Journal cover Journal topic
Climate of the Past An interactive open-access journal of the European Geosciences Union
https://doi.org/10.5194/cp-2018-2
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.
Research article
21 Feb 2018
Review status
This discussion paper is a preprint. It is a manuscript under review for the journal Climate of the Past (CP).
The effect of high dust amount on the surface temperature during the Last Glacial Maximum: A modelling study using MIROC-ESM
Rumi Ohgaito1, Ayako Abe-Ouchi2,1, Ryouta O'ishi2, Toshihiko Takemura3, Akinori Ito1, Tomohiro Hajima1, Shingo Watanabe1, and Michio Kawamiya1 1Japan Agency for Marine-Earth Science and Technology, Yokohama, 236-0001, Japan
2Atmosphere Ocean Research Institute, University of Tokyo, Kashiwa, Chiba 277-8564, Japan
3Research Institute for Applied Mechanics, Kyushu University, Fukuoka, 816-8580 Japan
Abstract. The effect of aerosols is one of the many uncertain factors in projections of the future climate. However, the behaviour of mineral dust aerosol (dust) can be investigated in the context of past climate changes. The Last Glacial Maximum (LGM) is known to have resulted in an enhancement of the dust deposition, especially over the polar regions. Using the Model for Interdisciplinary Research on Climate Earth System Model (MIROC-ESM), we investigated the impact of glaciogenic dust on the climate of the LGM and found that the effect of the enhancement of dust results in less cooling over the polar regions. One of the major reasons of the reduced cooling is the ageing of snow or ice, resulting in the reduction of the albedo by a high dust deposition, especially in the vicinity of high glaciogenic dust emissions. Although the net radiative perturbations in the lee of high glaciogenic dust provenances are negative, warming by ageing of snow overcomes this radiative perturbation in the Northern Hemisphere. In contrast, the radiative perturbation by the high dust loading in the troposphere acts to warm the surface surrounding Antarctica, which is mainly caused by the longwave aerosol–cloud interaction of dust and is likely the result of the greenhouse effect of the enhanced cloud fraction in the upper troposphere. Although our analysis mainly focused on the results of the experiments using the atmospheric part of the MIROC-ESM, we also conducted full MIROC-ESM experiments for a first trial of glacial dust modelling. The long-term trend to enhance warming in the Northern Hemisphere with the increase of glaciogenic dust was observed, whereas the warming level around Antarctica is almost unchanged, even after an extended interaction with the ocean.
Citation: Ohgaito, R., Abe-Ouchi, A., O'ishi, R., Takemura, T., Ito, A., Hajima, T., Watanabe, S., and Kawamiya, M.: The effect of high dust amount on the surface temperature during the Last Glacial Maximum: A modelling study using MIROC-ESM, Clim. Past Discuss., https://doi.org/10.5194/cp-2018-2, in review, 2018.
Rumi Ohgaito et al.
Rumi Ohgaito et al.
Rumi Ohgaito et al.

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Short summary
The behaviour of dust on climate can be investigated using past climate. The Last Glacial Maximum (LGM, 21 000 years before present) is known to be dustier. We investigated the impact of plausible dust distribution on the climate of the LGM using an Earth System Model and found that the effect of the LGM dust results in less cooling over the polar regions. Main finding is that the radiative perturbation by the high dust loading in the troposphere acts to warm the surface surrounding Antarctica.
The behaviour of dust on climate can be investigated using past climate. The Last Glacial...
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