Research Articles (Earth Sciences)

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Browsing Research Articles (Earth Sciences) by Subject "Climatic changes"

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    The emergence of modern sea ice cover in the Arctic Ocean
    (Springer Nature, 2014-07) Knies, Jochen; Cabedo-Sanz, Patricia; Belt, Simon T.; Baranwal, Soma; Fietz, Susanne; Rosell-Mele, Antoni
    Arctic sea ice coverage is shrinking in response to global climate change and summer ice-free conditions in the Arctic Ocean are predicted by the end of the century. The validity of this prediction could potentially be tested through the reconstruction of the climate of the Pliocene epoch (5.33–2.58 million years ago), an analogue of a future warmer Earth. Here we show that, in the Eurasian sector of the Arctic Ocean, ice-free conditions prevailed in the early Pliocene until sea ice expanded from the central Arctic Ocean for the first time ca. 4 million years ago. Amplified by a rise in topography in several regions of the Arctic and enhanced freshening of the Arctic Ocean, sea ice expanded progressively in response to positive ice-albedo feedback mechanisms. Sea ice reached its modern winter maximum extension for the first time during the culmination of the Northern Hemisphere glaciation, ca. 2.6 million years ago.
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    Temperature and monsoon tango in a tropical stalagmite : last glacial- Interglacial climate dynamics
    (Nature Research, 2018) Huguet, Carme; Routh, Joyanto; Fietz, Susanne; Lone, Mahjoor Ahmad; Kalpana, M. S.; Ghosh, Prosenjit; Mangini, Augusto; Kumar, Vikash; Rangarajan, Ravi
    High-resolution paleoclimate data on stable isotopes in a stalagmite were coupled to glycerol dialkyl glycerol tetraethers (GDGTs). The Indian Summer Monsoon (ISM) transitioned from limited rainfall during the Last Glacial Maximum (LGM) to intense precipitation during early Holocene (22 to 6 ka). This was associated with changes in stalagmite growth, abundance of branched (br) and isoprenoid (iso) GDGTs, as well as δ18O, δ13C, Sr/Ca and GDGT-derived signals providing both temperature and moisture information. The reconstructed mean annual air temperature (MAAT) of the most modern stalagmite sample at ~19 °C, matches the surface and cave MAAT, but was ~4 °C lower during LGM. Warming at the end of LGM occurred before ISM strengthened and indicate 6 ka lag consistent with sea surface temperature records. The isotope records during the Younger Dryas show rapid progressions to dry conditions and weak monsoons, but these shifts are not coupled to TEX86. Moreover, change to wetter and stronger ISM, along with warmer Holocene conditions are not continuous indicating a decoupling of local temperatures from ISM.