Last Deglaciation—Holocene Australian-Indonesian Monsoon Rainfall Changes Off Southwest Sumba, Indonesia

Previous studies suggested the multi-millennial scale changes of Australian-Indonesian monsoon (AIM) rainfall, but little is known about their mechanism. Here, AIM rainfall changes since the Last Deglaciation (~18 ka BP) are inferred from geochemical elemental ratios (terrigenous input) and palynological proxies (pollen and spores). Pollen and spores indicate drier Last Deglaciation (before ~11 ka BP) and wetter Holocene climates (after ~11 ka BP). Terrigenous input proxies infer three drier periods (i.e., before ~17, ~15–13.5, and 7–3 ka BP) and three wetter periods (i.e., ~17–15, ~13.5–7, and after ~3 ka BP) which represent the Australian-Indonesian summer monsoon (AISM) rainfall changes. Pollen and spores were highly responsive to temperature changes and showed less sensitivity to rainfall changes due to their wider source area, indicating their incompatibility as rainfall proxy. During the Last Deglaciation, AISM rainfall responded to high latitude climatic events related to the latitudinal shifts of the austral summer ITCZ. Sea level rise, solar activity, and orbitally-induced insolation were most likely the primary driver of AISM rainfall changes during the Holocene, but the driving mechanisms behind the latitudinal shifts of the austral summer ITCZ during this period are not yet understood.

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North Atlantic sea-surface temperature changes and the climate of western Iberia during the last deglaciation; a marine palynological approach

Global and Planetary Change ◽

10.1016/s0921-8181(01)00075-3 ◽

2001 ◽

Vol 30 (1-2) ◽

pp. 33-39 ◽

Cited By ~ 48

Author(s):

Karin P Boessenkool ◽

Henk Brinkhuis ◽

Joachim Schönfeld ◽

Jordi Targarona

Keyword(s):

Surface Temperature ◽

Sea Surface Temperature ◽

North Atlantic ◽

Sea Surface ◽

Last Deglaciation ◽

Temperature Changes ◽

The Last Deglaciation

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Long-chain alkenone-inferred temperatures from the last deglaciation to the early Holocene recorded by annually laminated sediments of the maar lake Sihailongwan, northeastern China

The Holocene ◽

10.1177/0959683618761546 ◽

2018 ◽

Vol 28 (7) ◽

pp. 1173-1180 ◽

Cited By ~ 3

Author(s):

Qing Sun ◽

Guoqiang Chu ◽

Manman Xie ◽

Yuan Ling ◽

Youliang Su ◽

...

Keyword(s):

Temperature Increase ◽

Growing Season ◽

Northeastern China ◽

Early Holocene ◽

Laminated Sediments ◽

Last Deglaciation ◽

Temperature Changes ◽

Maar Lake ◽

The Last Deglaciation ◽

Annually Laminated Sediments

Abrupt temperature changes during the last deglaciation are well recognized in Greenland ice cores and in deep-sea sediment records. On the continent of monsoonal Asia, however, only a few terrestrial temperature reconstructions extend to the Younger Dryas (YD). This hampers the understanding of how the Asian monsoon system responded to large-scale boundary changes in ice-sheet dynamics and reorganizations of atmospheric–oceanic circulation between the last deglaciation and the Holocene. Here, we report an alkenone-inferred temperature record from varved sediments of the maar lake Sihailongwan, northeastern China. Alkenone provides temperatures that represent the water temperature during the growing season when the lake is ice-free. Annually laminated sediments provide a reliable time control. Reconstructed temperatures reveal a distinctive pattern of variations during the last deglaciation: a temperature increase of 6°C at the onset of the Bølling–Allerød, two cold intervals (during the Older Dryas and the intra-Allerød cold period), a relatively minor temperature decrease of 1–3°C during the YD, and a rapid temperature increase of 4–5°C at the early Holocene. The reconstructed temperature records from Lake Sihailongwan and adjacent regions indicate that summer (or growing season) temperature changes were smaller than is evident in Greenland ice core records that are weighted toward winter.

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High-latitude warming initiated the onset of the last deglaciation in the tropics

Science Advances ◽

10.1126/sciadv.aaw2610 ◽

2019 ◽

Vol 5 (12) ◽

pp. eaaw2610 ◽

Cited By ~ 2

Author(s):

Margaret S. Jackson ◽

Meredith A. Kelly ◽

James M. Russell ◽

Alice M. Doughty ◽

Jennifer A. Howley ◽

...

Keyword(s):

High Latitude ◽

Global Climate ◽

Ice Sheet ◽

Polar Regions ◽

Last Deglaciation ◽

Low Latitude ◽

Temperature Changes ◽

The Last Deglaciation ◽

Climate Forcings ◽

The Tropics

Atmospheric greenhouse gas concentrations are thought to have synchronized global temperatures during Pleistocene glacial–interglacial cycles, yet their impact relative to changes in high-latitude insolation and ice-sheet extent remains poorly constrained. Here, we use tropical glacial fluctuations to assess the timing of low-latitude temperature changes relative to global climate forcings. We report 10Be ages of moraines in tropical East Africa and South America and show that glaciers reached their maxima at ~29 to 20 ka, during the global Last Glacial Maximum. Tropical glacial recession was underway by 20 ka, before the rapid CO2 rise at ~18.2 ka. This “early” tropical warming was influenced by rising high-latitude insolation and coincident ice-sheet recession in both polar regions, which lowered the meridional thermal gradient and reduced tropical heat export to the high latitudes.

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Modelling the firn thickness evolution during the last deglaciation: constrains on sensitivity to temperature and impurities

10.5194/cp-2016-91 ◽

2016 ◽

Author(s):

Camille Bréant ◽

Patricia Martinerie ◽

Anaïs Orsi ◽

Laurent Arnaud ◽

Amaëlle Landais

Keyword(s):

Accumulation Rate ◽

Ice Cores ◽

Ice Age ◽

Age Difference ◽

Last Deglaciation ◽

High Accumulation ◽

Temperature Changes ◽

Gas Trapping ◽

Different Temperatures ◽

The Last Deglaciation

Abstract. The transformation of snow into ice is a complex phenomenon difficult to model. Depending on surface temperature and accumulation rate, it may take several decades to millennia for air to be entrapped in ice. The air is thus always younger that the surrounding ice. The resulting gas-ice age difference is essential to document the phasing between CO2 and temperature changes especially during deglaciations. The air trapping depth can be inferred in the past using a firn densification model, or using δ15N of air measured in ice cores. All firn densification models applied to deglaciations show a large disagreement with δ15N measurements in several sites of East Antarctica, predicting larger firn thickness during the Last Glacial Maximum, whereas δ15N suggests a reduced firn thickness compared to the Holocene. We present here modifications of the LGGE firn densification model, which significantly reduce the model-data mismatch for the gas trapping depth evolution over the last deglaciation, while preserving the good agreement between measured and modelled modern firn density profiles. In particular, we introduce a dependency of the activation energy to temperature and impurities in the firn densification rate calculation. The temperature influence reflects the existence of different mechanisms for firn compaction at different temperatures. We show that both the new temperature parameterization and the influence of impurities contribute to the increased agreement between modelled and measured δ15N evolution during the last deglaciation at sites with low temperature and low accumulation rate, such as Dome C or Vostok. However, the inclusion of impurities effects deteriorates the agreement between modelled and measured δ15N evolution in Greenland and Antarctic sites with high accumulation.

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