice Cap ◽  
Glacier Length ◽  
Length Changes ◽  
Southern Norway

Abstract. Glacier mass balance changes lead to geometry changes and vice versa. To include this interdependence in the response of glaciers to climate change, models should include an interactive scheme coupling mass balance and ice dynamics. In this study, we couple a spatially distributed mass balance model to a two-dimensional ice-flow model and apply this coupled model to the ice cap Hardangerjøkulen in southern Norway. The available glacio-meteorological records, mass balance and glacier length change measurements were utilized for model calibration and validation. Driven with meteorological data from nearby synoptic weather stations, the coupled model realistically simulated the observed mass balance and glacier length changes during the 20th century. The mean climate for the period 1961–1990, computed from local meteorological data, was used as a basis to prescribe climate projections for the 21st century at Hardangerjøkulen. For a projected temperature increase of 3°C from 1961–1990 to 2071–2100, the modelled net mass balance soon becomes negative at all altitudes and Hardangerjøkulen disappears around the year 2100. The projected changes in the other meteorological variables could at most partly compensate for the effect of the projected warming.

scholarly journals The GRISLI-LSCE contribution to the Ice Sheet Model Intercomparison Project for phase 6 of the Coupled Model Intercomparison Project (ISMIP6) – Part 1: Projections of the Greenland ice sheet evolution by the end of the 21st century

2021 ◽  
Vol 15 (2) ◽  
pp. 1015-1030 ◽  
Author(s):  
Aurélien Quiquet ◽  
Christophe Dumas
Keyword(s):  
Mass Loss ◽  
Sea Level Rise ◽  
Sea Level ◽  
Ice Sheet ◽  
Coupled Model ◽  
Greenland Ice Sheet ◽  
Model Intercomparison ◽  
The Future ◽  
Intercomparison Project ◽  
Global Sea Level

Abstract. Polar amplification will result in amplified temperature changes in the Arctic with respect to the rest of the globe, making the Greenland ice sheet particularly vulnerable to global warming. While the ice sheet has been showing an increased mass loss in the past decades, its contribution to global sea level rise in the future is of primary importance since it is at present the largest single-source contribution after the thermosteric contribution. The question of the fate of the Greenland and Antarctic ice sheets for the next century has recently gathered various ice sheet models in a common framework within the Ice Sheet Model Intercomparison Project for the Coupled Model Intercomparison Project – phase 6 (ISMIP6). While in a companion paper we present the GRISLI-LSCE (Grenoble Ice Sheet and Land Ice model of the Laboratoire des Sciences du Climat et de l'Environnement) contribution to ISMIP6-Antarctica, we present here the GRISLI-LSCE contribution to ISMIP6-Greenland. We show an important spread in the simulated Greenland ice loss in the future depending on the climate forcing used. The contribution of the ice sheet to global sea level rise in 2100 can thus be from as low as 20 mm sea level equivalent (SLE) to as high as 160 mm SLE. Amongst the models tested in ISMIP6, the Coupled Model Intercomparison Project – phase 6 (CMIP6) models produce larger ice sheet retreat than their CMIP5 counterparts. Low-emission scenarios in the future drastically reduce the ice mass loss. The oceanic forcing contributes to about 10 mm SLE in 2100 in our simulations. In addition, the dynamical contribution to ice thickness change is small compared to the impact of surface mass balance. This suggests that mass loss is mostly driven by atmospheric warming and associated ablation at the ice sheet margin. With additional sensitivity experiments we also show that the spread in mass loss is only weakly affected by the choice of the ice sheet model mechanical parameters.

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