Rapid sea ice changes in the future Barents Sea

Observed and future winter Arctic sea ice loss is strongest in the Barents Sea. However, the anthropogenic signal of the sea ice decline is superimposed by pronounced internal variability that represents a large source of uncertainty in future climate projections. A notable manifestation of internal variability is rapid ice change events (RICEs) that greatly exceed the anthropogenic trend. These RICEs are associated with large displacements of the sea ice edge which could potentially have both local and remote impacts on the climate system. In this study we present the first investigation of the frequency and drivers of RICEs in the future Barents Sea, using multi-member ensemble simulations from CMIP5 and CMIP6. A majority of RICEs are triggered by trends in ocean heat transport or surface heat fluxes. Ice loss events are associated with increasing trends in ocean heat transport and decreasing trends in surface heat loss. RICEs are a common feature of the future Barents Sea until the region becomes close to ice-free. As their evolution over time is closely tied to the average sea ice conditions, rapid ice changes in the Barents Sea may serve as a precursor for future changes in adjacent seas.</p

PENGGUNAAN MODEL PEMBELAJARAN INKUIRI TERBIMBING UNTUK MENINGKATKAN HASIL BELAJAR PESERTA DIDIK

Penelitian ini dilatar belakangi oleh rendahnya sikap rasa ingin tahu dan hasil belajar peserta didik pada Subtema Makananku Sehat dan Bergizi yang pencapaiannya hanya 35% peserta didik yang tuntas memenuhi nilai KKM. Selain itu pendidik masih menggunakan metode atau model pembelajaran yang bersifat teacher centered, yaitu model ceramah.Pelaksanaan yang dilakukan peneiti yaitu dua siklus dan setiap siklus terdiri dari 3 pembelajaran.Model Pembelajaran yang digunakan peneliti yaitu inkuiri terbimbing, pengertian dari inkuiri terbimbing merupakan model pembelajaran yang memberikan kesempatan kepada peserta didik untuk aktif terlibat dalam proses pembelajaran dengan melakukan penyelidikan dan pemecahan masalah secara mandiri namum tetap dengan bimbingan pendidik agar peserta didik lebih mudah dalam memahami konsep pelajaran. Subjek penelitian ini adalah siswakelas IV D SDN Leuwipanjang dengan jumlah peserta didik sebanyak 35 orang. Instrument pembelajaran yang digunakan adalah berupa tes, lembar observasi (observasi pendidik dan observasi peserta didik), LKPD (Lembar Kerja Peserta Didik) dan lembar angket. Hasil penelitian dengan menggunakan model pembelajaran inkuiri terbimbing ditunjukan dengan perencanaan setiap siklusnya yang mengalami perbaikan berdasarkan hasil refleksi di siklus sebelumnya. Pelaksanaan pembelajaran dengan menggunakan model pembelajaran inkuiri terbimbing dapat dilihat dari aktivitas pendidik dan peserta didik pada setiap siklusnya yang mengalami peningkatan. Pencapaian hasil belajar afektif mencapai 44% pada siklus II mencapai 80% dan kognitif peserta didik pada siklus I mencapai rata-rata 35% Siklus II ketuntasan 80%. Adapun hasil belajar psikomotor peserta didik di siklus I mencapai ketuntasan 36%. Siklus II mencapai mencapai ketuntasan 88%. Ambatan yang dilami oleh peneiti yaitu alokasi waktu dan pengelolaan kelas, Upaya yang dilakukan peneliti adalah mengatur pelaksannaan pembelajaran sesuai dengan rencana yang kita persiapkan dengan baik dan mengatur suasana kelas dengan menyenangkan yaitu membuat media pembelajaran yang baik sehingga daapat menarik minat belajar peserta didik. Kata Kunci : Inkuiri Terbimbing, rasa ingin tahu, hasil belajar peserta didik, hambatan pelaksanaan, upaya peningkata

The Slowing Gulf Stream? What we know and potential impacts (Policy Brief)

Blue-Action aims to improve our ability to describe, model, and predict Arctic climate change and its impact on Northern Hemisphere climate, weather, and their extremes, and to deliver valuated climate services of societal benefit. Blue-Action contributes to the implementation of the Trans-Atlantic Ocean Research Alliance, to the EU’s Blue Growth Agenda, and to a long-term strategy to support sustainable growth in the marine and maritime sectors as a whole. Blue-Action supports the implementation of the Galway and the Belem Statements and the achievement of UN SDG 8, 9, 13

Forced and internal components of observed Arctic sea-ice changes

The Arctic sea-ice cover is strongly influenced by internal variability on decadal timescales, affecting both short-term trends and the timing of the first ice-free summer. Several mechanisms of variability have been proposed, but how these mechanisms manifest both spatially and temporally remains unclear. The relative contribution of internal variability to observed Arctic sea-ice changes also remains poorly quantified. Here, we use a novel technique called low-frequency component analysis to identify the dominant patterns of winter and summer decadal Arctic sea-ice variability in the satellite record. The identified patterns account for most of the observed regional sea-ice variability and trends, and they thus help to disentangle the role of forced and internal sea-ice changes over the satellite record. In particular, we identify a mode of decadal ocean–atmosphere–sea-ice variability, characterized by an anomalous atmospheric circulation over the central Arctic, that accounts for approximately 30 % of the accelerated decline in pan-Arctic summer sea-ice area between 2000 and 2012 but accounts for at most 10 % of the decline since 1979. For winter sea ice, we find that internal variability has dominated decadal trends in the Bering Sea but has contributed less to trends in the Barents and Kara seas. These results, which detail the first purely observation-based estimate of the contribution of internal variability to Arctic sea-ice trends, suggest a lower estimate of the contribution from internal variability than most model-based assessments.</p

Loss of sea ice during winter north of Svalbard

Sea ice loss in the Arctic Ocean has up to now been strongest during summer. In contrast, the sea ice concentration north of Svalbard has experienced a larger decline during winter since 1979. The trend in winter ice area loss is close to 10% per decade, and concurrent with a 0.3°C per decade warming of the Atlantic Water entering the Arctic Ocean in this region. Simultaneously, there has been a 2°C per decade warming of winter mean surface air temperature north of Svalbard, which is 20–45% higher than observations on the west coast. Generally, the ice edge north of Svalbard has retreated towards the northeast, along the Atlantic Water pathway. By making reasonable assumptions about the Atlantic Water volume and associated heat transport, we show that the extra oceanic heat brought into the region is likely to have caused the sea ice loss. The reduced sea ice cover leads to more oceanic heat transferred to the atmosphere, suggesting that part of the atmospheric warming is driven by larger open water area. In contrast to significant trends in sea ice concentration, Atlantic Water temperature and air temperature, there is no significant temporal trend in the local winds. Thus, winds have not caused the long-term warming or sea ice loss. However, the dominant winds transport sea ice from the Arctic Ocean into the region north of Svalbard, and the local wind has influence on the year-to-year variability of the ice concentration, which correlates with surface air temperatures, ocean temperatures, as well as the local wind

Sea-ice dynamics in an Arctic coastal polynya during the past 6500 years

The production of high-salinity brines during sea-ice freezing in circum-arctic coastal polynyas is thought to be part of northern deep water formation as it supplies additional dense waters to the Atlantic meridional overturning circulation system. To better predict the effect of possible future summer ice-free conditions in the Arctic Ocean on global climate, it is important to improve our understanding of how climate change has affected sea-ice and brine formation, and thus finally dense water formation during the past. Here, we show temporal coherence between sea-ice conditions in a key Arctic polynya (Storfjorden, Svalbard) and patterns of deep water convection in the neighbouring Nordic Seas over the last 6500 years. A period of frequent sea-ice melting and freezing between 6.5 and 2.8 ka BP coincided with enhanced deep water renewal in the Nordic Seas. Near-permanent sea-ice cover and low brine rejection after 2.8 ka BP likely reduced the overflow of high-salinity shelf waters, concomitant with a gradual slow down of deep water convection in the Nordic Seas, which occurred along with a regional expansion in sea-ice and surface water freshening. The Storfjorden polynya sea-ice factory restarted at ~0.5 ka BP, coincident with renewed deep water penetration to the Arctic and climate amelioration over Svalbard. The identified synergy between Arctic polynya sea-ice conditions and deep water convection during the present interglacial is an indication of the potential consequences for ocean ventilation during states with permanent sea-ice cover or future Arctic ice-free conditions

Recent progress in understanding and predicting Atlantic decadal climate variability

Recent Atlantic climate prediction studies are an exciting new contribution to an extensive body of research on Atlantic decadal variability and predictability that has long emphasized the unique role of the Atlantic Ocean in modulating the surface climate. We present a survey of the foundations and frontiers in our understanding of Atlantic variability mechanisms, the role of the Atlantic Meridional Overturning Circulation (AMOC), and our present capacity for putting that understanding into practice in actual climate prediction systems

Variable Nordic Seas inflow linked to shifts in North Atlantic circulation

The inflow across the Iceland-Scotland Ridge determines the amount of heat supplied to the Nordic Seas from the subpolar North Atlantic (SPNA). Consequently, variable inflow properties and volume transport at the ridge influence marine ecosystems and sea ice extent further north. Here, we identify the upstream pathways of the Nordic Seas inflow, and assess the mechanisms responsible for interannual inflow variability. Using an eddy-permitting ocean model hindcast and a Lagrangian analysis tool, numerical particles are released at the ridge during 1986-2015 and tracked backward in time. We find an inflow that is well-mixed in terms of its properties, where 64% comes from the subtropics and 26% has a subpolar or Arctic origin. The local instantaneous response to the NAO is important for the overall transport of both subtropical and Arctic-origin waters at the ridge. In the years before reaching the ridge, the subtropical particles are influenced by atmospheric circulation anomalies in the gyre boundary region and over the SPNA, forcing shifts in the North Atlantic Current (NAC) and the subpolar front. An equatorward shifted NAC and westward shifted subpolar front correspond to a warmer, more saline inflow. Atmospheric circulation anomalies over the SPNA also affect the amount of Arctic-origin water re-routed from the Labrador Current toward the Nordic Seas. A high transport of Arctic-origin water is associated with a colder, fresher inflow across the Iceland-Scotland Ridge. The results thus demonstrate the importance of gyre dynamics and wind forcing in affecting the Nordic Seas inflow properties and volume transport

On the Seasonal Signal of the Filchner Overflow, Weddell Sea, Antarctica

The cold ice shelf water (ISW) that formed below the Filchner–Ronne Ice Shelf in the southwestern Weddell Sea, Antarctica, escapes the ice shelf cavity through the Filchner Depression and spills over its sill at a rate of 1.6 Sverdrups (Sv; 1 Sv ≡ 106 m3 s−1), thus contributing significantly to the production of Weddell Sea Bottom Water. Here, the authors examine all available observational data from the region—including five year-long time series of mooring data from the Filchner sill—to examine the seasonal variability of the outflow. The temperature of the ISW outflow is found to vary seasonally by 0.07°C with a maximum in April. The accompanying signal in salinity causes a seasonal signal in density of 0.03–0.04 kg m−3, potentially changing the penetration depth of the ISW plume by more than 500 m. Contrary to recent modeling, the observations show no seasonal variability in outflow velocity. The seasonality observed at the sill is, at least partly, due to the admixture of high-salinity shelf water from the Berkner Bank. Observations and numerical modeling suggest, however, seasonal signals in the circulation upstream (i.e., in the ice shelf cavity and in the Filchner Depression) that—although processes and linkages are unclear—are likely to contribute to the seasonal signal observed at the sill. In the plume region downstream of the sill, the source variability is apparent only within the very densest portions of the ISW plume. In the more diluted part of the plume, the source variability is overcome by the seasonality in the properties of the water entrained at the shelf break. This will have implications for the properties of the generated bottom waters

Skillful prediction of northern climate provided by the ocean.

It is commonly understood that a potential for skillful climate prediction resides in the ocean. It nevertheless remains unresolved to what extent variable ocean heat is imprinted on the atmosphere to realize its predictive potential over land. Here we assess from observations whether anomalous heat in the Gulf Stream's northern extension provides predictability of northwestern European and Arctic climate. We show that variations in ocean temperature in the high latitude North Atlantic and Nordic Seas are reflected in the climate of northwestern Europe and in winter Arctic sea ice extent. Statistical regression models show that a significant part of northern climate variability thus can be skillfully predicted up to a decade in advance based on the state of the ocean. Particularly, we predict that Norwegian air temperature will decrease over the coming years, although staying above the long-term (1981-2010) average. Winter Arctic sea ice extent will remain low but with a general increase towards 2020