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Norske kulturminner i Antarktis: prioritering og mulige tiltak
Full text linkSiden Antarktis ble oppdaget i 1820 er det relativt sett bare et fåtalls mennesker som har besøkt kontinentet, og det er svært få synlige minner som vitner om den tidlige menneskelige aktiviteten. Nordmenn og norske aktører var tidlig aktive i Antarktis, og blant de fåtallige kulturminnene her er det derfor flere som har klare forbindelser til Norge og norsk virksomhet.
Stortingsmelding 16 (2004–2005) Leve med kulturminner understreker at norsk kulturminnepolitikk for Antarktis skal sikre at viktige kulturminner etter norsk virksomhet i Antarktis bevares. Videre understrekes det at en aktiv norsk deltakelse i det internasjonale samarbeidet for å ivareta kulturminner i Antarktis vil styrke Norges posisjon i det internasjonale antarktissamarbeidet. For å følge opp disse målsettingene skal det ifølge meldingen utarbeides en liste over norske kulturminner i Antarktis som kan være aktuelle for et internasjonalt bevaringssamarbeid, og det skal utarbeides en faglig begrunnet og begrenset prioriteringsliste over kulturminner hvor det er aktuelt å iverksette bevaringstiltak.
I 2015 gjentar regjeringen gjennom Stortingsmelding 32 (2014–2015) Norske interesser og politikk i Antarktis intensjonen om at «norske tryggings- og bevaringstiltak vert gjennomførte etter ei nærmare prioritert liste, i tråd med dei politiske føringane som er gjevne i St.meld. nr. 16 (2004–2005) Leve med kulturminner».
På grunnlag av disse føringene ba Klima- og miljødepartementet Norsk Polarinstitutt og Riksantikvaren i fellesskap, og i dialog med departementet, om å starte prosessen med å utarbeide en liste over prioriterte norske kulturminner i Antarktis, og å gi en vurdering av eventuelle tiltaksbehov knyttet til disse. Dette dokumentet presenterer resultatet av denne prosessen.
Innenfor traktatsamarbeidet er Det internasjonale geofysiske år (IGY), som fant sted i 1957/58, definert som et tidsskille som legges til grunn for vurdering av et objekts eller en lokalitets verdi som kulturminne (Resolution 5 (2001)). Denne listen over prioriterte norske kulturminner i Antarktis legger til grunn dette tidsskillet, og den avgrenser vurderingen til kulturminner og kulturminnelokaliteter fra IGY eller tidligere
The Southern Ocean Freshwater Input from Antarctica (SOFIA) Initiative: scientific objectives and experimental design
Full text linkAs the climate warms, the grounded ice sheet and floating ice shelves surrounding Antarctica are melting and releasing additional freshwater into the Southern Ocean. Nonetheless, almost all existing coupled climate models have fixed ice sheets and lack the physics required to represent the dominant sources of Antarctic melt. These missing ice dynamics represent a key uncertainty that is typically unaccounted for in current global climate change projections. Previous modelling studies that have imposed additional Antarctic meltwater have demonstrated regional impacts on Southern Ocean stratification, circulation, and sea ice, as well as remote changes in atmospheric circulation, tropical precipitation, and global temperature. However, these previous studies have used widely varying rates of freshwater forcing, have been conducted using different climate models and configurations, and have reached differing conclusions on the magnitude of meltwater–climate feedbacks. The Southern Ocean Freshwater Input from Antarctica (SOFIA) initiative brings together a team of scientists to quantify the climate system response to Antarctic meltwater input along with key aspects of the uncertainty. In this paper, we summarize the state of knowledge on meltwater discharge from the Antarctic ice sheet and ice shelves to the Southern Ocean and explain the scientific objectives of our initiative. We propose a series of coupled and ocean–sea ice model experiments, including idealized meltwater experiments, historical experiments with observationally consistent meltwater input, and future scenarios driven by meltwater inputs derived from stand-alone ice sheet models. Through coordinating a multi-model ensemble of simulations using a common experimental design, open data archiving, and facilitating scientific collaboration, SOFIA aims to move the community toward better constraining our understanding of the climate system response to Antarctic melt.publishedVersio
Natur- og kulturmiljøet på Jan Mayen: oppdatert kunnskap siden 1997, inkludert forslag til kunnskapsinnhenting
Full text linkReduced Deep Convection and Bottom Water Formation Due To Antarctic Meltwater in a Multi-Model Ensemble
Full text linkThe additional water from the Antarctic ice sheet and ice shelves due to climate-induced melt can impact ocean circulation and global climate. However, the major processes driving melt are not adequately represented in Coupled Model Intercomparison Project phase 6 (CMIP6) models. Here, we analyze a novel multi-model ensemble of CMIP6 models with consistent meltwater addition to examine the robustness of the modeled response to meltwater, which has not been possible in previous single-model studies. Antarctic meltwater addition induces a substantial weakening of open-ocean deep convection. Additionally, Antarctic Bottom Water warms, its volume contracts, and the sea surface cools. However, the magnitude of the reduction varies greatly across models, with differing anomalies correlated with their respective mean-state climatology, indicating the state-dependency of the climate response to meltwater. A better representation of the Southern Ocean mean state is necessary for narrowing the inter-model spread of response to Antarctic meltwater.publishedVersio
The Deep Arctic Ocean and Fram Strait in CMIP6 Models
Full text linkArctic sea ice loss has become a symbol of ongoing climate change, yet climate models still struggle to reproduce it accurately, let alone predict it. A reason for this is the increasingly clear role of the ocean, especially that of the “Atlantic layer,” on sea ice processes. We here quantify biases in that Atlantic layer and the Arctic Ocean deeper layers in 14 representative models that participated in phase 6 of the Climate Model Intercomparison Project. Compared to observational climatologies and hydrographic profiles, the modeled Atlantic layer core is on average too cold by −0.4°C and too deep by 400 m in the Nansen Basin. The Atlantic layer is too thick, extending to the seafloor in some models. Deep and bottom waters are in contrast too warm by 1.1° and 1.2°C. Furthermore, the modeled properties hardly change throughout the Arctic. We attribute these biases to an inaccurate representation of shelf processes: only three models seem to produce dense water overflows, at too few locations, and these do not sink deep enough. No model compensates with open ocean deep convection. Therefore, the properties are set by the inaccurate volume fluxes through Fram Strait, biased low by up to 6 Sv (1 Sv ≡ 106 m3 s−1), but coupled to a too-warm Fram Strait, resulting in a somewhat accurate heat inflow. These fluxes are related to biases in the Nordic seas, themselves previously attributed to inaccurate sea ice extent and atmospheric modes of variability, thus highlighting the need for overall improvements in the different model components and their coupling.publishedVersio