Cloud susceptibility and the first aerosol indirect forcing: Sensitivity to black carbon and aerosol concentrations

Chuang, Catherine C.; Penner, Joyce E.; Prospero, Joseph M.; Grant, K. E.; Rau, G.; Kawamoto, Kazuhiko

doi:10.1029/2000jd000215

Cited by 143 publications

(168 citation statements)

References 69 publications

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“…However, Bowman and Henze (2012) showed that for the short-lived greenhouse gas, O 3 , tropical emissions lead to an enhanced RF relative to extratropical emissions. This is also potentially important for aerosols, including direct effects, due to latitudinal changes in solar insolation, and indirect effects, due to regional differences in cloud regimes (Chuang et al, 2002). show that ascribing RF from short-lived forcing agents to individual locations based on proportional emissions is reasonable for comparing the climate impacts of developed countries, as a group, to developing countries.…”

Section: Ascribing Rf To the Gridmentioning

confidence: 99%

Local sources of global climate forcing from different categories of land use activities

Ward

Mahowald

2015

Earth Syst. Dynam.

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Abstract. Identifying and quantifying the sources of climate impacts from land use and land cover change (LULCC) is necessary to optimize policies regarding LULCC for climate change mitigation. These climate impacts are typically defined relative to emissions of CO 2 , or sometimes emissions of other long-lived greenhouse gases. Here we use previously published estimates of the radiative forcing (RF) of LULCC that include the short-lived forcing agents O 3 and aerosols, in addition to long-lived greenhouse gases and land albedo change, for six projections of LULCC as a metric for quantifying climate impacts. The LULCC RF is attributed to three categories of LULCC activities: direct modifications to land cover, agriculture, and wildfire response, and sources of the forcing are ascribed to individual grid points for each sector. Results for the year 2010 show substantial positive forcings from the direct modifications and agriculture sectors, particularly from south and southeast Asia, and a smaller magnitude negative forcing response from wildfires. The spatial distribution of future sources of LULCC RF is highly scenario-dependent, but we show that future forest area change can be used as a predictor of the future RF from direct modification activities, especially in the tropics, suggesting that deforestation-prevention policies that value land based on its C-content may be particularly effective at mitigating climate forcing originating in the tropics from this sector. However, the response of wildfire RF to tropical land cover changes is not as easily scalable and yet imposes a non-trivial feedback onto the total LULCC RF.

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Section: Ascribing Rf To the Gridmentioning

confidence: 99%

Local sources of global climate forcing from different categories of land use activities

Ward

Mahowald

2015

Earth Syst. Dynam.

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“…This suggests a globally important role for short-range transport of smoke from tropical fires on the easterly trade winds to nearcoast marine stratocumulus cloud decks. Chuang et al (2002) note that these clouds are particularly susceptible to changes in optical thickness from an influx of high aerosol number concentration because of the low marine aerosol number concentrations. In our simulations, fire aerosols cause a two-fold increase in cloud droplet number concentration (CDNC) in the low clouds in areas off the west coasts of South America and central Africa, as well as a 10 % decrease in cloud droplet effective radius in the same areas.…”

Section: Aerosol Direct Effectmentioning

confidence: 99%

The changing radiative forcing of fires: global model estimates for past, present and future

et al. 2012

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Abstract. Fires are a global phenomenon that impact climate and biogeochemical cycles, and interact with the biosphere, atmosphere and cryosphere. These impacts occur on a range of temporal and spatial scales and are difficult to quantify globally based solely on observations. Here we assess the role of fires in the climate system using model estimates of radiative forcing (RF) from global fires in preindustrial, present day, and future time periods. Fire emissions of trace gases and aerosols are derived from Community Land Model simulations and then used in a series of Community Atmosphere Model simulations with representative emissions from the years 1850, 2000, and 2100. Additional simulations are carried out with fire emissions from the Global Fire Emission Database for a present-day comparison. These results are compared against the results of simulations with no fire emissions to compute the contribution from fires. We consider the impacts of fire on greenhouse gas concentrations, aerosol effects (including aerosol effects on biogeochemical cycles), and land and snow surface albedo. Overall, we estimate that pre-industrial fires were responsible for a RF of −1 W m −2 with respect to a pre-industrial climate without fires. The largest magnitude pre-industrial forcing from fires was the indirect aerosol effect on clouds (−1.6 W m −2 ). This was balanced in part by an increase in carbon dioxide concentrations due to fires (+0.83 W m −2 ). The RF of fires increases by 0.5 W m −2 from 1850 to 2000 and 0.2 W m −2 from 1850 to 2100 in the model representation from a combination of changes in fire activity and changes in the background environment in which fires occur, especially increases and decreases in the anthropogenic aerosol burden. Thus, fires play an important role in both the natural equilibrium climate and the climate perturbed by anthropogenic activity and need to be considered in future climate projections.

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“…Some studies have estimated a global cloud albedo forcing of −0.5 W m −2 and predict net positive forcing (Hansen et al, 2005(Hansen et al, , 2007, while others suggest a large cloud albedo forcing of between −0.9 W m −2 (Lohmann et al, 2000) and −1.68 W m −2 (Chuang et al, 2002) potentially Published by Copernicus Publications on behalf of the European Geosciences Union. 9068 D. V. Spracklen et al: Global cloud condensation nuclei sufficient to produce a net negative forcing due to carbonaceous combustion aerosol.…”

Section: Introductionmentioning

confidence: 99%

“…However, carbonaceous combustion aerosol also contains particulate organic matter (POM), which can have a cooling effect on climate because it scatters solar radiation and can enable carbonaceous combustion aerosol to act as cloud condensation nuclei (CCN) and form cloud drops, increasing cloud albedo (Chuang et al, 2002;Lohmann et al, 2000) -the so-called first aerosol indirect effect (AIE). Some studies have estimated a global cloud albedo forcing of −0.5 W m −2 and predict net positive forcing (Hansen et al, 2005(Hansen et al, , 2007, while others suggest a large cloud albedo forcing of between −0.9 W m −2 (Lohmann et al, 2000) and −1.68 W m −2 (Chuang et al, 2002) potentially Published by Copernicus Publications on behalf of the European Geosciences Union.…”

Section: Introductionmentioning

confidence: 99%

Global cloud condensation nuclei influenced by carbonaceous combustion aerosol

et al. 2011

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Abstract. Black carbon in carbonaceous combustion aerosol warms the climate by absorbing solar radiation, meaning reductions in black carbon emissions are often perceived as an attractive global warming mitigation option. However, carbonaceous combustion aerosol can also act as cloud condensation nuclei (CCN) so they also cool the climate by increasing cloud albedo. The net radiative effect of carbonaceous combustion aerosol is uncertain because their contribution to CCN has not been evaluated on the global scale. By combining extensive observations of CCN concentrations with the GLOMAP global aerosol model, we find that the model is biased low (normalised mean bias = −77 %) unless carbonaceous combustion aerosol act as CCN. We show that carbonaceous combustion aerosol accounts for more than half (52-64 %) of global CCN with the range due to uncertainty in the emitted size distribution of carbonaceous combustion particles. The model predicts that wildfire and pollution (fossil fuel and biofuel) carbonaceous combustion aerosol causes a global mean cloud albedo aerosol indirect effect of −0.34 W m −2 , with stronger cooling if we assume smaller particle emission size. We calculate that carbonaceous combustion aerosol from pollution sources cause a global mean aerosol indirect effect of −0.23 W m −2 . The small size of carbonaceous combustion particles from fossil fuel sources means that whilst pollution sources account for only onethird of the emitted mass they cause two-thirds of the cloud albedo aerosol indirect effect that is due to carbonaceous combustion aerosol. This cooling effect must be accounted for, along with other cloud effects not studied here, to ensure that black carbon emissions controls that reduce the high number concentrations of fossil fuel particles have the desired net effect on climate.

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Cloud susceptibility and the first aerosol indirect forcing: Sensitivity to black carbon and aerosol concentrations

Cited by 143 publications

References 69 publications

Local sources of global climate forcing from different categories of land use activities

Local sources of global climate forcing from different categories of land use activities

The changing radiative forcing of fires: global model estimates for past, present and future

Global cloud condensation nuclei influenced by carbonaceous combustion aerosol

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