Sea Ice and Dynamical Controls on Preindustrial and Last Glacial Maximum Accumulation in Central Greenland

Rhines, A. N.; Huybers, Peter

doi:10.1175/jcli-d-14-00075.1

Cited by 10 publications

(7 citation statements)

References 72 publications

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“…Changes in sea-ice-extent also influence the seasonality of snow accumulation on the central Greenland ice sheet [28], which can strongly affect the isotopic composition recorded in ice cores [29]. Furthermore, changes in the moisture pathways as an atmospheric response to the large Northern Hemisphere ice sheets could also have caused changes in isotope variability unrelated to local temperatures [30].…”

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confidence: 99%

Global patterns of declining temperature variability from the Last Glacial Maximum to the Holocene

Rehfeld

Münch

et al. 2018

Nature

101

100

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wayChanges in climate variability are as important for society as are changes in mean climate 1 .Contrasting last Glacial and Holocene temperature variability can provide new insights into the relationship between the mean state of climate and its variability 2, 3 . However, although glacial-interglacial changes in variability have been quantified in Greenland 2 , a global view remains elusive. Here, we present the first quantitative reconstruction of changes in temperature variability between the Last Glacial Maximum and the Holocene, based on a global network of marine and terrestrial temperature proxies. We show that temperature variability decreased globally by a factor of 4 for a warming of 3-8 • C. The decrease displayed a clear zonal pattern with little change in the tropics (1.6-2.8) and greater change in the midlatitudes of both hemispheres (3.3-14). In contrast, Greenland ice-core records show a reduction of a factor of 73, suggesting a proxy-specific overprint or a decoupling of Greenland atmospheric from global surface temperature variability. The overall pattern of variability reduction can be explained by changes in the meridional temperature gradient, a mechanism 1

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confidence: 99%

Global patterns of declining temperature variability from the Last Glacial Maximum to the Holocene

Rehfeld

Münch

et al. 2018

Nature

101

100

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“…The origin of moisture may be different at GRIP and NGRIP. While both sites are expected to receive most of their moisture from the North Atlantic and North America (Werner et al, 2001;Landais et al, 2012;Langen and Vinther, 2009) with modulation partly linked to sea ice extent (Rhines et al, 2014), the northwestern NGRIP site may also receive moisture from the North Pacific (Langen and Vinther, 2009). Nevertheless, the two sites depict similar amplitudes of d-excess variations across DO events (Fig.…”

Section: Results: Water Isotopic Records At Ngripmentioning

confidence: 99%

Ice core evidence for decoupling between midlatitude atmospheric water cycle and Greenland temperature during the last deglaciation

et al. 2018

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Abstract. The last deglaciation represents the most recent example of natural global warming associated with large-scale climate changes. In addition to the long-term global temperature increase, the last deglaciation onset is punctuated by a sequence of abrupt changes in the Northern Hemisphere. Such interplay between orbital- and millennial-scale variability is widely documented in paleoclimatic records but the underlying mechanisms are not fully understood. Limitations arise from the difficulty in constraining the sequence of events between external forcing, high- and low- latitude climate, and environmental changes. Greenland ice cores provide sub-decadal-scale records across the last deglaciation and contain fingerprints of climate variations occurring in different regions of the Northern Hemisphere. Here, we combine new ice d-excess and 17O-excess records, tracing changes in the midlatitudes, with ice δ18O records of polar climate. Within Heinrich Stadial 1, we demonstrate a decoupling between climatic conditions in Greenland and those of the lower latitudes. While Greenland temperature remains mostly stable from 17.5 to 14.7 ka, significant change in the midlatitudes of the northern Atlantic takes place at ∼16.2 ka, associated with warmer and wetter conditions of Greenland moisture sources. We show that this climate modification is coincident with abrupt changes in atmospheric CO2 and CH4 concentrations recorded in an Antarctic ice core. Our coherent ice core chronological framework and comparison with other paleoclimate records suggests a mechanism involving two-step freshwater fluxes in the North Atlantic associated with a southward shift of the Intertropical Convergence Zone.

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“…Adding meltwater into the Weddell Sea does not cause large changes in the total δ 18 O p (< 0.5‰ for 0.50 Sv freshwater forcing) over Greenland and eastern Brazil (Figures a, d, and S5). We argue that the direct meltwater effect is nonnegligible in Greenland ice core δ 18 O records as long as the meltwater is discharged into any location in the North Atlantic, the Arctic Ocean, or even the North Pacific Ocean, because these are the major moisture source regions for precipitation over Greenland (see also Table S1 in the supporting information) (Charles et al, ; Rhines & Huybers, ; Sime et al, ; Sodemann et al, ; Werner, Mikolajewicz, Heimann, Hofmann, ). Similarly, the direct meltwater effect could significantly influence the eastern Brazil δ 18 O records, as long as the meltwater can be easily transported to the moisture source regions such as the tropical North and South Atlantic (Table S1) (Drumond et al, ; Lewis et al, ).…”

Section: Dependence Of the Direct Meltwater Effect On Characteristicsmentioning

confidence: 99%

Investigating the Direct Meltwater Effect in Terrestrial Oxygen‐Isotope Paleoclimate Records Using an Isotope‐Enabled Earth System Model

Zhu

Liu

Brady

et al. 2017

Geophysical Research Letters

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Variations in terrestrial oxygen-isotope reconstructions from ice cores and speleothems have been primarily attributed to climatic changes of surface air temperature, precipitation amount, or atmospheric circulation. Here we demonstrate with the fully coupled isotope-enabled Community Earth System Model an additional process contributing to the oxygen-isotope variations during glacial meltwater events. This process, termed "the direct meltwater effect," involves propagating large amounts of isotopically depleted meltwater throughout the hydrological cycle and is independent of climatic changes. We find that the direct meltwater effect can make up 15-35% of the δ 18 O signals in precipitation over Greenland and eastern Brazil for large freshwater forcings (0.25-0.50 sverdrup (10 6 m 3 /s)). Model simulations further demonstrate that the direct meltwater effect increases with the magnitude and duration of the freshwater forcing and is sensitive to both the location and shape of the meltwater. These new modeling results have important implications for past climate interpretations of δ 18 O.

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Sea Ice and Dynamical Controls on Preindustrial and Last Glacial Maximum Accumulation in Central Greenland

Cited by 10 publications

References 72 publications

Global patterns of declining temperature variability from the Last Glacial Maximum to the Holocene

Global patterns of declining temperature variability from the Last Glacial Maximum to the Holocene

Ice core evidence for decoupling between midlatitude atmospheric water cycle and Greenland temperature during the last deglaciation

Investigating the Direct Meltwater Effect in Terrestrial Oxygen‐Isotope Paleoclimate Records Using an Isotope‐Enabled Earth System Model

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