Alfred Wegener Institute for Polar and Marine Research
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Ice algae as supplementary food rather than major energy source for the Barents sea zooplankton community
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Dependency of the drag coefficient on boundary layer stability beneath drifting sea ice in the central Arctic Ocean
Get PDFThe ice-ocean drag coefficient Cw and turning angle θw are crucial parameters in ice-ocean coupled simulations, determining the transfer of momentum between the two media. These parameters are often treated as constants regardless of the static stability at the ice-ocean interface. This study investigates the variability of Cw and θw based on direct observations of thermal and kinetic energy balance. The observations were conducted beneath multiyear ice packs widely across the central Arctic during a period transitioning from ablation to refreezing, indicating significant variability of Cw = 1–130 × 10−3 and θw = − 19–1° at 5 m depth. Comparing different stations, the observations suggest a pronounced dependence of Cw on the stability parameter (μ) resulting from mechanical and buoyant forcing. Cw rapidly decays with increasing μ, indicating that the ice-to-ocean momentum transfer is enhanced for neutral or unstable conditions, while it is weakened for stable conditions. In addition, observed vertical profiles of currents revealed that |θw| tends to be smaller for unstable and larger for stable conditions. We suggest that numerical simulations using constant values could result in an underestimate of large-scale near-surface currents during the ice growing period
Stress-Adaptive Stiffening Structures Inspired by Diatoms: A Parametric Solution for Lightweight Surfaces
Get PDFThe intricate and highly complex morphologies of diatom frustules have long captured the attention of biomimetic researchers, initiating innovation in engineering solutions. This study investigates the potential of diatom-inspired surface stiffeners to determine whether the introduced innovative strategy is a viable alternative for addressing engineering challenges demanding enhanced stiffness. This interdisciplinary study focuses on the computer-aided generation of stress-adaptive lightweight structures aimed at optimizing bending stiffness. Through a comprehensive microscopical analysis, morphological characteristics of diatom frustules were identified and abstracted to be applied to a reference model using computer-aided methods and simulated to analyze their mechanical behavior under load-bearing conditions. Afterwards, the models are compared against a conventional engineering approach. The most promising biomimetic approach is successfully automated, extending its applicability to non-planar surfaces and diverse boundary conditions. It yields notable improvement in bending stiffness, which manifests in a decrease of displacement by approximately 93% in comparison to the reference model with an equivalent total mass. Nonetheless, for the specific load case considered, the engineering approach yields the least displacement. Although certain applications may favor conventional methods, the presented approach holds promise for scenarios subjected to varying stresses, necessitating lightweight and robust solutions
Modeling the mid-piacenzian warm climate using the water isotope-enabled Community Earth System Model (iCESM1.2-ITPCAS)
Get PDFThe mid-Piacenzian Warm Period (MPWP, ~ 3.264–3.025 Ma) is the most recent example of a persistently warmer climate in equilibrium with atmospheric CO2 concentrations similar to today. Towards studying patterns and dynamics of a warming climate the MPWP is often compared to today. Following the Pliocene Model Intercomparison Project, Phase 2 (PlioMIP2) protocol we prepare a water isotope-enabled Community Earth System Model (iCESM1.2) simulation that is warmer and wetter than the PlioMIP2 multi-model ensemble (MME). While our simulation resembles PlioMIP2 MME in many aspects we find added insights. (1) Considerable warmth at high latitudes exceeds previous simulations. Polar amplification (PA) is comparable to proxies, enabled by iCESM1.2’s high climate sensitivity and a distinct method of ocean initialization. (2) Major driver of warmth is the downward component of clear-sky surface long-wave radiation. (3) In iCESM1.2 modulated dominance of dynamic (δDY) processes causes different low-latitude (~ 30 S°–10°N) precipitation response than the PlioMIP2 MME, where thermodynamic processes (δTH) dominate. (4) Modulated local condensation leads to lower δ18O across tropical Indian Ocean and surrounding Asian-African-Australian monsoon regions. (5) We find contrasting changes in tropical atmospheric circulations (Hadley and Walker cells). Anomalous regional meridional (zonal) circulation, forced by changes in tropical-subtropical (tropical) diabatic processes, presents a more comprehensive perspective than explaining weakened and expanded Hadley circulation (strengthened and westward-shifted Walker circulation) via static stability. (6) Enhanced Atlantic meridional overturning circulation owes to a closed Bering Strait
Fostering Capacity Sharing in Permafrost Research Processes: Learnings from the APECS and Arctic PASSION’s Sharing Circle
Get PDFArctic research is moving towards being application-oriented to address the needs of those directly facing the impacts of accelerating change across permafrost landscapes. Capacity sharing is a two-way knowledge exchange process developed from a basis of reciprocity, communication and collaboration. Multi-directional knowledge exchange can exist in a variety of contexts including intercultural collaboration and the science-policy interface.
The Sharing Circle, a workshop organized by the Association of Polar Early Career Scientists (APECS) and the EU Horizon 2020 Arctic PASSION Project, took place in Sevettijärvi and Inari, Sápmi (northern Finland) in early October 2023. The event brought together Arctic youth and early career researchers (ECRs), with in total 18 participants. Hosted in the Skolt Sámi community, the event created a space that facilitated cross-cultural learning between each other and experienced collaborators (Indigenous and non-Indigenous) who have together co-created environmental monitoring and restoration projects.
The week was filled with a diverse range of activities including seminars circled around a wood fire and on the land learning activities. The program included both environmental and societal topics, contributing to the transdisciplinary nature of the event. Discussions and activities were centred around topics including: (1) a holistic understanding of the socio-ecological impacts of permafrost thaw (2) challenges and opportunities associated with fostering intercultural collaboration and (3) translating science into policy change.
Permafrost warming, a pressing challenge across the circumpolar Arctic (Biskaborn et al., 2019), and its associated impacts on environment and society was discussed heavily. This topic was introduced on an outdoor excursion to a palsa mire in Neiden, northern Norway. Participant-led presentations discussed the potential for co-created community-based monitoring approaches and challenges associated through the presentation of case studies from Tuktoyaktuk, Inuvialuit Settlement Region, Canada (Mercer et al., 2023a, 2023b).
The concept of co-management was presented by the Snowchange Cooperative (see at http://www.snowchange.org/). Due to high land-use pressure and climate change impacts, environmental degradation is evident in Sápmi. Long-term cross-cultural collaboration that addresses local priorities has led to successful management and restoration practices at regional scales. Learnings from Snowchange highlighted the need to weave together diverse knowledge systems to better preserve and restore biodiversity (Mustonen, 2021; Ogar et al., 2020).
As permafrost scientists, we carry a responsibility to acknowledge the land and empower Indigenous-led research. Doing so can produce greater equity in research outcomes and contribute to a better understanding of the multifaceted impacts of rapid change across permafrost landscapes. Capacity sharing processes help to build long-term and co-created research projects. Therefore, providing opportunities for ECRs to attend events like the Sharing Circle are crucial to creating a step-change in the way research is conducted in the Arctic
Thematic assessment on Hazardous Submerged Objects in the Baltic Sea - Warfare Materials in the Baltic Sea
Get PDFContemporary society’s perception of past wars is almost exclusively driven by historic sources such as film recordings, photographs and written documents that are presented in mass media.
However, the legacy of these wars is still present throughout European soil and waters, including
the Baltic Sea. The marine waters of every Baltic Sea state contain warfare materials. Resulting
risks may be direct and short-term. Fishermen, divers, offshore wind farm constructors and
beachgoers can potentially be exposed to their remains while performing their daily work or
while collecting objects in the surf. Other potential effects might be indirect and long-term such
as the accumulation of carcinogenic toxic substances and their metabolites in the marine food
web.
Since 1974 Contracting Parties of the Helsinki Convention are seeking to address the increasing
environmental challenges from human activities and that were having a severe impact on the
marine environment. This includes the protection of the Baltic Sea from all sources of pollution,
and thus munitions in the Baltic Sea are addressed by HELCOM since 1993. The convention
commits the signatories to take measures to conserve habitats and biological diversity and for
the sustainable use of marine resources. In addition, warfare materials potentially constitute a
hazard and an obstacle for the utilization of the sea floor for economic purposes. The global
ocean economy is predicted to double in size by 2030, as compared to 2010 (OECD 2016). In the
Blue Growth Strategy laid out by the European Commission the economic potential for the
extended economic usage of the oceans was recognized and focus was placed on five blue
growth sectors. Two of these sectors (ocean energy and seabed mining) require the ability to
safely access large areas of the sea floor (European Commission 2017). In order to exploit the
economic potential of the ocean energy and seabed resources sectors, the detection and
removal of warfare materials in affected areas will become increasingly important (European
Parliament 2021).
Recently, numerous HELCOM Contracting Parties supported increasing the knowledge
concerning warfare materials in the Baltic Sea and their effects on humans and the marine
environment of the Baltic Sea. As a result of national, regional and international scientific
research the understanding of the issue grows and consequentially numerous recommendations
are published on how the warfare materials challenge can be addressed. However, international
coordination is necessary to identify synergies and to avoid a duplication of efforts. This report
provides the current state of knowledge on warfare materials in the Baltic sea based on recent
research projects
Ice sheet–free West Antarctica during peak early Oligocene glaciation
Get PDFOne of Earth’s most fundamental climate shifts, the greenhouse-icehouse transition 34 million years ago, initiated Antarctic ice sheet buildup, influencing global climate until today. However, the extent of the ice sheet during the Early Oligocene Glacial Maximum (~33.7 to 33.2 million years ago) that immediately followed this transition—a critical knowledge gap for assessing feedbacks between permanently glaciated areas and early Cenozoic global climate reorganization—is uncertain. In this work, we present shallow-marine drilling data constraining earliest Oligocene environmental conditions on West Antarctica’s Pacific margin—a key region for understanding Antarctic ice sheet evolution. These data indicate a cool-temperate environment with mild ocean and air temperatures that prevented West Antarctic Ice Sheet formation. Climate–ice sheet modeling corroborates a highly asymmetric Antarctic ice sheet, thereby revealing its differential regional response to past and future climatic change
Direct observational evidence of strong CO2 uptake in the Southern Ocean
Get PDFThe Southern Ocean is the primary region for the uptake of anthropogenic carbon dioxide (CO2) and is, therefore, crucial for Earth’s climate. However, the Southern Ocean CO2 flux estimates reveal substantial uncertainties and lack direct validation. Using seven independent and directly measured air-sea CO2 flux datasets, we identify a 25% stronger CO2 uptake in the Southern Ocean than shipboard dataset–based flux estimates. Accounting for upper ocean temperature gradients and insufficient temporal resolution of flux products can bridge this flux gap. The gas transfer velocity parameterization is not the main reason for the flux disagreement. The profiling float data–based flux products and biogeochemistry models considerably underestimate the observed CO2 uptake, which may be due to the lack of representation of small-scale high-flux events. Our study suggests that the Southern Ocean may take up more CO2
than previously recognized, and that temperature corrections should be considered, and a higher resolution is needed in data-based bulk flux estimates
The role of hydraulic conductivity in the Pine Island Glacier's subglacial water distribution
Get PDFGlobal climate warming leads to ever-increasing glacier mass loss. Pine Island Glacier in Antarctica is one of the largest contributors to global sea level rise (SLR). One of the biggest uncertainties in the assessment of glacier contribution to SLR at present are subglacial hydrology processes which are less well known than other ice dynamical processes. We use the Glacier Drainage System (GlaDS) model which couples both distributed and channelized components to simulate the basal hydrology of Pine Island Glacier with basal sliding and meltwater production taken from a full-Stokes Elmer/Ice model fitting observed surface velocities. We find ≈100 km long Rothlisberger channels up to 26 m in diameter extending up glacier from the grounding line along the main trunk of Pine Island Glacier delivering 51 m3 s−1 of fresh water to the grounding line. Channelization occurs at high water pressure because of high basal melt rates (maximum of 1 m a−1) caused by high rates of shear heating in regions with fast ice flow (>1000 m a−1). We simulate a shallow “swamp” of 0.8 m water depth where flow transitions from a distributed system into the channels. We performed a set of 38 sensitivity experiments varying sheet and channel conductivity over 4 orders of magnitude. We find a threshold behavior in distributed sheet conductivity above which basal water pressures are unaffected by changing channel conductivities. Our findings suggest a strong need to better understand controls on basal water conductivity through the distributed system. This issue is critical to improve model-based predictive capability for the Pine Island Glacier and, more generally, the Antarctic Ice Sheet