| 1. |
- Acosta Navarro, Juan Camilo, et al.
(författare)
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Amplification of Arctic warming by past air pollution reductions in Europe
- 2016
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Ingår i: Nature Geoscience. - : Nature Publishing Group. - 1752-0894 .- 1752-0908. ; 9:4, s. 277-
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Tidskriftsartikel (refereegranskat)abstract
- The Arctic region is warming considerably faster than the rest of the globe(1), with important consequences for the ecosystems(2) and human exploration of the region(3). However, the reasons behind this Arctic amplification are not entirely clear(4). As a result of measures to enhance air quality, anthropogenic emissions of particulate matter and its precursors have drastically decreased in parts of the Northern Hemisphere over the past three decades(5). Here we present simulations with an Earth system model with comprehensive aerosol physics and chemistry that show that the sulfate aerosol reductions in Europe since 1980 can potentially explain a significant fraction of Arctic warming over that period. Specifically, the Arctic region receives an additional 0.3Wm(-2) of energy, and warms by 0.5 degrees C on annual average in simulations with declining European sulfur emissions in line with historical observations, compared with a model simulation with fixed European emissions at 1980 levels. Arctic warming is amplified mainly in fall and winter, but the warming is initiated in summer by an increase in incoming solar radiation as well as an enhanced poleward oceanic and atmospheric heat transport. The simulated summertime energy surplus reduces sea-ice cover, which leads to a transfer of heat from the Arctic Ocean to the atmosphere. We conclude that air quality regulations in the Northern Hemisphere, the ocean and atmospheric circulation, and Arctic climate are inherently linked.
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| 2. |
- Antonelli, Alexandre, 1978, et al.
(författare)
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Geological and climatic influences on mountain biodiversity
- 2018
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Ingår i: Nature Geoscience. - : Springer Science and Business Media LLC. - 1752-0894 .- 1752-0908. ; 11:10, s. 718-
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Tidskriftsartikel (refereegranskat)abstract
- Mountains are key features of the Earth's surface and host a substantial proportion of the world's species. However, the links between the evolution and distribution of biodiversity and the formation of mountains remain poorly understood. Here, we integrate multiple datasets to assess the relationships between species richness in mountains, geology and climate at global and regional scales. Specifically, we analyse how erosion, relief, soil and climate relate to the geographical distribution of terrestrial tetrapods, which include amphibians, birds and mammals. We find that centres of species richness correlate with areas of high temperatures, annual rainfall and topographic relief, supporting previous studies. We unveil additional links between mountain-building processes and biodiversity: species richness correlates with erosion rates and heterogeneity of soil types, with a varying response across continents. These additional links are prominent but under-explored, and probably relate to the interplay between surface uplift, climate change and atmospheric circulation through time. They are also influenced by the location and orientation of mountain ranges in relation to air circulation patterns, and how species diversification, dispersal and refugia respond to climate change. A better understanding of biosphere-lithosphere interactions is needed to understand the patterns and evolution of mountain biodiversity across space and time.
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| 3. |
- Arneth, A., et al.
(författare)
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Historical carbon dioxide emissions caused by land-use changes are possibly larger than assumed
- 2017
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Ingår i: Nature Geoscience. - : Springer Science and Business Media LLC. - 1752-0894 .- 1752-0908. ; 10:2, s. 79-84
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Forskningsöversikt (refereegranskat)abstract
- The terrestrial biosphere absorbs about 20% of fossil-fuel CO 2 emissions. The overall magnitude of this sink is constrained by the difference between emissions, the rate of increase in atmospheric CO 2 concentrations, and the ocean sink. However, the land sink is actually composed of two largely counteracting fluxes that are poorly quantified: fluxes from land-use change and CO 2 uptake by terrestrial ecosystems. Dynamic global vegetation model simulations suggest that CO 2 emissions from land-use change have been substantially underestimated because processes such as tree harvesting and land clearing from shifting cultivation have not been considered. As the overall terrestrial sink is constrained, a larger net flux as a result of land-use change implies that terrestrial uptake of CO 2 is also larger, and that terrestrial ecosystems might have greater potential to sequester carbon in the future. Consequently, reforestation projects and efforts to avoid further deforestation could represent important mitigation pathways, with co-benefits for biodiversity. It is unclear whether a larger land carbon sink can be reconciled with our current understanding of terrestrial carbon cycling. Our possible underestimation of the historical residual terrestrial carbon sink adds further uncertainty to our capacity to predict the future of terrestrial carbon uptake and losses.
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| 4. |
- Barlow, Natasha L. M., et al.
(författare)
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Lack of evidence for a substantial sea-level fluctuation within the Last Interglacial
- 2018
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Ingår i: Nature Geoscience. - : Springer Science and Business Media LLC. - 1752-0894 .- 1752-0908. ; 11:9, s. 627-634
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Forskningsöversikt (refereegranskat)abstract
- During the Last Interglacial, global mean sea level reached approximately 6 to 9 m above the present level. This period of high sea level may have been punctuated by a fall of more than 4 m, but a cause for such a widespread sea-level fall has been elusive. Reconstructions of global mean sea level account for solid Earth processes and so the rapid growth and decay of ice sheets is the most obvious explanation for the sea-level fluctuation. Here, we synthesize published geomorphological and stratigraphic indicators from the Last Interglacial, and find no evidence for ice-sheet regrowth within the warm interglacial climate. We also identify uncertainties in the interpretation of local relative sea-level data that underpin the reconstructions of global mean sea level. Given this uncertainty, and taking into account our inability to identify any plausible processes that would cause global sea level to fall by 4 m during warm climate conditions, we question the occurrence of a rapid sea-level fluctuation within the Last Interglacial. We therefore recommend caution in interpreting the high rates of global mean sea-level rise in excess of 3 to 7 m per 1,000 years that have been proposed for the period following the Last Interglacial sea-level lowstand.
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| 5. |
- Belonoshko, Anatoly B., et al.
(författare)
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Stabilization of body-centred cubic iron under inner-core conditions
- 2017
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Ingår i: Nature Geoscience. - : Nature Publishing Group. - 1752-0894 .- 1752-0908. ; 10:4, s. 312-
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Tidskriftsartikel (refereegranskat)abstract
- The Earth's solid core is mostly composed of iron. However, despite being central to our understanding of core properties, the stable phase of iron under inner-core conditions remains uncertain. The two leading candidates are hexagonal close-packed and body-centred cubic (bcc) crystal structures, but the dynamic and thermodynamic stability of bcc iron under inner-core conditions has been challenged. Here we demonstrate the stability of the bcc phase of iron under conditions consistent with the centre of the core using ab initio molecular dynamics simulations. We find that the bcc phase is stabilized at high temperatures by a diffusion mechanism that arises due to the dynamical instability of the phase at lower temperatures. On the basis of our simulations, we reinterpret experimental data as support for the stability of bcc iron under inner-core conditions. We suggest that the diffusion of iron atoms in solid state may explain both the anisotropy and the low shear modulus of the inner core.
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| 6. |
- Bishop, Kevin, et al.
(författare)
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Human domination of the global water cycle absent from depictions and perceptions
- 2019
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Ingår i: Nature Geoscience. - : Springer Science and Business Media LLC. - 1752-0894 .- 1752-0908. ; 12, s. 533-540
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Tidskriftsartikel (refereegranskat)abstract
- Human water use, climate change and land conversion have created a water crisis for billions of individuals and many ecosystems worldwide. Global water stocks and fluxes are estimated empirically and with computer models, but this information is conveyed to policymakers and researchers through water cycle diagrams. Here we compiled a synthesis of the global water cycle, which we compared with 464 water cycle diagrams from around the world. Although human freshwater appropriation now equals half of global river discharge, only 15% of the water cycle diagrams depicted human interaction with water. Only 2% of the diagrams showed climate change or water pollution-two of the central causes of the global water crisis-which effectively conveys a false sense of water security. A single catchment was depicted in 95% of the diagrams, which precludes the representation of teleconnections such as ocean-land interactions and continental moisture recycling. These inaccuracies correspond with specific dimensions of water mismanagement, which suggest that flaws in water diagrams reflect and reinforce the misunderstanding of global hydrology by policymakers, researchers and the public. Correct depictions of the water cycle will not solve the global water crisis, but reconceiving this symbol is an important step towards equitable water governance, sustainable development and planetary thinking in the Anthropocene.
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| 7. |
- Büntgen, Ulf, et al.
(författare)
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Cooling and societal change during the Late Antique Little Ice Age from 536 to around 660 AD
- 2016
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Ingår i: Nature Geoscience. - 1752-0894 .- 1752-0908. ; 9:3, s. 231-236
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Tidskriftsartikel (refereegranskat)abstract
- Climatic changes during the first half of the Common Era have been suggested to play a role in societal reorganizations in Europe and Asia. In particular, the sixth century coincides with rising and falling civilizations, pandemics, human migration and political turmoil. Our understanding of the magnitude and spatial extent as well as the possible causes and concurrences of climate change during this period is, however, still limited. Here we use tree-ring chronologies from the Russian Altai and European Alps to reconstruct summer temperatures over the past two millennia. We find an unprecedented, long-lasting and spatially synchronized cooling following a cluster of large volcanic eruptions in 536, 540 and 547 AD, which was probably sustained by ocean and sea-ice feedbacks, as well as a solar minimum. We thus identify the interval from 536 to about 660 AD as the Late Antique Little Ice Age. Spanning most of the Northern Hemisphere, we suggest that this cold phase be considered as an additional environmental factor contributing to the establishment of the Justinian plague, transformation of the eastern Roman Empire and collapse of the Sasanian Empire, movements out of the Asian steppe and Arabian Peninsula, spread of Slavic-speaking peoples and political upheavals in China.
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| 8. |
- Büntgen, Ulf, et al.
(författare)
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Reply to 'Limited Late Antique cooling'
- 2017
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Ingår i: Nature Geoscience. - : Springer Science and Business Media LLC. - 1752-0894 .- 1752-0908. ; 10:4, s. 243-243
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 9. |
- Catalan, Nuria, et al.
(författare)
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Organic carbon decomposition rates controlled by water retention time across inland waters
- 2016
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Ingår i: Nature Geoscience. - 1752-0894 .- 1752-0908. ; 9:7, s. 501-504
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Tidskriftsartikel (refereegranskat)abstract
- The loss of organic carbon during passage through the continuum of inland waters from soils to the sea is a critical component of the global carbon cycle(1-3). Yet, the amount of organic carbon mineralized and released to the atmosphere during its transport remains an open question(2,4-6), hampered by the absence of a common predictor of organic carbon decay rates(1,7). Here we analyse a compilation of existing field and laboratory measurements of organic carbon decay rates and water residence times across a wide range of aquatic ecosystems and climates. We find a negative relationship between the rate of organic carbon decay and water retention time across systems, entailing a decrease in organic carbon reactivity along the continuum of inland waters. We find that the half-life of organic carbon is short in inland waters (2.5 +/- 4.7 yr) compared to terrestrial soils and marine ecosystems, highlighting that freshwaters are hotspots of organic carbon degradation. Finally, we evaluate the response of organic carbon decay rates to projected changes in runoff(8). We calculate that regions projected to become drier or wetter as the global climate warms will experience changes in organic carbon decay rates of up to about 10%, which illustrates the influence of hydrological variability on the inland waters carbon cycle.
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| 10. |
- Christensen, Torben R.
(författare)
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Permafrost : It's a gas
- 2016
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Ingår i: Nature Geoscience. - : Springer Science and Business Media LLC. - 1752-0894 .- 1752-0908. ; 9:9, s. 647-648
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Tidskriftsartikel (refereegranskat)
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