Radiative forcing of climate by ice-age atmospheric dust

Claquin, T.; Roelandt, C.; Kohfeld, K. E.; Harrison, S. P.; Tegen, Ina; Prentice, I. Colin; Balkanski, Yves; Bergametti, Gilles; Hansson, Margareta; Mahowald, N. M.; Rodhe, Håkan; Schulz, Mıchael

doi:10.1007/s00382-002-0269-1

Cited by 149 publications

(101 citation statements)

References 38 publications

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“…Model-based estimates (Claquin et al 2003;Mahowald et al 2006) show the change in dust forcing is larger over land than over ocean, and the magnitude and even the sign of the forcing varies latitudinally. This could potentially contribute to the latitudinal differences found in the simulated temperature biases (see e.g.…”

Section: Discussionmentioning

confidence: 99%

“…Mahowald et al (2006) showed a small positive forcing over the equatorial oceans, which could help to explain why the present generation of models tends to overestimate SST cooling in the tropics. These two experiments (Claquin et al 2003;Mahowald et al 2006) are both constrained by observed LGM dust fluxes but give different results for the magnitude of the global dust forcing (-0.9 and -2.0 Wm -2 ) and also show different spatial patterns. Furthermore, these dust-forcing estimates do not take account of interactions between dust and clouds.…”

Section: Discussionmentioning

confidence: 99%

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Climate model benchmarking with glacial and mid-Holocene climates

et al. 2013

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Past climates provide a test of models' ability to predict climate change. We present a comprehensive evaluation of state-of-the-art models against Last Glacial Maximum and mid-Holocene climates, using reconstructions of land and ocean climates and simulations from the Palaeoclimate Modelling and Coupled Modelling Intercomparison Projects. Newer models do not perform better than earlier versions despite higher resolution and complexity. Differences in climate sensitivity only weakly account for differences in model performance. In the glacial, models consistently underestimate land cooling (especially in winter) and overestimate ocean surface cooling (especially in the tropics). In the mid-Holocene, models generally underestimate the precipitation increase in the northern monsoon regions, and overestimate summer warming in central Eurasia. Models generally capture large-scale gradients of climate change but have more limited ability to reproduce spatial patterns. Despite these common biases, some models perform better than others.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Climate model benchmarking with glacial and mid-Holocene climates

et al. 2013

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“…Calculations of the direct dust radiative forcing at TOA with a global climate model for LGM and present-day time slices by Claquin et al (2003) utilize the dust fields simulated by Mahowald et al (1999). These dust fields are vertically integrated and transformed to aerosol optical thickness (AOT) at a wavelength of 0.55 µm, resulting in mean AOT of 0.14 and 0.05 for LGM and modern climates, respectively.…”

Section: E Bauer and A Ganopolski: Sensitivity Simulations With Dusmentioning

confidence: 99%

“…Mahowald et al (2006b) find intermediate values of the net dust radiative forcing at TOA of −0.96 and −1.47 W m −2 for the two LGM cases without and with glaciogenic dust sources, respectively, and −0.87 W m −2 for preindustrial conditions. Different possibilities might be responsible for the stronger negative dust radiative forcing obtained by Claquin et al (2003) than by Takemura et al (2009). Differences in radiative forcing could be caused by different optical parameters and the use of different shortwave schemes which impede a direct comparison.…”

Section: E Bauer and A Ganopolski: Sensitivity Simulations With Dusmentioning

confidence: 99%

“…Differences in radiative forcing could be caused by different optical parameters and the use of different shortwave schemes which impede a direct comparison. Claquin et al (2003) used different single-scattering albedos for desert soils with different mineralogical composition. Takemura et al (2009) accounted for size-dependent extinction coefficients (Takemura et al, 2002) and used a RI value for soil dust (see Appendix) based on recent studies (Takemura et al, 2005).…”

Section: E Bauer and A Ganopolski: Sensitivity Simulations With Dusmentioning

confidence: 99%

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Sensitivity simulations with direct shortwave radiative forcing by aeolian dust during glacial cycles

Bauer

Ganopolski

2014

Clim. Past

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Abstract. Possible feedback effects between aeolian dust, climate and ice sheets are studied for the first time with an Earth system model of intermediate complexity over the late Pleistocene period. Correlations between climate and dust deposition records suggest that aeolian dust potentially plays an important role for the evolution of glacial cycles. Here climatic effects from the dust direct radiative forcing (DRF) caused by absorption and scattering of solar radiation are investigated. Key elements controlling the dust DRF are the atmospheric dust distribution and the absorption-scattering efficiency of dust aerosols. Effective physical parameters in the description of these elements are varied within uncertainty ranges known from available data and detailed model studies. Although the parameters can be reasonably constrained, the simulated dust DRF spans a wide uncertainty range related to the strong nonlinearity of the Earth system. In our simulations, the dust DRF is highly localized. Medium-range parameters result in negative DRF of several watts per square metre in regions close to major dust sources and negligible values elsewhere. In the case of high absorption efficiency, the local dust DRF can reach positive values and the global mean DRF can be insignificantly small. In the case of low absorption efficiency, the dust DRF can produce a significant global cooling in glacial periods, which leads to a doubling of the maximum glacial ice volume relative to the case with small dust DRF. DRF-induced temperature and precipitation changes can either be attenuated or amplified through a feedback loop involving the dust cycle. The sensitivity experiments suggest that depending on dust optical parameters, dust DRF has the potential to either damp or reinforce glacial-interglacial climate changes.

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Improved dust representation in the Community Atmosphere Model

Albani

Mahowald

Perry

et al. 2014

J Adv Model Earth Syst

302

466

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Aerosol-climate interactions constitute one of the major sources of uncertainty in assessing changes in aerosol forcing in the anthropocene as well as understanding glacial-interglacial cycles. Here we focus on improving the representation of mineral dust in the Community Atmosphere Model and assessing the impacts of the improvements in terms of direct effects on the radiative balance of the atmosphere. We simulated the dust cycle using different parameterization sets for dust emission, size distribution, and optical properties. Comparing the results of these simulations with observations of concentration, deposition, and aerosol optical depth allows us to refine the representation of the dust cycle and its climate impacts. We propose a tuning method for dust parameterizations to allow the dust module to work across the wide variety of parameter settings which can be used within the Community Atmosphere Model. Our results include a better representation of the dust cycle, most notably for the improved size distribution. The estimated net top of atmosphere direct dust radiative forcing is 20.23 6 0.14 W/m 2 for present day and 20.32 6 0.20 W/m 2 at the Last Glacial Maximum. From our study and sensitivity tests, we also derive some general relevant findings, supporting the concept that the magnitude of the modeled dust cycle is sensitive to the observational data sets and size distribution chosen to constrain the model as well as the meteorological forcing data, even within the same modeling framework, and that the direct radiative forcing of dust is strongly sensitive to the optical properties and size distribution used.

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Radiative forcing of climate by ice-age atmospheric dust

Cited by 149 publications

References 38 publications

Climate model benchmarking with glacial and mid-Holocene climates

Climate model benchmarking with glacial and mid-Holocene climates

Sensitivity simulations with direct shortwave radiative forcing by aeolian dust during glacial cycles

Improved dust representation in the Community Atmosphere Model

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