scholarly journals Changes in the aerosol direct radiative forcing from 2001 to 2015: observational constraints and regional mechanisms

2018 ◽  
Vol 18 (17) ◽  
pp. 13265-13281 ◽  
Author(s):  
Fabien Paulot ◽  
David Paynter ◽  
Paul Ginoux ◽  
Vaishali Naik ◽  
Larry W. Horowitz
Keyword(s):  
Black Carbon ◽  
Radiative Forcing ◽  
Western Europe ◽  
Emission Inventory ◽  
Climate Model ◽  
Eastern China ◽  
Radiant Energy ◽  
Model Bias ◽  
Anthropogenic Aerosols ◽  
The Us

Abstract. We present estimates of changes in the direct aerosol effects (DRE) and its anthropogenic component (DRF) from 2001 to 2015 using the GFDL chemistry–climate model AM3 driven by CMIP6 historical emissions. AM3 is evaluated against observed changes in the clear-sky shortwave direct aerosol effect (DREswclr) derived from the Clouds and the Earth's Radiant Energy System (CERES) over polluted regions. From 2001 to 2015, observations suggest that DREclrsw increases (i.e., less radiation is scattered to space by aerosols) over western Europe (0.7–1 W m−2 decade−1) and the eastern US (0.9–1.4 W m−2 decade−1), decreases over India (−1 to −1.6 W m−2 decade−1), and does not change significantly over eastern China. AM3 captures these observed regional changes in DREclrsw well in the US and western Europe, where they are dominated by the decline of sulfate aerosols, but not in Asia, where the model overestimates the decrease of DREclrsw. Over India, the model bias can be partly attributed to a decrease of the dust optical depth, which is not captured by our model and offsets some of the increase of anthropogenic aerosols. Over China, we find that the decline of SO2 emissions after 2007 is not represented in the CMIP6 emission inventory. Accounting for this decline, using the Modular Emission Inventory for China, and for the heterogeneous oxidation of SO2 significantly reduces the model bias. For both India and China, our simulations indicate that nitrate and black carbon contribute more to changes in DREclrsw than in the US and Europe. Indeed, our model suggests that black carbon (+0.12 W m−2) dominates the relatively weak change in DRF from 2001 to 2015 (+0.03 W m−2). Over this period, the changes in the forcing from nitrate and sulfate are both small and of the same magnitude (−0.03 W m−2 each). This is in sharp contrast to the forcing from 1850 to 2001 in which forcings by sulfate and black carbon largely cancel each other out, with minor contributions from nitrate. The differences between these time periods can be well understood from changes in emissions alone for black carbon but not for nitrate and sulfate; this reflects non-linear changes in the photochemical production of nitrate and sulfate associated with changes in both the magnitude and spatial distribution of anthropogenic emissions.

scholarly journals Changes in the aerosol direct radiative forcing from 2001 to 2015: observational constraints and regional mechanisms

2018 ◽  
Author(s):  
Fabien Paulot ◽  
David Paynter ◽  
Paul Ginoux ◽  
Vaishali Naik ◽  
Larry Horowitz
Keyword(s):  
Black Carbon ◽  
Radiative Forcing ◽  
Western Europe ◽  
Climate Model ◽  
Eastern China ◽  
Radiant Energy ◽  
Present Observation ◽  
So2 Emissions ◽  
Clear Sky ◽  
Direct Forcing

Abstract. We present observation and model-based estimates of the changes in the direct shortwave effect of aerosols under clear-sky (SDRECS) from 2001 to 2015. Observation-based estimates are obtained from changes in the outgoing shortwave clear-sky radiation (Rsutcs) measured by the Clouds and the Earth's Radiant Energy System (CERES), accounting for the effect of variability in surface albedo, water vapor, and ozone. We find increases in SDRECS (i.e., less radiation scattered to space by aerosols) over Western Europe (0.7–1 W m−2 dec−1) and the Eastern US (0.9–1.8 W m−2 dec−1), decreases over India (−0.5– −1.9 W m−2 dec−1) and no significant change over Eastern China. Comparisons with the GFDL chemistry climate model AM3, driven by CMIP6 historical emissions, show that changes in SDRECS over Western Europe and the Eastern US are well captured, which largely reflects the mature understanding of the sulfate budget in these regions. In contrast, the model overestimates the trends in SDRECS over India and Eastern China. Over China, this bias can be partly attributed to the decline of SO2 emissions after 2007, which is not captured by the CMIP6 emissions. In both India and Eastern China, we find much larger contributions of nitrate and black carbon to changes in SDRECS than in the US and Europe, which highlights the need to better constrain their precursors and chemistry. Globally, our model shows that changes in the all-sky aerosol direct forcing between 2001 and 2015 (+0.03 W m−2) are dominated by black carbon (+0.12 W m−2) with significant offsets from nitrate (−0.03 W m−2) and sulfate (−0.03 W m−2). Changes in the sulfate (+7 %) and nitrate (+60 %) all-sky direct forcing between 2001 and 2015 are only weakly related to changes in the emissions of their precursors (−12.5 % and 19 % for SO2 and NH3, respectively), due mostly to chemical non linearities.

scholarly journals Detecting the influence of fossil fuel and bio-fuel black carbon aerosols on near surface temperature changes

2011 ◽  
Vol 11 (2) ◽  
pp. 799-816 ◽  
Author(s):  
G. S. Jones ◽  
N. Christidis ◽  
P. A. Stott
Keyword(s):  
Greenhouse Gases ◽  
Greenhouse Gas ◽  
Black Carbon ◽  
20Th Century ◽  
Radiative Forcing ◽  
Fossil Fuel ◽  
Climate Model ◽  
Global Climate ◽  
Anthropogenic Aerosols ◽  
Near Surface

Abstract. Past research has shown that the dominant influence on recent global climate changes is from anthropogenic greenhouse gas increases with implications for future increases in global temperatures. One mitigation proposal is to reduce black carbon aerosol emissions. How much warming can be offset by controlling black carbon is unclear, especially as its influence on past climate has not been previously unambiguously detected. In this study observations of near-surface warming over the last century are compared with simulations using a climate model, HadGEM1. In the simulations black carbon, from fossil fuel and bio-fuel sources (fBC), produces a positive radiative forcing of about +0.25 Wm−2 over the 20th century, compared with +2.52 Wm−2 for well mixed greenhouse gases. A simulated warming of global mean near-surface temperatures over the twentieth century from fBC of 0.14 ± 0.1 K compares with 1.06 ± 0.07 K from greenhouse gases, −0.58 ± 0.10 K from anthropogenic aerosols, ozone and land use changes and 0.09 ± 0.09 K from natural influences. Using a detection and attribution methodology, the observed warming since 1900 has detectable influences from anthropogenic and natural factors. Fossil fuel and bio-fuel black carbon is found to have a detectable contribution to the warming over the last 50 yr of the 20th century, although the results are sensitive to the period being examined as fBC is not detected for the later fifty year period ending in 2006. The attributed warming of fBC was found to be consistent with the warming from fBC unscaled by the detection analysis. This study suggests that there is a possible significant influence from fBC on global temperatures, but its influence is small compared to that from greenhouse gas emissions.

scholarly journals Detecting the influence of fossil fuel and bio-fuel black carbon aerosols on near surface temperature changes

2010 ◽  
Vol 10 (9) ◽  
pp. 20921-20974
Author(s):  
G. S. Jones ◽  
N. Christidis ◽  
P. A. Stott
Keyword(s):  
Greenhouse Gases ◽  
Greenhouse Gas ◽  
Black Carbon ◽  
20Th Century ◽  
Radiative Forcing ◽  
Fossil Fuel ◽  
Climate Model ◽  
Global Climate ◽  
Anthropogenic Aerosols ◽  
Near Surface

Abstract. Past research has shown that the dominant influence on recent global climate changes is from anthropogenic greenhouse gas increases with implications for future increases in global temperatures. One mitigation proposal is to reduce black carbon aerosol emissions. How much warming can be offset by the aerosol's control is unclear, especially as its influence on past climate has not been previously unambiguously detected. In this study observations of near-surface warming over the last century are compared with simulations using a climate model, HadGEM1. In the simulations black carbon, from fossil fuel and bio-fuel sources (fBC), produces a positive radiative forcing of about + 0.25 Wm−2 over the 20th century, compared with a little under + 2.5 Wm−2 for well mixed greenhouse gases. A simulated warming of global mean near-surface temperatures over the twentieth century from fBC of 0.14 ± 0.1 K compares with 1.06 ± 0.07 K from greenhouse gases, -0.58 ± 0.10 K from anthropogenic aerosols, ozone and land use changes and 0.09 ± 0.09 K from natural influences. Using a detection and attribution methodology, the observed warming since 1900 has detectable influences from anthropogenic and natural factors. Fossil fuel and bio-fuel black carbon is found to have a detectable contribution to the warming over the last 50 years of the 20th century, although the results are sensitive to a number of analysis choices, and fBC is not detected for the later fifty year period ending in 2006. The attributed warming of fBC was found to be consistent with the warming from the unscaled simulation. This study suggests that there is a possible significant influence from fBC on global temperatures, but its influence is small compared to that from greenhouse gas emissions.

scholarly journals Ozone-vegetation feedback through dry deposition and isoprene emissions in a global chemistry-carbon-climate model

2019 ◽  
Author(s):  
Cheng Gong ◽  
Yadong Lei ◽  
Yimian Ma ◽  
Xu Yue ◽  
Hong Liao
Keyword(s):  
Stomatal Conductance ◽  
Dry Deposition ◽  
Radiative Forcing ◽  
Western Europe ◽  
Climate Model ◽  
Eastern China ◽  
Vegetation Feedback ◽  
Increased Temperature ◽  
Fully Coupled ◽  
Surface O3

Abstract. Ozone-vegetation feedback is essential to tropospheric ozone (O3) concentrations. The O3 stomatal uptake damages leaf photosynthesis and stomatal conductance and, in turn, influences O3 dry deposition. Further, O3 directly influences isoprene emissions, an important precursor of O3. The effects of O3 on vegetation further alter local meteorological fields and indirectly influence O3 concentrations. In this study, we apply a fully coupled chemistry-carbon-climate global model (ModelE2-YIBs) to evaluate changes in O3 concentrations caused by O3–vegetation interactions. Different parameterizations and sensitivities of the effect of O3 damage on photosynthesis, stomatal conductance, and isoprene emissions (IPE) are implemented in the model. The results show that O3-induced inhibition of stomatal conductance increases surface O3 on average by + 2.1 (+ 1.4) ppbv in eastern China, + 1.6 (− 0.5) ppbv in the eastern U.S., and + 1.3 (+ 1.0) ppbv in western Europe at high (low) damage sensitivity. Such positive feedback is dominated by reduced O3 dry deposition, in addition to the increased temperature and decreased relative humidity from weakened transpiration. Including the effect of O3 damage on IPE slightly reduces surface O3 concentrations by influencing precursors. However, the reduced IPE weakens surface shortwave radiative forcing of secondary organic aerosols leading to increased temperature and O3 concentrations in the eastern U.S. This study highlights the importance of interactions between O3 and vegetation with regard to O3 concentrations and the resultant air quality.

scholarly journals Ozone–vegetation feedback through dry deposition and isoprene emissions in a global chemistry–carbon–climate model

2020 ◽  
Vol 20 (6) ◽  
pp. 3841-3857 ◽  
Author(s):  
Cheng Gong ◽  
Yadong Lei ◽  
Yimian Ma ◽  
Xu Yue ◽  
Hong Liao
Keyword(s):  
Stomatal Conductance ◽  
Dry Deposition ◽  
Radiative Forcing ◽  
Western Europe ◽  
Climate Model ◽  
Eastern China ◽  
Vegetation Feedback ◽  
Increased Temperature ◽  
Fully Coupled ◽  
Surface O3

Abstract. Ozone–vegetation feedback is essential to tropospheric ozone (O3) concentrations. The O3 stomatal uptake damages leaf photosynthesis and stomatal conductance and, in turn, influences O3 dry deposition. Further, O3 directly influences isoprene emissions, an important precursor of O3. The effects of O3 on vegetation further alter local meteorological fields and indirectly influence O3 concentrations. In this study, we apply a fully coupled chemistry–carbon–climate global model (ModelE2-YIBs) to evaluate changes in O3 concentrations caused by O3–vegetation interactions. Different parameterizations and sensitivities of the effect of O3 damage on photosynthesis, stomatal conductance, and isoprene emissions (IPE) are implemented in the model. The results show that O3-induced inhibition of stomatal conductance increases surface O3 on average by +2.1 ppbv (+1.2 ppbv) in eastern China, +1.8 ppbv (−0.3 ppbv) in the eastern US, and +1.3 ppbv (+1.0 ppbv) in western Europe at high (low) damage sensitivity. Such positive feedback is dominated by reduced O3 dry deposition in addition to the increased temperature and decreased relative humidity from weakened transpiration. Including the effect of O3 damage on IPE slightly reduces surface O3 concentrations by influencing precursors. However, the reduced IPE weaken surface shortwave radiative forcing of secondary organic aerosols, leading to increased temperature and O3 concentrations in the eastern US. This study highlights the importance of interactions between O3 and vegetation with regard to O3 concentrations and the resultant air quality.

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.

scholarly journals Impacts of East Asian Summer and Winter Monsoon on Interannual Variations of Mass Concentrations and Direct Radiative Forcing of Black Carbon over Eastern China

2016 ◽  
Author(s):  
Yu Hao Mao ◽  
Hong Liao
Keyword(s):  
Black Carbon ◽  
Radiative Forcing ◽  
Southern China ◽  
East Asian ◽  
Eastern China ◽  
Northern China ◽  
Winter Monsoon ◽  
Interannual Variations ◽  
Direct Radiative Forcing ◽  
Asian Summer

Abstract. We applied a global three-dimensional chemical transport model (GEOS-Chem) to examine the impacts of the East Asian monsoon on the interannual variations of mass concentrations and direct radiative forcing (DRF) of black carbon (BC) over eastern China (110–125° E, 20–45° N). With emissions fixed at the year 2010 levels, model simulations were driven by the Goddard Earth Observing System (GEOS-4) meteorological fields for 1986–2006 and the Modern Era Retrospective-analysis for Research and Applications (MERRA) meteorological fields for 1980–2010. During the period of 1986–2006, simulated JJA and DJF surface BC concentrations were higher in MERRA than in GEOS-4 by 0.30 µg m−3 (44 %) and 0.77 µg m−3 (54 %), respectively, because of the generally weaker precipitation in MERRA. We found that the strength of the East Asian summer monsoon (EASM, (East Asian winter monsoon, EAWM)) negatively correlated with simulated JJA (DJF) surface BC concentrations (r = –0.7 (–0.7) in GEOS-4 and –0.4 (–0.7) in MERRA), mainly by the changes in atmospheric circulation. Relative to the five strongest EASM years, simulated JJA surface BC concentrations in the five weakest monsoon years were higher over northern China (110–125° E, 28–45° N) by 0.04–0.09 µg m−3 (3–11 %), but lower over southern China (110–125° E, 20–27° N) by 0.03–0.04 µg m−3 (10–11 %). Compared to the five strongest EAWM years, simulated DJF surface BC concentrations in the five weakest monsoon years were higher by 0.13–0.15 µg m−3 (5–8 %) in northern China and by 0.04–0.10 µg m−3 (3–12 %) in southern China. The resulting JJA (DJF) mean all-sky DRF of BC at the top of the atmosphere were 0.04 W m−2 (3 %, (0.03 W m−2, 2 %)) higher in northern China but 0.06 W m−2 (14 %, (0.03 W m−2, 3 %)) lower in southern China. In the weakest monsoon years, the weaker vertical convection led to the lower BC concentrations above 1–2 km in southern China, and therefore the lower BC DRF in the region. The differences in vertical profiles of BC between the weakest and strongest EASM years (1998–1997) and EAWM years (1990–1996) reached up to –0.09 µg m−3 (–46 %) and –0.08 µg m−3 (–11 %) at 1–2 km in eastern China.

scholarly journals Sensitivity of aerosol radiative effects to different mixing assumptions in the AEROPT 1.0 submodel of the EMAC atmospheric-chemistry–climate model

2014 ◽  
Vol 7 (5) ◽  
pp. 2503-2516 ◽  
Author(s):  
K. Klingmüller ◽  
B. Steil ◽  
C. Brühl ◽  
H. Tost ◽  
J. Lelieveld
Keyword(s):  
Optical Properties ◽  
Radiative Transfer ◽  
Black Carbon ◽  
Atmospheric Chemistry ◽  
Radiative Forcing ◽  
Climate Model ◽  
Mixing Rule ◽  
Aerosol Optical Properties ◽  
Internal Mixing ◽  
Aerosol Radiative

Abstract. The modelling of aerosol radiative forcing is a major cause of uncertainty in the assessment of global and regional atmospheric energy budgets and climate change. One reason is the strong dependence of the aerosol optical properties on the mixing state of aerosol components, such as absorbing black carbon and, predominantly scattering sulfates. Using a new column version of the aerosol optical properties and radiative-transfer code of the ECHAM/MESSy atmospheric-chemistry–climate model (EMAC), we study the radiative transfer applying various mixing states. The aerosol optics code builds on the AEROPT (AERosol OPTical properties) submodel, which assumes homogeneous internal mixing utilising the volume average refractive index mixing rule. We have extended the submodel to additionally account for external mixing, partial external mixing and multilayered particles. Furthermore, we have implemented the volume average dielectric constant and Maxwell Garnett mixing rule. We performed regional case studies considering columns over China, India and Africa, corroborating much stronger absorption by internal than external mixtures. Well-mixed aerosol is a good approximation for particles with a black-carbon core, whereas particles with black carbon at the surface absorb significantly less. Based on a model simulation for the year 2005, we calculate that the global aerosol direct radiative forcing for homogeneous internal mixing differs from that for external mixing by about 0.5 W m−2.

scholarly journals Effective radiative forcing in the aerosol–climate model CAM5.3-MARC-ARG

2018 ◽  
Author(s):  
Benjamin S. Grandey ◽  
Daniel Rothenberg ◽  
Alexander Avramov ◽  
Qinjian Jin ◽  
Hsiang-He Lee ◽  
...  
Keyword(s):  
Radiative Forcing ◽  
Climate Model ◽  
Regional Distribution ◽  
Radiative Effect ◽  
Mixing State ◽  
Anthropogenic Aerosols ◽  
Effective Radiative Forcing ◽  
Aerosol Module ◽  
Aerosol Emissions ◽  
Global Mean

Abstract. We quantify the effective radiative forcing (ERF) of anthropogenic aerosols modelled by the aerosol–climate model CAM5.3-MARC-ARG. CAM5.3-MARC-ARG is a new configuration of the Community Atmosphere Model version 5.3 (CAM5.3) in which the default aerosol module has been replaced by the two-Moment, Multi-Modal, Mixing-state-resolving Aerosol model for Research of Climate (MARC). CAM5.3-MARC-ARG uses the default ARG aerosol activation scheme, consistent with the default configuration of CAM5.3. We compute differences between simulations using year-1850 aerosol emissions and simulations using year-2000 aerosol emissions in order to assess the radiative effects of anthropogenic aerosols. We compare the aerosol column burdens, cloud properties, and radiative effects produced by CAM5.3-MARC-ARG with those produced by the default configuration of CAM5.3, which uses the modal aerosol module with three log-normal modes (MAM3). Compared with MAM3, we find that MARC produces stronger cooling via the direct radiative effect, stronger cooling via the surface albedo radiative effect, and stronger warming via the cloud longwave radiative effect. The global mean cloud shortwave radiative effect is similar between MARC and MAM3, although the regional distributions differ. Overall, MARC produces a global mean net ERF of −1.75 ± 0.04 W m−2, which is stronger than the global mean net ERF of −1.57 ± 0.04 W m−2 produced by MAM3. The regional distribution of ERF also differs between MARC and MAM3, largely due to differences in the regional distribution of the cloud shortwave radiative effect. We conclude that the specific representation of aerosols in global climate models, including aerosol mixing state, has important implications for climate modelling.

scholarly journals Impact of methane and black carbon mitigation on forcing and temperature: a multi-model scenario analysis

2020 ◽  
Vol 163 (3) ◽  
pp. 1427-1442 ◽  
Author(s):  
Steven J Smith ◽  
Jean Chateau ◽  
Kalyn Dorheim ◽  
Laurent Drouet ◽  
Olivier Durand-Lasserve ◽  
...  
Keyword(s):  
Black Carbon ◽  
Radiative Forcing ◽  
Climate Model ◽  
Economic Structure ◽  
Time Frame ◽  
Focused Attention ◽  
Carbon Mitigation ◽  
Global Mean Temperature ◽  
Model Parameter Uncertainty ◽  
Global Mean

AbstractThe relatively short atmospheric lifetimes of methane (CH4) and black carbon (BC) have focused attention on the potential for reducing anthropogenic climate change by reducing Short-Lived Climate Forcer (SLCF) emissions. This paper examines radiative forcing and global mean temperature results from the Energy Modeling Forum (EMF)-30 multi-model suite of scenarios addressing CH4 and BC mitigation, the two major short-lived climate forcers. Central estimates of temperature reductions in 2040 from an idealized scenario focused on reductions in methane and black carbon emissions ranged from 0.18–0.26 °C across the nine participating models. Reductions in methane emissions drive 60% or more of these temperature reductions by 2040, although the methane impact also depends on auxiliary reductions that depend on the economic structure of the model. Climate model parameter uncertainty has a large impact on results, with SLCF reductions resulting in as much as 0.3–0.7 °C by 2040. We find that the substantial overlap between a SLCF-focused policy and a stringent and comprehensive climate policy that reduces greenhouse gas emissions means that additional SLCF emission reductions result in, at most, a small additional benefit of ~ 0.1 °C in the 2030–2040 time frame.

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