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7. Western Pacific hydroclimate linked to global climate variability over the past two millennia.

Author

Griffiths, Michael L, Kimbrough, Alena K, Gagan, Michael K, Drysdale, Russell N, Cole, Julia E, Johnson, Kathleen R, Zhao, Jian-Xin, Cook, Benjamin I, Hellstrom, John C, and Hantoro, Wahyoe S

Abstract

Interdecadal modes of tropical Pacific ocean-atmosphere circulation have a strong influence on global temperature, yet the extent to which these phenomena influence global climate on multicentury timescales is still poorly known. Here we present a 2,000-year, multiproxy reconstruction of western Pacific hydroclimate from two speleothem records for southeastern Indonesia. The composite record shows pronounced shifts in monsoon rainfall that are antiphased with precipitation records for East Asia and the central-eastern equatorial Pacific. These meridional and zonal patterns are best explained by a poleward expansion of the Australasian Intertropical Convergence Zone and weakening of the Pacific Walker circulation (PWC) between ∼1000 and 1500 CE Conversely, an equatorward contraction of the Intertropical Convergence Zone and strengthened PWC occurred between ∼1500 and 1900 CE. Our findings, together with climate model simulations, highlight the likelihood that century-scale variations in tropical Pacific climate modes can significantly modulate radiatively forced shifts in global temperature.

Published
2016

9. Intensification of the meridional temperature gradient in the Great Barrier Reef following the Last Glacial Maximum.

Author

Felis, Thomas, McGregor, Helen V, Linsley, Braddock K, Tudhope, Alexander W, Gagan, Michael K, Suzuki, Atsushi, Inoue, Mayuri, Thomas, Alexander L, Esat, Tezer M, Thompson, William G, Tiwari, Manish, Potts, Donald C, Mudelsee, Manfred, Yokoyama, Yusuke, and Webster, Jody M

Abstract

Tropical south-western Pacific temperatures are of vital importance to the Great Barrier Reef (GBR), but the role of sea surface temperatures (SSTs) in the growth of the GBR since the Last Glacial Maximum remains largely unknown. Here we present records of Sr/Ca and δ(18)O for Last Glacial Maximum and deglacial corals that show a considerably steeper meridional SST gradient than the present day in the central GBR. We find a 1-2 °C larger temperature decrease between 17° and 20°S about 20,000 to 13,000 years ago. The result is best explained by the northward expansion of cooler subtropical waters due to a weakening of the South Pacific gyre and East Australian Current. Our findings indicate that the GBR experienced substantial meridional temperature change during the last deglaciation, and serve to explain anomalous deglacial drying of northeastern Australia. Overall, the GBR developed through significant SST change and may be more resilient than previously thought.

Published
2014

17. Tropical vegetation productivity and atmospheric methane over the last 40,000 years from model simulations and stalagmites in Sulawesi, Indonesia.

Author

Krause, Claire E., Kimbrough, Alena K., Gagan, Michael K., Hopcroft, Peter O., Dunbar, Gavin B., Hantoro, Wahyoe S., Hellstrom, John C., Cheng, Hai, Edwards, R. Lawrence, Wong, Henri, Suwargadi, Bambang W., Valdes, Paul J., and Rifai, Hamdi

Subjects
STALACTITES & stalagmites, SOIL respiration, ANTARCTIC ice, ICE cores, SOIL productivity, ATMOSPHERIC methane, VEGETATION dynamics
Abstract

Recent research has shown the potential of speleothem δ13C to record a range of environmental processes. Here, we report on 230Th-dated stalagmite δ13C records for southwest Sulawesi, Indonesia, over the last 40,000 yr to investigate the relationship between tropical vegetation productivity and atmospheric methane concentrations. We demonstrate that the Sulawesi stalagmite δ13C record is driven by changes in vegetation productivity and soil respiration and explore the link between soil respiration and tropical methane emissions using HadCM3 and the Sheffield Dynamic Global Vegetation Model. The model indicates that changes in soil respiration are primarily driven by changes in temperature and CO2, in line with our interpretation of stalagmite δ13C. In turn, modelled methane emissions are driven by soil respiration, providing a mechanism that links methane to stalagmite δ13C. This relationship is particularly strong during the last glaciation, indicating a key role for the tropics in controlling atmospheric methane when emissions from high-latitude boreal wetlands were suppressed. With further investigation, the link between δ13C in stalagmites and tropical methane could provide a low-latitude proxy complementary to polar ice core records to improve our understanding of the glacial–interglacial methane budget. [ABSTRACT FROM AUTHOR]

Published
2024
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26. Dealing with climate change: Palaeoclimate research in Australia

Author

Meissner, Katrin, Abram, Nerilie, Armand, Leanne, Chase, Zanna, De Deckker, Patrick, Ellwood, Michael, Exon, Neville, Gagan, Michael, Goodwin, Ian, Howard, Will, Lough, Janice, McCulloch, Malcolm, McGregor, Helen, Moy, Andrew, O’Leary, Mick, Phipps, Steven, Skilbeck, Greg, Webster, Jody, Welsh, Kevin, and Zinke, Jens

Published
2015

32. Palaeoenvironmental change in tropical Australasia over the last 30,000 years – a synthesis by the OZ-INTIMATE group

Author

Reeves, Jessica M., Bostock, Helen C., Ayliffe, Linda K., Barrows, Timothy T., De Deckker, Patrick, Devriendt, Laurent S., Dunbar, Gavin B., Drysdale, Russell N., Fitzsimmons, Kathryn E., Gagan, Michael K., Griffiths, Michael L., Haberle, Simon G., Jansen, John D., Krause, Claire, Lewis, Stephen, McGregor, Helen V., Mooney, Scott D., Moss, Patrick, Nanson, Gerald C., Purcell, Anthony, and van der Kaars, Sander

Published
2013
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47. Seasonal characteristics of the Indian Ocean Dipole during the Holocene epoch

Author

Abram, Nerilie J., Gagan, Michael K., Liu, Zhengyu, Hantoro, Wahyoe S., McCulloch, Malcolm T., and Suwargadi, Bambang W.

Subjects
Environmental issues, Science and technology, Zoology and wildlife conservation
Abstract

Author(s): Nerilie J. Abram (corresponding author) [1, 6]; Michael K. Gagan (corresponding author) [1]; Zhengyu Liu [2, 3, 4]; Wahyoe S. Hantoro [5]; Malcolm T. McCulloch [1]; Bambang W. Suwargadi [...]

Published
2007
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