scholarly journals Dynamic climate emulators for solar geoengineering

2016 ◽  
Vol 16 (24) ◽  
pp. 15789-15799 ◽  
Author(s):  
Douglas G. MacMartin ◽  
Ben Kravitz
Keyword(s):  
Sea Ice ◽  
Northern Hemisphere ◽  
General Circulation ◽  
Circulation Model ◽  
Sea Ice Extent ◽  
Regional Effects ◽  
Temperature And Precipitation ◽  
Solar Geoengineering ◽  
Intercomparison Project ◽  
The Difference

Abstract. Climate emulators trained on existing simulations can be used to project project the climate effects that result from different possible future pathways of anthropogenic forcing, without further relying on general circulation model (GCM) simulations. We extend this idea to include different amounts of solar geoengineering in addition to different pathways of greenhouse gas concentrations, by training emulators from a multi-model ensemble of simulations from the Geoengineering Model Intercomparison Project (GeoMIP). The emulator is trained on the abrupt 4 × CO2 and a compensating solar reduction simulation (G1), and evaluated by comparing predictions against a simulated 1 % per year CO2 increase and a similarly smaller solar reduction (G2). We find reasonable agreement in most models for predicting changes in temperature and precipitation (including regional effects), and annual-mean Northern Hemisphere sea ice extent, with the difference between simulation and prediction typically being smaller than natural variability. This verifies that the linearity assumption used in constructing the emulator is sufficient for these variables over the range of forcing considered. Annual-minimum Northern Hemisphere sea ice extent is less well predicted, indicating a limit to the linearity assumption.

scholarly journals Multi-model dynamic climate emulator for solar geoengineering

2016 ◽  
Author(s):  
Douglas G. MacMartin ◽  
Ben Kravitz
Keyword(s):  
Sea Ice ◽  
Northern Hemisphere ◽  
General Circulation ◽  
Circulation Model ◽  
Nonlinear Effects ◽  
Accurate Estimate ◽  
Natural Variability ◽  
Sea Ice Extent ◽  
Temperature And Precipitation ◽  
Solar Geoengineering

Abstract. Climate emulators trained on existing simulations can be used to project the climate effects that would result from different possible future pathways of anthropogenic forcing, without relying on general circulation model (GCM) simulations for every possible pathway. We extend this idea to include different amounts of solar geoengineering in addition to different pathways of green-house gas concentrations by training emulators from a multi-model ensemble of simulations from the Geoengineering Model Intercomparison Project (GeoMIP). The emulator is trained on the abrupt 4 x CO2 and a compensating solar reduction simulation (G1), and evaluated by comparing predictions against a simulated 1 % per year CO2 increase and a similarly smaller solar reduction (G2). We find reasonable agreement in most models for predicting changes in temperature and precipitation (including regional effects), and annual-mean Northern hemisphere sea ice extent, with the difference between simulation and prediction typically smaller than natural variability. This verifies that the linearity assumption used in constructing the emulator is sufficient for these variables over the range of forcing considered. Annual-minimum Northern hemisphere sea ice extent is less-well predicted, indicating the limits of the linearity assumption. For future pathways involving relatively small forcing from solar geoengineering, the errors introduced from nonlinear effects may be smaller than the uncertainty due to natural variability, and the emulator prediction may be a more accurate estimate of the forced component of the models' response than an actual simulation would be.

The Response of Northern Hemisphere Extratropical Climate and Vegetation to Orbitally Induced Changes in Insolation during the Last Interglaciation

1995 ◽  
Vol 43 (2) ◽  
pp. 174-184 ◽  
Author(s):  
Sandy P. Harrison ◽  
John E. Kutzbach ◽  
I. Colin Prentice ◽  
Pat J. Behling ◽  
Martin T. Sykes
Keyword(s):  
Sea Ice ◽  
Northern Hemisphere ◽  
General Circulation ◽  
Vegetation Change ◽  
Regional Climate ◽  
Circulation Model ◽  
The Arctic ◽  
Sea Ice Extent ◽  
Global Vegetation ◽  
Induced Changes

AbstractThe last interglaciation (substage 5e) provides an opportunity to examine the effects of extreme orbital changes on regional climates. We have made two atmospheric general circulation model experiments: P+T+ approximated the northern hemisphere seasonality maximum near the beginning of 5e; P-T- approximated the minimum near the end of 5e. Simulated regional climate changes have been translated into biome changes using a physiologically based model of global vegetation types. Major climatic and vegetational changes were simulated for the northern hemisphere extratropics, due to radiational effects that were both amplified and modified by atmospheric circulation changes and sea-ice feedback. P+T+ showed mid-continental summers up to 8°C warmer than present. Mid-latitude winters were 2-4°C cooler than present but in the Arctic, summer warmth reduced sea-ice extent and thickness, producing winters 2-8°C warmer than present. The tundra and taiga biomes were displaced poleward, while warm-summer steppes expanded in the mid latitudes due to drought. P-T- showed summers up to 5°C cooler than present, especially in mid latitudes. Sea ice and snowpack were thicker and lasted longer; polar desert, tundra, and taiga biomes were displaced equatorward, while cool-summer steppes and semideserts expanded due to the cooling. A slight winter warming in mid latitudes, however, caused warm-temperate evergreen forests and scrub to expand poleward. Such qualitative contrasts in the direction of climate and vegetation change during 5e should be identifiable in the paleorecord.

scholarly journals Modeling Northern Hemisphere ice-sheet distribution during MIS 5 and MIS 7 glacial inceptions

2014 ◽  
Vol 10 (1) ◽  
pp. 269-291 ◽  
Author(s):  
F. Colleoni ◽  
S. Masina ◽  
A. Cherchi ◽  
A. Navarra ◽  
C. Ritz ◽  
...  
Keyword(s):  
Sea Ice ◽  
Northern Hemisphere ◽  
General Circulation ◽  
Climate Model ◽  
Ice Sheet ◽  
Circulation Model ◽  
Cold Climate ◽  
High Latitudes ◽  
The Difference ◽  
Mis 5

Abstract. The present manuscript compares Marine Isotope Stage 5 (MIS 5, 125–115 kyr BP) and MIS 7 (236–229 kyr BP) with the aim to investigate the origin of the difference in ice-sheet growth over the Northern Hemisphere high latitudes between these last two inceptions. Our approach combines a low resolution coupled atmosphere–ocean–sea-ice general circulation model and a 3-D thermo-mechanical ice-sheet model to simulate the state of the ice sheets associated with the inception climate states of MIS 5 and MIS 7. Our results show that external forcing (orbitals and GHG) and sea-ice albedo feedbacks are the main factors responsible for the difference in the land-ice initial state between MIS 5 and MIS 7 and that our cold climate model bias impacts more during a cold inception, such as MIS 7, than during a warm inception, such as MIS 5. In addition, if proper ice-elevation and albedo feedbacks are not taken into consideration, the evolution towards glacial inception is hardly simulated, especially for MIS 7. Finally, results highlight that while simulated ice volumes for MIS 5 glacial inception almost fit with paleo-reconstructions, the lack of precipitation over high latitudes, identified as a bias of our climate model, does not allow for a proper simulation of MIS 7 glacial inception.

scholarly journals Response of the Northern Hemisphere sea ice to greenhouse forcing in a global climate model

2001 ◽  
Vol 33 ◽  
pp. 513-520 ◽  
Author(s):  
Larissa Nazarenko ◽  
James Hansen ◽  
Nikolai Tausnev ◽  
Reto Ruedy
Keyword(s):  
Sea Ice ◽  
Northern Hemisphere ◽  
General Circulation ◽  
Climate Model ◽  
Global Climate ◽  
Global Climate Model ◽  
Circulation Model ◽  
High Sensitivity ◽  
Ice Cover ◽  
Sea Ice Extent

AbstractThe Q.-flux Goddard Institute of Space Studies (GISS) global climate model, in which an atmospheric general circulation model is coupled to a mixed-layer ocean with specified horizontal heat transports, is used to simulate the transient and equilibrium climate response to a gradual increase of carbon dioxide (1% per year increase of CO2 to doubled CO2). The results indicate that the current GISS model has a high sensitivity with a global annual warming of about 4°C for doubled CO2 . Enhanced warming is found at higher latitudes near sea-ice margins due to retreat of sea ice in the greenhouse experiment. Surface warming is larger in winter than in summer, in part because of the reductions in ice cover and thickness that insulate the winter atmosphere from the ocean. The annual mean reduction of sea-ice cover due to doubled CO2 is about 30% for the Northern Hemisphere. The CO2 experiment has a 70% reduction of sea-ice area and 55% thinning of ice in August in the Northern Hemisphere. Noticeable reduction of sea-ice cover has been found in both historical records and satellite observations. The largest reduction of simulated sea-ice extent occurs in summer, consistent with observations.

Seasonal Forecasts of the Pan-Arctic Sea Ice Extent Using a GCM-Based Seasonal Prediction System

2013 ◽  
Vol 26 (16) ◽  
pp. 6092-6104 ◽  
Author(s):  
Matthieu Chevallier ◽  
David Salas y Mélia ◽  
Aurore Voldoire ◽  
Michel Déqué ◽  
Gilles Garric
Keyword(s):  
Sea Ice ◽  
General Circulation ◽  
Global Climate Model ◽  
Circulation Model ◽  
Ice Cover ◽  
Arctic Sea Ice ◽  
The Arctic ◽  
Seasonal Forecasts ◽  
Sea Ice Extent ◽  
Arctic Sea

Abstract An ocean–sea ice model reconstruction spanning the period 1990–2009 is used to initialize ensemble seasonal forecasts with the Centre National de Recherches Météorologiques Coupled Global Climate Model version 5.1 (CNRM-CM5.1) coupled atmosphere–ocean general circulation model. The aim of this study is to assess the skill of fully initialized September and March pan-Arctic sea ice forecasts in terms of climatology and interannual anomalies. The predictions are initialized using “full field initialization” of each component of the system. In spite of a drift due to radiative biases in the coupled model during the melt season, the full initialization of the sea ice cover on 1 May leads to skillful forecasts of the September sea ice extent (SIE) anomalies. The skill of the prediction is also significantly high when considering anomalies of the SIE relative to the long-term linear trend. It confirms that the anomaly of spring sea ice cover in itself plays a role in preconditioning a September SIE anomaly. The skill of predictions for March SIE initialized on 1 November is also encouraging, and it can be partly attributed to persistent features of the fall sea ice cover. The present study gives insight into the current ability of state-of-the-art coupled climate systems to perform operational seasonal forecasts of the Arctic sea ice cover up to 5 months in advance.

scholarly journals High sensitivity of Bering Sea winter sea ice to winter insolation and carbon dioxide over the last 5500 years

2020 ◽  
Vol 6 (36) ◽  
pp. eaaz9588
Author(s):  
Miriam C. Jones ◽  
Max Berkelhammer ◽  
Katherine J. Keller ◽  
Kei Yoshimura ◽  
Matthew J. Wooller
Keyword(s):  
Sea Ice ◽  
Bering Sea ◽  
Radiative Forcing ◽  
General Circulation ◽  
Circulation Model ◽  
High Sensitivity ◽  
Sea Ice Extent ◽  
The North ◽  
Winter Insolation ◽  
The Bering Sea

Anomalously low winter sea ice extent and early retreat in CE 2018 and 2019 challenge previous notions that winter sea ice in the Bering Sea has been stable over the instrumental record, although long-term records remain limited. Here, we use a record of peat cellulose oxygen isotopes from St. Matthew Island along with isotope-enabled general circulation model (IsoGSM) simulations to generate a 5500-year record of Bering Sea winter sea ice extent. Results show that over the last 5500 years, sea ice in the Bering Sea decreased in response to increasing winter insolation and atmospheric CO2, suggesting that the North Pacific is highly sensitive to small changes in radiative forcing. We find that CE 2018 sea ice conditions were the lowest of the last 5500 years, and results suggest that sea ice loss may lag changes in CO2 concentrations by several decades.

scholarly journals Ice-Age Climate and Continental Ice Sheets: Some Experiments with A General Circulation Model

1984 ◽  
Vol 5 ◽  
pp. 100-105 ◽  
Author(s):  
S. Manabe ◽  
A. J. Broccoli
Keyword(s):  
North America ◽  
General Circulation Model ◽  
Northern Hemisphere ◽  
General Circulation ◽  
Ice Sheets ◽  
Ice Sheet ◽  
Circulation Model ◽  
Geological Evidence ◽  
The Difference ◽  
Continental Ice Sheets

The climatic influence of the land ice which existed 18 ka BP is investigated using a climate model developed at the Geophysical Fluid Dynamics Laboratory of the National Oceanic and Atmospheric Administration. The model consists of an atmospheric general circulation model coupled with a static mixed layer ocean model. Simulated climates are obtained from each of two versions of the model: one with the land-ice distribution of the present and the other with that of 18 ka BP.In the northern hemisphere, the difference in the distribution of sea surface temperature (SST) between the two experiments resembles the difference between the SST at 18 ka BP and at present as estimated by CLIMAP Project Members (1981). In the northern hemisphere a substantial lowering of air temperature also occurs in winter, with a less pronounced cooling during summer. The mid-tropospheric flow field is influenced by the Laurentide ice sheet and features a split jet stream straddling the ice sheet and a long wave trough along the east coast of North America. In the southern hemisphere of 18 ka BP, the ice sheet has little influence on temperature. An examination of hemispheric heat balances indicates that this is because only a small change in interhemispheric heat transport exists, as the In situ radiative compensation in the northern hemisphere counterbalances the effective reflection of solar radiation by continental ice sheets.Hydrologic changes in the model climate are also found, with statistically significant decreases in soil moisture occurring in a zone located to the south of the ice sheets in North America and Eurasia. These findings are consistent with some geological evidence of regionally drier climates from the last glacial maximum.

scholarly journals A Comparison of Two Dust Uplift Schemes within the Same General Circulation Model

2012 ◽  
Vol 2012 ◽  
pp. 1-13 ◽  
Author(s):  
Duncan Ackerley ◽  
Manoj M. Joshi ◽  
Eleanor J. Highwood ◽  
Claire L. Ryder ◽  
Mark A. J. Harrison ◽  
...  
Keyword(s):  
General Circulation ◽  
Surface Air Temperature ◽  
Circulation Model ◽  
General Circulation Models ◽  
System Modelling ◽  
Global Circulation ◽  
Temperature And Precipitation ◽  
Dust Size Distribution ◽  
West African Coast ◽  
Intercomparison Project

Aeolian dust modelling has improved significantly over the last ten years and many institutions now consistently model dust uplift, transport and deposition in general circulation models (GCMs). However, the representation of dust in GCMs is highly variable between modelling communities due to differences in the uplift schemes employed and the representation of the global circulation that subsequently leads to dust deflation. In this study two different uplift schemes are incorporated in the same GCM. This approach enables a clearer comparison of the dust uplift schemes themselves, without the added complexity of several different transport and deposition models. The global annual mean dust aerosol optical depths (at 550 nm) using two different dust uplift schemes were found to be 0.014 and 0.023—both lying within the estimates from the AeroCom project. However, the models also have appreciably different representations of the dust size distribution adjacent to the West African coast and very different deposition at various sites throughout the globe. The different dust uplift schemes were also capable of influencing the modelled circulation, surface air temperature, and precipitation despite the use of prescribed sea surface temperatures. This has important implications for the use of dust models in AMIP-style (Atmospheric Modelling Intercomparison Project) simulations and Earth-system modelling.

scholarly journals The effect of tides on dense water formation in Arctic shelf seas

Ocean Science ◽  
2011 ◽  
Vol 7 (2) ◽  
pp. 203-217 ◽  
Author(s):  
C. F. Postlethwaite ◽  
M. A. Morales Maqueda ◽  
V. le Fouest ◽  
G. R. Tattersall ◽  
J. Holt ◽  
...  
Keyword(s):  
Sea Ice ◽  
Ocean Circulation ◽  
General Circulation ◽  
Circulation Model ◽  
Salt Flux ◽  
The Arctic ◽  
Ocean Tides ◽  
Sea Ice Extent ◽  
Salt Budget ◽  
The Impact

Abstract. Ocean tides are not explicitly included in many ocean general circulation models, which will therefore omit any interactions between tides and the cryosphere. We present model simulations of the wind and buoyancy driven circulation and tides of the Barents and Kara Seas, using a 25 km × 25 km 3-D ocean circulation model coupled to a dynamic and thermodynamic sea ice model. The modeled tidal amplitudes are compared with tide gauge data and sea ice extent is compared with satellite data. Including tides in the model is found to have little impact on overall sea ice extent but is found to delay freeze up and hasten the onset of melting in tidally active coastal regions. The impact that including tides in the model has on the salt budget is investigated and found to be regionally dependent. The vertically integrated salt budget is dominated by lateral advection. This increases significantly when tides are included in the model in the Pechora Sea and around Svalbard where tides are strong. Tides increase the salt flux from sea ice by 50% in the Pechora and White Seas but have little impact elsewhere. This study suggests that the interaction between ocean tides and sea ice should not be neglected when modeling the Arctic.

Modeling a modern-like pCO2 Warm period with two versions of IPSL AOGCM

2021 ◽  
Author(s):  
Ning Tan ◽  
Camille Contoux ◽  
Gilles Ramstein ◽  
Yong Sun ◽  
Christophe Dumas ◽  
...  
Keyword(s):  
High Latitude ◽  
General Circulation ◽  
Surface Air Temperature ◽  
Circulation Model ◽  
Warm Period ◽  
Meridional Overturning Circulation ◽  
Sea Ice Extent ◽  
Intercomparison Project ◽  
Meridional Overturning ◽  
Series Of Experiments

<p>The mid-Piacenzian warm period (3.264 to 3.025 Ma) is the most recent geological period with present-like atmospheric pCO<sub>2</sub>. A specific interglacial (Marine Isotope Stage KM5c, MIS KM5c; 3.205 Ma) has been selected for the Pliocene Model Intercomparison Project phase 2 (PlioMIP 2). We carried out a series of experiments according to the design of PlioMIP2 with two versions of IPSL atmosphere–ocean coupled general circulation model (AOGCM): IPSL-CM5A and IPSL-CM5A2. Our results show that the simulated MIS KM5c climate presents enhanced warming at mid- to high latitudes when compared to the PlioMIP 1, resulting from the enhanced Atlantic Meridional Overturning Circulation caused by the high-latitude seaway changes. The sensitivity experiments, conducted with IPSL- CM5A2, show that, apart from the pCO2,  both modified orography and reduced ice sheets contribute substantially to mid- to high latitude warming in MIS KM5c. When considering the pCO2 uncertainties (+/−50 ppmv) during the Pliocene, the response of the modeled mean annual surface air temperature to changes to pCO<sub>2</sub> (+/−50 ppmv) is not symmetric, which is likely due to the nonlinear response of the cryosphere (snow cover and sea ice extent).</p>

Sign in / Sign up

Export Citation Format

Share Document