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• Straume, Eivind Olavson; Nummelin, Aleksi Henrynpoika; Gaina, Carmen & Nisancioglu, Kerim Hestnes (2022). Climate transition at the Eocene-Oligocene influenced by bathymetric changes to the Atlantic-Arctic oceanic gateways. Proceedings of the National Academy of Sciences of the United States of America. ISSN 0027-8424. 119(17), p. 1–9. doi: 10.1073/pnas.2115346119. Full text in Research Archive
• Frank, Thomas; Åkesson, Henning; Fleurian, Basile de; Morlighem, M. & Nisancioglu, Kerim Hestnes (2022). Geometric controls of tidewater glacier dynamics. The Cryosphere. ISSN 1994-0416. 16(2), p. 581–601. doi: 10.5194/tc-16-581-2022.
• Berntell, Ellen; Zhang, Qiong; Li, Qiang; Haywood, Alan M.; Tindall, Julia C. & Hunter, Stephen J. [Show all 29 contributors for this article] (2021). Mid-Pliocene West African Monsoon rainfall as simulated in the PlioMIP2 ensemble. Climate of the Past. ISSN 1814-9324. 17(4), p. 1777–1794. doi: 10.5194/cp-17-1777-2021. Full text in Research Archive Show summary

  The mid-Pliocene warm period (mPWP; ∼3.2 million years ago) is seen as the most recent time period characterized by a warm climate state, with similar to modern geography and ∼400 ppmv atmospheric CO2 concentration, and is therefore often considered an interesting analogue for near-future climate projections. Paleoenvironmental reconstructions indicate higher surface temperatures, decreasing tropical deserts, and a more humid climate in West Africa characterized by a strengthened West African Monsoon (WAM). Using model results from the second phase of the Pliocene Modelling Intercomparison Project (PlioMIP2) ensemble, we analyse changes of the WAM rainfall during the mPWP by comparing them with the control simulations for the pre-industrial period. The ensemble shows a robust increase in the summer rainfall over West Africa and the Sahara region, with an average increase of 2.5 mm/d, contrasted by a rainfall decrease over the equatorial Atlantic. An anomalous warming of the Sahara and deepening of the Saharan Heat Low, seen in >90 % of the models, leads to a strengthening of the WAM and an increased monsoonal flow into the continent. A similar warming of the Sahara is seen in future projections using both phase 3 and 5 of the Coupled Model Intercomparison Project (CMIP3 and CMIP5). Though previous studies of future projections indicate a west–east drying–wetting contrast over the Sahel, PlioMIP2 simulations indicate a uniform rainfall increase in that region in warm climates characterized by increasing greenhouse gas forcing. We note that this effect will further depend on the long-term response of the vegetation to the CO2 forcing.

• Rheinlænder, Jonathan Winfield; Smedsrud, Lars Henrik & Nisancioglu, Kerim Hestnes (2021). Internal Ocean Dynamics Control the Long-Term Evolution of Weddell Sea Polynya Activity. Frontiers in Climate. ISSN 2624-9553. 3. doi: 10.3389/fclim.2021.718016. Full text in Research Archive
• Zhang, Zhongshi; Li, Xiangyu; Guo, Chuncheng; Otterå, Odd Helge; Nisancioglu, Kerim Hestnes & Tan, Ning [Show all 29 contributors for this article] (2021). Mid-Pliocene Atlantic Meridional Overturning Circulation simulated in PlioMIP2. Climate of the Past. ISSN 1814-9324. 17(1), p. 529–543. doi: 10.5194/cp-17-529-2021.
• Oldeman, Arthur M.; Baatsen, Michiel L. J.; Von Der Heydt, Anna S.; Dijkstra, Henk A.; Tindall, Julia C. & Abe-Ouchi, Ayako [Show all 33 contributors for this article] (2021). Reduced El Niño variability in the mid-Pliocene according to the PlioMIP2 ensemble. Climate of the Past. ISSN 1814-9324. 17(6), p. 2427–2450. doi: 10.5194/cp-17-2427-2021. Full text in Research Archive
• Han, Zixuan; Zhang, Qiong; Li, Qiang; Feng, Ran; Haywood, Alan M. & Tindall, Julia C. [Show all 29 contributors for this article] (2021). Evaluating the large-scale hydrological cycle response within the Pliocene Model Intercomparison Project Phase 2 (PlioMIP2) ensemble. Climate of the Past. ISSN 1814-9324. 17(6), p. 2537–2558. doi: 10.5194/cp-17-2537-2021. Full text in Research Archive
• Bretones, Anais Magali; Nisancioglu, Kerim Hestnes; Jensen, Mari Fjalstad; Brakstad, Ailin & Yang, Shuting (2021). Transient Increase in Arctic Deep-Water Formation and Ocean Circulation under Sea Ice Retreat . Journal of Climate. ISSN 0894-8755. 35(1), p. 109–124. doi: 10.1175/JCLI-D-21-0152.1. Full text in Research Archive
• Plach, Andreas; Vinther, Bo M.; Nisancioglu, Kerim Hestnes; Vudayagiri, Sindhu & Blunier, Thomas (2021). Greenland climate simulations show high Eemian surface melt which could explain reduced total air content in ice cores. Climate of the Past. ISSN 1814-9324. 17(1), p. 317–330. doi: 10.5194/cp-17-317-2021. Show summary

  This study presents simulations of Greenland surface melt for the Eemian interglacial period (∼130 000 to 115 000 years ago) derived from regional climate simulations with a coupled surface energy balance model. Surface melt is of high relevance due to its potential effect on ice core observations, e.g., lowering the preserved total air content (TAC) used to infer past surface elevation. An investigation of surface melt is particularly interesting for warm periods with high surface melt, such as the Eemian interglacial period. Furthermore, Eemian ice is the deepest and most compressed ice preserved on Greenland, resulting in our inability to identify melt layers visually. Therefore, simulating Eemian melt rates and associated melt layers is beneficial to improve the reconstruction of past surface elevation. Estimated TAC, based on simulated melt during the Eemian, could explain the lower TAC observations. The simulations show Eemian surface melt at all deep Greenland ice core locations and an average of up to ∼30 melt days per year at Dye-3, corresponding to more than 600 mm water equivalent (w.e.) of annual melt. For higher ice sheet locations, between 60 and 150 mmw.e.yr−1 on average are simulated. At the summit of Greenland, this yields a refreezing ratio of more than 25 % of the annual accumulation. As a consequence, high melt rates during warm periods should be considered when interpreting Greenland TAC fluctuations as surface elevation changes. In addition to estimating the influence of melt on past TAC in ice cores, the simulated surface melt could potentially be used to identify coring locations where Greenland ice is best preserved.

• Morée, Anne L.; Sun, Tianyi; Bretones, Anaïs; Straume, Eivind Olavson; Nisancioglu, Kerim Hestnes & Gebbie, Geoffrey (2021). Cancellation of the precessional cycle in δ18O records during the Early Pleistocene . Geophysical Research Letters. ISSN 0094-8276. 48(3). doi: 10.1029/2020GL090035. Show summary

  The dominant pacing of glacial‐interglacial cycles in deep‐ocean δ18O records changed substantially during the Mid‐Pleistocene Transition. The precessional cycle (∼23 ky) is absent during the Early Pleistocene, which we show can be explained by cancellation of the hemispherically anti‐phased precessional cycle in the Early Pleistocene interior ocean. Such cancellation develops due to mixing of North Atlantic and Southern Ocean δ18O signals at depth, and shows characteristic spatial patterns. We explore the cancellation potential for different North Atlantic and Southern Ocean deep‐water source δ18O values using a tracer transport ocean model. Cancellation of precession occurs for all signal strengths and is widespread for a signal strength typical for the Early Pleistocene. Early Pleistocene precessional power is therefore likely incompletely archived in deep‐sea δ18O records, concealing the true periodicity of the glacial cycles in the two hemispheres.

• Otto-Bliesner, Bette L.; Brady, Esther C.; Zhao, Anni; Brierley, Chris M.; Axford, Yarrow & Capron, Emilie [Show all 39 contributors for this article] (2021). Large-scale features of Last Interglacial climate: results from evaluating the lig127k simulations for the Coupled Model Intercomparison Project (CMIP6)–Paleoclimate Modeling Intercomparison Project (PMIP4). Climate of the Past. ISSN 1814-9324. 17(1), p. 63–94. doi: 10.5194/cp-17-63-2021. Full text in Research Archive
• Kageyama, Masa; Sime, Louise C.; Sicard, Marie; Guarino, Maria-Vittoria; De Vernal, Anne & Stein, Ruediger [Show all 36 contributors for this article] (2021). A multi-model CMIP6-PMIP4 study of Arctic sea ice at 127 ka: sea ice data compilation and model differences. Climate of the Past. ISSN 1814-9324. 17(1), p. 37–62. doi: 10.5194/cp-17-37-2021. Show summary

  The Last Interglacial period (LIG) is a period with increased summer insolation at high northern latitudes, which results in strong changes in the terrestrial and marine cryosphere. Understanding the mechanisms for this response via climate modelling and comparing the models' representation of climate reconstructions is one of the objectives set up by the Paleoclimate Modelling Intercomparison Project for its contribution to the sixth phase of the Coupled Model Intercomparison Project. Here we analyse the results from 16 climate models in terms of Arctic sea ice. The multi-model mean reduction in minimum sea ice area from the pre industrial period (PI) to the LIG reaches 50 % (multi-model mean LIG area is 3.20×106 km2, compared to 6.46×106 km2 for the PI). On the other hand, there is little change for the maximum sea ice area (which is 15–16×106 km2 for both the PI and the LIG. To evaluate the model results we synthesise LIG sea ice data from marine cores collected in the Arctic Ocean, Nordic Seas and northern North Atlantic. The reconstructions for the northern North Atlantic show year-round ice-free conditions, and most models yield results in agreement with these reconstructions. Model–data disagreement appear for the sites in the Nordic Seas close to Greenland and at the edge of the Arctic Ocean. The northernmost site with good chronology, for which a sea ice concentration larger than 75 % is reconstructed even in summer, discriminates those models which simulate too little sea ice. However, the remaining models appear to simulate too much sea ice over the two sites south of the northernmost one, for which the reconstructed sea ice cover is seasonal. Hence models either underestimate or overestimate sea ice cover for the LIG, and their bias does not appear to be related to their bias for the pre-industrial period. Drivers for the inter-model differences are different phasing of the up and down short-wave anomalies over the Arctic Ocean, which are associated with differences in model albedo; possible cloud property differences, in terms of optical depth; and LIG ocean circulation changes which occur for some, but not all, LIG simulations. Finally, we note that inter-comparisons between the LIG simulations and simulations for future climate with moderate (1 % yr−1) CO2 increase show a relationship between LIG sea ice and sea ice simulated under CO2 increase around the years of doubling CO2. The LIG may therefore yield insight into likely 21st century Arctic sea ice changes using these LIG simulations.

• Mojtabavi, Seyedhamidreza; Wilhelms, Frank; Cook, Eliza; Davies, Siwan M.; Sinnl, Giulia & Skov Jensen, Mathias [Show all 20 contributors for this article] (2020). A first chronology for the East Greenland Ice-core Project (EGRIP) over the Holocene and last glacial termination. Climate of the Past. ISSN 1814-9324. 16(6), p. 2359–2380. doi: 10.5194/cp-16-2359-2020. Full text in Research Archive
• Åkesson, Henning; Gyllencreutz, Richard; Mangerud, Jan; Svendsen, John-Inge; Nick, Faezeh M. & Nisancioglu, Kerim Hestnes (2020). Rapid retreat of a Scandinavian marine outlet glacier in response to warming at the last glacial termination. Quaternary Science Reviews. ISSN 0277-3791. 250. doi: 10.1016/j.quascirev.2020.106645. Full text in Research Archive Show summary

  Marine outlet glaciers on Greenland are retreating, yet it is unclear if the recent fast retreat will persist, and how atmosphere and ocean warming will impact future retreat. We show how a marine outlet glacier in Hardangerfjorden retreated rapidly in response to the abrupt warming following the Younger Dryas cold period (approximately 11,600 years before present). This almost 1000 m deep fjord, with several sills at 300–500 m depth, hosted a 175 km long outlet glacier at the western rim of the Scandinavian Ice Sheet. We use a dynamic ice-flow model constrained by well-dated terminal and lateral moraines to simulate the reconstructed 500-year retreat of Hardangerfjorden glacier. The model includes an idealized oceanic and atmospheric forcing based on reconstructions, but excludes the surface mass balance-elevation feedback. Our simulations show a highly episodic retreat driven by surface melt and warming fjord waters, paced by the fjord bathymetry. Warming air and ocean temperatures by 4–5 °C during the period of retreat result in a 125-km retreat of Hardangerfjorden glacier in 500 years. Retreat rates throughout the deglaciation vary by an order of magnitude from 50 to 2500 m a−1, generally close to 200 m a−1, punctuated by brief events of swift retreat exceeding 500 m a−1, each event lasting a few decades. We show that the fastest retreat rates occur in regions of the bed with the largest retrograde slopes; ice shelf length and fjord water depth is less important. Our results have implications for modern glacial fjord settings similar to Hardangerfjorden, where high retreat rates have been observed. Our findings imply that increasing air temperatures and warming subsurface waters in Greenland fjords will continue to drive extensive retreat of marine outlet glaciers. However, the recent high retreat rates are not expected to be sustained for longer than a few decades due to constraints by the fjord bathymetry.

• Jansen, Eystein; Christensen, Jens Hesselbjerg; Dokken, Trond Martin; Nisancioglu, Kerim Hestnes; Vinther, Bo M. & Capron, Emilie [Show all 16 contributors for this article] (2020). Past perspectives on the present era of abrupt Arctic climate change. Nature Climate Change. ISSN 1758-678X. 10, p. 714–721. doi: 10.1038/s41558-020-0860-7.
• Haywood, Alan M.; Tindall, Julia C.; Dowsett, Harry J.; Dolan, Aisling M.; Foley, Kevin M. & Hunter, Stephen J. [Show all 31 contributors for this article] (2020). The Pliocene Model Intercomparison Project Phase 2: large-scale climate features and climate sensitivity. Climate of the Past. ISSN 1814-9324. 16(6). doi: 10.5194/cp-16-2095-2020. Show summary

  The Pliocene epoch has great potential to improve our understanding of the long-term climatic and environmental consequences of an atmospheric CO2 concentration near ~ 400 parts per million by volume. Here we present the large-scale features of Pliocene climate as simulated by a new ensemble of climate models of varying complexity and spatial resolution and based on new reconstructions of boundary conditions (the Pliocene Model Intercomparison Project Phase 2; PlioMIP2). As a global annual average, modelled surface air temperatures increase by between 1.4 and 4.7 °C relative to pre-industrial with a multi-model mean value of 2.8 °C. Annual mean total precipitation rates increase by 6 % (range: 2 %–13 %). On average, surface air temperature (SAT) increases are 1.3 °C greater over the land than over the oceans, and there is a clear pattern of polar amplification with warming polewards of 60° N and 60° S exceeding the global mean warming by a factor of 2.4. In the Atlantic and Pacific Oceans, meridional temperature gradients are reduced, while tropical zonal gradients remain largely unchanged. Although there are some modelling constraints, there is a statistically significant relationship between a model's climate response associated with a doubling in CO2 (Equilibrium Climate Sensitivity; ECS) and its simulated Pliocene surface temperature response. The mean ensemble earth system response to doubling of CO2 (including ice sheet feedbacks) is approximately 50 % greater than ECS, consistent with results from the PlioMIP1 ensemble. Proxy-derived estimates of Pliocene sea-surface temperatures are used to assess model estimates of ECS and indicate a range in ECS from 2.5 to 4.3 °C. This result is in general accord with the range in ECS presented by previous IPCC Assessment Reports.

• Rheinlænder, Jonathan Winfield; Ferreira, David & Nisancioglu, Kerim Hestnes (2020). Topological Constraints by the Greenland–Scotland Ridge on AMOC and Climate. Journal of Climate. ISSN 0894-8755. 33(13). doi: 10.1175/JCLI-D-19-0726.1. Show summary

  Changes in the geometry of ocean basins have been influential in driving climate change throughout Earth’s history. Here, we focus on the emergence of the Greenland–Scotland Ridge (GSR) and its influence on the ocean state, including large-scale circulation, heat transport, water mass properties, and global climate. Using a coupled atmosphere–ocean–sea ice model, we consider the impact of introducing the GSR in an idealized Earth-like geometry, comprising a narrow Atlantic-like basin and a wide Pacific-like basin. Without the GSR, deep-water formation occurs near the North Pole in the Atlantic basin, associated with a deep meridional overturning circulation (MOC). By introducing the GSR, the volume transport across the sill decreases by 64% and deep convection shifts south of the GSR, dramatically altering the structure of the high-latitude MOC. Due to compensation by the subpolar gyre, the northward ocean heat transport across the GSR only decreases by ~30%. As in the modern Atlantic Ocean, a bidirectional circulation regime is established with warm Atlantic water inflow and a cold dense overflow across the GSR. In sharp contrast to the large changes north of the GSR, the strength of the Atlantic MOC south of the GSR is unaffected. Outside the high latitudes of the Atlantic basin, the surface climate response is surprisingly small, suggesting that the GSR has little impact on global climate. Our results suggest that caution is required when interpreting paleoproxy and ocean records, which may record large local changes, as indicators of basin-scale changes in the overturning circulation and global climate.

• McClymont, Erin L.; Ford, Heather; Ho, Sze Ling; Tindall, Julia C.; Haywood, Alan M. & Alonso-Garcia, Montserrat [Show all 36 contributors for this article] (2020). Lessons from a high-CO2 world: an ocean view from  ∼ 3 million years ago. Climate of the Past. ISSN 1814-9324. 16. doi: 10.5194/cp-16-1599-2020. Show summary

  A range of future climate scenarios are projected for high atmospheric CO2 concentrations, given uncertainties over future human actions as well as potential environmental and climatic feedbacks. The geological record offers an opportunity to understand climate system response to a range of forcings and feedbacks which operate over multiple temporal and spatial scales. Here, we examine a single interglacial during the late Pliocene (KM5c, ca. 3.205±0.01 Ma) when atmospheric CO2 exceeded pre-industrial concentrations, but were similar to today and to the lowest emission scenarios for this century. As orbital forcing and continental configurations were almost identical to today, we are able to focus on equilibrium climate system response to modern and near-future CO2. Using proxy data from 32 sites, we demonstrate that global mean sea-surface temperatures were warmer than pre-industrial values, by ∼2.3 ∘C for the combined proxy data (foraminifera Mg∕Ca and alkenones), or by ∼3.2–3.4 ∘C (alkenones only). Compared to the pre-industrial period, reduced meridional gradients and enhanced warming in the North Atlantic are consistently reconstructed. There is broad agreement between data and models at the global scale, with regional differences reflecting ocean circulation and/or proxy signals. An uneven distribution of proxy data in time and space does, however, add uncertainty to our anomaly calculations. The reconstructed global mean sea-surface temperature anomaly for KM5c is warmer than all but three of the PlioMIP2 model outputs, and the reconstructed North Atlantic data tend to align with the warmest KM5c model values. Our results demonstrate that even under low-CO2 emission scenarios, surface ocean warming may be expected to exceed model projections and will be accentuated in the higher latitudes.

• Loose, Nora; Heimbach, Patrick; Pillar, Helen R. & Nisancioglu, Kerim Hestnes (2020). Quantifying dynamical proxy potential through shared adjustment pysics in the North Atlantic. Journal of Geophysical Research (JGR): Oceans. ISSN 2169-9275. 125( 9). doi: 10.1029/2020JC016112. Show summary

  Oceanic quantities of interest (QoIs), for example, ocean heat content or transports, are often inaccessible to direct observation, due to the high cost of instrument deployment and logistical challenges. Therefore, oceanographers seek proxies for undersampled or unobserved QoIs. Conventionally, proxy potential is assessed via statistical correlations, which measure covariability without establishing causality. This paper introduces an alternative method: quantifying dynamical proxy potential. Using an adjoint model, this method unambiguously identifies the physical origins of covariability. A North Atlantic case study illustrates our method within the ECCO (Estimating the Circulation and Climate of the Ocean) state estimation framework. We find that wind forcing along the eastern and northern boundaries of the Atlantic drives a basin‐wide response in North Atlantic circulation and temperature. Due to these large‐scale teleconnections, a single subsurface temperature observation in the Irminger Sea informs heat transport across the remote Iceland‐Scotland ridge (ISR), with a dynamical proxy potential of 19%. Dynamical proxy potential allows two equivalent interpretations: Irminger Sea subsurface temperature (i) shares 19% of its adjustment physics with ISR heat transport and (ii) reduces the uncertainty in ISR heat transport by 19% (independent of the measured temperature value), if the Irminger Sea observation is added without noise to the ECCO state estimate. With its two interpretations, dynamical proxy potential is simultaneously rooted in (i) ocean dynamics and (ii) uncertainty quantification and optimal observing system design, the latter being an emerging branch in computational science. The new method may therefore foster dynamics‐based, quantitative ocean observing system design in the coming years.

• Kajanto, Karita Anneli; Seroussi, Hélène; de Fleurian, Basile & Nisancioglu, Kerim Hestnes (2020). Present day Jakobshavn Isbræ close to the Holocene minimum extent. Quaternary Science Reviews. ISSN 0277-3791. 246. doi: 10.1016/j.quascirev.2020.106492. Show summary

  Marine terminating glaciers evolve on millenial timescales in response to changes in oceanic and atmospheric conditions. However, the relative role of oceanic and atmospheric drivers remains uncertain. The evolution of marine terminating glaciers under the warmer than present Holocene Climate Optimum climate can give important insights into the dynamics of ice streams as the climate evolves. The early Holocene evolution of Jakobshavn Isbræ, from the Last Glacial Maximum extent up to 8.2 ka BP is well constrained by geomorphological studies in the area. However, the Holocene minimum extent of the glacier is unknown. Here, we use a high-resolution regional ice sheet model to study the retreat and readvance of Jakobshavn Isbræ from the Mid-Holocene to the Little Ice Age. This model of Jakobshavn Isbræ accurately tracks the terrestrial ice margin and agrees with available estimates of marine grounding line evolution. We find that the Holocene minimum extent of both the terrestrial ice margin and the grounding line, reached at 6–5 ka BP, is close to the present day extent of the glacier. We also find that the glacier is currently located close to a tipping point, from beyond which readvance would require a longer and more significant cooling than the Little Ice Age. We assess the importance of the ocean forcing in explaining the Holocene evolution of Jakobshavn, and find that cooling within the fjord during the Mid-Holocene is critical for the glacier to readvance. This finding emphasizes the role of ocean forcing when trying to understand the millenial scale evolution of marine terminating glaciers.

• Smith-Johnsen, Silje; de Fleurian, Basile; Schlegel, Nicole; Seroussi, Hélène & Nisancioglu, Kerim Hestnes (2020). Exceptionally high heat flux needed to sustain the Northeast Greenland Ice Stream. The Cryosphere. ISSN 1994-0416. 14, p. 841–854. doi: 10.5194/tc-14-841-2020. Show summary

  The Northeast Greenland Ice Stream (NEGIS) currently drains more than 10 % of the Greenland Ice Sheet area and has recently undergone significant dynamic changes. It is therefore critical to accurately represent this feature when assessing the future contribution of Greenland to sea level rise. At present, NEGIS is reproduced in ice sheet models by inferring basal conditions using observed surface velocities. This approach helps estimate conditions at the base of the ice sheet but cannot be used to estimate the evolution of basal drag in time, so it is not a good representation of the evolution of the ice sheet in future climate warming scenarios. NEGIS is suggested to be initiated by a geothermal heat flux anomaly close to the ice divide, left behind by the movement of Greenland over the Icelandic plume. However, the heat flux underneath the ice sheet is largely unknown, except for a few direct measurements from deep ice core drill sites. Using the Ice Sheet System Model (ISSM), with ice dynamics coupled to a subglacial hydrology model, we investigate the possibility of initiating NEGIS by inserting heat flux anomalies with various locations and intensities. In our model experiment, a minimum heat flux value of 970 mW m−2 located close to the East Greenland Ice-core Project (EGRIP) is required locally to reproduce the observed NEGIS velocities, giving basal melt rates consistent with previous estimates. The value cannot be attributed to geothermal heat flux alone and we suggest hydrothermal circulation as a potential explanation for the high local heat flux. By including high heat flux and the effect of water on sliding, we successfully reproduce the main characteristics of NEGIS in an ice sheet model without using data assimilation.

• Straume, Eivind Olavson; Gaina, Carmen; Medvedev, Sergei & Nisancioglu, Kerim Hestnes (2020). Global Cenozoic Paleobathymetry with a focus on the Northern Hemisphere Oceanic Gateways. Gondwana Research. ISSN 1342-937X. 86, p. 126–143. doi: 10.1016/j.gr.2020.05.011. Full text in Research Archive
• de Nooijer, W.; Zhang, Q.; Li, Q.; Zhang, Qiong; Li, Xiangyu & Zhang, Zhongshi [Show all 29 contributors for this article] (2020). Evaluation of Arctic warming in mid-Pliocene climate simulations. Climate of the Past. ISSN 1814-9324. 16(6), p. 2325–2341. doi: 10.5194/cp-16-2325-2020.
• Smith-Johnsen, Silje; de Fleurian, Basile & Nisancioglu, Kerim Hestnes (2020). The role of subglacial hydrology in ice streams with elevated geothermal heat flux. Journal of Glaciology. ISSN 0022-1430. 66(256), p. 303–312. doi: 10.1017/jog.2020.8. Full text in Research Archive Show summary

  The spatial distribution of geothermal heat flux (GHF) under ice sheets is largely unknown. Nonetheless, it is an important boundary condition in ice-sheet models, and suggested to control part of the complex surface velocity patterns observed in some regions. Here we investigate the effect of including subglacial hydrology when modelling ice streams with elevated GHF. We use an idealised ice stream geometry and a thermomechanical ice flow model coupled to subglacial hydrology in the Ice Sheet System Model (ISSM). Our results show that the dynamic response of the ice stream to elevated GHF is greatly enhanced when including the interactive subglacial hydrology. On the other hand, the impact of GHF on ice temperature is reduced when subglacial hydrology is included. In conclusion, the sensitivity of ice stream dynamics to GHF is likely to be underestimated in studies neglecting subglacial hydrology.

• Smith-Johnsen, Silje; Schlegel, Nicole; de Fleurian, Basile & Nisancioglu, Kerim Hestnes (2019). Sensitivity of the Northeast Greenland Ice Stream to Geothermal Heat. Journal of Geophysical Research (JGR): Earth Surface. ISSN 2169-9003. 125(1). doi: 10.1029/2019JF005252. Full text in Research Archive Show summary

  Recent observations of ice flow surface velocities have helped improve our understanding of basal processes on Greenland and Antarctica, though these processes still constitute some of the largest uncertainties driving ice flow change today. The Northeast Greenland Ice Stream is driven largely by basal sliding, believed to be related to subglacial hydrology and the availability of heat. Characterization of the uncertainties associated with Northeast Greenland Ice Stream is crucial for constraining Greenland's potential contribution to sea level rise in the upcoming centuries. Here, we expand upon past work using the Ice Sheet System Model to quantify the uncertainties in models of the ice flow in the Northeast Greenland Ice Stream by perturbing the geothermal heat flux. Utilizing a subglacial hydrology model simulating sliding beneath the Greenland Ice Sheet, we investigate the sensitivity of the Northeast Greenland Ice Stream ice flow to various estimates of geothermal heat flux, and implications of basal heat flux uncertainties on modeling the hydrological processes beneath Greenland's major ice stream. We find that the uncertainty due to sliding at the bed is 10 times greater than the uncertainty associated with internal ice viscosity. Geothermal heat flux dictates the size of the area of the subglacial drainage system and its efficiency. The uncertainty of ice discharge from the Northeast Greenland Ice Stream to the ocean due to uncertainties in the geothermal heat flux is estimated at 2.10 Gt/yr. This highlights the urgency in obtaining better constraints on the highly uncertain subglacial hydrology parameters.

• Smith-Johnsen, Silje; de Fleurian, Basile; Schlegel, Nicole; Seroussi, Helene & Nisancioglu, Kerim Hestnes (2019). Exceptionally High Geothermal Heat Flux Needed to Sustain the Northeast Greenland Ice Stream. The Cryosphere Discussions. ISSN 1994-0432. doi: 10.5194/tc-2019-212. Show summary

  The Northeast Greenland Ice Stream (NEGIS) currently drains more than 10 % of the Greenland Ice Sheet area, and has recently undergone significant dynamic changes. It is therefore critical to accurately represent this feature when assessing the future contribution of Greenland to sea level rise. At present, NEGIS is reproduced in ice sheet models by inferring basal conditions using observed surface velocities. This approach helps estimate conditions at the base of the ice sheet, but cannot be used to estimate the evolution of basal drag in time, so it is not a good representation of the evolution of the ice sheet in future climate warming scenarios. NEGIS is suggested to be initiated by a geothermal heat flux anomaly close to the ice divide, left behind by the movement of Greenland over the Icelandic plume. However, the heat flux underneath the ice sheet is largely unknown, except for a few direct measurements from deep ice core drill sites. Using the Ice Sheet System Model (ISSM), with ice dynamics coupled to a subglacial hydrology model, we investigate the possibility of initiating NEGIS by inserting hotspots with various locations and intensities. We find that a minimum geothermal heat flux value of 970 mW/m2 located close to EastGRIP is required locally to reproduce the observed NEGIS velocities, consistent with previous estimates. By including high geothermal heat flux and the effect of water on sliding, we successfully reproduce the main characteristics of NEGIS in an ice sheet model without using data assimilation.

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• Mathismoen, Ole; Isaksen, Ketil; Muilwijk, Morven; Andreassen, Liss Marie; Nesje, Atle & Jansen, Eystein [Show all 20 contributors for this article] (2021). Varm is. Når verden tiner og alt forandres. Kagge. ISBN 978-82-489-2849-2. 169 p.

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• Nisancioglu, Kerim Hestnes (2022). One Ocean Expedition snakker Om i Morgen. Show summary

  I august 2021 seilte Statsraad Lehmkhul ut fra Arendal på den 20 måneder lange “One Ocean Expedition”. Fra mai til august 2022 er det ventet hele 90 studenter fra faget universitetsfafget “SDG200” ombord! I samarbeid med «Om i morgen» inviterer vi til et spektakulært innblikk i hvordan det er å seile med Statsraad Lehmkhul og One Ocean expidition! Hvordan er det å oppleve klimaendringer på nærthold? Hvilke forventninger har studentene i møte med klima endringene? Og hvilke tanker har de gjort seg i etterkant? Bli med på en visuell og muntlig jordomseiling!

• Nisancioglu, Kerim Hestnes; Hviding, Edvard & Freng Dale, Ragnhild (2022). Klimaerfaringer fra Grønland til Stillehavet. Show summary

  Mens havet stiger langs øygruppene i Stillehavet, synker havet langs kysten av Grønland. Klimaendringene er globale, men det er ofte langt mellom årsak og konsekvens. Ettersom isen på Grønland smelter, er konsekvensene først tydelige i tropiske områder. Begge steder bor det mennesker som lever i pakt med naturen og har en inngående forståelse av endring over tid. Hvordan kan mennesker fra vidt forskjellige verdensdeler og kulturer sammen øke vår forståelse av årsakene og konsekvensene av klimaendringene? Er klimafortellinger en del av løsningen på klimautfordringene vi står ovenfor?

• Nisancioglu, Kerim Hestnes (2022). Kerim’s Climate Odyssey: The Climate Change Classroom on the Sea. [TV]. Al Jazeera. Show summary

  A Norwegian climatologist sets sail in the Caribbean to understand the effects of climate change. Kerim Nisancioglu is a climatology professor in Norway. He knows the best way to engage the next generation of climate scientists is not in a lecture theatre, but on a ship-turned-research vessel in the Caribbean Sea. He joins an international team of academics, activists and students on the One Ocean Expedition. Their mission is to learn about the effects of climate change through the experiences of coastal communities on the front line. After months of preparation, they set sail to collect and share climate data with governments around the world. Kerim’s Climate Odyssey by Rosie Collyer.

• Nisancioglu, Kerim Hestnes & Åkesson, Henning (2022). Hardangerjøkulen - fortidshistorien og fremtidsutsiktene.
• Nisancioglu, Kerim Hestnes; Johanne, Skrefsrud & Anne-Marie, Karlsen (2022). Klima og havnivå – en reise fra Arktis til tropene.
• Nisancioglu, Kerim Hestnes (2022). Bærekraft og klimahandling – hva er utfordringene og hva kreves av oss? Show summary

  På seminaret vil alle ansatte på Nordahl Grieg vgs delta. Dette inkluderer miljøarbeidere, lærere, merkantile, tegnspråktolker og ledere. Hovedtemaet for dagene (4.-5/4) vil være de tre tverrfaglige temaene i fagfornyelsen; folkehelse og livsmestring, bærekraftig utviking og demokrati og medborgerskap.

• Nisancioglu, Kerim Hestnes (2022). Klima og havnivå – en reise fra Arktis til tropene.
• Nisancioglu, Kerim Hestnes & Dietrich, Laura Jasmin (2022). Klima og havnivå – en reise fra Arktis til tropene (biblioteket). Show summary

  I samband med Klimaveka i Kvam 2022, kjem professor Kerim Hestnes Nisancigolu og stipendiat Laura Dietrich for å ta oss gjennom eit interessant føredrag om Klima og havnivå. Gratis og ope for alle Why does the Greenland Ice Sheet matter for the islands in the Caribbean? How can we reduce our CO2 emissions most efficiently? Which strategies can be used to mitigate the rapid climate change in coastal areas? We will cover these and many more questions and discuss solutions to the challenge of global warming. Climate scientists Kerim Nisancioglu and Laura Dietrich from the University of Bergen will share insights into their work

• Nisancioglu, Kerim Hestnes & Dietrich, Laura Jasmin (2022). Klimaveka i Kvam (VGS). Show summary

  Klima og havnivå – en reise fra Arktis til tropene

• Nisancioglu, Kerim Hestnes (2022). Kronprins ekspedisjon. [TV]. NRK Dagsrevyen.
• Nisancioglu, Kerim Hestnes; Halas, Paul Lucas; Wahl, Sonja & Smedsrud, Lars Henrik (2022). Outreach at the Ice Music Festival in Bergsjøstølen - Greenland and sea level rise. Show summary

  https://www.bjerknes.uib.no/en/article/music-and-science-icy-symbiose

• Nisancioglu, Kerim Hestnes (2022). Historiske målinger av dyphavstemperatur fra Statsraad Lehmkhul. Show summary

  I august 2021 kasta Statsraad Lehmkuhl loss for jordomseglinga «One Ocean Expidition». Målet er å skape merksemd og dele kunnskap om havet si viktige rolle for ei berekraftig framtid i eit globalt perspektiv. Gjennom forsking og teknologi skal det samlast inn meir kunnskap om korleis menneske påverkar havet. Ein av personane som har hatt ei særskilt rolle om bord er Dr. Kerim Hestnes Nisancioglu, professor ved institutt for geofag ved Universitetet i Bergen. Som ein viktig del av undervisinga- og forskingsaktiviteten har han hatt feltarbeid samen med 25 studentar om bord. Her gjennomførte dei ein rekonstruksjon av dei originale vatnmålingane, som vart gjort på forskingstokta til HMS Challenger for 150 år sidan. Til dette prosjektet leverte reiparbanen på Hardanger fartøyvernsenter 1000 meter med hampetau, for å gjere vatnmålingane så historisk korrekte som mogleg og likt den prøve som vart teken på tidleg 1900-tal. 10. februar kl. 19.00 på Hardanger fartøyvernsenter skal me høyre Kerim fortelje om forskingsprosjektet og korleis det gjekk med vatnprøvane – kvifor vart dei tekne i første omgang? Kva kan dei fortelje oss? Kva skal dei brukast til? Og viktigast av alt – kan dei brukast til å seie noko om konsekvensar, årsaker og løysningar på klimautfordringane me har i dag?

• Nisancioglu, Kerim Hestnes (2021). SDG313 One Ocean Field Course - Research and Teaching at Sea.
• Nisancioglu, Kerim Hestnes (2021). Klimaendringer i Arktis.
• Nisancioglu, Kerim Hestnes (2021). Slik gjorde klimaforskeren villaen fra 1880 om til et nullutslipphus. [Journal]. Teknisk Ukeblad.
• Nisancioglu, Kerim Hestnes (2021). Norwegian climate politics.
• Nisancioglu, Kerim Hestnes (2021). Hva vi alle kan bidra med for å sikre at vi når målet om 1,5C?
• Nisancioglu, Kerim Hestnes (2021). Huset uten utslipp. [Newspaper]. Bergens Tidende. Show summary

  – Det nytter ikke bare å fortelle hva andre skal gjøre. Det er også viktig å gjøre det man kan selv, sier Kerim Hestnes Nisancioglu. Grå himmel har lagt seg over det okergule tømmerhuset i Breistølsveien. At sur maivind sveiper over Fjellsiden, ser ikke ut til å bry den blide trønderen. Professoren ved Bjerknessenteret er vant til både 20 og 30 minusgrader i Arktis, der han i mange år har forsket på klimautfordringene.

• Nisancioglu, Kerim Hestnes (2021). Ti år etter at arbeidet med prosjektet starta, kom Kerim gjennom nålauga. [Internet]. Khrono.no. Show summary

  Kerim Hestnes Nisancioglu får nesten 24 milionar kroner frå Forskingsrådet. Han er sjølvsagt nøgd, men: — Det svir å vita at nålauga er så trangt, seier klimaforskaren.

• Nisancioglu, Kerim Hestnes (2021). ET PUSLESPILL OM KLIMAENDRINGER I ARKTIS. [Internet]. Universitetet i Bergen. Show summary

  Hva blir konsekvensene av at isen på Grønland og i Arktis smelter i et alarmerende tempo? Det var et av spørsmålene professor Kerim Hestnes Nisancioglu og kolleger ville finne svar på i det største ERC-prosjektet i Norden noensinne; Synergy Grant-prosjektet ice2ice.

• Nisancioglu, Kerim Hestnes (2021). Ein vekkjar for mange - Klimakonferanse i Rosendal: Vil ikkje lenger sjå breen frå dalane. [Newspaper]. Hardanger Folkeblad. Show summary

  Samstundes som den urovekkande rapporten til FN sitt klimapanel er på alle sine lepper, blir tema rundt klima og omstilling diskutert inngåande på kaien i Rosendal.

• Nisancioglu, Kerim Hestnes (2021). Høge ambisjonar om Vestland som leiande region globalt. [Newspaper]. Grenda. Show summary

  osendalsveko sette det grøne skiftet på dagsorden. Under siste post på programmet onsdag, Lukkast Vestlandet – Lukkast Noreg, vart regionen belyst i eit globalt perspektiv.

• Nisancioglu, Kerim Hestnes (2021). Snart klart for Rosendalsveko: Klima, energi, næring og berekraft på Vestlandet. [Newspaper]. Kvinnheringen. Show summary

  Store ord er igjen tema for den andre Rosendalsveko i Folgefonnsenteret 9.–11. august.

• Nisancioglu, Kerim Hestnes (2021). Lokal klimakonferanse på høgaktuelt tidspunkt: – Når vi først har sett avtrykk, er det ingen veg tilbake. [Newspaper]. Kvinnheringen. Show summary

  Samstundes som den urovekkande rapporten til FN sitt klimapanel er på alle sine lepper, blir tema rundt klima og omstilling diskutert inngåande på kaien i Rosendal.

• Nisancioglu, Kerim Hestnes (2021). Inviterer til ungdoms-camp i forkant av Rosendalsveko. [Newspaper]. Grenda. Show summary

  osendalsveko er i år utvida med ein ungdoms-camp som vil finna stad på Folgefonnsenteret. Ungdomsprogrammet er lagt til helga 7. og 8. august, kor mellom anna studentar vert inviterte til å delta.

• Nisancioglu, Kerim Hestnes (2021). Visit of prime minister of Jamaica - the honorary Andre Holness. Show summary

  Visit of prime minister of Jamaica - the honorary Andre Holnes

• Nisancioglu, Kerim Hestnes (2021). Teaching Climate Action at Sea.
• Nisancioglu, Kerim Hestnes & Baardsen, Aurora (2021). Scientists of the Caribbean. [Internet]. På Høyden. Show summary

  UiB-student Aurora Baardsen tilbringer november om bord på Statsraad Lehmkuhl i Karibia. Under ledelse av UiB-forskere skal studenter fra flere land undersøke klimaendringene og utvikle felles forståelse.

• Nisancioglu, Kerim Hestnes (2021). The UWI Mona Campus hosts the One Ocean Expedition research vessel. [Internet]. Trinidad and Tobago Newsday. Show summary

  Participants aboard the Norwegian, Statsraad Lehmkuhl research vessel which docked at Jamaica’s Port Royal earlier this month, were hosted by UWI's Mona Campus on November 16. The 33 visiting students and lecturers, who are on the One Ocean Expedition led by University of Bergen (UiB), toured the Mona Campus’ Port Royal Marine Laboratory, then participated in an organised knowledge exchange forum, said a media release.

• Nisancioglu, Kerim Hestnes (2021). THE UNIVERSITY OF THE WEST INDIES & UNIVERSITY OF BERGEN SIGN MOU ABOARD ‘ONE OCEAN EXPEDITION’ RESEARCH SAILING VESSEL. [Internet]. The Barbados Advocate.
• Nisancioglu, Kerim Hestnes (2021). SENATOR JOHNSON SMITH ATTENDS RECEPTION ABOARD THE NORWEGIAN VESSEL. [Internet]. Entorno inteligente. Show summary

  Entornointeligente.com / Minister of Foreign Affairs and Foreign Trade, Senator the Hon. Kamina Johnson Smith (right), and Norway’s Ambassador to Jamaica, Her Excellency Beate Stirø (left), share a moment with Professor of Climate Dynamics, University of Bergen, Norway, Dr. Kerim Nisancioglu (left, seated), and Pro-Vice Chancellor, Global Affairs, University of the West Indies, Dr. Stacy Richards Kennedy, following the signing of a Memorandum of Understanding (MOU) between the institutions on Saturday (November 13).

• Nisancioglu, Kerim Hestnes (2021). Blue economy on agenda as Norway, Jamaica strengthen ties. [Internet]. The Jamaica Gleaner. Show summary

  The Naval Dockyard in Port Royal on Saturday welcomed the Statsraad Lehmkuhl Norwegian tour and research vessel for five days to its port as part of its two-year round- the-world ‘One Ocean Expedition’. The 107-year-old, 98-metre-long ship, which has sailed 55,000 nautical miles and visited 36 ports across the world, is one of the world’s largest and oldest ships.

• Nisancioglu, Kerim Hestnes (2021). The UWI signs MOU with Bergen University aboard ‘One Ocean Expedition’ research sailing vessel. [Internet]. Trinidad and Tobago Guardian. Show summary

  (The UWI, Jamaica)—The University of the West Indies (The UWI) and Norway’s University of Bergen (UiB) formalised ongoing collaborations with the signing of a Memorandum of Understanding on Saturday, November 13. In this MOU, the two universities committed to advancing research and action on the United Nation’s Sustainable Development Goals 13 (Climate action) and 14 (Life Below Water).

• Nisancioglu, Kerim Hestnes (2021). UWI signs MoU with Norwegian university. [Internet]. Loop TT News. Show summary

  The University of the West Indies has joined forces with the University of Bergen via a Memorandum of Understanding (MoU) which was signed aboard the ‘One Ocean Expedition’ research sailing vessel. In a statement the UWI said the signing took place on November 13 aboard the Norwegian, Statsraad Lehmkuhl training vessel which was docked at Jamaica's Port Royal, hosted by Norwegian Ambassador H.E. Beate Stiro, for the crew of One Ocean Expedition.

• Nisancioglu, Kerim Hestnes (2021). Jamaica bands with Norway on climate change awareness. [Internet]. The Jamaica Gleaner. Show summary

  As part of the One Ocean Expedition expected to run until 2023, Jamaica welcomed on Saturday the Norwegian vessel Statsraad Lehmkuhl, one of the world's largest sailing ships, to the historic Naval Dockyard in Port Royal. The vessel, currently on a circumnavigation of the world with officials, researchers, and students from different parts of the globe, is aiming to create awareness and share knowledge about the positive impact of safe environmental practices, which the protection of the ocean can have on mitigating the adverse impacts of climate change and ensuring sustainability.

• Nisancioglu, Kerim Hestnes (2021). UWI students aboard ‘One Ocean Expedition’ research vessel. [Internet]. The Jamaica Gleaner. Show summary

  The Norwegian, Statsraad Lehmkuhl sail training vessel enters the English-speaking Caribbean leg of its historic 55,000-mile ‘One Ocean Expedition’, this weekend. Today, the 107-year old, 98-metre long sail ship docks at Port Royal in Kingston, Jamaica. Onboard for this extraordinary research expedition are two postgraduate researchers from The University of the West Indies (The UWI) Mona Campus, Chauntelle Green from the Department of Life Sciences and Deron Maitland from the Department of Physics.

• Nisancioglu, Kerim Hestnes (2021). UWI students sight home as Norwegian expedition to dock in Jamaica on Saturday. [Internet]. Our Today.
• Nisancioglu, Kerim Hestnes (2021). SDG313 OneOcean Field Course - research and teaching at sea.
• Nisancioglu, Kerim Hestnes (2021). Teaching Climate Action at Sea.
• Nisancioglu, Kerim Hestnes (2021). One Ocean Open Day for school pupils - Cuba. Show summary

  One Ocean Open Day for school pupils - Cuba

• Nisancioglu, Kerim Hestnes (2021). One Ocean Open Day for school pupils - Jamaica.
• Nisancioglu, Kerim Hestnes (2021). UWI students aboard ‘One Ocean Expedition’ research vessel docking in Jamaica this weekend. [Internet]. UWI TV Global. Show summary

  The Norwegian, Statsraad Lehmkuhl sail training vessel enters the English-speaking Caribbean leg of its historic 55,000-mile, ‘One Ocean Expedition’ this weekend. On Saturday, November 13, the 107-year old, 98-metre long sail ship docks at Port Royal in Kingston, Jamaica. Onboard for this extraordinary research expedition, are two postgraduate researchers from The University of the West Indies (The UWI) Mona Campus, Chauntelle Green from the Department of Life Sciences and Deron Maitland from the Department of Physics.

• Nisancioglu, Kerim Hestnes (2021). The University of the West Indies & University of Bergen sign MOU aboard ‘One Ocean Expedition’ research sailing vessel. [Internet]. UWI TV Global. Show summary

  The University of the West Indies (The UWI) and Norway’s University of Bergen (UiB) formalised ongoing collaborations with the signing of a Memorandum of Understanding on Saturday, November 13. UiB’s Professor Kerim Nisancioglu and The UWI’s Dr. Stacy Richards-Kennedy display sign copies of the MOU. The University of the West Indies (The UWI) and Norway’s University of Bergen (UiB) formalised ongoing collaborations with the signing of a Memorandum of Understanding on Saturday, November 13. In this MOU, the two universities committed to advancing research and action on the United Nation’s Sustainable Development Goals 13 (Climate action) and 14 (Life Below Water).

• Nisancioglu, Kerim Hestnes (2021). The UWI Mona Campus hosts participants from the ‘One Ocean Expedition’ research vessel. [Internet]. UWI TV Global. Show summary

  Participants aboard the Norwegian, Statsraad Lehmkuhl research vessel which docked at Jamaica’s Port Royal earlier this month, were hosted by The University of the West Indies (The UWI) Mona Campus on Tuesday, November 16, 2021. The 33 visiting students and lecturers who are on the One Ocean Expedition led by University of Bergen (UiB), toured the Mona Campus’ Port Royal Marine Laboratory, then participated in an organised Knowledge Exchange Forum.

• Nisancioglu, Kerim Hestnes (2021). Derfor hermer Lehmkuhl-forskerne etter dette legendariske skipet. [Internet]. Bergens Tidene. Show summary

  Statsraaden er omgjort til en hypermoderne forskningsskip. Likevel kopierer forskerne om bord eldgamle metoder. Inspirasjonen er den myteomspunne «Challenger»-ekspedisjonen.

• Kajanto, Karita Anneli & Nisancioglu, Kerim Hestnes (2021). The role of icebergs in a Greenland fjord.
• Nisancioglu, Kerim Hestnes; Morée, Anne; Sun, Tianyi; Bretones, Anais Magali; Straume, Eivind Olavson & Gebbie, Geoffrey (2021). Cancellation of the precessional cycle in δ18O records during the Early Pleistocene. Show summary

  The dominant pacing of glacial‐interglacial cycles in deep‐ocean δ18O records changed substantially during the Mid‐Pleistocene Transition. The precessional cycle (∼23 ky) is absent during the Early Pleistocene, which we show can be explained by cancellation of the hemispherically anti‐phased precessional cycle in the Early Pleistocene interior ocean. Such cancellation develops due to mixing of North Atlantic and Southern Ocean δ18O signals at depth, and shows characteristic spatial patterns. We explore the cancellation potential for different North Atlantic and Southern Ocean deep‐water source δ18O values using a tracer transport ocean model. Cancellation of precession occurs for all signal strengths and is widespread for a signal strength typical for the Early Pleistocene. Early Pleistocene precessional power is therefore likely incompletely archived in deep‐sea δ18O records, concealing the true periodicity of the glacial cycles in the two hemispheres.

• Nisancioglu, Kerim Hestnes (2021). Bærekraft of klimahandling - hva er utfordingene og hva krever det av oss?
• Nisancioglu, Kerim Hestnes (2021). Communicating the science of ice and climate.
• Nisancioglu, Kerim Hestnes (2021). SDG313 OneOcean Field Course - research and teaching at sea.
• Nisancioglu, Kerim Hestnes (2021). ClimateNarratives - SDG-13 i forskning, utdanning og internasjonalt samarbeid.
• Nisancioglu, Kerim Hestnes; Faber, Anne-Katrine & Zolles, Tobias (2021). IceFinse field course.
• Bretones, Anais Magali; Nisancioglu, Kerim Hestnes; Nummelin, Aleksi & Jensen, Mari Fjalstad (2021). Deep-water formation and Arctic circulation under sea-ice retreat: a comparison between CMIP6 models.
• Nisancioglu, Kerim Hestnes; Bretones, Anais Magali & Jensen, Mari Fjalstad (2021). Ice-ocean interactions and the stability of the Greenland ice sheet. Show summary

  The webinar “The Changing Arctic” for strengthening the Arctic research cooperation between Estonia and Norway will take place on Wednesday, 14 April 2021 at 09:00 (in Norway) / 10:00 (in Estonia). The Arctic has gained increased interest over the last decade as global climate change continues to transform the region. Norway and Estonia are both maritime countries with a long history of polar exploration and research. Now we are looking into new opportunities of Arctic research cooperation. Researchers from Estonia and Norway offer an insight into the state of play and their work in the Arctic – the glaciers and the sea, the indigenous people and the governance, methane seeps, algal blooms and the fungi. The webinar celebrates the 100th anniversary of the diplomatic relations between Estonia and Norway, and the Norwegian-Estonian cooperation in climate change under the EEA and Norway Grants. Organisers: The Estonian Academy of Sciences, Tallinn University of Technology (TalTech), the Bjerknes Centre for Climate Research/University of Bergen and the Academia Europaea Bergen Knowledge Hub in cooperation with the Norwegian Embassy in Tallinn.

• Nisancioglu, Kerim Hestnes (2021). Ekspertintervjuet: Grønlandsisen nær vippepunktet. [Internet]. Energi og Klima. Show summary

  For flere tusen år siden var temperaturen bare litt høyere enn i dag. Da var Grønlandsisen 1/3 mindre enn den er i dag. Forskjellen er at den gangen varte varmeperiode over flere tusen år, og temperaturen steg langsommere enn den gjør i dag, forklarer professor Kerim Nisancioglu ved Universitetet i Bergen og Bjerknessenteret.

• Nisancioglu, Kerim Hestnes & Jensen, Mari Fjalstad (2020). Changes in Overturning Circulation under Arctic Sea Ice Retreat in EC-Earth.
• Bretones, Anaïs; Nisancioglu, Kerim Hestnes; Jensen, Mari Fjalstad & Brakstad, Ailin Dale (2020). Changes in Overturning Circulation under Arctic Sea Ice Retreat in EC-Earth.
• Kajanto, Karita Anneli; Seroussi, Hélène; de Fleurian, Basile & Nisancioglu, Kerim Hestnes (2020). Holocene minimum extent of Jakobshavn Isbræ shows an approaching tipping point.
• Conrad, Clinton Phillips; Selway, Kate; Weerdesteijn, Maaike Francine Maria; Smith-Johnsen, Silje; Nisancioglu, Kerim Hestnes & Karlsson, Nanna B (2020). Magnetotelluric Constraints on Upper Mantle Viscosity Structure and Basal Melt Beneath the Greenland Ice Sheet.
• Conrad, Clinton Phillips; Selway, Kate; Weerdesteijn, Maaike Francine Maria; Smith-Johnsen, Silje; Nisancioglu, Kerim Hestnes & Karlsson, Nanna B (2020). Magnetotelluric Constraints on Upper Mantle Viscosity Structure and Basal Melt Beneath the Greenland Ice Sheet.
• Nisancioglu, Kerim Hestnes (2020). Hun elsket kjøttdeig, plastposer og shopping. Slik fikk hun familien på fem til å leve mer miljøvennlig. [Newspaper]. Aftenposten.
• Nisancioglu, Kerim Hestnes (2020). Klimaforskere: – Fra nå vil norske utslipp bare synke. [Internet]. NRK.no. Show summary

  Norske klimagassutslipp gikk ned med to prosent det siste året, viser foreløpig statistikk. Flere klimaforskere tror trenden er kommet for å bli.

• Frank, Thomas; Åkesson, Henning; de Fleurian, Basile & Nisancioglu, Kerim Hestnes (2020). Geometric Controls of Fjord Glacier Dynamics. Show summary

  Retreat of marine outlet glaciers and ice shelves may initiate depletion of inland ice and lead to ice loss that by far exceeds what would be expected from ocean and atmospheric warming alone. Many marine outlet glaciers draining large parts of past and present ice masses have shown non-linear and variable retreat rates, with adjacent glaciers sometimes showing a highly different response to the same large-scale climate forcing. This suggests that individual glacier characteristics play a dominant role in governing retreat. There is widespread evidence that the dynamic glacier adjustment to an external forcing is highly influenced by fjord topography. However, whether this stabilizes the glacier, or promotes enhanced retreat, depends on the shape of the fjord. So far, no rigorous, systematic assessment of the exact influence of certain geometric features such as overdeepenings or embayments has been undertaken in a model framework that incorporates all relevant processes in a 3D layout. Here, we analyze a multitude of topographic settings and scenarios using the Ice Sheet System Model (ISSM), which accounts for all relevant physics in a 3D framework. Using artificial fjord geometries, we investigate glacier-topography interaction and quantify the modeled glacier response directly in relation to topographic features. In light of our modeled topographic influence on glacier retreat, we consider whether we reliably can extrapolate observations from a few well-monitored glaciers to those less studied. Furthermore, we discuss implications for past and future ice sheet mass loss and associated sea-level rise. Finally, a deeper understanding of processes at the glacier front improves confidence in the climate signal derived from the deglacial landscape, as glacier-proximal landforms can more confidently be linked to climate.

• Maffezzoli, Niccolo; Patrizia, Ferretti; Delmonte, Barbara; Nisancioglu, Kerim Hestnes & Barbante, Carlo (2020). The ICELEARNING project - Artificial Intelligence techniques for ice core analyses. Show summary

  The detection of insoluble particles trapped in ice cores, like volcanic and dust particles, pollen grains, foraminifera and diatom assemblages, represents the experimental basis for multiple lines of environmental paleoresearch regarding the atmosphere, the biosphere and volcanology. To date, except for ice core dust, the detection of such particles is achieved through observations by manual microscopy. Artificial Intelligence predictive models are already applied to several research fields within geoscience, but up to date its implementation to ice core science is missing. The recently EU funded Marie Curie ICELEARNING project (2020-2022) aims to develop a two-phase routine for the automatic quantification of insoluble particles trapped in ice cores. The routine is based on a commercial Flow Imaging Microscope producing micro-scale images of insoluble particles from melted ice core samples. The image collection of mineral dust, tephra, pollen and marine foraminifera obtained from natural and/or ad-hoc prepared samples will constitute the training datasets. The images will be then analyzed by Pattern Recognition algorithms developed for automatic particle classification and counting. The routine will be specifically developed in order to be implemented in ice core Continuous Flow Analysis (CFA) systems, thus improving the more traditional methods and potentially providing continuous ice core insoluble particle records. The ICELEARNING methodology is suitable for melted ice core samples and any diluted aqueous sample, thus representing a ground-breaking analytical advancement for a wide range of research fields, from ice core science to marine geology. The innovative routine here presented is automatic and non-destructive, imperative prerequisites for future Antarctic ice core projects.

• Jensen, Mari Fjalstad; Nisancioglu, Kerim Hestnes; Spall, Michael A. & Våge, Kjetil (2020). Changing sea ice in the Nordic Seas and its effect on water mass transformation.
• Nisancioglu, Kerim Hestnes (2020). SDG213 Climate Action - Causes and Consequences of Climate Change .
• Jensen, Mari Fjalstad & Nisancioglu, Kerim Hestnes (2020). SnowHow. [TV]. NRK. Show summary

  Vinteren endrer alt. Den byr på store muligheter og en masse trøbbel. Hva har vinteren gjort med oss som bor her nord, og hva gjør vi med vinteren?

• Nisancioglu, Kerim Hestnes (2020). Forskere deler sine klimabekymringer – Når isen beveger seg, er den ustoppelig. [Internet]. ABC Nyheter. Show summary

  Årlige besøk til Grønlandsisen har fått klimaforsker Kerim Hestnes Nisancioglu til å innse at det er umulig å stoppe de menneskeskapte, globale klimaendringene. Det beste vi kan håpe på er å bremse det litt.

• Conrad, Clinton Phillips; Selway, Kate; Weerdesteijn, Maaike Francine Maria; Smith-Johnsen, Silje; Nisancioglu, Kerim Hestnes & Karlsson, Nanna B (2019). Magnetotelluric Constraints on Upper Mantle Viscosity Structure and Basal Melt Beneath the Greenland Ice Sheet.
• Kajanto, Karita Anneli; Seroussi, Hélène; de Fleurian, Basile & Nisancioglu, Kerim Hestnes (2019). Holocene retreat of Jakobshavn isbrae – matching model results to data.
• Morée, Anne; Sun, Tianyi; Bretones, Anaïs; Straume, Eivind Olavson; Nisancioglu, Kerim Hestnes & Gebbie, Geoffrey (2019). Cancellation of the precessional cycle in δ18O records during the Early Pleistocene. Show summary

  Deep-sea δ18O records show a pronounced difference in Milankovitch periodicity between the Early and Late Pleistocene. δ18O is interpreted as a proxy for ice sheet volume and temperature, which led to the conclusion that glacial-interglacial cycles considerably changed their rhythm during the mid-Pleistocene. This transition is referred to as the mid-Pleistocene Transition (MPT). Specifically, the precessional component of the Milankovitch cycles is absent in Early Pleistocene δ18O records, despite its continuous presence in solar insolation forcing to the ice sheets. Climate feedbacks involving (sea) ice, geological processes and carbon and nutrient cycling have been proposed as causes of this marked change. We however show that the absence of an Early Pleistocene precession signal in deep-sea δ18O records could be the result of destructive interference of the precessional cycle in the interior ocean. Such cancellation is caused by the anti-phasing of the precessional cycle between the North Atlantic and Southern Ocean deep-water sources (see Figure). We explore the potential for cancellation in the transient setup of the Total Matrix Intercomparison model for a wide range of source signal strengths. Our results show that cancellation can cause the absence of the precessional signal due to cancellation in the interior South-Atlantic, Indian and Pacific basins. Cancellation is especially widespread for a relative end-member contribution typical for the Early Pleistocene. We therefore conclude that the precessional component is likely incompletely archived in Early Pleistocene δ18O records, and appears as an actual change in Milankovitch periodicity across the MPT. Proxies not susceptible to cancellation of precession (such as those currently retrieved across the MPT from Antarctica) would be able to verify to what extent deep-sea δ18O correctly represents Pleistocene climate.

• Straume, Eivind Olavson; Morée, Anne; Nisancioglu, Kerim Hestnes & Gebbie, Geoffrey (2019). Orbital Forcing of Climate and the Mid-Pleistocene Transition . Show summary

  Climate archives, based on records of oxygen isotopes from marine sediments, show a pronounced change in the periodicity of the glacial cycles during the mid-Pleistocene (~1 million years ago). Before this time, and possibly from the initiation of major glaciations, the periodicity is dominated by the 41 kyr obliquity cycle of orbital insolation. However, in the past million years the ~21 and ~100 kyr cycles of precession and eccentricity have dominated the records of glacial cycles, and the records of atmospheric greenhouse gasses. This climate transition, the mid-Pleistocene Transition (MPT), is not fully understood. Nor are the dynamics of the glacial cycles. In this session we welcome contributions with perspectives on the MPT as well as the dynamics of the glacial cycles based on proxy records, theory and models. The topic is also timely in light of ongoing efforts to extract a continuous Antarctic ice core record spanning the MPT.

• Bjartnes, Anders; Michelsen, Lars-Henrik Paarup; Skaugen, Håvar; Ursin, Lars; Darelius, Elin Maria K. & Kutti, Tina [Show all 12 contributors for this article] (2021). Vippepunkter i klimasystemet. Norsk klimastiftelse.

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