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  • Open Access English
    Authors: 
    A. M. Haywood; J. C. Tindall; H. J. Dowsett; A. M. Dolan; K. M. Foley; S. J. Hunter; D. J. Hill; W.-L. Chan; A. Abe-Ouchi; C. Stepanek; +26 more
    Publisher: HAL CCSD
    Countries: United Kingdom, Norway, France
    Project: NSERC , EC | PLIO-ESS (278636), NSF | Collaborative Research: A... (1418411), NWO | Mechanisms of major clima... (32604), NSF | The Management and Operat... (1852977)

    The Pliocene epoch has great potential to improve our understanding of the long-term climatic and environmental consequences of an atmospheric CO2 concentration near ∼400 parts per million by volume. Here we present the large-scale features of Pliocene climate as simulated by a new ensemble of climate models of varying complexity and spatial resolution based on new reconstructions of boundary conditions (the Pliocene Model Intercomparison Project Phase 2; PlioMIP2). As a global annual average, modelled surface air temperatures increase by between 1.7 and 5.2 ∘C relative to the pre-industrial era with a multi-model mean value of 3.2 ∘C. Annual mean total precipitation rates increase by 7 % (range: 2 %–13 %). On average, surface air temperature (SAT) increases by 4.3 ∘C over land and 2.8 ∘C over the oceans. There is a clear pattern of polar amplification with warming polewards of 60∘ N and 60∘ S exceeding the global mean warming by a factor of 2.3. In the Atlantic and Pacific oceans, meridional temperature gradients are reduced, while tropical zonal gradients remain largely unchanged. There is a statistically significant relationship between a model's climate response associated with a doubling in CO2 (equilibrium climate sensitivity; ECS) and its simulated Pliocene surface temperature response. The mean ensemble Earth system response to a doubling of CO2 (including ice sheet feedbacks) is 67 % greater than ECS; this is larger than the increase of 47 % obtained from the PlioMIP1 ensemble. Proxy-derived estimates of Pliocene sea surface temperatures are used to assess model estimates of ECS and give an ECS range of 2.6–4.8 ∘C. This result is in general accord with the ECS range presented by previous Intergovernmental Panel on Climate Change (IPCC) Assessment Reports.

  • Open Access English
    Authors: 
    Noorbergen, Lars J.; Abels, Hemmo A.; Hilgen, Frits J.; Robson, Brittany E.; de Jong, Edwin; Dekkers, Mark J.; Krijgsman, Wout; Smit, Jan; Collinson, Margaret E.; Kuiper, Klaudia F.; +4 more
    Country: Netherlands
    Project: NWO | Tephrostratigraphy and ge... (10363)

    Fluvial systems in which peat formation occurs are typified by autogenic processes such as river meandering, crevasse splaying and channel avulsion. Nevertheless, autogenic processes cannot satisfactorily explain the repetitive nature and lateral continuity of many coal seams (compacted peats). The fluvial lower Palaeocene Tullock Member of the Fort Union Formation (Western Interior Williston Basin; Montana, USA) contains lignite rank coal seams that are traceable over distances of several kilometres. This sequence is used to test the hypothesis that peat formation in the fluvial system was controlled by orbitally forced climate change interacting with autogenic processes. Major successions are documented with an average thickness of 6·8 m consisting of ca 6 m thick intervals of channel and overbank deposits overlain by ca 1 m thick coal seam units. These major coal seams locally split and merge. Time-stratigraphic correlation, using a Cretaceous-Palaeogene boundary event horizon, several distinctive volcanic ash-fall layers, and the C29r/C29n magnetic polarity reversal, shows consistent lateral recurrence of seven successive major successions along a 10 km wide fence panel perpendicular to east/south-east palaeo-flow. The stratigraphic pattern, complemented by stratigraphic age control and cyclostratigraphic tests, suggests that the major peat-forming phases, resulting in major coal seams, were driven by 100 kyr eccentricity-related climate cycles. Two distinct conceptual models were developed, both based on the hypothesis that the major peat-forming phases ended when enhanced seasonal contrast, at times of minimum precession during increasing eccentricity, intensified mire degradation and flooding. In model 1, orbitally forced climate change controls the timing of peat compaction, leading to enhancement of autogenic channel avulsions. In model 2, orbitally forced climate change controls upstream sediment supply and clastic influx determining the persistence of peat-forming conditions. At the scale of the major successions, model 2 is supported because interfingering channel sandstones do not interrupt lateral continuity of major coal seams.

  • Open Access English
    Authors: 
    Pierik, H.J.; Van Lanen, Rowin; Gouw-Bouman, M.T.I.J.; Groenewoudt, Bert; Wallinga, Jakob; Hoek, W.Z.; Biogeomorphology of Rivers and Estuaries; Geomorfologie; Coastal dynamics, Fluvial systems and Global change;
    Country: Netherlands
    Project: NWO | The Dark Age of the Lowla... (8847)

    Holocene drift-sand activity in the northwest European sand belt is commonly directly linked to population pressure (agricultural activity) or to climate change (e.g. storminess). In the Pleistocene sand areas of the Netherlands, small-scale Holocene drift-sand activity began in the Mesolithic, whereas large-scale sand drifting started during the Middle Ages. This last phase not only coincides with the intensification of farming and demographic pressure but also is commonly associated with a colder climate and enhanced storminess. This raises the question to what extent drift-sand activity can be attributed to either human activities or natural forcing factors. In this study, we compare the spatial and temporal patterns of drift-sand occurrence for the four characteristic Pleistocene sand regions in the Netherlands for the period between 1000 BC and AD 1700. To this end, we compiled a new supra-regional overview of drift-sand activity based on age estimates (14C, optically stimulated luminescence (OSL), archaeological and historical ages). The occurrence of sand drifting was then compared in time and space with historical-route networks, relative vegetation openness and climate. Results indicate a constant but low drift-sand activity between 1000 BC and AD 1000, interrupted by a remarkable decrease in activity around the BC/AD transition. It is evident that human pressure on the landscape was most influential on initiating sand drifting: this is supported by more frequent occurrences close to routes and the uninterrupted increase of drift-sand activity from AD 900 onwards, a period of high population density and large-scale deforestation. Once triggered by human activities, this drift-sand development was probably further intensified several centuries later during the cold and stormier ‘Little Ice Age’ (LIA; AD 1570–1850).

  • Open Access English
    Authors: 
    Mengqi Zhang; Richard J. A. M. Stevens;
    Country: Netherlands
    Project: NWO | Understanding the interac... (26789)

    The present work studies the large coherent structures in large eddy simulations of windfarms using proper orthogonal decomposition (POD) method. In order to evaluate the effect of wind turbines on coherent structures, we consider three cases. One is a reference flow of a neutral atmospheric boundary layer and the other two are periodic and developing aligned windfarms. The number of wind turbines is large, 16 × 12 for periodic windfarm, and 12 × 12 for developing windfarm. The simulations are run for a long time in order to generate a sufficient database for POD analysis. In all cases, elongated streamwise counter rotating roll structures, covering 1 or 2 turbines in spanwise direction, are identified as the dominant POD mode. Another pattern, varying in streamwise direction, also appears in all the three cases.

  • Open Access English
    Authors: 
    Contreras, L.; Pross, J.; Bijl, P.K.; O'Hara, R.B.; Raine, J.I.; Sluijs, A.; Brinkhuis, H.; NWO-NNPP: Reconstructing the evolution and dynamics of the Antarctic cryosphere from Ocean Drilling; a dinoflagellate perspective; NWO-VENI: The Dawn of Greenhouse Earth: climate and carbon cycle dynamics of the Palaeocene; Marine palynology and palaeoceanography;
    Countries: Netherlands, Germany
    Project: EC | DINOPRO (259627), NWO | The Dawn of a Greenhouse ... (10684)

    Reconstructing the early Palaeogene climate dynamics of terrestrial settings in the high southern latitudes is important to assess the role of high-latitude physical and biogeochemical processes in the global climate system. However, whereas a number of high-quality Palaeogene climate records has become available for the marine realm of the high southern latitudes over the recent past, the long-term evolution of coeval terrestrial climates and ecosystems is yet poorly known. We here explore the climate and vegetation dynamics on Tasmania from the middle Palaeocene to the early Eocene (60.7–54.2 Ma) based on a sporomorph record from Ocean Drilling Program (ODP) Site 1172 on the East Tasman Plateau. Our results show that three distinctly different vegetation types thrived on Tasmania under a high-precipitation regime during the middle Palaeocene to early Eocene, with each type representing different temperature conditions: (i) warm-temperate forests dominated by gymnosperms that were dominant during the middle and late Palaeocene (excluding the middle/late Palaeocene transition); (ii) cool-temperate forests dominated by southern beech (Nothofagus) and araucarians that transiently prevailed across the middle/late Palaeocene transition interval (~ 59.5 to ~ 59.0 Ma); and (iii) paratropical forests rich in ferns that were established during and in the wake of the Palaeocene–Eocene Thermal Maximum (PETM). The transient establishment of cool-temperate forests lacking any frost-sensitive elements (i.e. palms and cycads) across the middle/late Palaeocene transition interval indicates markedly cooler conditions, with the occurrence of frosts in winter, on Tasmania during that time. The integration of our sporomorph data with previously published TEX86-based sea-surface temperatures from ODP Site 1172 documents that the vegetation dynamics on Tasmania were closely linked with the temperature evolution in the Tasman sector of the Southwest Pacific region. Moreover, the comparison of our season-specific climate estimates for the sporomorph assemblages from ODP Site 1172 with the TEX86L- and TEX86H-based temperature data suggests a warm bias of both calibrations for the early Palaeogene of the high southern latitudes.

  • Open Access English
    Authors: 
    Craig A. Grove; Jens Zinke; Frank Peeters; Wonsun Park; Tim Scheufen; Sebastian Kasper; Bemahafaly Randriamanantsoa; Malcolm T. McCulloch; Geert-Jan A Brummer;
    Countries: Germany, Netherlands
    Project: NWO | CLIMATCH:Climatic and ant... (6256)

    Abstract. Pacific Ocean sea surface temperatures (SST) influence rainfall variability on multidecadal and interdecadal timescales in concert with the Pacific Decadal Oscillation (PDO) and Interdecadal Pacific Oscillation (IPO). Rainfall variations in locations such as Australia and North America are therefore linked to phase changes in the PDO. Furthermore, studies have suggested teleconnections exist between the western Indian Ocean and Pacific Decadal Variability (PDV), similar to those observed on interannual timescales related to the El Niño Southern Oscillation (ENSO). However, as instrumental records of rainfall are too short and sparse to confidently assess multidecadal climatic teleconnections, here we present four coral climate archives from Madagascar spanning up to the past 300 yr (1708–2008) to assess such decadal variability. Using spectral luminescence scanning to reconstruct past changes in river runoff, we identify significant multidecadal and interdecadal frequencies in the coral records, which before 1900 are coherent with Asian-based PDO reconstructions. This multidecadal relationship with the Asian-based PDO reconstructions points to an unidentified teleconnection mechanism that affects Madagascar rainfall/runoff, most likely triggered by multidecadal changes in North Pacific SST, influencing the Asian Monsoon circulation. In the 20th century we decouple human deforestation effects from rainfall-induced soil erosion by pairing luminescence with coral geochemistry. Positive PDO phases are associated with increased Indian Ocean temperatures and runoff/rainfall in eastern Madagascar, while precipitation in southern Africa and eastern Australia declines. Consequently, the negative PDO phase that started in 1998 may contribute to reduced rainfall over eastern Madagascar and increased precipitation in southern Africa and eastern Australia. We conclude that multidecadal rainfall variability in Madagascar and the western Indian Ocean needs to be taken into account when considering water resource management under a future warming climate.

  • Open Access English
    Authors: 
    Geert W. van der Plas; Erik J. de Boer; Henry Hooghiemstra; F. B. Vincent Florens; Cláudia Baider; Johannes van der Plicht;
    Country: Netherlands
    Project: NWO | Mauritius since the last ... (5091)

    A 10 m long peat core from the Kanaka Crater (20 degrees 25' S, 57 degrees 31' E), located at 560 m elevation in Mauritius, was analyzed for microfossils. Eight radiocarbon ages show the pollen record reflects environmental and climatic change of the last ca. 38 cal ka BP. The record shows that the island was continuously covered by forest with Erica heath (Philippia) in the uplands. Cyperaceous reedswamp with Pandanus trees was abundant in the coastal lowlands as well as locally in the waterlogged crater. The record shows changes in climatic humidity (wet from 38.0 to 22.7 cal ka BP, drier from 22.7 to 10.6 cal ka BP, and wetter again from 10.6 cal ka BP to recent) as the main response to climate change. A high turnover in montane forest species is evidenced at 22.7 cal ka BP and at the start of the Holocene. The limited altitudinal ranges in the mountains of Mauritius (maximum altitude 828 m), and changing humidity being more important than changing temperature, suggests that in response to climate change a reassortment in taxonomic composition of montane forests might be equally important as displacement of forest types to new altitudinal intervals. We found weak impact of the latitudinal migration of the Intertropical Convergence Zone and data suggest that the Indian Ocean Dipole is a more important driver for climatic change in the southwest Indian Ocean. Copyright (c) 2011 John Wiley & Sons, Ltd.

Advanced search in Research products
Research products
arrow_drop_down
Searching FieldsTerms
Any field
arrow_drop_down
includes
arrow_drop_down
Include:
The following results are related to Digital Humanities and Cultural Heritage. Are you interested to view more results? Visit OpenAIRE - Explore.
7 Research products, page 1 of 1
  • Open Access English
    Authors: 
    A. M. Haywood; J. C. Tindall; H. J. Dowsett; A. M. Dolan; K. M. Foley; S. J. Hunter; D. J. Hill; W.-L. Chan; A. Abe-Ouchi; C. Stepanek; +26 more
    Publisher: HAL CCSD
    Countries: United Kingdom, Norway, France
    Project: NSERC , EC | PLIO-ESS (278636), NSF | Collaborative Research: A... (1418411), NWO | Mechanisms of major clima... (32604), NSF | The Management and Operat... (1852977)

    The Pliocene epoch has great potential to improve our understanding of the long-term climatic and environmental consequences of an atmospheric CO2 concentration near ∼400 parts per million by volume. Here we present the large-scale features of Pliocene climate as simulated by a new ensemble of climate models of varying complexity and spatial resolution based on new reconstructions of boundary conditions (the Pliocene Model Intercomparison Project Phase 2; PlioMIP2). As a global annual average, modelled surface air temperatures increase by between 1.7 and 5.2 ∘C relative to the pre-industrial era with a multi-model mean value of 3.2 ∘C. Annual mean total precipitation rates increase by 7 % (range: 2 %–13 %). On average, surface air temperature (SAT) increases by 4.3 ∘C over land and 2.8 ∘C over the oceans. There is a clear pattern of polar amplification with warming polewards of 60∘ N and 60∘ S exceeding the global mean warming by a factor of 2.3. In the Atlantic and Pacific oceans, meridional temperature gradients are reduced, while tropical zonal gradients remain largely unchanged. There is a statistically significant relationship between a model's climate response associated with a doubling in CO2 (equilibrium climate sensitivity; ECS) and its simulated Pliocene surface temperature response. The mean ensemble Earth system response to a doubling of CO2 (including ice sheet feedbacks) is 67 % greater than ECS; this is larger than the increase of 47 % obtained from the PlioMIP1 ensemble. Proxy-derived estimates of Pliocene sea surface temperatures are used to assess model estimates of ECS and give an ECS range of 2.6–4.8 ∘C. This result is in general accord with the ECS range presented by previous Intergovernmental Panel on Climate Change (IPCC) Assessment Reports.

  • Open Access English
    Authors: 
    Noorbergen, Lars J.; Abels, Hemmo A.; Hilgen, Frits J.; Robson, Brittany E.; de Jong, Edwin; Dekkers, Mark J.; Krijgsman, Wout; Smit, Jan; Collinson, Margaret E.; Kuiper, Klaudia F.; +4 more
    Country: Netherlands
    Project: NWO | Tephrostratigraphy and ge... (10363)

    Fluvial systems in which peat formation occurs are typified by autogenic processes such as river meandering, crevasse splaying and channel avulsion. Nevertheless, autogenic processes cannot satisfactorily explain the repetitive nature and lateral continuity of many coal seams (compacted peats). The fluvial lower Palaeocene Tullock Member of the Fort Union Formation (Western Interior Williston Basin; Montana, USA) contains lignite rank coal seams that are traceable over distances of several kilometres. This sequence is used to test the hypothesis that peat formation in the fluvial system was controlled by orbitally forced climate change interacting with autogenic processes. Major successions are documented with an average thickness of 6·8 m consisting of ca 6 m thick intervals of channel and overbank deposits overlain by ca 1 m thick coal seam units. These major coal seams locally split and merge. Time-stratigraphic correlation, using a Cretaceous-Palaeogene boundary event horizon, several distinctive volcanic ash-fall layers, and the C29r/C29n magnetic polarity reversal, shows consistent lateral recurrence of seven successive major successions along a 10 km wide fence panel perpendicular to east/south-east palaeo-flow. The stratigraphic pattern, complemented by stratigraphic age control and cyclostratigraphic tests, suggests that the major peat-forming phases, resulting in major coal seams, were driven by 100 kyr eccentricity-related climate cycles. Two distinct conceptual models were developed, both based on the hypothesis that the major peat-forming phases ended when enhanced seasonal contrast, at times of minimum precession during increasing eccentricity, intensified mire degradation and flooding. In model 1, orbitally forced climate change controls the timing of peat compaction, leading to enhancement of autogenic channel avulsions. In model 2, orbitally forced climate change controls upstream sediment supply and clastic influx determining the persistence of peat-forming conditions. At the scale of the major successions, model 2 is supported because interfingering channel sandstones do not interrupt lateral continuity of major coal seams.

  • Open Access English
    Authors: 
    Pierik, H.J.; Van Lanen, Rowin; Gouw-Bouman, M.T.I.J.; Groenewoudt, Bert; Wallinga, Jakob; Hoek, W.Z.; Biogeomorphology of Rivers and Estuaries; Geomorfologie; Coastal dynamics, Fluvial systems and Global change;
    Country: Netherlands
    Project: NWO | The Dark Age of the Lowla... (8847)

    Holocene drift-sand activity in the northwest European sand belt is commonly directly linked to population pressure (agricultural activity) or to climate change (e.g. storminess). In the Pleistocene sand areas of the Netherlands, small-scale Holocene drift-sand activity began in the Mesolithic, whereas large-scale sand drifting started during the Middle Ages. This last phase not only coincides with the intensification of farming and demographic pressure but also is commonly associated with a colder climate and enhanced storminess. This raises the question to what extent drift-sand activity can be attributed to either human activities or natural forcing factors. In this study, we compare the spatial and temporal patterns of drift-sand occurrence for the four characteristic Pleistocene sand regions in the Netherlands for the period between 1000 BC and AD 1700. To this end, we compiled a new supra-regional overview of drift-sand activity based on age estimates (14C, optically stimulated luminescence (OSL), archaeological and historical ages). The occurrence of sand drifting was then compared in time and space with historical-route networks, relative vegetation openness and climate. Results indicate a constant but low drift-sand activity between 1000 BC and AD 1000, interrupted by a remarkable decrease in activity around the BC/AD transition. It is evident that human pressure on the landscape was most influential on initiating sand drifting: this is supported by more frequent occurrences close to routes and the uninterrupted increase of drift-sand activity from AD 900 onwards, a period of high population density and large-scale deforestation. Once triggered by human activities, this drift-sand development was probably further intensified several centuries later during the cold and stormier ‘Little Ice Age’ (LIA; AD 1570–1850).

  • Open Access English
    Authors: 
    Mengqi Zhang; Richard J. A. M. Stevens;
    Country: Netherlands
    Project: NWO | Understanding the interac... (26789)

    The present work studies the large coherent structures in large eddy simulations of windfarms using proper orthogonal decomposition (POD) method. In order to evaluate the effect of wind turbines on coherent structures, we consider three cases. One is a reference flow of a neutral atmospheric boundary layer and the other two are periodic and developing aligned windfarms. The number of wind turbines is large, 16 × 12 for periodic windfarm, and 12 × 12 for developing windfarm. The simulations are run for a long time in order to generate a sufficient database for POD analysis. In all cases, elongated streamwise counter rotating roll structures, covering 1 or 2 turbines in spanwise direction, are identified as the dominant POD mode. Another pattern, varying in streamwise direction, also appears in all the three cases.

  • Open Access English
    Authors: 
    Contreras, L.; Pross, J.; Bijl, P.K.; O'Hara, R.B.; Raine, J.I.; Sluijs, A.; Brinkhuis, H.; NWO-NNPP: Reconstructing the evolution and dynamics of the Antarctic cryosphere from Ocean Drilling; a dinoflagellate perspective; NWO-VENI: The Dawn of Greenhouse Earth: climate and carbon cycle dynamics of the Palaeocene; Marine palynology and palaeoceanography;
    Countries: Netherlands, Germany
    Project: EC | DINOPRO (259627), NWO | The Dawn of a Greenhouse ... (10684)

    Reconstructing the early Palaeogene climate dynamics of terrestrial settings in the high southern latitudes is important to assess the role of high-latitude physical and biogeochemical processes in the global climate system. However, whereas a number of high-quality Palaeogene climate records has become available for the marine realm of the high southern latitudes over the recent past, the long-term evolution of coeval terrestrial climates and ecosystems is yet poorly known. We here explore the climate and vegetation dynamics on Tasmania from the middle Palaeocene to the early Eocene (60.7–54.2 Ma) based on a sporomorph record from Ocean Drilling Program (ODP) Site 1172 on the East Tasman Plateau. Our results show that three distinctly different vegetation types thrived on Tasmania under a high-precipitation regime during the middle Palaeocene to early Eocene, with each type representing different temperature conditions: (i) warm-temperate forests dominated by gymnosperms that were dominant during the middle and late Palaeocene (excluding the middle/late Palaeocene transition); (ii) cool-temperate forests dominated by southern beech (Nothofagus) and araucarians that transiently prevailed across the middle/late Palaeocene transition interval (~ 59.5 to ~ 59.0 Ma); and (iii) paratropical forests rich in ferns that were established during and in the wake of the Palaeocene–Eocene Thermal Maximum (PETM). The transient establishment of cool-temperate forests lacking any frost-sensitive elements (i.e. palms and cycads) across the middle/late Palaeocene transition interval indicates markedly cooler conditions, with the occurrence of frosts in winter, on Tasmania during that time. The integration of our sporomorph data with previously published TEX86-based sea-surface temperatures from ODP Site 1172 documents that the vegetation dynamics on Tasmania were closely linked with the temperature evolution in the Tasman sector of the Southwest Pacific region. Moreover, the comparison of our season-specific climate estimates for the sporomorph assemblages from ODP Site 1172 with the TEX86L- and TEX86H-based temperature data suggests a warm bias of both calibrations for the early Palaeogene of the high southern latitudes.

  • Open Access English
    Authors: 
    Craig A. Grove; Jens Zinke; Frank Peeters; Wonsun Park; Tim Scheufen; Sebastian Kasper; Bemahafaly Randriamanantsoa; Malcolm T. McCulloch; Geert-Jan A Brummer;
    Countries: Germany, Netherlands
    Project: NWO | CLIMATCH:Climatic and ant... (6256)

    Abstract. Pacific Ocean sea surface temperatures (SST) influence rainfall variability on multidecadal and interdecadal timescales in concert with the Pacific Decadal Oscillation (PDO) and Interdecadal Pacific Oscillation (IPO). Rainfall variations in locations such as Australia and North America are therefore linked to phase changes in the PDO. Furthermore, studies have suggested teleconnections exist between the western Indian Ocean and Pacific Decadal Variability (PDV), similar to those observed on interannual timescales related to the El Niño Southern Oscillation (ENSO). However, as instrumental records of rainfall are too short and sparse to confidently assess multidecadal climatic teleconnections, here we present four coral climate archives from Madagascar spanning up to the past 300 yr (1708–2008) to assess such decadal variability. Using spectral luminescence scanning to reconstruct past changes in river runoff, we identify significant multidecadal and interdecadal frequencies in the coral records, which before 1900 are coherent with Asian-based PDO reconstructions. This multidecadal relationship with the Asian-based PDO reconstructions points to an unidentified teleconnection mechanism that affects Madagascar rainfall/runoff, most likely triggered by multidecadal changes in North Pacific SST, influencing the Asian Monsoon circulation. In the 20th century we decouple human deforestation effects from rainfall-induced soil erosion by pairing luminescence with coral geochemistry. Positive PDO phases are associated with increased Indian Ocean temperatures and runoff/rainfall in eastern Madagascar, while precipitation in southern Africa and eastern Australia declines. Consequently, the negative PDO phase that started in 1998 may contribute to reduced rainfall over eastern Madagascar and increased precipitation in southern Africa and eastern Australia. We conclude that multidecadal rainfall variability in Madagascar and the western Indian Ocean needs to be taken into account when considering water resource management under a future warming climate.

  • Open Access English
    Authors: 
    Geert W. van der Plas; Erik J. de Boer; Henry Hooghiemstra; F. B. Vincent Florens; Cláudia Baider; Johannes van der Plicht;
    Country: Netherlands
    Project: NWO | Mauritius since the last ... (5091)

    A 10 m long peat core from the Kanaka Crater (20 degrees 25' S, 57 degrees 31' E), located at 560 m elevation in Mauritius, was analyzed for microfossils. Eight radiocarbon ages show the pollen record reflects environmental and climatic change of the last ca. 38 cal ka BP. The record shows that the island was continuously covered by forest with Erica heath (Philippia) in the uplands. Cyperaceous reedswamp with Pandanus trees was abundant in the coastal lowlands as well as locally in the waterlogged crater. The record shows changes in climatic humidity (wet from 38.0 to 22.7 cal ka BP, drier from 22.7 to 10.6 cal ka BP, and wetter again from 10.6 cal ka BP to recent) as the main response to climate change. A high turnover in montane forest species is evidenced at 22.7 cal ka BP and at the start of the Holocene. The limited altitudinal ranges in the mountains of Mauritius (maximum altitude 828 m), and changing humidity being more important than changing temperature, suggests that in response to climate change a reassortment in taxonomic composition of montane forests might be equally important as displacement of forest types to new altitudinal intervals. We found weak impact of the latitudinal migration of the Intertropical Convergence Zone and data suggest that the Indian Ocean Dipole is a more important driver for climatic change in the southwest Indian Ocean. Copyright (c) 2011 John Wiley & Sons, Ltd.