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.

scholarly journals Sea-ice and North Atlantic climate response to CO2-induced warming and cooling conditions

2006 ◽  
Vol 52 (178) ◽  
pp. 433-439 ◽  
Author(s):  
Larissa Nazarenko ◽  
Nickolai Tausnev ◽  
James Hansen
Keyword(s):  
Sea Ice ◽  
Northern Hemisphere ◽  
Surface Pressure ◽  
Climate Model ◽  
Global Climate Model ◽  
Ice Cover ◽  
The Arctic ◽  
Normal Surface ◽  
Sea Ice Extent ◽  
Polar Cell

AbstractUsing a global climate model coupled with an ocean and a sea-ice model, we compare the effects of doubling CO2 and halving CO2 on sea-ice cover and connections with the atmosphere and ocean. An overall warming in the 2 × CO2 experiment causes reduction of sea-ice extent by 15%, with maximum decrease in summer and autumn, consistent with observed seasonal sea-ice changes. The intensification of the Northern Hemisphere circulation is reflected in the positive phase of the Arctic Oscillation (AO), associated with higher-than-normal surface pressure south of about 50° N and lower-than-normal surface pressure over the high northern latitudes. Strengthening the polar cell causes enhancement of westerlies around the Arctic perimeter during winter. Cooling, in the 0.5 × CO2 experiment, leads to thicker and more extensive sea ice. In the Southern Hemisphere, the increase in ice-covered area (28%) dominates the ice-thickness increase (5%) due to open ocean to the north. In the Northern Hemisphere, sea-ice cover increases by only 8% due to the enclosed land/sea configuration, but sea ice becomes much thicker (108%). Substantial weakening of the polar cell due to increase in sea-level pressure over polar latitudes leads to a negative trend of the winter AO index. The model reproduces large year-to-year variability under both cooling and warming conditions.

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 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.

scholarly journals Composite Analysis of Winter Cyclones in a GCM: Influence on Climatological Humidity

2006 ◽  
Vol 19 (9) ◽  
pp. 1652-1672 ◽  
Author(s):  
Mike Bauer ◽  
Anthony D. Del Genio
Keyword(s):  
Water Vapor ◽  
General Circulation ◽  
Climate Model ◽  
Global Climate ◽  
Global Climate Model ◽  
Circulation Model ◽  
Cloud Properties ◽  
Frontal Zones ◽  
Goddard Institute ◽  
Ageostrophic Circulation

Abstract The role of midlatitude baroclinic cyclones in maintaining the extratropical winter distribution of water vapor in an operational global climate model is investigated. A cyclone identification and tracking algorithm is used to compare the frequency of occurrence, propagation characteristics, and composite structure of 10 winters of storms in the Goddard Institute for Space Studies general circulation model (GCM) and in two reanalysis products. Cyclones are the major dynamical source of water vapor over the extratropical oceans in the reanalyses. The GCM produces fewer, generally weaker, and slower-moving cyclones than the reanalyses and is especially deficient in storms associated with secondary cyclogenesis. Composite fields show that GCM cyclones are shallower and drier aloft than those in the reanalyses and that their vertical structure is less tilted in the frontal region because of the GCM’s weaker ageostrophic circulation. This is consistent with the GCM’s underprediction of midlatitude cirrus. The GCM deficiencies do not appear to be primarily due to parameterization errors; the model is too dry despite producing less storm precipitation than is present in the reanalyses and in an experimental satellite precipitation dataset, and the weakness and shallow structure of GCM cyclones is already present at storm onset. These shortcomings may be common to most climate GCMs that do not resolve the mesoscale structure of frontal zones, and this may account for some universal problems in climate GCM midlatitude cloud properties.

scholarly journals Northern Hemisphere storminess in the Norwegian Earth System Model (NorESM1-M)

2014 ◽  
Vol 7 (6) ◽  
pp. 8975-9015
Author(s):  
E. M. Knudsen ◽  
J. E. Walsh
Keyword(s):  
Sea Ice ◽  
Sea Level ◽  
Northern Hemisphere ◽  
Climate Model ◽  
Global Climate ◽  
Global Climate Model ◽  
System Model ◽  
High Latitudes ◽  
Earth System ◽  
Projected Changes

Abstract. Metrics of storm activity in Northern Hemisphere high- and midlatitudes are evaluated from historical output and future projections by the Norwegian Earth System Model (NorESM1-M) coupled global climate model. The European Re-Analysis Interim (ERA-Interim) and the Community Climate System Model (CCSM4), a global climate model of the same vintage as NorESM1-M, provide benchmarks for comparison. The focus is on the autumn and early winter (September through December), the period when the ongoing and projected Arctic sea ice retreat is greatest. Storm tracks derived from a vorticity-based algorithm for storm identification are reproduced well by NorESM1-M, although the tracks are somewhat better resolved in the higher-resolution ERA-Interim and CCSM4. The tracks are projected to shift polewards in the future as climate changes under the Representative Concentration Pathway (RCP) forcing scenarios. Cyclones are projected to become generally more intense in the high-latitudes, especially over the Alaskan region, although in some other areas the intensity is projected to decrease. While projected changes in track density are less coherent, there is a general tendency towards less frequent storms in midlatitudes and more frequent storms in high-latitudes, especially the Baffin Bay/Davis Strait region. Autumn precipitation is projected to increase significantly across the entire high-latitudes. Together with the projected increases in storm intensity and sea level and the loss of sea ice, this increase in precipitation implies a greater vulnerability to coastal flooding and erosion, especially in the Alaskan region. The projected changes in storm intensity and precipitation (as well as sea ice and sea level pressure) scale generally linearly with the RCP value of the forcing and with time through the 21st century.

scholarly journals Modelling the impacts of climate change on tropospheric ozone over three centuries

2011 ◽  
Vol 11 (2) ◽  
pp. 6805-6843 ◽  
Author(s):  
G. B. Hedegaard ◽  
A. Gross ◽  
J. H. Christensen ◽  
W. May ◽  
H. Skov ◽  
...  
Keyword(s):  
Climate Change ◽  
Ozone Concentration ◽  
General Circulation ◽  
Climate Model ◽  
Transport Model ◽  
Global Climate ◽  
Global Climate Model ◽  
Circulation Model ◽  
Ocean General Circulation Model ◽  
The Arctic

Abstract. The ozone chemistry over three centuries has been simulated based on climate prediction from a global climate model and constant anthropogenic emissions in order to separate out the effects on air pollution from climate change. Four decades in different centuries has been simulated using the chemistry version of the atmospheric long-range transport model; the Danish Eulerian Hemispheric Model (DEHM) forced with meteorology predicted by the ECHAM5/MPI-OM coupled Atmosphere-Ocean General Circulation Model. The largest changes in both meteorology, ozone and its precursors is found in the 21st century, however, also significant changes are found in the 22nd century. At surface level the ozone concentration is predicted to increase due to climate change in the areas where substantial amounts of ozone precursors are emitted. Elsewhere a significant decrease is predicted at the surface. In the free troposphere a general increase is found in the entire Northern Hemisphere except in the tropics, where the ozone concentration is decreasing. In the Arctic the ozone concentration will increase in the entire air column, which most likely is due to changes in transport. The change in temperature, humidity and the naturally emitted Volatile Organic Compounds (VOCs) are governing with respect to changes in ozone both in the past, present and future century.

scholarly journals The Tropical Atmospheric El Niño Signal in Satellite Precipitation Data and a Global Climate Model

2007 ◽  
Vol 20 (14) ◽  
pp. 3580-3601 ◽  
Author(s):  
Yonghua Chen ◽  
Anthony D. Del Genio ◽  
Junye Chen
Keyword(s):  
El Niño ◽  
General Circulation ◽  
Climate Model ◽  
El Nino ◽  
Global Climate ◽  
Global Climate Model ◽  
Circulation Model ◽  
Western Indian Ocean ◽  
Correlation Technique ◽  
Atmospheric Response

Abstract Aspects of the tropical atmospheric response to El Niño related to the global energy and water cycle are examined using satellite retrievals from the Tropical Rainfall Measuring Mission and the Advanced Microwave Scanning Radiometer-E and simulations from the Goddard Institute for Space Studies (GISS) general circulation model (GCM). The El Niño signal is extracted from climate fields using a linear cross-correlation technique that captures local and remote in-phase and lagged responses. Passive microwave and radar precipitation anomalies for the 1997/98 and 2002/03 El Niños and the intervening La Niña are highly correlated, but anomalies in stratiform–convective rainfall partitioning in the two datasets are not. The GISS GCM produces too much rainfall in general over ocean and too little over land. Its atmospheric response to El Niño is weaker and decays a season too early. Underestimated stratiform rainfall fraction (SRF) and convective downdraft mass flux in the GISS GCM and excessive shallow convective and low stratiform cloud result in latent heating that peaks at lower altitudes than inferred from the data. The GISS GCM also underestimates the column water vapor content throughout the Tropics, which causes it to overestimate outgoing longwave radiation. The response of both quantities to interannual Hadley circulation anomalies is too weak. The GISS GCM’s Walker circulation also exhibits a weak remote response to El Niño, especially over the Maritime Continent and western Indian Ocean. This appears to be a consequence of weak static stability due to the model’s lack of upper-level stratiform anvil heating, excessive low-level heating, and excessive dissipation due to cumulus momentum mixing. Our results suggest that parameterizations of mesoscale updrafts, convective downdrafts, and cumulus-scale pressure gradient effects on momentum transport are keys to a reasonable GISS GCM simulation of tropical interannual variability.

scholarly journals Mid-Pliocene global climate simulation with MRI-CGCM2.3: set-up and initial results of PlioMIP Experiments 1 and 2

2012 ◽  
Vol 5 (3) ◽  
pp. 793-808 ◽  
Author(s):  
Y. Kamae ◽  
H. Ueda
Keyword(s):  
General Circulation ◽  
Climate Model ◽  
Global Climate ◽  
Global Climate Model ◽  
Circulation Model ◽  
Ocean General Circulation Model ◽  
Climate Simulation ◽  
Polar Regions ◽  
The North ◽  
Set Up

Abstract. The mid-Pliocene (3.3 to 3.0 million yr ago), a globally warm period before the Quaternary, is recently attracting attention as a new target for paleoclimate modelling and data-model synthesis. This paper reports set-ups and results of experiments proposed in Pliocene Model Intercomparison Project (PlioMIP) using a global climate model, MRI-CGCM2.3. We conducted pre-industrial and mid-Pliocene runs by using the coupled atmosphere-ocean general circulation model (AOGCM) and its atmospheric component (AGCM) for the PlioMIP Experiments 2 and 1, respectively. In addition, we conducted two types of integrations in AOGCM simulation, with and without flux adjustments on sea surface. General characteristics of differences in the simulated mid-Pliocene climate relative to the pre-industrial in the three integrations are compared. In addition, patterns of predicted mid-Pliocene biomes resulting from the three climate simulations are compared in this study. Generally, difference of simulated surface climate between AGCM and AOGCM is larger than that between the two AOGCM runs, with and without flux adjustments. The simulated climate shows different pattern between AGCM and AOGCM particularly over low latitude oceans, subtropical land regions and high latitude oceans. The AOGCM simulations do not reproduce wetter environment in the subtropics relative to the present-day, which is suggested by terrestrial proxy data. The differences between the two types of AOGCM runs are small over the land, but evident over the ocean particularly in the North Atlantic and polar regions.

scholarly journals Northern Hemisphere storminess in the Norwegian Earth System Model (NorESM1-M)

2016 ◽  
Vol 9 (7) ◽  
pp. 2335-2355 ◽  
Author(s):  
Erlend M. Knudsen ◽  
John E. Walsh
Keyword(s):  
Sea Ice ◽  
Sea Level ◽  
Northern Hemisphere ◽  
Climate Model ◽  
Global Climate ◽  
Global Climate Model ◽  
System Model ◽  
High Latitudes ◽  
Earth System ◽  
Projected Changes

Abstract. Metrics of storm activity in Northern Hemisphere high and midlatitudes are evaluated from historical output and future projections by the Norwegian Earth System Model (NorESM1-M) coupled global climate model. The European Re-Analysis Interim (ERA-Interim) and the Community Climate System Model (CCSM4), a global climate model of the same vintage as NorESM1-M, provide benchmarks for comparison. The focus is on the autumn and early winter (September through December) – the period when the ongoing and projected Arctic sea ice retreat is the greatest. Storm tracks derived from a vorticity-based algorithm for storm identification are reproduced well by NorESM1-M, although the tracks are somewhat better resolved in the higher-resolution ERA-Interim and CCSM4. The tracks show indications of shifting polewards in the future as climate changes under the Representative Concentration Pathway (RCP) forcing scenarios. Cyclones are projected to become generally more intense in the high latitudes, especially over the Alaskan region, although in some other areas the intensity is projected to decrease. While projected changes in track density are less coherent, there is a general tendency towards less frequent storms in midlatitudes and more frequent storms in high latitudes, especially the Baffin Bay/Davis Strait region in September. Autumn precipitation is projected to increase significantly across the entire high latitudes. Together with the projected loss of sea ice and increases in storm intensity and sea level, this increase in precipitation implies a greater vulnerability to coastal flooding and erosion, especially in the Alaskan region. The projected changes in storm intensity and precipitation (as well as sea ice and sea level pressure) scale generally linearly with the RCP value of the forcing and with time through the 21st century.

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.

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