scholarly journals Wet/dry status change in global closed basins between the mid-Holocene and the Last Glacial Maximum and its implication for future projection

2020 ◽  
Author(s):  
Xinzhong Zhang ◽  
Yu Li ◽  
Wangting Ye ◽  
Simin Peng ◽  
Yuxin Zhang ◽  
...  
Keyword(s):  
Last Glacial Maximum ◽  
Global Scale ◽  
Glacial Maximum ◽  
Interglacial Period ◽  
Moisture Change ◽  
Last Glacial ◽  
Closed Basins ◽  
The Last Glacial Maximum ◽  
The Last Glacial

Abstract. Closed basins, mainly located in subtropic and temperate drylands, have experienced alarming decline in water storage in recent years. However, a long-term assessment of hydroclimate changes in the region remains unquantified at a global scale. By intergrating the lake records, PMIP3/CMIP5 simulations and modern observations, we assess the wet/dry status during the Last Glacial Maximum, mid-Holocene, pre-industrial, 20th and 21th century periods in global closed basins. Results show comparable wetting at a global scale during the mid-Holocene and modern warming periods with regional mechanism differences, attributed to the boreal winter and summer precipitation increasing, respectively. The long-term moisture change pattern is mainly controlled by the millennial-scale insolation variation, which lead to the poleward moving of westerlies and strengthening of monsoons during the interglacial period. However, modern moisture change trends are significantly associated with ENSO in most of closed basins, indicating strong connection with ocean oscillation. Our research suggests that moisture changes in global closed basins are more resilient than previous thought to warm periods.

scholarly journals Wet–dry status change in global closed basins between the mid-Holocene and the Last Glacial Maximum and its implication for future projection

2020 ◽  
Vol 16 (5) ◽  
pp. 1987-1998
Author(s):  
Xinzhong Zhang ◽  
Yu Li ◽  
Wangting Ye ◽  
Simin Peng ◽  
Yuxin Zhang ◽  
...  
Keyword(s):  
Last Glacial Maximum ◽  
Glacial Maximum ◽  
Future Climate Change ◽  
Boreal Summer ◽  
Interglacial Period ◽  
Last Glacial ◽  
Closed Basins ◽  
The Last Glacial Maximum ◽  
The Last Glacial

Abstract. Closed basins, mainly located in subtropical and temperate drylands, have experienced alarming declines in water storage in recent years. An assessment of long-term hydroclimate change in those regions remains unquantified at a global scale as of yet. By integrating lake records, PMIP3–CMIP5 simulations and modern observations, we assess the wet–dry status of global closed basins during the Last Glacial Maximum, mid-Holocene, pre-industrial, and 20th and 21st century periods. Results show comparable patterns of general wetter climate during the mid-Holocene and near-future warm period, mainly attributed to the boreal summer and winter precipitation increasing, respectively. The long-term pattern of moisture change is highly related to the high-latitude ice sheets and low-latitude solar radiation, which leads to the poleward moving of westerlies and strengthening of monsoons during the interglacial period. However, modern moisture changes show correlations with El Niño–Southern Oscillation in most closed basins, such as the opposite significant correlations between North America and southern Africa and between central Eurasia and Australia, indicating strong connection with ocean oscillation. The strategy for combating future climate change should be more resilient to diversified hydroclimate responses in different closed basins.

scholarly journals Climate impacts on deglaciation and vegetation dynamics since the Last Glacial Maximum at Moossee (Switzerland)

2019 ◽  
Author(s):  
Fabian Rey ◽  
Erika Gobet ◽  
Christoph Schwörer ◽  
Albert Hafner ◽  
Willy Tinner
Keyword(s):  
Climate Change ◽  
Last Glacial Maximum ◽  
Fagus Sylvatica ◽  
Glacial Maximum ◽  
Future Climate ◽  
Central European ◽  
Last Glacial ◽  
The Last Glacial Maximum ◽  
The Last Glacial

Abstract. Since the Last Glacial Maximum (LGM, end ca. 19 000 cal BP) Central European plant communities were shaped by changing climatic and anthropogenic disturbances. Understanding long-term ecosystem reorganizations in response to past environmental changes is crucial to draw conclusions about the impact of future climate change. So far, it has been difficult to address the post-deglaciation timing and ecosystem dynamics due to a lack of well-dated and continuous sediment sequences covering the entire period after the LGM. Here, we present a new palaeoecological study with exceptional chronological time control using pollen, spores and microscopic charcoal from Moossee (Swiss Plateau, 521 m a.s.l.) to reconstruct the vegetation and fire history over the last ca. 19 000 years. After lake formation in response to deglaciation, five major pollen-inferred ecosystem rearrangements occurred at ca. 18 800 cal BP (establishment of steppe tundra), 16 000 cal BP (spread of shrub tundra), 14 600 cal BP (expansion of boreal forests), 11 600 cal BP (establishment of first temperate deciduous tree stands composed of e.g. Quercus, Ulmus, Alnus) and 8200 cal BP (first occurence of mesophilous Fagus sylvatica trees). These vegetation shifts were released by climate changes at 19 000, 16 000, 14 700, 11 700 and 8200 cal BP. Vegetation responses occurred with no apparent time lag to climate change, if the mutual chronological uncertainties are considered. This finding is in agreement with further evidence from Southern and Central Europe and might be explained with proximity to the refugia of boreal and temperate trees (< 400 km) and rapid species spreads. Our palynological record sets the beginning of millennial-scale land use with periodically increased fire and agricultural activities of the Neolithic period at ca. 7000 cal BP (5050 cal BC). Subsequently, humans rather than climate triggered changes in vegetation composition and structure. We conclude that Fagus sylvatica forests were resilient to long-term anthropogenic and climatic impacts of the mid and the late Holocene. However, future climate warming and in particular declining moisture availability may cause unprecedented reorganizations of Central European beech-dominated forest ecosystems.

Timescale-dependent responses of hydrological changes from global closed basins since the last glacial maximum

2021 ◽  
pp. 030913332110519
Author(s):  
Xinzhong Zhang ◽  
Yu Li ◽  
Qin Han ◽  
Yuxin Zhang
Keyword(s):  
Last Glacial Maximum ◽  
Glacial Maximum ◽  
Ice Age ◽  
Last Glacial ◽  
Future Global Warming ◽  
Precipitation Seasonality ◽  
Cold Events ◽  
Closed Basins ◽  
The Last Glacial Maximum ◽  
The Last Glacial

Water shortage has plagued the social development and human well-being of global closed basins. However, the hydroclimate research on different time scales in these regions remains inadequate at a global scale. In this paper, the hydrological responses from global closed basins to millennial-scale and centennial-scale cold/warm events since the Last Glacial Maximum were explored. Closed-basin lake records indicate that the westerlies-dominated closed basins are generally wetter during cold events than the corresponding warm ones on the millennial and centennial scales. In contrast, the monsoon-influenced closed basins prevail wetter climates during warm events. According to the hydroclimate simulations, precipitation seasonality plays a significant role in causing above spatial–temporal patterns. There is more winter rainfall in westerlies-dominated closed basins during cold events in the Last Glacial Maximum and Little Ice Age and more summer rainfall in monsoon-influenced closed basins during warm events in the mid-Holocene and Medieval Climate Anomaly. Under modern and future global warming, the hydroclimate changes in global closed basins show more regional differentiation, resulting in wetter mid-latitude Asian and low-latitude African closed basins but drier southwest North American and Australian closed basins.

scholarly journals Committed and projected future changes in global peatlands – continued transient model simulations since the Last Glacial Maximum

2021 ◽  
Vol 18 (12) ◽  
pp. 3657-3687
Author(s):  
Jurek Müller ◽  
Fortunat Joos
Keyword(s):  
Last Glacial Maximum ◽  
Glacial Maximum ◽  
Future Scenarios ◽  
Dynamic Global Vegetation Model ◽  
Last Glacial ◽  
Climate Anomalies ◽  
The Future ◽  
The Last Glacial Maximum ◽  
The Last Glacial

Abstract. Peatlands are diverse wetland ecosystems distributed mostly over the northern latitudes and tropics. Globally they store a large portion of the global soil organic carbon and provide important ecosystem services. The future of these systems under continued anthropogenic warming and direct human disturbance has potentially large impacts on atmospheric CO2 and climate. We performed global long-term projections of peatland area and carbon over the next 5000 years using a dynamic global vegetation model forced with climate anomalies from 10 models of the Coupled Model Intercomparison Project (CMIP6) and three standard future scenarios. These projections are seamlessly continued from a transient simulation from the Last Glacial Maximum to the present to account for the full transient history and are continued beyond 2100 with constant boundary conditions. Our results suggest short to long-term net losses of global peatland area and carbon, with higher losses under higher-emission scenarios. Large parts of today's active northern peatlands are at risk, whereas peatlands in the tropics and, in case of mitigation, eastern Asia and western North America can increase their area and carbon stocks. Factorial simulations reveal committed historical changes and future rising temperature as the main driver of future peatland loss and increasing precipitations as the driver for regional peatland expansion. Additional simulations forced with climate anomalies from a subset of climate models which follow the extended CMIP6 scenarios, transient until 2300, show qualitatively similar results to the standard scenarios but highlight the importance of extended transient future scenarios for long-term carbon cycle projections. The spread between simulations forced with different climate model anomalies suggests a large uncertainty in projected peatland changes due to uncertain climate forcing. Our study highlights the importance of quantifying the future peatland feedback to the climate system and its inclusion into future earth system model projections.

scholarly journals Global peatlands under future climate – seamless model projections from the Last Glacial Maximum

2021 ◽  
Author(s):  
Jurek Müller ◽  
Fortunat Joos
Keyword(s):  
Last Glacial Maximum ◽  
Climate Model ◽  
Coupled Model ◽  
Glacial Maximum ◽  
Dynamic Global Vegetation Model ◽  
Last Glacial ◽  
The Future ◽  
The Last Glacial Maximum ◽  
The Last Glacial

Abstract. Peatlands are diverse wetland ecosystems distributed mostly over the northern latitudes and tropics. Globally they store a large portion of the global soil organic carbon and provide important ecosystem services. The future of these systems under continued anthropogenic warming and direct human disturbance has potentially large impacts on atmospheric CO2 and climate. We performed global long term projections of peatland area and carbon over the next 5000 years using a dynamic global vegetation model forced with climate anomalies from ten models of the Coupled Model Intercomparison Project (CMIP6) and three scenarios. These projections are continued from a transient simulation from the Last Glacial Maximum to the present to account for the full transient history. Our results suggest short to long term net losses of global peatland area and carbon, with higher losses under higher emission scenarios. Large parts of today's active northern peatlands are at risk. Conditions for peatlands in the tropics and, in case of mitigation, eastern Asia and western north America improve. Factorial simulations reveal committed historical changes and future rising temperature as the main driver of future peatland loss and increasing precipitations as driver for regional peatland expansion. Additional simulations forced with two CMIP6 scenarios extended transiently beyond 2100, show qualitatively similar results to the standard scenarios, but highlight the importance of extended future scenarios for long term carbon cycle projections. The spread between simulations forced with different climate model anomalies suggests a large uncertainty in projected peatland variables due to uncertain climate forcing. Our study highlights the importance of quantifying the future peatland feedback to the climate system and its inclusion into future earth system model projections.

scholarly journals 230Th normalization: New insights on an essential tool for quantifying sedimentary fluxes in the modern and Quaternary ocean

2020 ◽  
Author(s):  
Kassandra Costa ◽  
Keyword(s):  
Last Glacial Maximum ◽  
Global Scale ◽  
Glacial Maximum ◽  
Global Ocean ◽  
Last Glacial ◽  
High Particle ◽  
Mass Fluxes ◽  
The Last Glacial Maximum ◽  
Boundary Scavenging ◽  
The Last Glacial

&lt;p&gt;&lt;sup&gt;230&lt;/sup&gt;Th-normalization is a valuable paleoceanographic tool for reconstructing high-resolution sediment fluxes during the late Pleistocene (last ~500,000 years). As its application has expanded to ever more complex marine environments, the nuances of &lt;sup&gt;230&lt;/sup&gt;Th systematics, with regards to particle type, particle size, lateral advective/diffusive redistribution, and other processes, have emerged. We synthesized over 1000 sedimentary records of &lt;sup&gt;230&lt;/sup&gt;Th from across the global ocean at two time slices, the Late Holocene (0-5000 years ago, or 0-5 ka) and the Last Glacial Maximum (18.5-23.5 ka), and investigated the spatial structure of &lt;sup&gt;230&lt;/sup&gt;Th-normalized mass fluxes. On a global scale, sedimentary mass fluxes were significantly higher during the Last Glacial Maximum (1.79-2.17 g/cm&lt;sup&gt;2&lt;/sup&gt;kyr, 95% confidence) relative to the Holocene (1.48-1.68 g/cm&lt;sup&gt;2&lt;/sup&gt;kyr, 95% confidence). We then examined the potential confounding influences of boundary scavenging, nepheloid layers, hydrothermal scavenging, size dependent sediment fractionation, and carbonate dissolution on the efficacy of &lt;sup&gt;230&lt;/sup&gt;Th as a constant flux proxy. Anomalous &lt;sup&gt;230&lt;/sup&gt;Th behavior is sometimes observed proximal to hydrothermal ridges and in continental margins where high particle fluxes and steep continental slopes can lead to the combined effects of boundary scavenging and nepheloid interference. Notwithstanding these limitations, we found that &lt;sup&gt;230&lt;/sup&gt;Th-normalization is a robust tool for determining sediment mass accumulation rates in the majority of pelagic (&gt; 1000 m) marine settings.&lt;/p&gt;

Luminescence Dating of Sediments from the Luthern Valley, Central Switzerland, and Implications for the Chronology of the Last Glacial Cycle

2001 ◽  
Vol 55 (2) ◽  
pp. 215-222 ◽  
Author(s):  
Frank Preusser ◽  
Benjamin U. Müller ◽  
Christian Schlüchter
Keyword(s):  
Last Glacial Maximum ◽  
Glacial Maximum ◽  
Cold Climate ◽  
Luminescence Dating ◽  
Interglacial Period ◽  
Braided River ◽  
Glacial Cycle ◽  
Last Glacial ◽  
The Last Glacial Maximum ◽  
The Last Glacial

AbstractThe advancing glaciers of the last glacial maximum either eroded or deeply buried older sediments in the Swiss Alpine Foreland. However, part of the Swiss Plateau was not covered by ice and is therefore an excellent area for investigating climate and environmental change during the Upper Pleistocene. Repeated fluvial sequences can be studied in several pits along the Luthern Valley. The chronological framework is based on lithostratigraphy, pollen analysis, U/Th dating, and recently, heavy mineral analysis and luminescence dating. The oldest unit, the Untere Zeller Schotter braided river deposit, represents cold climate conditions and presumably a glaciation prior to the Eemian Interglaciation. The last interglacial period and the very beginning of the last glacial cycle is represented by the Mittlere Zeller Schotter, sediments of a meandering fluvial system. Younger braided river sediments, the Obere Zeller Schotter, seem to correlate with the cold climate of oxygen isotope stage (OIS) 4. Weathering of the top of the Obere Zeller Schotter is likely to represent the OIS 3. The advancing Reuss glacier caused erosion of the recent Luthern Valley, cutting into older sediments, with local loess accumulation during the last glacial maximum as indicated by cover sediments on top of the fluvial sequence.

scholarly journals Paleoclimatic reconstruction for the late pleistocene period of the plain part of Ukraine

2010 ◽  
pp. 3-11
Author(s):  
L. Bezusko ◽  
S. Mosyakin ◽  
A. Bezusko
Keyword(s):  
Last Glacial Maximum ◽  
Late Pleistocene ◽  
Glacial Maximum ◽  
Interglacial Period ◽  
Upper Pleistocene ◽  
Last Glacial ◽  
Paleoclimatic Reconstruction ◽  
Climatic Characteristics ◽  
The Last Glacial Maximum ◽  
The Last Glacial

The article summarizes the results of quantitative paleoclimatic reconstructions conducted using different methods based on the palinological records of the Upper Pleistocene deposits of the plain part of Ukraine. Quantitative climatic characteristics for the Riss-Wurm interglacial period, Dubno interstadial and the Last Glacial Maximum are provided. It is concluded that primary refugia of thermophilic and hydrophilic trees on the plain areas did not exist during the Last Glacial Maximum. Key words: paleoclimatic reconstructions, Late Pleistocene, Riss-Wurm interglacial period, Dubno interstadial.

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