Blar i forfatter "Smik, Lukas"

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    • Complementary biomarker-based methods for characterising Arctic sea ice conditions: A case study comparison between multivariate analysis and the PIP25 index 

      Koseoglu, Denizcan; Belt, Simon T.; Smik, Lukas; Yao, Haoyi; Panieri, Giuliana; Knies, Jochen (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-11-10)
      The discovery of IP25 as a qualitative biomarker proxy for Arctic sea ice and subsequent introduction of the so-called PIP25 index for semi-quantitative descriptions of sea ice conditions has significantly advanced our understanding of long-term paleo Arctic sea ice conditions over the past decade. We investigated the potential for classification tree1 (CT) models to provide a further approach ...

    • A novel biomarker-based proxy for the spring phytoplankton bloom in Arctic and sub-arctic settings – HBI T25 

      Belt, Simon T.; Smik, Lukas; Köseoğlu, Denizcan; Knies, Jochen; Husum, Katrine (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-07-19)
      The spring phytoplankton bloom is a characteristic feature of mid-high latitudes in modern times, but can be challenging to identify in palaeo records. In the current study, we investigated the absolute and relative distributions of two diatom-derived tri-unsaturated highly branched isoprenoid (HBI) lipids, at least one of which has previously been suggested to be a possible proxy for the productive ...

    • Reduced Arctic sea ice extent during the mid-Pliocene Warm Period concurrent with increased Atlantic-climate regime 

      Rahaman, Waliur; Smik, Lukas; Köseoğlu, Denizcan; Lathika, N.; Tarique, Mohd; Thamban, Meloth; Haywood, Alan; Belt, Simon T.; Knies, Jochen (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-09-01)
      Quantifying the contribution of poleward oceanic heat transport to the Arctic Ocean is important for making future sea ice and climate predictions. To highlight its potential importance in a warmer world, we present a new record of water-mass exchange between the Atlantic and the Arctic Oceans using the authigenic neodymium isotopic composition of marine sediments from the Fram Strait during the ...

    • Sea ice-ocean coupling during Heinrich Stadials in the Atlantic–Arctic gateway 

      el Bani Altuna, Naima; Mohamed, Mohamed Mahmoud Ezat Ahmed; Smik, Lukas; Muschitiello, Francesco; Belt, Simon T.; Knies, Jochen Manfred; Rasmussen, Tine Lander (Journal article; Tidsskriftartikkel; Peer reviewed, 2024-01-11)
      The variability of Arctic sea-ice during abrupt stadial-interstadial shifts in the last glacial period remain poorly understood. Here, we investigated the millennial-scale relationship, with a focus on Heinrich Stadials (HS), between sea-ice cover and bottom water temperature (BWT) during Marine Isotope Stages (MIS) 3 and 2 (64–13 ka) in the Fram Strait using new molecular sea ice biomarker data and ...

    • Seasonal sea ice persisted through the Holocene Thermal Maximum at 80°N 

      Pieńkowski, Anna J.; Husum, Katrine; Belt, Simon T.; Ninnemann, Ulysses S; Köseoğlu, Denizcan; Divine, Dmitry V.; Smik, Lukas; Knies, Jochen; Hogan, Kelly; Noormets, Riko (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-06-15)
      The cryospheric response to climatic warming responsible for recent Arctic sea ice decline can be elucidated using marine geological archives which offer an important long-term perspective. The Holocene Thermal Maximum, between 10 and 6 thousand years ago, provides an opportunity to investigate sea ice during a warmer-than-present interval. Here we use organic biomarkers and benthic foraminiferal ...