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- Hatun, H., et al.
(author)
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The subpolar gyre regulates silicate concentrations in the North Atlantic
- 2017
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In: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 7
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Journal article (peer-reviewed)abstract
- The North Atlantic is characterized by diatom-dominated spring blooms that results in significant transfer of carbon to higher trophic levels and the deep ocean. These blooms are terminated by limiting silicate concentrations in summer. Numerous regional studies have demonstrated phytoplankton community shifts to lightly-silicified diatoms and non-silicifying plankton at the onset of silicate limitation. However, to understand basin-scale patterns in ecosystem and climate dynamics, nutrient inventories must be examined over sufficient temporal and spatial scales. Here we show, from a new comprehensive compilation of data from the subpolar Atlantic Ocean, clear evidence of a marked pre-bloom silicate decline of 1.5-2 mu M throughout the winter mixed layer during the last 25 years. This silicate decrease is primarily attributed to natural multi-decadal variability through decreased winter convection depths since the mid-1990s, a weakening and retraction of the subpolar gyre and an associated increased influence of nutrient-poor water of subtropical origin. Reduced Arctic silicate import and the projected hemispheric-scale climate change-induced weakening of vertical mixing may have acted to amplify the recent decline. These marked fluctuations in pre-bloom silicate inventories will likely have important consequences for the spatial and temporal extent of diatom blooms, thus impacting ecosystem productivity and ocean-atmosphere climate dynamics.
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| 2. |
- Leijonhufvud, Gustaf, 1977-, et al.
(author)
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Results of the EU Project Climate For Culture: Future Climate-induced Risks to Historic Buildings and their Interiors
- 2014
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Conference paper (peer-reviewed)abstract
- The EU funded Climate for Culture (CfC) Project is finalized to forecast the impact ofclimate change on either indoor or outdoor Cultural Heritage and advise on relatedrisks. CfC has produced high-resolution thematic maps over Europe to highlight theexpected changes and related risks for a number of key materials, building types,deterioration mechanisms for the near and far future based on two emissionscenarios as developed by IPCC. The procedure to obtain a thematic map is asfollows: to simulate outdoor climate change; to pass from outdoor to indoor climatechange through building simulation and case studies measurements; to use damagefunctions and literature results to evaluate potential risk for buildings and objects; tomap the above results for advice and stakeholders use. This methodology hasproduced 55,650 thematic maps of future climate induced risks to historic buildingsand collections in their interiors. The results can be used for climate change impactassessments and for planning adaption and mitigation measures in view ofpreventive conservation or other applications, e.g. human health, energyconsumption, cultural tourism. This paper presents some of the main projectoutcomes.
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| 5. |
- Sudarchikova, N., et al.
(author)
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Modelling of mineral dust for interglacial and glacial climate conditions with a focus on Antarctica
- 2015
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In: Climate of the Past. - : Copernicus GmbH. - 1814-9332. ; 11:5, s. 765-779
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Journal article (peer-reviewed)abstract
- The mineral dust cycle responds to climate variations and plays an important role in the climate system by affecting the radiative balance of the atmosphere and modifying biogeochemistry. Polar ice cores provide unique information about deposition of aeolian dust particles transported over long distances. These cores are a palaeoclimate proxy archive of climate variability thousands of years ago. The current study is a first attempt to simulate past interglacial dust cycles with a global aerosol-climate model ECHAM5-HAM. The results are used to explain the dust deposition changes in Antarctica in terms of quantitative contribution of different processes, such as emission, atmospheric transport and precipitation, which will help to interpret palaeo-data from Antarctic ice cores. The investigated periods include four interglacial time slices: the pre-industrial control (CTRL), mid-Holocene (6000 yr BP; hereafter referred to as "6 kyr"), last glacial inception (115 000 yr BP; hereafter "115 kyr") and Eemian (126 000 yr BP; hereafter "126 kyr"). One glacial time interval, the Last Glacial Maximum (LGM) (21 000 yr BP; hereafter "21 kyr"), was simulated as well to be a reference test for the model. Results suggest an increase in mineral dust deposition globally, and in Antarctica, in the past interglacial periods relative to the pre-industrial CTRL simulation. Approximately two-thirds of the increase in the mid-Holocene and Eemian is attributed to enhanced Southern Hemisphere dust emissions. Slightly strengthened transport efficiency causes the remaining one-third of the increase in dust deposition. The moderate change in dust deposition in Antarctica in the last glacial inception period is caused by the slightly stronger poleward atmospheric transport efficiency compared to the pre-industrial. Maximum dust deposition in Antarctica was simulated for the glacial period. LGM dust deposition in Antarctica is substantially increased due to 2.6 times higher Southern Hemisphere dust emissions, 2 times stronger atmospheric transport towards Antarctica, and 30% weaker precipitation over the Southern Ocean. The model is able to reproduce the order of magnitude of dust deposition globally and in Antarctica for the pre-industrial and LGM climates.
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| 6. |
- Vizcaino, M., et al.
(author)
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Climate modification by future ice sheet changes and consequences for ice sheet mass balance
- 2010
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In: Climate Dynamics. - : Springer Science and Business Media LLC. - 1432-0894 .- 0930-7575. ; 34:2-3, s. 301-324
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Journal article (peer-reviewed)abstract
- The future evolution of global ice sheets under anthropogenic greenhouse forcing and its impact on the climate system, including the regional climate of the ice sheets, are investigated with a comprehensive earth system model consisting of a coupled Atmosphere-Ocean General Circulation Model, a dynamic vegetation model and an ice sheet model. The simulated control climate is realistic enough to permit a direct coupling of the atmosphere and ice sheet components, avoiding the use of anomaly coupling, which represents a strong improvement with respect to previous modelling studies. Glacier ablation is calculated with an energy-balance scheme, a more physical approach than the commonly used degree-day method. Modifications of glacier mask, topographic height and freshwater fluxes by the ice sheets influence the atmosphere and ocean via dynamical and thermodynamical processes. Several simulations under idealized scenarios of greenhouse forcing have been performed, where the atmospheric carbon dioxide stabilizes at two and four times pre-industrial levels. The evolution of the climate system and the ice sheets in the simulations with interactive ice sheets is compared with the simulations with passively coupled ice sheets. For a four-times CO2 scenario forcing, a faster decay rate of the Greenland ice sheet is found in the non-interactive case, where melting rates are higher. This is caused by overestimation of the increase in near-surface temperature that follows the reduction in topographic height. In areas close to retreating margins, melting rates are stronger in the interactive case, due to changes in local albedo. Our results call for careful consideration of the feedbacks operating between ice sheets and climate after substantial decay of the ice sheets.
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