Offsetting effects of aerosols on Arctic and global climate in the late 20th century

Abstract. We examine the impacts of atmospheric aerosols on Arctic and global climate using a series of 20th century transient simulations from Community Climate System Model version 4 (CCSM4). We focus on the response of surface air temperature to the direct radiative forcing driven by changes in sulfate and black carbon (BC) concentrations from 1975 to 2005 and we also examine the response to changes in sulfate, BC, and organic carbon (OC) aerosols collectively. The direct forcing from sulfate dominates the aerosol climate effect. Globally averaged, simultaneous changes in all three aerosols produce a cooling trend of 0.015 K decade−1 during the period 1975–2005. In the Arctic, surface air temperature has large spatial variations in response to changes in aerosol concentrations. Over the European Arctic, aerosols induce about 0.6 K decade−1 warming, which is about 1.8 K warming over the 30-year period. This warming is triggered mainly by the reduction in sulfate and BC emissions over Europe since the 1970s and is reinforced by sea ice loss and a strengthening in atmospheric northward heat transport. Changes in sulfate concentrations account for about two thirds of the warming and BC for the remaining one third. Over the Siberian and North American Arctic, surface air temperature is likely influenced by changes in aerosol concentrations over Asia. An increase in sulfate optical depth over Asia induces a large cooling while an increase in BC over Asia causes a significant warming.

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Offsetting effects of aerosols on Arctic and global climate in the late 20th century

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-13-30929-2013 ◽

2013 ◽

Vol 13 (11) ◽

pp. 30929-30943

Author(s):

Q. Yang ◽

C. M. Bitz ◽

S. J. Doherty

Keyword(s):

20Th Century ◽

Air Temperature ◽

Radiative Forcing ◽

Global Climate ◽

Surface Air Temperature ◽

The Arctic ◽

Late 20Th Century ◽

Climate Effect ◽

Climate System Model ◽

Arctic Surface

Abstract. We examine the impacts of atmospheric aerosols on Arctic and global climate using a series of 20th century transient simulations from Community Climate System Model version 4 (CCSM4). We focus on the response of surface air temperature to the direct radiative forcing driven by changes in sulfate and black carbon (BC) concentrations from 1975 to 2005 and we also examine the response to sulfate, BC, and organic carbon aerosols varying at once. The direct forcing from sulfate dominates the aerosol climate effect. Globally averaged, all three aerosols produce a cooling trend of 0.015 K decade−1 during the period 1975–2005. In the Arctic, surface air temperature has large spatial variations in response to changes in aerosol concentrations. Over the European Arctic, aerosols induce about 0.6 K decade−1 warming which is about 1.8 K warming over the 30 yr period. This warming is triggered mainly by the reduction in sulfate and BC emissions over Europe since the 1970s and is reinforced by sea ice loss and a strengthening in atmospheric northward heat transport. Over the Siberian and North American Arctic, surface air temperature is likely influenced primarily by changes in aerosol emissions from Asia. An increase in sulfate emissions over Asia induces a large cooling while an increase in BC over Asia causes a significant warming.

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An Intraseasonal Mode Linking Wintertime Surface Air Temperature over Arctic and Eurasian Continent

Journal of Climate ◽

10.1175/jcli-d-21-0495.1 ◽

2021 ◽

pp. 1-47

Keyword(s):

Air Temperature ◽

Climate Model ◽

Global Climate ◽

Global Climate Model ◽

Surface Air Temperature ◽

Arctic Sea Ice ◽

The Arctic ◽

Free Atmosphere ◽

Temperature Anomalies ◽

Downward Longwave Radiation

Abstract Key processes associated with the leading intraseasonal variability mode of wintertime surface air temperature (SAT) over Eurasia and the Arctic region are investigated in this study. Characterized by a dipole distribution in SAT anomalies centered over north Eurasia and the Arctic, respectively, and coherent temperature anomalies vertically extending from the surface to 300hPa, this leading intraseasonal SAT mode and associated circulation have pronounced influences on global surface temperature anomalies including the East Asian winter monsoon region. By taking advantage of realistic simulations of the intraseasonal SAT mode in a global climate model, it is illustrated that temperature anomalies in the troposphere associated with the leading SAT mode are mainly due to dynamic processes, especially via the horizontal advection of winter mean temperature by intraseasonal circulation. While the cloud-radiative feedback is not critical in sustaining the temperature variability in the troposphere, it is found to play a crucial role in coupling temperature anomalies at the surface and in the free-atmosphere through anomalous surface downward longwave radiation. The variability in clouds associated with the intraseasonal SAT mode is closely linked to moisture anomalies generated by similar advective processes as for temperature anomalies. Model experiments suggest that this leading intraseasonal SAT mode can be sustained by internal atmospheric processes in the troposphere over the mid-to-high latitudes by excluding forcings from Arctic sea ice variability, tropical convective variability, and the stratospheric processes.

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EC-Earth3-AerChem, a global climate model with interactive aerosols and atmospheric chemistry participating in CMIP6

10.5194/gmd-2020-413 ◽

2020 ◽

Author(s):

Twan van Noije ◽

Tommi Bergman ◽

Philippe Le Sager ◽

Declan O'Donnell ◽

Risto Makkonen ◽

...

Keyword(s):

20Th Century ◽

Southern Hemisphere ◽

Air Temperature ◽

Atmospheric Chemistry ◽

Climate Model ◽

Global Climate ◽

Global Climate Model ◽

Surface Air Temperature ◽

Model Intercomparison ◽

Intercomparison Project

Abstract. This paper documents the global climate model EC-Earth3-AerChem, one of the members of the EC-Earth3 family of models participating in the Coupled Model Intercomparison Project phase 6 (CMIP6). EC-Earth3-AerChem has interactive aerosols and atmospheric chemistry and contributes to the Aerosols and Chemistry Model Intercomparison Project (AerChemMIP). In this paper, we give an overview of the model and describe in detail how it differs from the other EC-Earth3 configurations, and what the new features are compared to the previously documented version of the model (EC-Earth 2.4). We explain how the model was tuned and spun up under pre-industrial conditions and characterize the model's general performance on the basis of a selection of coupled simulations conducted for CMIP6. The mean energy imbalance at the top of the atmosphere in the pre-industrial control simulation is −0.10 ± 0.25 W m−2 and shows no significant drift. The corresponding mean global surface air temperature is 14.05 ± 0.16 °C, with a small drift of −0.075 ± 0.009 °C per century. The model's effective equilibrium climate sensitivity is estimated at 3.9 °C and its transient climate response at 2.1 °C. The CMIP6 historical simulation displays spurious interdecadal variability in Northern Hemisphere temperatures, resulting in a large spread among ensemble members and a tendency to underestimate observed annual surface temperature anomalies from the early 20th century onwards. The observed warming of the Southern Hemisphere is well reproduced by the model. Compared to the ERA5 reanalysis of the European Centre for Medium-Range Weather Forecasts, the ensemble mean surface air temperature climatology for 1995–2014 has an average bias of −0.86 ± 0.35 °C in the Northern Hemisphere and 1.29 ± 0.05 °C in the Southern Hemisphere. The Southern Hemisphere warm bias is largely caused by errors in shortwave cloud radiative effects over the Southern Ocean, a deficiency of many climate models. Changes in the emissions of near-term climate forcers (NTCFs) have significant climate effects from the 20th century onwards. For the SSP3-7.0 shared socio-economic pathway, the model gives a global warming at the end of the 21st century (2091–2100) of 4.9 °C above the pre-industrial mean. A 0.5 °C stronger warming is obtained for the AerChemMIP scenario with reduced emissions of NTCFs. With concurrent reductions of future methane concentrations, the warming is projected to be reduced by 0.5 °C.

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Late 20th century increase in northern Svalbard glacier-derived runoff tracked by encrusting coralline algae

10.5194/egusphere-egu2020-3053 ◽

2020 ◽

Author(s):

Steffen Hetzinger ◽

Jochen Halfar ◽

Zoltan Zajacz ◽

Marco Möller ◽

Max Wisshak

Keyword(s):

Global Warming ◽

Air Temperature ◽

Surface Air Temperature ◽

High Arctic ◽

Climate System ◽

Coralline Algae ◽

The Arctic ◽

Surface Ocean ◽

The Impact ◽

Arctic Surface

The Arctic cryosphere is changing at a rapid pace due to global warming and the large-scale changes observed in the Arctic during the past decades exert a strong influence throughout the global climate system. The warming of Arctic surface air temperatures is more than twice as large as the global average over the last two decades and recent events indicate new extremes in the Arctic climate system, e.g. for the last five years Arctic annual surface air temperature exceeded that of any year since 1900 AD. Northern Spitsbergen, Svalbard, located in the High Arctic at 80&#176;N, is a warming hotspot with an observed temperature rise of ~6&#176;C over the last three decades indicating major global warming impacts. However, even the longest available datasets on Svalbard climatic conditions do not extend beyond the 1950s, inhibiting the study of long-term natural variability before anthropogenic influence. Ongoing climate trends strongly affect the state of both glaciers and seasonal snow in Svalbard. Modeled data suggest a marked increase in glacier runoff during recent decades in northern Svalbard. However, observational data are sparse and short and the potential effects on the surface ocean are unclear. This study focuses on the ultra-high-resolution analysis of calcified coralline algal buildups growing attached to the shallow seafloor along Arctic coastlines. Analysis of these new annually-layered climate archives is based on the long-lived encrusting coralline algae Clathromorphum compactum, providing a historic perspective on recently observed changes. Here, we present a 200-year record of past surface ocean variability from Mosselbukta, Spitsbergen, northern Svalbard. By using algal Ba/Ca ratios as a proxy for past glacier-derived meltwater input, we investigate past multi-decadal-scale fluctuations in land-based freshwater contributions to the ocean surface layer. Our records, based on multiple coralline algal specimens, show a strong and statistically significant increasing trend in algal Ba/Ca ratios from the 1990s onwards, suggesting a drastic increase in land-based runoff at Mosselbukta. The drastic rate of increase is unprecedented during the last two centuries, directly capturing the impact of amplified surface air temperature warming on coastal high Arctic surface ocean environments.&#160;

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Mechanisms of Arctic Surface Air Temperature Change in Response to the Madden–Julian Oscillation

Journal of Climate ◽

10.1175/jcli-d-11-00566.1 ◽

2012 ◽

Vol 25 (17) ◽

pp. 5777-5790 ◽

Cited By ~ 94

Author(s):

Changhyun Yoo ◽

Sukyoung Lee ◽

Steven B. Feldstein

Keyword(s):

Heat Flux ◽

Air Temperature ◽

Phase 1 ◽

Surface Air Temperature ◽

The Arctic ◽

Boreal Winter ◽

Convective Heating ◽

Madden Julian Oscillation ◽

Eddy Heat Flux ◽

Arctic Surface

Abstract Using lagged composites and projections with the thermodynamic energy equation, in this study the mechanisms that drive the boreal winter Arctic surface air temperature (SAT) change associated with the Madden–Julian oscillation (MJO) are investigated. The Wheeler and Hendon MJO index, which divides the MJO into 8 phases, where phase 1 (phase 5) corresponds to reduced (enhanced) convection over the Maritime Continent and western Pacific Ocean, is used. It is shown that the more zonally localized (uniform) tropical convective heating associated with MJO phase 5 (phase 1) leads to enhanced (reduced) excitation of poleward-propagating Rossby waves, which contribute to Arctic warming (cooling). Adiabatic warming/cooling, eddy heat flux, and the subsequent change in downward infrared radiation (IR) flux are found to be important for the Arctic SAT change. The adiabatic warming/cooling initiates the Arctic SAT change, however, subsequent eddy heat flux makes a greater contribution. The resulting SAT change is further amplified by alteration in downward IR. It is shown that changes in surface sensible and latent heat fluxes oppose the contribution by the above processes.

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An Improved Parameterization for Simulating Arctic Cloud Amount in the CCSM3 Climate Model

Journal of Climate ◽

10.1175/2008jcli2299.1 ◽

2008 ◽

Vol 21 (21) ◽

pp. 5673-5687 ◽

Cited By ~ 75

Author(s):

Steve Vavrus ◽

Duane Waliser

Keyword(s):

Radiative Forcing ◽

Climate Model ◽

Global Climate ◽

Global Climate Model ◽

Cloud Amount ◽

The Arctic ◽

Climate Simulation ◽

Polar Regions ◽

Climate System Model ◽

Model Version

Abstract A simple alternative parameterization for predicting cloud fraction in the Community Climate System Model, version 3 (CCSM3) global climate model is presented. This formula, dubbed “freeezedry,” is designed to alleviate the bias of excessive low clouds during polar winter by reducing the cloud amount under very dry conditions. During winter, freezedry decreases the low cloud amount over the coldest regions in high latitudes by over 50% locally and more than 30% averaged across the Arctic. The cloud reduction causes an Arctic-wide drop of 15 W m−2 in surface cloud radiative forcing (CRF) during winter and about a 50% decrease in mean annual Arctic CRF. Consequently, wintertime surface temperatures fall by up to 4 K on land and 2–8 K over the Arctic Ocean, thus significantly reducing the model’s pronounced warm bias. Freezedry also affects CCSM3’s sensitivity to greenhouse forcing. In a transient-CO2 experiment, the model version with freezedry warms up to 20% less in the North Polar and South Polar regions (1.5- and 0.5-K-smaller warming, respectively). Paradoxically, the muted high-latitude response occurs despite a much larger increase in cloud amount with freezedry during nonsummer months (when clouds warm the surface), apparently because of the colder modern reference climate. While improving the polar climate simulation in CCSM3, freezedry has virtually no influence outside of very cold regions and has already been implemented in another climate model, the Global Environmental and Ecological Simulation of Ecological Systems, version 1 (GENESIS1). Furthermore, the simplicity of this parameterization allows it to be readily incorporated into other GCMs, many of which also suffer from excessive wintertime polar cloudiness.

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Mechanisms of Decadal Arctic Climate Variability in the Community Climate System Model, Version 2 (CCSM2)

Journal of Climate ◽

10.1175/jcli3476.1 ◽

2005 ◽

Vol 18 (17) ◽

pp. 3552-3570 ◽

Cited By ~ 39

Author(s):

Hugues Goosse ◽

Marika M. Holland

Keyword(s):

Climate Variability ◽

Air Temperature ◽

North Atlantic ◽

Surface Air Temperature ◽

System Model ◽

Arctic Climate ◽

The Arctic ◽

Community Climate System Model ◽

Climate System Model ◽

Climate Conditions

Abstract Several mechanisms have been proposed to explain natural climate variability in the Arctic. These include processes related to the influence of the North Atlantic Oscillation/Arctic Oscillation (NAO/AO), anticyclonic/cyclonic regimes, changes in the oceanic and atmospheric North Atlantic–Arctic exchange, and changes in the Atlantic meridional overturning circulation. After a brief critical review, the influence and interrelation of the above processes in a long climate integration of the Community Climate System Model, version 2 (CCSM2) are examined. The analysis is based on the time series of surface air temperature integrated northward of 70°N, which serves as a useful proxy for general Arctic climate conditions. This gives a large-scale view of the evolution of Arctic climate. It is found that changes in oceanic exchange and heat transport in the Barents Sea dominate in forcing the Arctic surface air temperature variability in CCSM2. Changes in atmospheric circulation are consistent with a wind forcing of this variability, while changes in the deep overturning circulation in the Atlantic are more weakly related in CCSM2. Over some time periods, the NAO/AO is significantly related to these changes in Arctic climate conditions. However, this is not robust over longer time scales.

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Seasonal and Regional Variation of Pan-Arctic Surface Air Temperature over the Instrumental Record*

Journal of Climate ◽

10.1175/1520-0442(2004)017<3263:sarvop>2.0.co;2 ◽

2004 ◽

Vol 17 (17) ◽

pp. 3263-3282 ◽

Cited By ~ 83

Author(s):

James E. Overland ◽

Michael C. Spillane ◽

Donald B. Percival ◽

Muyin Wang ◽

Harold O. Mofjeld

Keyword(s):

Air Temperature ◽

Regional Variation ◽

Surface Air Temperature ◽

Instrumental Record ◽

Arctic Surface

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Mechanism of Seasonal Arctic Sea Ice Evolution and Arctic Amplification

10.5194/tc-2016-69 ◽

2016 ◽

Author(s):

Kwang-Yul Kim ◽

Benjamin D. Hamlington ◽

Hanna Na ◽

Jinju Kim

Keyword(s):

Heat Flux ◽

Sea Ice ◽

Air Temperature ◽

Surface Air Temperature ◽

Longwave Radiation ◽

The Arctic ◽

Turbulent Heat ◽

Arctic Amplification ◽

Ice Melting ◽

Downward Longwave Radiation

Abstract. Sea ice melting is proposed as a primary reason for the Artic amplification, although physical mechanism of the Arctic amplification and its connection with sea ice melting is still in debate. In the present study, monthly ERA-interim reanalysis data are analyzed via cyclostationary empirical orthogonal function analysis to understand the seasonal mechanism of sea ice melting in the Arctic Ocean and the Arctic amplification. While sea ice melting is widespread over much of the perimeter of the Arctic Ocean in summer, sea ice remains to be thin in winter only in the Barents-Kara Seas. Excessive turbulent heat flux through the sea surface exposed to air due to sea ice melting warms the atmospheric column. Warmer air increases the downward longwave radiation and subsequently surface air temperature, which facilitates sea surface remains to be ice free. A 1 % reduction in sea ice concentration in winter leads to ~ 0.76 W m−2 increase in upward heat flux, ~ 0.07 K increase in 850 hPa air temperature, ~ 0.97 W m−2 increase in downward longwave radiation, and ~ 0.26 K increase in surface air temperature. This positive feedback mechanism is not clearly observed in the Laptev, East Siberian, Chukchi, and Beaufort Seas, since sea ice refreezes in late fall (November) before excessive turbulent heat flux is available for warming the atmospheric column in winter. A detailed seasonal heat budget is presented in order to understand specific differences between the Barents-Kara Seas and Laptev, East Siberian, Chukchi, and Beaufort Seas.

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Halogenated Greenhouse Gases Made Global Warming Primarily

10.21203/rs.3.rs-1230021/v1 ◽

2022 ◽

Author(s):

Qing-Bin Lu

Keyword(s):

Sea Ice ◽

Greenhouse Gases ◽

Land Surface ◽

Southern Oscillation ◽

Theoretical Calculations ◽

Global Climate ◽

Surface Air Temperature ◽

The Arctic ◽

Sea Ice Extent ◽

Snow Cover Extent

Abstract Time-series observations of global lower stratospheric temperature (GLST), global land surface air temperature (LSAT), global mean surface temperature (GMST), sea ice extent (SIE) and snow cover extent (SCE), together with observations reported in Paper I, combined with theoretical calculations of GLSTs and GMSTs, have provided strong evidence that ozone depletion and global climate changes are dominantly caused by human-made halogen-containing ozone-depleting substances (ODSs) and greenhouse gases (GHGs) respectively. Both GLST and SCE have become constant since the mid-1990s and GMST/LSAT has reached a peak since the mid-2000s, while regional continued warmings at the Arctic coasts (particularly Russia and Alaska) in winter and spring and at some areas of Antarctica are observed and can be well explained by a sea-ice-loss warming amplification mechanism. The calculated GMSTs by the parameter-free warming theory of halogenated GHGs show an excellent agreement with the observed GMSTs after the natural El Niño southern oscillation (ENSO) and volcanic effects are removed. These results provide a convincing mechanism of global climate change and will make profound changes in our understanding of atmospheric processes. This study also emphasizes the critical importance of continued international efforts in phasing out all anthropogenic halogenated ODSs and GHGs.

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