Will marine dimethylsulfide emissions amplify or alleviate global warming? A model study

2004 ◽  
Vol 61 (5) ◽  
pp. 826-835 ◽  
Author(s):  
Laurent Bopp ◽  
Olivier Boucher ◽  
Olivier Aumont ◽  
Sauveur Belviso ◽  
Jean-Louis Dufresne ◽  
...  
Keyword(s):  
Global Warming ◽  
Radiative Forcing ◽  
Sulfur Compound ◽  
Cloud Condensation Nuclei ◽  
Regional Climate ◽  
Climate Feedback ◽  
Model Study ◽  
Radiative Impact ◽  
Radiative Perturbation ◽  
First Time

Dimethylsulfide (DMS) is the most abundant volatile sulfur compound at the sea surface and has a strong marine phytoplanktonic origin. Once outgased into the atmosphere, it contributes to the formation of sulfate aerosol particles that affect the radiative budget as precursors of cloud condensation nuclei (CCN). It has been postulated that climate may be partly modulated by variations in DMS production. We test this hypothesis in the context of anthro pogenic climate change and present here, modelled for the first time, an estimate of the radiative impact resulting from changes in DMS air–sea fluxes caused by global warming. At 2× CO2, our model estimates a small increase (3%) in the global DMS flux to the atmosphere but with large spatial heterogeneities (from –15% to 30%). The radiative perturbation resulting from the DMS-induced change in cloud albedo is estimated to be –0.05 W·m–2, which represents only a small negative climate feedback on global warming. However, there are large regional changes, such as a perturbation of up to –1.5 W·m–2 in summer between 40°S and 50°S, that can impact the regional climate. In the Southern Ocean, the radiative impact resulting from changes in the DMS cycle may partly alleviate the radiative forcing resulting from anthropogenic CO2.

scholarly journals Time-Varying Climate Sensitivity from Regional Feedbacks

2013 ◽  
Vol 26 (13) ◽  
pp. 4518-4534 ◽  
Author(s):  
Kyle C. Armour ◽  
Cecilia M. Bitz ◽  
Gerard H. Roe
Keyword(s):  
Surface Temperature ◽  
Climate Sensitivity ◽  
Time Variation ◽  
Radiative Forcing ◽  
Global Climate ◽  
Regional Climate ◽  
Climate Feedback ◽  
Climate Feedbacks ◽  
Geographic Pattern ◽  
Surface Warming

Abstract The sensitivity of global climate with respect to forcing is generally described in terms of the global climate feedback—the global radiative response per degree of global annual mean surface temperature change. While the global climate feedback is often assumed to be constant, its value—diagnosed from global climate models—shows substantial time variation under transient warming. Here a reformulation of the global climate feedback in terms of its contributions from regional climate feedbacks is proposed, providing a clear physical insight into this behavior. Using (i) a state-of-the-art global climate model and (ii) a low-order energy balance model, it is shown that the global climate feedback is fundamentally linked to the geographic pattern of regional climate feedbacks and the geographic pattern of surface warming at any given time. Time variation of the global climate feedback arises naturally when the pattern of surface warming evolves, actuating feedbacks of different strengths in different regions. This result has substantial implications for the ability to constrain future climate changes from observations of past and present climate states. The regional climate feedbacks formulation also reveals fundamental biases in a widely used method for diagnosing climate sensitivity, feedbacks, and radiative forcing—the regression of the global top-of-atmosphere radiation flux on global surface temperature. Further, it suggests a clear mechanism for the “efficacies” of both ocean heat uptake and radiative forcing.

scholarly journals Indirect radiative forcing by ion-mediated nucleation of aerosol

2012 ◽  
Vol 12 (23) ◽  
pp. 11451-11463 ◽  
Author(s):  
F. Yu ◽  
G. Luo ◽  
X. Liu ◽  
R. C. Easter ◽  
X. Ma ◽  
...  
Keyword(s):  
Radiative Forcing ◽  
Climate Model ◽  
Cloud Condensation Nuclei ◽  
Spatial Variations ◽  
Climate Feedback ◽  
Formation Mechanisms ◽  
Clear Understanding ◽  
Liquid Water Path ◽  
Cloud Forcing ◽  
Indirect Radiative Forcing

Abstract. A clear understanding of particle formation mechanisms is critical for assessing aerosol indirect radiative forcing and associated climate feedback processes. Recent studies reveal the importance of ion-mediated nucleation (IMN) in generating new particles and cloud condensation nuclei (CCN) in the atmosphere. Here we implement the IMN scheme into the Community Atmosphere Model version 5 (CAM5). Our simulations show that, compared to globally averaged results based on H2SO4-H2O binary homogeneous nucleation (BHN), the presence of ionization (i.e., IMN) halves H2SO4 column burden, but increases the column integrated nucleation rate by around one order of magnitude, total particle number burden by a factor of ~3, CCN burden by ~10% (at 0.2% supersaturation) to 65% (at 1.0% supersaturation), and cloud droplet number burden by ~18%. Compared to BHN, IMN increases cloud liquid water path by 7.5%, decreases precipitation by 1.1%, and increases total cloud cover by 1.9%. This leads to an increase of total shortwave cloud radiative forcing (SWCF) by 3.67 W m−2 (more negative) and longwave cloud forcing by 1.78 W m−2 (more positive), with large spatial variations. The effect of ionization on SWCF derived from this study (3.67 W m−2) is a factor of ~3 higher that of a previous study (1.15 W m−2) based on a different ion nucleation scheme and climate model. Based on the present CAM5 simulation, the 5-yr mean impacts of solar cycle induced changes in ionization rates on CCN and cloud forcing are small (~−0.02 W m−2) but have larger inter-annual (from −0.18 to 0.17 W m−2) and spatial variations.

scholarly journals The Nonlinear and Nonlocal Nature of Climate Feedbacks

2013 ◽  
Vol 26 (21) ◽  
pp. 8289-8304 ◽  
Author(s):  
Nicole Feldl ◽  
Gerard H. Roe
Keyword(s):  
Radiative Forcing ◽  
Global Climate ◽  
Regional Climate ◽  
Critical Role ◽  
Nonlinear Effects ◽  
Climate Feedback ◽  
Climate Response ◽  
Positive Feedbacks ◽  
Local Climate ◽  
Two Factors

Abstract The climate feedback framework partitions the radiative response to climate forcing into contributions from individual atmospheric processes. The goal of this study is to understand the closure of the energy budget in as much detail and precision as possible, within as clean an experimental setup as possible. Radiative kernels and radiative forcing are diagnosed for an aquaplanet simulation under perpetual equinox conditions. The role of the meridional structure of feedbacks, heat transport, and nonlinearities in controlling the local climate response is characterized. Results display a combination of positive subtropical feedbacks and polar amplified warming. These two factors imply a critical role for transport and nonlinear effects, with the latter acting to substantially reduce global climate sensitivity. At the hemispheric scale, a rich picture emerges: anomalous divergence of heat flux away from positive feedbacks in the subtropics; nonlinear interactions among and within clear-sky feedbacks, which reinforce the pattern of tropical cooling and high-latitude warming tendencies; and strong ice-line feedbacks that drive further amplification of polar warming. These results have implications for regional climate predictability, by providing an indication of how spatial patterns in feedbacks combine to affect both the local and nonlocal climate response, and how constraining uncertainty in those feedbacks may constrain the climate response.

scholarly journals Regional Climate Responses in East Asia to the Black Carbon Aerosol Direct Effects from India and China in Summer

2020 ◽  
Vol 33 (22) ◽  
pp. 9783-9800 ◽  
Author(s):  
Huimin Chen ◽  
Bingliang Zhuang ◽  
Jane Liu ◽  
Shu Li ◽  
Tijian Wang ◽  
...  
Keyword(s):  
East Asia ◽  
Black Carbon ◽  
Radiative Forcing ◽  
Regional Climate ◽  
Cloud Amount ◽  
Climate Feedback ◽  
Direct Effects ◽  
Aerosol Loading ◽  
Highly Nonlinear ◽  
Climate Responses

AbstractBlack carbon (BC) aerosol is a significant and short-lived climate forcing factor. Here, the direct effects of BC emissions from India (IDBC) and China (CNBC) are investigated in East Asia during summer using the state-of-the-art regional climate model RegCM4. In summer, IDBC and CNBC account for approximately 30% and 46% of the total BC emissions in Asia, respectively. The total BC column burden from the two countries and corresponding TOA effective radiative forcing are 1.58 mg m−2 and +1.87 W m−2 in East Asia, respectively. The regional air temperature increases over 0.3 K at maximum and precipitation decreases 0.028 mm day−1 on average. Individually, IDBC and CNBC each can bring about rather different effects on regional climate. IDBC can result in a cooling perturbation accompanied by a substantially increased cloud amount and scattering aerosol loading, resulting in a complex response in the regional precipitation, while CNBC can lead to regional warming, and further induce a local flood in northern China or drought in southern China depending on the opposite but significant circulation anomalies. CNBC plays a dominant role in modulating the regional climate over East Asia due to its higher magnitude, wider coverage, and stronger climate feedback. The direct effect of the total BC from both countries is not a linear combination of that of IDBC and CNBC individually, suggesting that the regional climate responses are highly nonlinear to the emission intensity or aerosol loading, which may be greatly related to the influences of the perturbed atmospheric circulations and climate feedback.

scholarly journals Trends and source apportionment of aerosols in Europe during 1980–2018

2019 ◽  
Author(s):  
Yang Yang ◽  
Sijia Lou ◽  
Hailong Wang ◽  
Pinya Wang ◽  
Hong Liao
Keyword(s):  
Radiative Forcing ◽  
Regional Climate ◽  
Regional Climate Change ◽  
Comparable Rate ◽  
Near Surface ◽  
Source Regions ◽  
Community Atmosphere Model ◽  
Radiative Impact ◽  
Local Emissions ◽  
Aerosol Source

Abstract. Aerosols have significantly affected health, environment and climate in Europe. Aerosol concentrations have been declining since 1980s in Europe, mainly owing to the reduction of local aerosol and precursor emissions. Emissions from other source regions of the world, which have been changing rapidly as well, may also perturb the historical and future trends of aerosols and change their radiative impact in Europe. This study examines trends of aerosols in Europe during 1980–2018 and quantify contributions from sixteen source regions using the Community Atmosphere Model version 5 with an Explicit Aerosol Source Tagging technique (CAM5-EAST). The simulated near-surface total mass concentration of sulfate, black carbon and primary organic carbon had a 62 % decrease during 1980–2018, of which the majority was contributed by reductions of local emissions in Europe and 8 %–9 % was induced by the decrease in emissions from Russia–Belarus–Ukraine. With the decreases in the fractional contribution of local emissions, aerosols transported from other source regions are increasingly important to air quality in Europe. During 1980–2018, the decrease in sulfate loading leads to a warming effect of 2.0 W m−2 in Europe, with 12 % coming from changes in non-European sources, especially from North America and Russia–Belarus–Ukraine. According to the Shared Socioeconomic Pathways (SSP) scenarios, contributions to the sulfate radiative forcing over Europe from both European local emissions and non-European emissions would decrease at a comparable rate in the next three decades, suggesting that future changes in non-European emissions are as important as European emissions in causing possible regional climate change associated with aerosols in Europe.

scholarly journals The Atmospheric Pathway of the Cloud-Radiative Impact on the Circulation Response to Global Warming: Important and Uncertain

2019 ◽  
Vol 32 (10) ◽  
pp. 3051-3067 ◽  
Author(s):  
Aiko Voigt ◽  
Nicole Albern ◽  
Georgios Papavasileiou
Keyword(s):  
Global Warming ◽  
Climate Models ◽  
Global Climate ◽  
Regional Climate ◽  
Regional Climate Change ◽  
Global Climate Models ◽  
Radiative Heating ◽  
Substantial Part ◽  
Radiative Impact ◽  
High Level

Abstract Previous work showed that the poleward expansion of the annual-mean zonal-mean atmospheric circulation in response to global warming is strongly modulated by changes in clouds and their radiative heating of the surface and atmosphere. Here, a hierarchy and an ensemble of global climate models are used to study the circulation impact of changes in atmospheric cloud-radiative heating in the absence of changes in sea surface temperature (SST), which is referred to as the atmospheric pathway of the cloud-radiative impact. For the MPI-ESM model, the atmospheric pathway is responsible for about half of the total cloud-radiative impact, and in fact half of the total circulation response. Changes in atmospheric cloud-radiative heating are substantial in both the lower and upper troposphere. However, because SST is prescribed the atmospheric pathway is dominated by changes in upper-tropospheric cloud-radiative heating, which in large part results from the upward shift of high-level clouds. The poleward circulation expansion via the atmospheric pathway and changes in upper-tropospheric cloud-radiative heating are qualitatively robust across three global models, yet their magnitudes vary by a factor of 3. A substantial part of these magnitude differences are related to the upper-tropospheric radiative heating by high-level clouds in the present-day climate. A comparison with observations highlights the model deficits in representing the radiative heating by high-level clouds and indicates that reducing these deficits can contribute to improved predictions of regional climate change.

scholarly journals Trends and source apportionment of aerosols in Europe during 1980–2018

2020 ◽  
Vol 20 (4) ◽  
pp. 2579-2590 ◽  
Author(s):  
Yang Yang ◽  
Sijia Lou ◽  
Hailong Wang ◽  
Pinya Wang ◽  
Hong Liao
Keyword(s):  
Radiative Forcing ◽  
Regional Climate ◽  
Regional Climate Change ◽  
Comparable Rate ◽  
Near Surface ◽  
Source Regions ◽  
Community Atmosphere Model ◽  
Radiative Impact ◽  
Local Emissions ◽  
Aerosol Source

Abstract. Aerosols have significantly affected health, environment, and climate in Europe. Aerosol concentrations have been declining since the 1980s in Europe, mainly owing to a reduction of local aerosol and precursor emissions. Emissions from other source regions of the world, which have been changing rapidly as well, may also perturb the historical and future trends of aerosols and change their radiative impact in Europe. This study examines trends of aerosols in Europe during 1980–2018 and quantifies contributions from 16 source regions using the Community Atmosphere Model version 5 with Explicit Aerosol Source Tagging (CAM5-EAST). The simulated near-surface total mass concentration of sulfate, black carbon, and primary organic carbon had a 62 % decrease during 1980–2018. The majority of which was contributed to reductions of local emissions in Europe, and 8 %–9 % was induced by a decrease in emissions from Russia–Belarus–Ukraine. With the decreases in the fractional contribution of local emissions, aerosols transported from other source regions are increasingly important for air quality in Europe. During 1980–2018, the decrease in sulfate loading led to a warming effect of 2.0 W m−2 in Europe, with 12 % coming from changes in non-European sources, especially from North America and Russia–Belarus–Ukraine. According to the Shared Socioeconomic Pathways (SSP) scenarios, contributions to the sulfate radiative forcing over Europe from both local European emissions and non-European emissions should decrease at a comparable rate in the next 3 decades, suggesting that future changes in non-European emissions are as important as European emissions for causing possible regional climate change associated with aerosols in Europe.

scholarly journals Indirect radiative forcing by ion-mediated nucleation of aerosol

2012 ◽  
Vol 12 (7) ◽  
pp. 17347-17365
Author(s):  
F. Yu ◽  
G. Luo ◽  
X. Liu ◽  
R. C. Easter ◽  
X. Ma ◽  
...  
Keyword(s):  
Radiative Forcing ◽  
Climate Models ◽  
Climate Model ◽  
Cloud Condensation Nuclei ◽  
Particle Formation ◽  
Climate Feedback ◽  
Formation Mechanisms ◽  
Clear Understanding ◽  
Cloud Forcing ◽  
Indirect Radiative Forcing

Abstract. A clear understanding of particle formation mechanisms is critical for assessing aerosol indirect radiative forcing and associated climate feedback processes. Recent studies reveal the importance of ion-mediated nucleation (IMN) in generating new particles and cloud condensation nuclei (CCN) in the atmosphere. Here we implement for the first time a physically-based treatment of IMN into the Community Atmosphere Model version 5. Our simulations show that, compared to globally averaged results based on binary homogeneous nucleation (BHN), the presence of ionization (i.e., IMN) halves H2SO4 column burden, but increases the column integrated nucleation rate by around one order of magnitude, total particle number burden by a factor of ~3, CCN burden by ~10% (at 0.2% supersaturation) to 65% (at 1.0% supersaturation), and cloud droplet number burden by ~18%. Compared to BHN, IMN increases cloud liquid water path by 7.5%, decreases precipitation by 1.1%, and increases total cloud cover by 1.9%. This leads to an increase of total shortwave cloud radiative forcing (SWCF) by 3.67 W m−2 (more negative) and longwave cloud forcing by 1.78 W m−2 (more positive), with large spatial variations. The effect of ionization on SWCF derived from this study (3.67 W m−2) is a factor of ~3 higher that of a previous study (1.15 W m−2) based on a different ion nucleation scheme and climate model. The large sensitivity of cloud forcing to nucleation process again calls for improving representation of secondary particle formation processes and aerosol-cloud interactions in climate models.

scholarly journals Simulation study on the indirect effect of sulfate on the summer climate over the eastern China monsoon region

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Dongdong Wang ◽  
Bin Zhu ◽  
Hongbo Wang ◽  
Li Sun
Keyword(s):  
Radiative Forcing ◽  
Asian Summer Monsoon ◽  
Cloud Condensation Nuclei ◽  
Eastern China ◽  
Summer Precipitation ◽  
Cloud Droplet ◽  
Monsoon Region ◽  
Liquid Water Path ◽  
Surface Cooling ◽  
Community Atmosphere Model

AbstractIn this study, we designed a sensitivity test using the half number concentration of sulfate in the nucleation calculation process to study the aerosol-cloud interaction (ACI) of sulfate on clouds, precipitation, and monsoon intensity in the summer over the eastern China monsoon region (ECMR) with the National Center for Atmospheric Research Community Atmosphere Model version 5. Numerical experiments show that the ACI of sulfate led to an approximately 30% and 34% increase in the cloud condensation nuclei and cloud droplet number concentrations, respectively. Cloud droplet effective radius below 850 hPa decreased by approximately 4% in the southern ECMR, while the total liquid water path increased by 11%. The change in the indirect radiative forcing due to sulfate at the top of the atmosphere in the ECMR during summer was − 3.74 W·m−2. The decreased radiative forcing caused a surface cooling of 0.32 K and atmospheric cooling of approximately 0.3 K, as well as a 0.17 hPa increase in sea level pressure. These changes decreased the thermal difference between the land and sea and the gradient of the sea-land pressure, leading to a weakening in the East Asian summer monsoon (EASM) and a decrease in the total precipitation rate in the southern ECMR. The cloud lifetime effect has a relatively weaker contribution to summer precipitation, which is dominated by convection. The results show that the ACI of sulfate was one possible reason for the weakening of the EASM in the late 1970s.

scholarly journals Incorrect Asian aerosols affecting the attribution and projection of regional climate change in CMIP6 models

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Zhili Wang ◽  
Lei Lin ◽  
Yangyang Xu ◽  
Huizheng Che ◽  
Xiaoye Zhang ◽  
...  
Keyword(s):  
Climate Change ◽  
Radiative Forcing ◽  
Impact Analysis ◽  
Climate Model ◽  
Regional Climate ◽  
Eastern China ◽  
Coupled Model ◽  
Regional Climate Change ◽  
Anthropogenic Aerosol ◽  
Wide Range

AbstractAnthropogenic aerosol (AA) forcing has been shown as a critical driver of climate change over Asia since the mid-20th century. Here we show that almost all Coupled Model Intercomparison Project Phase 6 (CMIP6) models fail to capture the observed dipole pattern of aerosol optical depth (AOD) trends over Asia during 2006–2014, last decade of CMIP6 historical simulation, due to an opposite trend over eastern China compared with observations. The incorrect AOD trend over China is attributed to problematic AA emissions adopted by CMIP6. There are obvious differences in simulated regional aerosol radiative forcing and temperature responses over Asia when using two different emissions inventories (one adopted by CMIP6; the other from Peking university, a more trustworthy inventory) to driving a global aerosol-climate model separately. We further show that some widely adopted CMIP6 pathways (after 2015) also significantly underestimate the more recent decline in AA emissions over China. These flaws may bring about errors to the CMIP6-based regional climate attribution over Asia for the last two decades and projection for the next few decades, previously anticipated to inform a wide range of impact analysis.

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