Climate response to the spatial and temporal evolutions of anthropogenic aerosol forcing

2021 ◽  
Author(s):  
Hai Wang ◽  
Yu-Jun Wen
Keyword(s):  
Climate Response ◽  
Anthropogenic Aerosol ◽  
Aerosol Forcing

scholarly journals Comparison of Climate Response to Anthropogenic Aerosol versus Greenhouse Gas Forcing: Distinct Patterns

2016 ◽  
Vol 29 (14) ◽  
pp. 5175-5188 ◽  
Author(s):  
Hai Wang ◽  
Shang-Ping Xie ◽  
Qinyu Liu
Keyword(s):  
Northern Hemisphere ◽  
Radiative Forcing ◽  
Climate Model ◽  
East Asian Monsoon ◽  
Climate Response ◽  
Anthropogenic Aerosols ◽  
Anthropogenic Aerosol ◽  
Asian Monsoon Region ◽  
Surface Temperature Change ◽  
Aerosol Forcing

Abstract Spatial patterns of climate response to changes in anthropogenic aerosols and well-mixed greenhouse gases (GHGs) are investigated using climate model simulations for the twentieth century. The climate response shows both similarities and differences in spatial pattern between aerosol and GHG runs. Common climate response between aerosol and GHG runs tends to be symmetric about the equator. This work focuses on the distinctive patterns that are unique to the anthropogenic aerosol forcing. The tropospheric cooling induced by anthropogenic aerosols is locally enhanced in the midlatitude Northern Hemisphere with a deep vertical structure around 40°N, anchoring a westerly acceleration in thermal wind balance. The aerosol-induced negative radiative forcing in the Northern Hemisphere requires a cross-equatorial Hadley circulation to compensate interhemispheric energy imbalance in the atmosphere. Associated with a southward shift of the intertropical convergence zone, this interhemispheric asymmetric mode is unique to aerosol forcing and absent in GHG runs. Comparison of key climate response pattern indices indicates that the aerosol forcing dominates the interhemispheric asymmetric climate response in historical all-forcing simulations, as well as regional precipitation change such as the drying trend over the East Asian monsoon region. While GHG forcing dominates global mean surface temperature change, its effect is on par with and often opposes the aerosol effect on precipitation, making it difficult to detect anthropogenic change in rainfall from historical observations.

Implication of the reduction in anthropogenic aerosols due to the COVID-19 pandemic and the future recovery scenarios for radiative forcing

2021 ◽  
Author(s):  
Stephanie Fiedler ◽  
Klaus Wyser ◽  
Rogelj Joeri ◽  
Twan van Noije
Keyword(s):  
Radiative Forcing ◽  
Internal Variability ◽  
Climate Response ◽  
Emission Scenarios ◽  
Radiative Effects ◽  
Anthropogenic Aerosols ◽  
Anthropogenic Aerosol ◽  
Aerosol Forcing ◽  
Effective Radiative Forcing ◽  
Aerosol Emissions

<p>The COVID-19 pandemic has led to unprecedented reductions in socio-economic activities. Associated decreases in anthropogenic aerosol emissions are not represented in the original CMIP6 emission scenarios. Here we estimate the implications of the pandemic for the aerosol forcing in 2020 and quantify the spread in aerosol forcing associated with the differences in the post-pandemic recovery pathways. To this end, we use new emission scenarios taking the COVID-19 crisis into account and projecting different socio-economic developments until 2050 with fossil-fuel based and green pathways (Forster et al., 2020). We use the new emission data to generate input for the anthropogenic aerosol parameterization MACv2-SP for CMIP6 models. In this presentation, we first show the results for the anthropogenic aerosol optical depth and associated effects on clouds from the new MACv2-SP data for 2020 to 2050 (Fiedler et al., in review). We then use the MACv2-SP data to provide estimates of the effective radiative effects of the anthropogenic aerosols for 2020 and 2050. Our forcing estimates are based on new atmosphere-only simulations with the CMIP6 model EC-Earth3. The model uses MACv2-SP to represent aerosol-radiation and aerosol-cloud interactions including aerosol effects on cloud lifetime. For each anthropogenic aerosol pattern, we run EC-Earth3 simulations for fifty years to substantially reduce the impact of model-internal variability on the forcing estimate. Our results highlight: (1) a change of +0.04 Wm<sup>-2</sup> in the global mean effective radiative forcing of anthropogenic aerosols for 2020 due to the pandemic, which is small compared to the magnitude of internal variability, (2) a spread of -0.38 to -0.68 Wm<sup>-2</sup> for the effective radiative forcing associated with anthropogenic aerosols in 2050 depending on the recovery scenario in MACv2-SP, and (3) a more negative (stronger) anthropogenic aerosol forcing for a strong green than a moderate green development in 2050 due to higher ammonium emissions in a highly decarbonized society (Fiedler et al., in review). The new MACv2-SP data are now used in climate models participating in the model intercomparison project on the climate response to the COVID-19 crisis (Covid-MIP, Jones et al., in review, Lamboll et al., in review).</p><p><strong>References:</strong></p><p>Fiedler, S., Wyser, K., Joeri, R., and van Noije, T.: Radiative effects of reduced aerosol emissions during the COVID-19 pandemic and the future recovery, in review, [preprint] https://doi.org/10.1002/essoar.10504704.1.</p><p>Forster, P.M., Forster, H.I., Evans, M.J. et al.: Current and future global climate impacts resulting from COVID-19. Nat. Clim. Chang. 10, 913–919, 2020, https://doi.org/10.1038/s41558-020-0883-0.</p><p>Jones. C., Hickman, J., Rumbold, S., et al.: The Climate Response to Emissions Reductions due to COVID-19, Geophy. Res. Lett., in review.</p><p>Lamboll, R. D., Jones, C. D., Skeie, R. B., Fiedler, S., Samset, B. H., Gillett, N. P., Rogelj, J., and Forster, P. M.: Modifying emission scenario projections to account for the effects of COVID-19: protocol for Covid-MIP, in review, [preprint] https://doi.org/10.5194/gmd-2020-373.</p>

scholarly journals Detecting cross‐equatorial wind change as a fingerprint of climate response to anthropogenic aerosol forcing

2016 ◽  
Vol 43 (7) ◽  
pp. 3444-3450 ◽  
Author(s):  
Hai Wang ◽  
Shang‐Ping Xie ◽  
Hiroki Tokinaga ◽  
Qinyu Liu ◽  
Yu Kosaka
Keyword(s):  
Climate Response ◽  
Anthropogenic Aerosol ◽  
Aerosol Forcing

scholarly journals Global impact of smoke aerosols from landscape fires on climate and the Hadley circulation

2013 ◽  
Vol 13 (10) ◽  
pp. 5227-5241 ◽  
Author(s):  
M. G. Tosca ◽  
J. T. Randerson ◽  
C. S. Zender
Keyword(s):  
Hadley Circulation ◽  
Surface Radiation ◽  
Climate Response ◽  
Fire Emissions ◽  
Aerosol Forcing ◽  
Surface Temperatures ◽  
Community Atmosphere Model ◽  
Tropospheric Heating ◽  
Aerosol Effects ◽  
Global Precipitation

Abstract. Each year landscape fires across the globe emit black and organic carbon smoke particles that can last in the atmosphere for days to weeks. We characterized the climate response to these aerosols using an Earth system model. We used remote sensing observations of aerosol optical depth (AOD) and simulations from the Community Atmosphere Model, version 5 (CAM5) to optimize satellite-derived smoke emissions for high biomass burning regions. Subsequent global simulations using the adjusted fire emissions produced AODs that were in closer agreement with surface and space-based measurements. We then used CAM5, which included radiative aerosol effects, to evaluate the climate response to the fire-aerosol forcing. We conducted two 52 yr simulations, one with four sets of monthly cycling 1997–2009 fire emissions and one without. Fire emissions increased global mean annual AOD by 10% (+0.02) and decreased net all-sky surface radiation by 1% (1.3 W m−2). Elevated AODs reduced global surface temperatures by 0.13 ± 0.01 °C. Though global precipitation declined only slightly, patterns of precipitation changed, with large reductions near the Equator offset by smaller increases north and south of the intertropical convergence zone (ITCZ). A combination of increased tropospheric heating and reduced surface temperatures increased equatorial subsidence and weakened the Hadley circulation. As a consequence, precipitation decreased over tropical forests in South America, Africa and equatorial Asia. These results are consistent with the observed correlation between global temperatures and the strength of the Hadley circulation and studies linking tropospheric heating from black carbon aerosols with tropical expansion.

scholarly journals Weaker cooling by aerosols due to dust–pollution interactions

2020 ◽  
Vol 20 (23) ◽  
pp. 15285-15295
Author(s):  
Klaus Klingmüller ◽  
Vlassis A. Karydis ◽  
Sara Bacer ◽  
Georgiy L. Stenchikov ◽  
Jos Lelieveld
Keyword(s):  
Atmospheric Chemistry ◽  
Climate Model ◽  
Cloud Condensation Nuclei ◽  
Radiative Effect ◽  
Dust Pollution ◽  
Aerosol Composition ◽  
Anthropogenic Aerosol ◽  
Aerosol Forcing ◽  
Condensed Water ◽  
Chemical Ageing

Abstract. The interactions between aeolian dust and anthropogenic air pollution, notably chemical ageing of mineral dust and coagulation of dust and pollution particles, modify the atmospheric aerosol composition and burden. Since the aerosol particles can act as cloud condensation nuclei, this affects the radiative transfer not only directly via aerosol–radiation interactions, but also indirectly through cloud adjustments. We study both radiative effects using the global ECHAM/MESSy atmospheric chemistry-climate model (EMAC) which combines the Modular Earth Submodel System (MESSy) with the European Centre/Hamburg (ECHAM) climate model. Our simulations show that dust–pollution–cloud interactions reduce the condensed water path and hence the reflection of solar radiation. The associated climate warming outweighs the cooling that the dust–pollution interactions exert through the direct radiative effect. In total, this results in a net warming by dust–pollution interactions which moderates the negative global anthropogenic aerosol forcing at the top of the atmosphere by (0.2 ± 0.1) W m−2.

scholarly journals Air pollution control and decreasing new particle formation lead to strong climate warming

2011 ◽  
Vol 11 (9) ◽  
pp. 25991-26007 ◽  
Author(s):  
R. Makkonen ◽  
A. Asmi ◽  
V.-M. Kerminen ◽  
M. Boy ◽  
A. Arneth ◽  
...  
Keyword(s):  
Air Pollution ◽  
Pollution Control ◽  
Cloud Condensation Nuclei ◽  
Particle Formation ◽  
Control Measures ◽  
Air Pollution Control ◽  
New Particle Formation ◽  
Anthropogenic Aerosol ◽  
Aerosol Forcing ◽  
Year 2000

Abstract. The number of cloud droplets determines several climatically relevant cloud properties. A major cause for the high uncertainty in the indirect aerosol forcing is the availability of cloud condensation nuclei (CCN), which in turn is highly sensitive to atmospheric new particle formation. Here we present the effect of new particle formation on anthropogenic aerosol forcing in present-day (year 2000) and future (year 2100) conditions. The total aerosol forcing (−1.61 W m−2 in year 2000) is simulated to be greatly reduced in the future, to −0.23 W m−2, mainly due to decrease in SO2 emissions and resulting decrease in new particle formation. With the total aerosol forcing decreasing in response to air pollution control measures taking effect, warming from increased greenhouse gas concentrations can potentially increase at a very rapid rate.

scholarly journals Aerosol radiative effects with MACv2

2019 ◽  
Author(s):  
Stefan Kinne
Keyword(s):  
Anthropogenic Sources ◽  
Transfer Model ◽  
Strong Impact ◽  
Radiative Effects ◽  
Anthropogenic Aerosols ◽  
Anthropogenic Aerosol ◽  
Aerosol Forcing ◽  
Aerosol Radiative Effects ◽  
The Impact ◽  
Aerosol Radiative

Abstract. onthly global maps for aerosol properties of the MACv2 climatology are applied in an off-line radiative transfer model to determine aerosol radiative effects. For details beyond global averages in most cases global maps are presented to visualize regional and seasonal details. Aside from the direct radiative (aerosol presence) effect, including those for aerosol components as extracted from MACv2 aerosol optics, also the major aerosol indirect radiative effect is covered. Hereby, the impact of smaller drops in water clouds due to added anthropogenic aerosol was simulated by applying a satellite retrieval based fit from locally associations between aerosol and drop concentrations over oceans. Present-day anthropogenic aerosols of MACv2 – on a global average basis – reduce the radiative net-fluxes at the top of the atmosphere (TOA) by −1.0 W/m2 and at the surface by −2.1 W/m2. Direct cooling contributions are only about half of indirect contributions (−.35 vs −.65) at TOA, but about twice at the surface (−1.45 vs −.65), as solar absorption of the direct effect warms the atmosphere by +1.1 W/m2. Natural aerosols are on average less absorbing (for a relatively larger solar TOA cooling) and larger in size (now contributing with IR greenhouse warming). Thus, average TOA direct forcing efficiencies for total and anthropogenic aerosol happen to be similar: −11 W/m2/AOD at all-sky and −24 W/m2/AOD at clear-sky conditions. The present-day direct impact by all soot (BC) is globally averaged +0.55W/m2 and at least half of it should be attributed to anthropogenic sources. Hereby any accuracy of anthropogenic impacts, not just for soot, suffers from the limited access to a pre-industrial reference. Anthropogenic uncertainty has a particular strong impact on aerosol indirect effects, which dominate the (TOA) forcing. Accounting for uncertainties in the anthropogenic definition, present-day aerosol forcing is estimated to stay within the −0.7 to −1.6 W/m2 range, with a best estimate at −1 W/m2. Calculations with model predicted temporal changes to anthropogenic AOD indicate that qualitatively the anthropogenic aerosol forcing has not changed much over the last decades and is not likely to increase over the next decades, despite strong regional shifts. These regional shifts explain most solar insolation (brightening or dimming) trends that have been observed by ground-based radiation data.

scholarly journals Influence of future air pollution mitigation strategies on total aerosol radiative forcing

2008 ◽  
Vol 8 (21) ◽  
pp. 6405-6437 ◽  
Author(s):  
S. Kloster ◽  
F. Dentener ◽  
J. Feichter ◽  
F. Raes ◽  
J. van Aardenne ◽  
...  
Keyword(s):  
Air Pollution ◽  
Radiative Forcing ◽  
Mitigation Strategies ◽  
Radiation Budget ◽  
Anthropogenic Aerosol ◽  
Aerosol Radiative Forcing ◽  
Pollution Mitigation ◽  
Aerosol Forcing ◽  
Future Air Pollution ◽  
Aerosol Radiative

Abstract. We apply different aerosol and aerosol precursor emission scenarios reflecting possible future control strategies for air pollution in the ECHAM5-HAM model, and simulate the resulting effect on the Earth's radiation budget. We use two opposing future mitigation strategies for the year 2030: one in which emission reduction legislation decided in countries throughout the world are effectively implemented (current legislation; CLE 2030) and one in which all technical options for emission reductions are being implemented independent of their cost (maximum feasible reduction; MFR 2030). We consider the direct, semi-direct and indirect radiative effects of aerosols. The total anthropogenic aerosol radiative forcing defined as the difference in the top-of-the-atmosphere radiation between 2000 and pre-industrial times amounts to −2.00 W/m2. In the future this negative global annual mean aerosol radiative forcing will only slightly change (+0.02 W/m2) under the "current legislation" scenario. Regionally, the effects are much larger: e.g. over Eastern Europe radiative forcing would increase by +1.50 W/m2 because of successful aerosol reduction policies, whereas over South Asia it would decrease by −1.10 W/m2 because of further growth of emissions. A "maximum feasible reduction" of aerosols and their precursors would lead to an increase of the global annual mean aerosol radiative forcing by +1.13 W/m2. Hence, in the latter case, the present day negative anthropogenic aerosol forcing could be more than halved by 2030 because of aerosol reduction policies and climate change thereafter will be to a larger extent be controlled by greenhouse gas emissions. We combined these two opposing future mitigation strategies for a number of experiments focusing on different sectors and regions. In addition, we performed sensitivity studies to estimate the importance of future changes in oxidant concentrations and the importance of the aerosol microphysical coupling within the range of expected future changes. For changes in oxidant concentrations caused by future air pollution mitigation, we do not find a significant effect for the global annual mean radiative aerosol forcing. In the extreme case of only abating SO2 or carbonaceous emissions to a maximum feasible extent, we find deviations from additivity for the radiative forcing over anthropogenic source regions up to 10% compared to an experiment abating both at the same time.

scholarly journals Reply to “Comment on ‘Rethinking the Lower Bound on Aerosol Radiative Forcing’”

2017 ◽  
Vol 30 (16) ◽  
pp. 6585-6589 ◽  
Author(s):  
Bjorn Stevens ◽  
Stephanie Fiedler
Keyword(s):  
Twentieth Century ◽  
Lower Bound ◽  
Radiative Forcing ◽  
Climate Models ◽  
Anthropogenic Aerosols ◽  
Anthropogenic Aerosol ◽  
Aerosol Radiative Forcing ◽  
Clear Sky ◽  
The North ◽  
Aerosol Forcing

Kretzschmar et al., in a comment in 2017, use the spread in the output of aerosol–climate models to argue that the models refute the hypothesis (presented in a paper by Stevens in 2015) that for the mid-twentieth-century warming to be consistent with observations, then the present-day aerosol forcing, [Formula: see text] must be less negative than −1 W m−2. The main point of contention is the nature of the relationship between global SO2 emissions and [Formula: see text] In contrast to the concave (log-linear) relationship used by Stevens and in earlier studies, whereby [Formula: see text] becomes progressively less sensitive to SO2 emissions, some models suggest a convex relationship, which would imply a less negative lower bound. The model that best exemplifies this difference, and that is most clearly in conflict with the hypothesis of Stevens, does so because of an implausible aerosol response to the initial rise in anthropogenic aerosol precursor emissions in East and South Asia—already in 1975 this model’s clear-sky reflectance from anthropogenic aerosol over the North Pacific exceeds present-day estimates of the clear-sky reflectance by the total aerosol. The authors perform experiments using a new (observationally constrained) climatology of anthropogenic aerosols to further show that the effects of changing patterns of aerosol and aerosol precursor emissions during the late twentieth century have, for the same global emissions, relatively little effect on [Formula: see text] These findings suggest that the behavior Kretzschmar et al. identify as being in conflict with the lower bound in Stevens arises from an implausible relationship between SO2 emissions and [Formula: see text] and thus provides little basis for revising this lower bound.

scholarly journals MACv2-SP: a parameterization of anthropogenic aerosol optical properties and an associated Twomey effect for use in CMIP6

2017 ◽  
Vol 10 (1) ◽  
pp. 433-452 ◽  
Author(s):  
Bjorn Stevens ◽  
Stephanie Fiedler ◽  
Stefan Kinne ◽  
Karsten Peters ◽  
Sebastian Rast ◽  
...  
Keyword(s):  
Optical Properties ◽  
Radiative Forcing ◽  
Industrial Emissions ◽  
Max Planck ◽  
Aerosol Optical Properties ◽  
Anthropogenic Aerosol ◽  
Aerosol Radiative Forcing ◽  
Clear Sky ◽  
Aerosol Forcing ◽  
Aerosol Radiative

Abstract. A simple plume implementation of the second version (v2) of the Max Planck Institute Aerosol Climatology, MACv2-SP, is described. MACv2-SP provides a prescription of anthropogenic aerosol optical properties and an associated Twomey effect. It was created to provide a harmonized description of post-1850 anthropogenic aerosol radiative forcing for climate modeling studies. MACv2-SP has been designed to be easy to implement, change and use, and thereby enable studies exploring the climatic effects of different patterns of aerosol radiative forcing, including a Twomey effect. MACv2-SP is formulated in terms of nine spatial plumes associated with different major anthropogenic source regions. The shape of the plumes is fit to the Max Planck Institute Aerosol Climatology, version 2, whose present-day (2005) distribution is anchored by surface-based observations. Two types of plumes are considered: one predominantly associated with biomass burning, the other with industrial emissions. These differ in the prescription of their annual cycle and in their optical properties, thereby implicitly accounting for different contributions of absorbing aerosol to the different plumes. A Twomey effect for each plume is prescribed as a change in the host model's background cloud-droplet population density using relationships derived from satellite data. Year-to-year variations in the amplitude of the plumes over the historical period (1850–2016) are derived by scaling the plumes with associated national emission sources of SO2 and NH3. Experiments using MACv2-SP are performed with the Max Planck Institute Earth System Model. The globally and annually averaged instantaneous and effective aerosol radiative forcings are estimated to be −0.6 and −0.5 W m−2, respectively. Forcing from aerosol–cloud interactions (the Twomey effect) offsets the reduction of clear-sky forcing by clouds, so that the net effect of clouds on the aerosol forcing is small; hence, the clear-sky forcing, which is more readily measurable, provides a good estimate of the total aerosol forcing.

Sign in / Sign up

Export Citation Format

Share Document