Deuterium excess in an East Antarctic ice core suggests higher relative humidity at the oceanic surface during the last glacial maximum

Nature ◽  
1982 ◽  
Vol 299 (5885) ◽  
pp. 688-691 ◽  
Author(s):  
Jean Jouzel ◽  
Liliane Merlivat ◽  
Claude Lorius
Keyword(s):  
Relative Humidity ◽  
Last Glacial Maximum ◽  
Ice Core ◽  
Glacial Maximum ◽  
Deuterium Excess ◽  
Last Glacial ◽  
Oceanic Surface ◽  
The Last Glacial Maximum ◽  
The Last Glacial

Ice-core palaeoclimate records in tropical South America since the Last Glacial Maximum

2000 ◽  
Vol 15 (4) ◽  
pp. 377-394 ◽  
Author(s):  
Lonnie G. Thompson ◽  
Ellen Mosley-Thompson ◽  
Keith A. Henderson
Keyword(s):  
South America ◽  
Last Glacial Maximum ◽  
Ice Core ◽  
Glacial Maximum ◽  
Last Glacial ◽  
The Last Glacial Maximum ◽  
The Last Glacial ◽  
Tropical South America

Paleo-climate of the Boise area, Idaho from the last glacial maximum to the present based on groundwater δ2H and δ18O compositions

2009 ◽  
Vol 71 (2) ◽  
pp. 172-180 ◽  
Author(s):  
Melissa E. Schlegel ◽  
Alan L. Mayo ◽  
Steve Nelson ◽  
Dave Tingey ◽  
Rachel Henderson ◽  
...  
Keyword(s):  
Isotopic Composition ◽  
Last Glacial Maximum ◽  
Glacial Maximum ◽  
Deuterium Excess ◽  
Moisture Source ◽  
Last Glacial ◽  
Stable Isotopic Composition ◽  
Stable Isotopic ◽  
The Last Glacial Maximum ◽  
The Last Glacial

AbstractA 30 ka paleo-climate record of the Boise area, Idaho, USA has been delineated using groundwater stable isotopic compositions. Groundwater ages are modern (cold batholith), 5–15 ka (thermal batholith), 10–20 ka (frontal fault), and 20–30 ka (Snake River plain thermal). The stable isotopic composition of groundwaters have been used as a surrogate for the stable isotopic composition of precipitation. Using δ2H and δ18O compositions, local groundwater lines (LGWL's) were defined for each system. Each LGWL has been evaluated with defined slopes of 6.94 and 8, respectively, and resulting deuterium excess values (d) were found for each groundwater system for each slope. Time dependent changes in moisture source humidity and temperature, and Boise area recharge temperatures, calculated from stable isotopic data and the deuterium excess factors, agree with previous paleo-climate studies. Results indicate that from the last glacial maximum to the present time the humidity over the ocean moisture source increased by 9%, sea surface temperature at the moisture source increased 6–7°C, and local Boise temperature increased by 4–5°C. A greater increase of temperature at the moisture source as compared to the Boise area may impart be due to a shift in the moisture source area.

scholarly journals Response of methane emissions from wetlands to the Last Glacial Maximum and an idealized Dansgaard–Oeschger climate event: insights from two models of different complexity

2013 ◽  
Vol 9 (1) ◽  
pp. 149-171 ◽  
Author(s):  
B. Ringeval ◽  
P. O. Hopcroft ◽  
P. J. Valdes ◽  
P. Ciais ◽  
G. Ramstein ◽  
...  
Keyword(s):  
Last Glacial Maximum ◽  
General Circulation ◽  
Ice Core ◽  
Glacial Maximum ◽  
Ch4 Emissions ◽  
Last Glacial ◽  
Emission Models ◽  
Time Periods ◽  
The Last Glacial Maximum ◽  
The Last Glacial

Abstract. The role of different sources and sinks of CH4 in changes in atmospheric methane ([CH4]) concentration during the last 100 000 yr is still not fully understood. In particular, the magnitude of the change in wetland CH4 emissions at the Last Glacial Maximum (LGM) relative to the pre-industrial period (PI), as well as during abrupt climatic warming or Dansgaard–Oeschger (D–O) events of the last glacial period, is largely unconstrained. In the present study, we aim to understand the uncertainties related to the parameterization of the wetland CH4 emission models relevant to these time periods by using two wetland models of different complexity (SDGVM and ORCHIDEE). These models have been forced by identical climate fields from low-resolution coupled atmosphere–ocean general circulation model (FAMOUS) simulations of these time periods. Both emission models simulate a large decrease in emissions during LGM in comparison to PI consistent with ice core observations and previous modelling studies. The global reduction is much larger in ORCHIDEE than in SDGVM (respectively −67 and −46%), and whilst the differences can be partially explained by different model sensitivities to temperature, the major reason for spatial differences between the models is the inclusion of freezing of soil water in ORCHIDEE and the resultant impact on methanogenesis substrate availability in boreal regions. Besides, a sensitivity test performed with ORCHIDEE in which the methanogenesis substrate sensitivity to the precipitations is modified to be more realistic gives a LGM reduction of −36%. The range of the global LGM decrease is still prone to uncertainty, and here we underline its sensitivity to different process parameterizations. Over the course of an idealized D–O warming, the magnitude of the change in wetland CH4 emissions simulated by the two models at global scale is very similar at around 15 Tg yr−1, but this is only around 25% of the ice-core measured changes in [CH4]. The two models do show regional differences in emission sensitivity to climate with much larger magnitudes of northern and southern tropical anomalies in ORCHIDEE. However, the simulated northern and southern tropical anomalies partially compensate each other in both models limiting the net flux change. Future work may need to consider the inclusion of more detailed wetland processes (e.g. linked to permafrost or tropical floodplains), other non-wetland CH4 sources or different patterns of D–O climate change in order to be able to reconcile emission estimates with the ice-core data for rapid CH4 events.

scholarly journals The influence of föhn winds on Glacial Lake Washburn and palaeotemperatures in the McMurdo Dry Valleys, Antarctica, during the Last Glacial Maximum

2017 ◽  
Vol 29 (5) ◽  
pp. 457-467 ◽  
Author(s):  
M.K. Obryk ◽  
P.T. Doran ◽  
E.D. Waddington ◽  
C.P. Mckay
Keyword(s):  
Last Glacial Maximum ◽  
Ice Core ◽  
Glacial Maximum ◽  
Mcmurdo Dry Valleys ◽  
Glacial Lake ◽  
Dry Valleys ◽  
Glacial Lakes ◽  
Last Glacial ◽  
The Last Glacial Maximum ◽  
The Last Glacial

AbstractLarge glacial lakes, including Glacial Lake Washburn, were present in the McMurdo Dry Valleys, Antarctica, during the Last Glacial Maximum (LGM) despite a colder and drier climate. To address the mechanism capable of generating enough meltwater to sustain these large lakes, a conceptual model was developed based on the warming potential of infrequent contemporary föhn winds. The model suggests that föhn winds were capable of generating enough meltwater to sustain large glacial lakes during the LGM by increasing degree days above freezing (DDAF) and prolonging the melt season. A present-day relationship between infrequent summer föhn winds and DDAF was established. It is assumed that the Taylor Dome ice core record represents large-scale palaeoclimatic variations for the McMurdo Dry Valleys region. This analysis suggests that because of the warming influence of the more frequent föhn winds, summer DDAF in the McMurdo Dry Valleys during the LGM were equivalent to present-day values, but this enhanced summer signal is not preserved in the annually averaged ice core temperature record.

scholarly journals Response of methane emissions from wetlands to the Last Glacial Maximum and an idealized Dansgaard-Oeschger climate event: insights from two models of different complexity

2012 ◽  
Vol 8 (4) ◽  
pp. 3093-3142 ◽  
Author(s):  
B. Ringeval ◽  
P. O. Hopcroft ◽  
P. J. Valdes ◽  
P. Ciais ◽  
G. Ramstein ◽  
...  
Keyword(s):  
Last Glacial Maximum ◽  
General Circulation ◽  
Ice Core ◽  
Circulation Model ◽  
Glacial Maximum ◽  
Ch4 Emissions ◽  
Last Glacial ◽  
Time Periods ◽  
The Last Glacial Maximum ◽  
The Last Glacial

Abstract. The role of different sources and sinks of CH4 in changes in atmospheric methane ([CH4]) concentration during the last 100 000 yr is still not fully understood. In particular, the magnitude of the change in wetland CH4 emissions at the last glacial maximum (LGM) relative to the pre-industrial period (PI) as well as during abrupt climatic warmings or Dansgaard-Oeschger events of the last glacial period, is largely unconstrained. In the present study, we aim to understand the uncertainties related to the parameterization of the wetland CH4 emissions models relevant to these time periods by using two wetland models of different complexity (SDGVM and ORCHIDEE). These models have been forced by identical climate fields from low resolution coupled atmosphere-ocean general circulation model (FAMOUS) simulations of these time periods. Both emissions models simulate a large decrease in emissions during LGM in comparison to PI consistent with ice core observations and previous modeling studies. The global reduction is much larger in ORCHIDEE than in SDGVM (respectively −67 and −46%), and whilst the differences can be partially explained by different model sensitivities to temperature (i.e. Q10 values), the major reason for spatial differences between the models, is the inclusion of freezing of soil water in ORCHIDEE and the resultant impact on methanogenesis substrate availability in boreal regions. Besides, a sensitivity test performed with ORCHIDEE in which the methanogenesis substrate sensitivity to the precipitations is modified to be more realistic gives a LGM reduction of −36%. The range of the global LGM decrease is still prone to uncertainty and here, we underline its sensitivity to different process parameterizations. Over the course of an idealized D-O warming, the magnitude of the change in wetland CH4 emissions simulated by the two models at global scale is very similar at around 15 Tg yr−1, but this is only around 25% of the ice-core measured changes in [CH4]. The two models do show regional differences in emissions sensitivity to climate with much larger magnitudes of Northern and Southern tropical anomalies in ORCHIDEE. However, the simulated Northern and Southern tropical anomalies partially compensate each other in both models limiting the net flux change. Future work may need to consider the inclusion of more detailed wetland processes (e.g. linked to permafrost or tropical floodplains), other non-wetland CH4 sources or different patterns of D-O climate change in order to be able to reconcile emissions estimates with the ice-core data for rapid CH4 events.

Continental/Cordilleran ice interactions: a dominant cause of westward super-elevation of the last glacial maximum continental ice limit in southwestern Alberta, Canada

2001 ◽  
Vol 30 (1) ◽  
pp. 43-52 ◽  
Author(s):  
Edward C. Little ◽  
Lionel E. Jackson ◽  
Thomas S. James ◽  
Stephen R. Hicock ◽  
Elizabeth R. Leboe
Keyword(s):  
Last Glacial Maximum ◽  
Glacial Maximum ◽  
Last Glacial ◽  
The Last Glacial Maximum ◽  
The Last Glacial

Mollusk record of millennial climate variability in the Loess Plateau during the Last Glacial Maximum

Boreas ◽  
2002 ◽  
Vol 31 (1) ◽  
pp. 20-27 ◽  
Author(s):  
Naiqin Wu ◽  
Tungsheng Liu ◽  
Xiuping Liu ◽  
Zhaoyan Gu
Keyword(s):  
Climate Variability ◽  
Last Glacial Maximum ◽  
Loess Plateau ◽  
Glacial Maximum ◽  
The Loess Plateau ◽  
Last Glacial ◽  
The Last Glacial Maximum ◽  
The Last Glacial
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