Toward understanding the dust deposition in Antarctica during the Last Glacial Maximum: Sensitivity studies on plausible causes

2010 ◽  
Vol 115 (D24) ◽  
Author(s):  
Fuyu Li ◽  
V. Ramaswamy ◽  
Paul Ginoux ◽  
Anthony J. Broccoli ◽  
Thomas Delworth ◽  
...  
Keyword(s):  
Last Glacial Maximum ◽  
Glacial Maximum ◽  
Maximum Sensitivity ◽  
Dust Deposition ◽  
Last Glacial ◽  
Sensitivity Studies ◽  
The Last Glacial Maximum ◽  
The Last Glacial

scholarly journals Effect of high dust amount on surface temperature during the Last Glacial Maximum: a modelling study using MIROC-ESM

2018 ◽  
Vol 14 (11) ◽  
pp. 1565-1581 ◽  
Author(s):  
Rumi Ohgaito ◽  
Ayako Abe-Ouchi ◽  
Ryouta O'ishi ◽  
Toshihiko Takemura ◽  
Akinori Ito ◽  
...  
Keyword(s):  
Last Glacial Maximum ◽  
Northern Hemisphere ◽  
Glacial Maximum ◽  
Polar Regions ◽  
Dust Deposition ◽  
Last Glacial ◽  
Radiative Perturbation ◽  
The Last Glacial Maximum ◽  
High Dust ◽  
The Last Glacial

Abstract. The effect of aerosols is one of many uncertain factors in projections of future climate. However, the behaviour of mineral dust aerosols (dust) can be investigated within the context of past climate change. The Last Glacial Maximum (LGM) is known to have had enhanced dust deposition in comparison with the present, especially over polar regions. Using the Model for Interdisciplinary Research on Climate Earth System Model (MIROC-ESM), we conducted a standard LGM experiment following the protocol of the Paleoclimate Modelling Intercomparison Project phase 3 and sensitivity experiments. We imposed glaciogenic dust on the standard LGM experiment and investigated the impacts of glaciogenic dust and non-glaciogenic dust on the LGM climate. Global mean radiative perturbations by glaciogenic and non-glaciogenic dust were both negative, consistent with previous studies. However, glaciogenic dust behaved differently in specific regions; e.g. it resulted in less cooling over the polar regions. One of the major reasons for reduced cooling is the ageing of snow or ice, which results in albedo reduction via high dust deposition, especially near sources of high glaciogenic dust emission. Although the net radiative perturbations in the lee of high glaciogenic dust provenances are negative, warming by the ageing of snow overcomes this radiative perturbation in the Northern Hemisphere. In contrast, the radiative perturbation due to high dust loading in the troposphere acts to warm the surface in areas surrounding Antarctica, primarily via the longwave aerosol–cloud interaction of dust, and it is likely the result of the greenhouse effect attributable to the enhanced cloud fraction in the upper troposphere. Although our analysis focused mainly on the results of experiments using the atmospheric part of the MIROC-ESM, we also conducted full MIROC-ESM experiments for an initial examination of the effect of glaciogenic dust on the oceanic general circulation module. A long-term trend of enhanced warming was observed in the Northern Hemisphere with increased glaciogenic dust; however, the level of warming around Antarctica remained almost unchanged, even after extended coupling with the ocean.

scholarly journals The effect of high dust amount on the surface temperature during the Last Glacial Maximum: A modelling study using MIROC-ESM

2018 ◽  
Author(s):  
Rumi Ohgaito ◽  
Ayako Abe-Ouchi ◽  
Ryouta O'ishi ◽  
Toshihiko Takemura ◽  
Akinori Ito ◽  
...  
Keyword(s):  
Last Glacial Maximum ◽  
Northern Hemisphere ◽  
Glacial Maximum ◽  
Polar Regions ◽  
Dust Deposition ◽  
Last Glacial ◽  
Radiative Perturbation ◽  
The Last Glacial Maximum ◽  
High Dust ◽  
The Last Glacial

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.

Simulation of the Direct Radiative Effect of Mineral Dust Aerosol on the Climate at the Last Glacial Maximum

2011 ◽  
Vol 24 (3) ◽  
pp. 843-858 ◽  
Author(s):  
Xu Yue ◽  
Huijun Wang ◽  
Hong Liao ◽  
Dabang Jiang
Keyword(s):  
Last Glacial Maximum ◽  
Dust Emission ◽  
Glacial Maximum ◽  
Dust Aerosol ◽  
Radiative Effect ◽  
Last Glacial ◽  
Dust Sources ◽  
Sensitivity Studies ◽  
The Last Glacial Maximum ◽  
The Last Glacial

Abstract The climatic responses to the direct radiative effect of dust aerosol at the Last Glacial Maximum (LGM) are examined using a general circulation model with online simulation of dust. The predicted global dust emission at the LGM is 2.3 times as large as the present-day value, which is the combined effect of the expansion of dust sources and the favorable meteorological parameters (MPs; e.g., the strong surface wind and the low air humidity) under the LGM climate. Simulated global dust emission is 1966 Tg yr−1 with present-day dust sources and MPs, 2820 Tg yr−1 with LGM dust sources and current MPs, 2599 Tg yr−1 with present-day dust sources and LGM MPs, and 4579 Tg yr−1 with LGM sources and MPs. The simulated percentage increases of dust concentrations are the largest at high latitudes in both hemispheres, which are consistent with the deposition data from geological records. The LGM dust is estimated to exert global annual-mean shortwave (SW) and longwave (LW) radiative forcing (RF) of −4.69 and +1.70 W m−2 at the surface, respectively, and −0.58 and +0.68 W m−2 at the top of the atmosphere, respectively. On a global- and annual-mean basis, surface air temperature (SAT) is predicted to be reduced by 0.18 K and precipitation is reduced by 0.06 mm day−1, as a result of the net (SW and LW) radiative effect of dust at the LGM. Two sensitivity studies are performed to identify the uncertainties in simulated climatic effect of LGM dust that arise from the assumed LW and/or SW absorption by dust: 1) in the absence of dust LW radiative effect, the LGM global- and annual-mean SAT is predicted to be further reduced by 0.19 K; and 2) when the single scattering albedo of the Saharan dust at 0.55 μm is increased from 0.89 to 0.98 in the LGM climate simulation, the LGM dust-induced annual- and global-mean surface cooling increases from 0.18 to 0.63 K even with both SW and LW radiative effects of dust. In these two sensitivity studies, the LGM dust is predicted to induce an average cooling of 0.42 and 0.72 K in SAT, respectively, over the tropical oceans.

Reconstructions of the past distribution of Testudo graeca mitochondrial lineages in the Middle East and Transcaucasia support multiple refugia since the Last Glacial Maximum

2021 ◽  
pp. 10-17
Author(s):  
Oguz Turkozan
Keyword(s):  
Middle East ◽  
Last Glacial Maximum ◽  
Glacial Maximum ◽  
Testudo Graeca ◽  
Last Glacial ◽  
The Past ◽  
Precipitation Seasonality ◽  
Multiple Refugia ◽  
The Last Glacial Maximum ◽  
The Last Glacial

A cycle of glacial and interglacial periods in the Quaternary caused species’ ranges to expand and contract in response to climatic and environmental changes. During interglacial periods, many species expanded their distribution ranges from refugia into higher elevations and latitudes. In the present work, we projected the responses of the five lineages of Testudo graeca in the Middle East and Transcaucasia as the climate shifted from the Last Glacial Maximum (LGM, Mid – Holocene), to the present. Under the past LGM and Mid-Holocene bioclimatic conditions, models predicted relatively more suitable habitats for some of the lineages. The most significant bioclimatic variables in predicting the present and past potential distribution of clades are the precipitation of the warmest quarter for T. g. armeniaca (95.8 %), precipitation seasonality for T. g. buxtoni (85.0 %), minimum temperature of the coldest month for T. g. ibera (75.4 %), precipitation of the coldest quarter for T. g. terrestris (34.1 %), and the mean temperature of the driest quarter for T. g. zarudyni (88.8 %). Since the LGM, we hypothesise that the ranges of lineages have either expanded (T. g. ibera), contracted (T. g. zarudnyi) or remained stable (T. g. terrestris), and for other two taxa (T. g. armeniaca and T. g. buxtoni) the pattern remains unclear. Our analysis predicts multiple refugia for Testudo during the LGM and supports previous hypotheses about high lineage richness in Anatolia resulting from secondary contact.

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