scholarly journals Radiative effects of inter-annually varying versus inter-annually invariant aerosol emissions from fires

2016 ◽  
Author(s):  
Benjamin S. Grandey ◽  
Hsiang-He Lee ◽  
Chien Wang
Keyword(s):  
Organic Carbon ◽  
Atmospheric Aerosols ◽  
Fast Response ◽  
Climate System ◽  
Radiative Effect ◽  
Radiative Effects ◽  
Annual Variability ◽  
Community Atmosphere Model ◽  
Earth’S Climate ◽  
Aerosol Emissions

Abstract. Open-burning fires play an important role in the Earth's climate system. In addition to contributing a substantial fraction of global emissions of carbon dioxide, they are also a major source of atmospheric aerosols such as organic carbon, black carbon, and sulphate. These "fire aerosols" can influence the climate via both direct and indirect radiative effects. In this study, we investigate these radiative effects and the hydrological fast response using the Community Atmosphere Model version 5 (CAM5). Emissions of fire aerosols exert a global mean net radiative effect of −1.0 W m−2, dominated by the cloud shortwave response to organic carbon aerosol. The net radiative effect is particularly strong over boreal regions. By comparing simulations using inter-annually varying versus inter-annually invariant emissions, we find that ignoring the inter-annual variability of the emissions can lead to systematic overestimation of the strength of the net radiative effect of the fire aerosols. Globally, the overestimation is +23 % (−0.2 W m−2). Regionally, the overestimation can be substantially larger. For example, over Australia and New Zealand the overestimation is +58 % (−1.2 W m−2), while over Boreal Asia the overestimation is +43 % (−1.9 W m−2). The systematic overestimation of the net radiative effect of the fire aerosols is likely due to the non-linear influence of aerosols on clouds. However, ignoring inter-annual variability in the emissions does not appear to significantly impact the hydrological fast response. In order to improve understanding of the climate system, we need to more accurately quantify the effects of aerosols, taking into account important characteristics such as inter-annual variability.

scholarly journals Radiative effects of interannually varying vs. interannually invariant aerosol emissions from fires

2016 ◽  
Vol 16 (22) ◽  
pp. 14495-14513 ◽  
Author(s):  
Benjamin S. Grandey ◽  
Hsiang-He Lee ◽  
Chien Wang
Keyword(s):  
Organic Carbon ◽  
Interannual Variability ◽  
Atmospheric Aerosols ◽  
Fast Response ◽  
Climate System ◽  
Climate Modelling ◽  
Radiative Effect ◽  
Radiative Effects ◽  
Modelling Studies ◽  
Aerosol Emissions

Abstract. Open-burning fires play an important role in the earth's climate system. In addition to contributing a substantial fraction of global emissions of carbon dioxide, they are a major source of atmospheric aerosols containing organic carbon, black carbon, and sulfate. These “fire aerosols” can influence the climate via direct and indirect radiative effects. In this study, we investigate these radiative effects and the hydrological fast response using the Community Atmosphere Model version 5 (CAM5). Emissions of fire aerosols exert a global mean net radiative effect of −1.0 W m−2, dominated by the cloud shortwave response to organic carbon aerosol. The net radiative effect is particularly strong over boreal regions. Conventionally, many climate modelling studies have used an interannually invariant monthly climatology of emissions of fire aerosols. However, by comparing simulations using interannually varying emissions vs. interannually invariant emissions, we find that ignoring the interannual variability of the emissions can lead to systematic overestimation of the strength of the net radiative effect of the fire aerosols. Globally, the overestimation is +23 % (−0.2 W m−2). Regionally, the overestimation can be substantially larger. For example, over Australia and New Zealand the overestimation is +58 % (−1.2 W m−2), while over Boreal Asia the overestimation is +43 % (−1.9 W m−2). The systematic overestimation of the net radiative effect of the fire aerosols is likely due to the non-linear influence of aerosols on clouds. However, ignoring interannual variability in the emissions does not appear to significantly impact the hydrological fast response. In order to improve understanding of the climate system, we need to take into account the interannual variability of aerosol emissions.

scholarly journals Radiative Effect and Climate Impacts of Brown Carbon with the Community Atmosphere Model (CAM5)

2018 ◽  
Author(s):  
Hunter Brown ◽  
Xiaohong Liu ◽  
Yan Feng ◽  
Yiquan Jiang ◽  
Mingxuan Wu ◽  
...  
Keyword(s):  
Model Comparison ◽  
Climate Impacts ◽  
The Arctic ◽  
Radiation Absorption ◽  
Wave Radiation ◽  
Radiative Effect ◽  
Radiative Effects ◽  
Brown Carbon ◽  
Community Atmosphere Model ◽  
Atmosphere Model

Abstract. A recent development in the representation of aerosols in climate models is the realization that some components of organic aerosol (OA), emitted from biomass and biofuel burning, can have a significant contribution to short-wave radiation absorption in the atmosphere. The absorbing fraction of OA is referred to as brown carbon (BrC). This study introduces one of the first implementations of BrC into the Community Atmosphere Model version 5 (CAM5), using a parameterization for BrC absorptivity described in Saleh et al. (2014). 9-year experiments are run (2003–2011) with prescribed emissions and sea surface temperatures to analyze the effect of BrC in the atmosphere. Model validation is conducted via model comparison to single-scatter albedo and aerosol optical depth from the Aerosol Robotic Network (AERONET). This comparison reveals a model underestimation of SSA in biomass burning regions for both default and BrC model runs, while a comparison between AERONET and model absorption Angstrom exponent shows a marked improvement with BrC implementation. Global annual average radiative effects are calculated due to aerosol-radiation interactions (REari; 0.13 ± 0.01 W m−2) and aerosol-cloud interactions (REaci; 0.01 ± 0.04 W m−2). REari is similar to other studies' estimations of BrC direct radiative effect, while REaci indicates a global reduction in low clouds due to the BrC semi-direct effect. The mechanisms for these physical changes are investigated and found to correspond with changes in global circulation patterns. Comparisons of BrC implementation approaches find that this implementation predicts a lower BrC REari in the Arctic regions than previous studies with CAM5. Implementation of BrC bleaching effect shows a significant reduction in REari (0.06 ± 0.008 W m−2). Also, variations in OA density can lead to differences in REari and REaci, indicating the importance of specifying this property when estimating the BrC radiative effects and when comparing similar studies.

scholarly journals Radiative effect and climate impacts of brown carbon with the Community Atmosphere Model (CAM5)

2018 ◽  
Vol 18 (24) ◽  
pp. 17745-17768 ◽  
Author(s):  
Hunter Brown ◽  
Xiaohong Liu ◽  
Yan Feng ◽  
Yiquan Jiang ◽  
Mingxuan Wu ◽  
...  
Keyword(s):  
Model Comparison ◽  
Climate Impacts ◽  
Shortwave Radiation ◽  
The Arctic ◽  
Radiation Absorption ◽  
Radiative Effect ◽  
Radiative Effects ◽  
Brown Carbon ◽  
Community Atmosphere Model ◽  
Atmosphere Model

Abstract. A recent development in the representation of aerosols in climate models is the realization that some components of organic aerosol (OA), emitted from biomass and biofuel burning, can have a significant contribution to shortwave radiation absorption in the atmosphere. The absorbing fraction of OA is referred to as brown carbon (BrC). This study introduces one of the first implementations of BrC into the Community Atmosphere Model version 5 (CAM5), using a parameterization for BrC absorptivity described in Saleh et al. (2014). Nine-year experiments are run (2003–2011) with prescribed emissions and sea surface temperatures to analyze the effect of BrC in the atmosphere. Model validation is conducted via model comparison to single-scatter albedo and aerosol optical depth from the Aerosol Robotic Network (AERONET). This comparison reveals a model underestimation of single scattering albedo (SSA) in biomass burning regions for both default and BrC model runs, while a comparison between AERONET and the model absorption Ångström exponent shows a marked improvement with BrC implementation. Global annual average radiative effects are calculated due to aerosol–radiation interaction (REari; 0.13±0.01 W m−2) and aerosol–cloud interaction (REaci; 0.01±0.04 W m−2). REari is similar to other studies' estimations of BrC direct radiative effect, while REaci indicates a global reduction in low clouds due to the BrC semi-direct effect. The mechanisms for these physical changes are investigated and found to correspond with changes in global circulation patterns. Comparisons of BrC implementation approaches find that this implementation predicts a lower BrC REari in the Arctic regions than previous studies with CAM5. Implementation of BrC bleaching effect shows a significant reduction in REari (0.06±0.008 W m−2). Also, variations in OA density can lead to differences in REari and REaci, indicating the importance of specifying this property when estimating the BrC radiative effects and when comparing similar studies.

scholarly journals Simultaneous reductions in emissions of black carbon and co-emitted species will weaken the aerosol net cooling effect

2015 ◽  
Vol 15 (7) ◽  
pp. 3671-3685 ◽  
Author(s):  
Z. L. Wang ◽  
H. Zhang ◽  
X. Y. Zhang
Keyword(s):  
Global Warming ◽  
Black Carbon ◽  
Carbonaceous Material ◽  
Distinct Type ◽  
Climate System ◽  
Cooling Effect ◽  
Strong Light ◽  
Earth’S Climate ◽  
Aerosol Emissions ◽  
Year 2000

Abstract. Black carbon (BC), a distinct type of carbonaceous material formed from the incomplete combustion of fossil and biomass based fuels under certain conditions, can interact with solar radiation and clouds through its strong light-absorption ability, thereby warming the Earth's climate system. Some studies have even suggested that global warming could be slowed down in the short term by eliminating BC emission due to its short lifetime. In this study, we estimate the influence of removing some sources of BC and other co-emitted species on the aerosol radiative effect by using an aerosol–climate atmosphere-only model BCC_AGCM2.0.1_CUACE/Aero with prescribed sea surface temperature and sea ice cover, in combination with the aerosol emissions from the Representative Concentration Pathways (RCPs) scenarios. We find that the global annual mean aerosol net cooling effect at the top of the atmosphere (TOA) will be enhanced by 0.12 W m−2 compared with recent past year 2000 levels if the emissions of only BC are reduced to the level projected for 2100 based on the RCP2.6 scenario. This will be beneficial~for the mitigation of global warming. However, both aerosol negative direct and indirect radiative effects are weakened when BC and its co-emitted species (sulfur dioxide and organic carbon) are simultaneously reduced. Relative to year 2000 levels, the global annual mean aerosol net cooling effect at the TOA will be weakened by 1.7–2.0 W m−2 if the emissions of all these aerosols are decreased to the levels projected for 2100 in different ways based on the RCP2.6, RCP4.5, and RCP8.5 scenarios. Because there are no effective ways to remove the BC exclusively without influencing the other co-emitted components, our results therefore indicate that a reduction in BC emission can lead to an unexpected warming on the Earth's climate system in the future.

Essentials of the Earth's Climate System

2014 ◽  
Author(s):  
Roger G. Barry ◽  
Eileen A. Hall-McKim
Keyword(s):  
Climate System ◽  
Earth’S Climate

From “Inconvenient Truth” to Effective Governance

2018 ◽  
Author(s):  
Richard Passarelli ◽  
David Michel ◽  
William Durch
Keyword(s):  
Climate Change ◽  
Global Climate ◽  
Climate System ◽  
Global Public Good ◽  
Environmental Groups ◽  
Quarter Century ◽  
Effective Governance ◽  
Political Response ◽  
Earth’S Climate ◽  
National Governments

The Earth’s climate system is a global public good. Maintaining it is a collective action problem. This chapter looks at a quarter-century of efforts to understand and respond to the challenges posed by global climate change and why the collective political response, until very recently, has seemed to lag so far behind our scientific knowledge of the problem. The chapter tracks the efforts of the main global, intergovernmental process for negotiating both useful and politically acceptable responses to climate change, the UN Framework Convention on Climate Change, but also highlights efforts by scientific and environmental groups and, more recently, networks of sub-national governments—especially cities—and of businesses to redefine interests so as to meet the dangers of climate system disruption.

scholarly journals Intra‐annual variability of organic carbon concentrations in running waters: Drivers along a climatic gradient

2014 ◽  
Vol 28 (4) ◽  
pp. 451-464 ◽  
Author(s):  
Mattias Winterdahl ◽  
Martin Erlandsson ◽  
Martyn N. Futter ◽  
Gesa A. Weyhenmeyer ◽  
Kevin Bishop
Keyword(s):  
Organic Carbon ◽  
Running Waters ◽  
Climatic Gradient ◽  
Annual Variability ◽  
Carbon Concentrations

scholarly journals Permafrost-Affected Soils of the Russian Arctic and their Carbon Pools

2014 ◽  
Vol 6 (1) ◽  
pp. 619-655
Author(s):  
S. Zubrzycki ◽  
L. Kutzbach ◽  
E.-M. Pfeiffer
Keyword(s):  
Organic Matter ◽  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Carbon Sink ◽  
Global Climate ◽  
Fundamental Property ◽  
Climate System ◽  
The Arctic ◽  
Quaternary Period ◽  
Permafrost Regions

Abstract. Permafrost-affected soils have accumulated enormous pools of organic matter during the Quaternary Period. The area occupied by these soils amounts to more than 8.6 million km2, which is about 27% of all land areas north of 50° N. Therefore, permafrost-affected soils are considered to be one of the most important cryosphere elements within the climate system. Due to the cryopedogenic processes that form these particular soils and the overlying vegetation that is adapted to the arctic climate, organic matter has accumulated to the present extent of up to 1024 Pg (1 Pg = 1015 g = 1 Gt) of soil organic carbon stored within the uppermost three meters of ground. Considering the observed progressive climate change and the projected polar amplification, permafrost-affected soils will undergo fundamental property changes. Higher turnover and mineralization rates of the organic matter are consequences of these changes, which are expected to result in an increased release of climate-relevant trace gases into the atmosphere. As a result, permafrost regions with their distinctive soils are likely to trigger an important tipping point within the global climate system, with additional political and social implications. The controversy of whether permafrost regions continue accumulating carbon or already function as a carbon source remains open until today. An increased focus on this subject matter, especially in underrepresented Siberian regions, could contribute to a more robust estimation of the soil organic carbon pool of permafrost regions and at the same time improve the understanding of the carbon sink and source functions of permafrost-affected soils.

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