| 1. |
- Nordell, Bo
(författare)
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Thermal pollution causes global warming
- 2003
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Ingår i: Global and Planetary Change. - 0921-8181 .- 1872-6364. ; 38:3-4, s. 305-312
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Tidskriftsartikel (refereegranskat)abstract
- Over longer time-scales there is no net heat inflow to Earth since incoming solar energy is re-emitted at exactly the same rate. To maintain Earth's thermal equilibrium, however, there must be a net outflow equal to the geothermal heat flow. Performed calculations show that the net heat outflow in 1880 was equal to the geothermal heat flow, which is the only natural net heat source on Earth. Since then, heat dissipation from the global use of nonrenewable energy sources has resulted in additional net heating. In, e.g. Sweden, which is a sparsely populated country, this net heating is about three times greater than the geothermal heat flow. Such thermal pollution contributes to global warming until the global temperature has reached a level where this heat is also emitted to space. Heat dissipation from the global use of fossil fuels and nuclear power is the main source of thermal pollution. Here, it was found that one third of current thermal pollution is emitted to space and that a further global temperature increase of 1.8 °C is required until Earth is again in thermal equilibrium.
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| 2. |
- Adler, Ruth E., et al.
(författare)
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Sediment record from the western Arctic Ocean with an improved Late Quaternary age resolution : HOTRAX core HLY0503-8JPC, Mendeleev Ridge
- 2009
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Ingår i: Global and Planetary Change. - : Elsevier BV. - 0921-8181 .- 1872-6364. ; 68:02-jan, s. 18-29
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Tidskriftsartikel (refereegranskat)abstract
- Sediment core HLY0503-8JPC raised by the HOTRAX'05 expedition from the Mendeleev Ridge was analyzed for multiple lithological, paleontological. and stable-isotopic proxies to reconstruct paleoceanographic conditions in the western Arctic Ocean during the Late Quaternary. The core, extensively sampled in the upper 5 m, reveals pronounced changes in sedimentary environments during the ca. 250 kyr interval encompassing Marine Isotopic Stages (MIS) 1 to 7. An estimated average resolution of 500 yr/sample, at least for the last glacial cycle including the last interglacial, provides more detail than seen in other sedimentary records from the western Arctic Ocean. The age control is provided by C-14 and amino acid racemization measurements on planktonic foraminifers and correlations with the stratigraphy developed for the central Lomonosov Ridge and with glacial events at the Eurasian Arctic margin. Cyclic variations in lithology combined with foraminiferal abundance and stable-isotopic composition indicate profound changes in hydrographic and depositional environments between interglacial-type and glacial-type periods apparently reflecting a combination of 100-kyr and precessional time scales. This periodicity is complicated by abrupt iceberg- and/or meltwater-discharge events with variable (Laurentide vs. Eurasian) provenance. The proxy record from the interval identified as the last interglacial (MIS 5e), which may aid in understanding the future state of the Arctic Ocean, indicates low ice conditions and possibly enhanced stratification of the water column.
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| 3. |
- Adroit, Benjamin, et al.
(författare)
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Patterns of insect damage types reflect complex environmental signal in Miocene forest biomes of Central Europe and the Mediterranean
- 2021
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Ingår i: Global and Planetary Change. - Amsterdam : Elsevier. - 0921-8181 .- 1872-6364. ; 199
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Tidskriftsartikel (refereegranskat)abstract
- Ecosystems are defined by the community of living organisms and how they interact together and with theirenvironment. Insects and plants are key taxa in terrestrial ecosystems and their network determines the trophicstructure of the environment. However, what drives the interactions between plants and insects in modern andfossil ecosystems is not well understood. In this study, we analyzed insect damage richness and frequency in 5000 fossil leaves deposited during the early Miocene at 20–17 Ma along a latitudinal gradient from Europe (twolocalities in Czech Republic) to Turkey (one locality) in a temperate climate setting. Damage frequency wasmainly linked with abiotic factors (temperature, precipitation seasonality) whereas damage richness was mainlylinked with biotic factors (plant richness, biome). Univariate analysis of insect damage types consistently suggested closer trophic similarity between the Mediterranean and either the one or the other Central European plant assemblage. In contrast, multivariate analysis of all insect damage types indicated closer similarity between the two Central European sites highlighting the importance of biogeographic legacy and geographic closeness to the plant-insect interaction patterns. Our results underscore the high complexity of the herbivory network andcall for careful interpretations of plant-insect interaction patterns in palaeoecological studies. Finally, comparing the trophic similarity between different localities using total evidence plots as done in this work might be apromising complementary method in comparative studies of plant-insect interactions.
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| 4. |
- Ahmad, Waqas, et al.
(författare)
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Analysis of long term meteorological trends in the middle and lower Indus Basin of Pakistan-A non-parametric statistical approach
- 2014
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Ingår i: Global and Planetary Change. - : Elsevier BV. - 0921-8181 .- 1872-6364. ; 122, s. 282-291
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Tidskriftsartikel (refereegranskat)abstract
- The Indus basin of Pakistan is vulnerable to climate change which would directly affect the livelihoods of poor people engaged in irrigated agriculture. The situation could be worse in middle and lower part of this basin which occupies 90% of the irrigated area. The objective of this research is to analyze the long term meteorological trends in the middle and lower parts of Indus basin of Pakistan. We used monthly data from 1971 to 2010 and applied non-parametric seasonal Kendal test for trend detection in combination with seasonal Kendall slope estimator to quantify the magnitude of trends. The meteorological parameters considered were mean maximum and mean minimum air temperature, and rainfall from 12 meteorological stations located in the study region. We examined the reliability and spatial integrity of data by mass-curve analysis and spatial correlation matrices, respectively. Analysis was performed for four seasons (spring-March to May, summer-June to August-fall-September to November and winter-December to February). The results show that max. temperature has an average increasing trend of magnitude +0.16, +0.03, 0.0 and +0.04 degrees C/decade during all the four seasons, respectively. The average trend of min. temperature during the four seasons also increases with magnitude of +0.29, +0.12, +0.36 and +0.36 degrees C/decade, respectively. Persistence of the increasing trend is more pronounced in the min. temperature as compared to the max. temperature on annual basis. Analysis of rainfall data has not shown any noteworthy trend during winter, fall and on annual basis. However during spring and summer season, the rainfall trends vary from -1.15 to +0.93 and -3.86 to +2.46 mm/decade, respectively. It is further revealed that rainfall trends during all seasons are statistically non-significant. Overall the study area is under a significant warming trend with no changes in rainfall.
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| 5. |
- Akperov, Mirseid, et al.
(författare)
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Future projections of cyclone activity in the Arctic for the 21st century from regional climate models (Arctic-CORDEX)
- 2019
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Ingår i: Global and Planetary Change. - : Elsevier BV. - 0921-8181 .- 1872-6364. ; 182
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Tidskriftsartikel (refereegranskat)abstract
- Changes in the characteristics of cyclone activity (frequency, depth and size) in the Arctic are analyzed based on simulations with state-of-the-art regional climate models (RCMs) from the Arctic-CORDEX initiative and global climate models (GCMs) from CMIP5 under the Representative Concentration Pathway (RCP) 8.5 scenario. Most of RCMs show an increase of cyclone frequency in winter (DJF) and a decrease in summer (JJA) to the end of the 21st century. However, in one half of the RCMs, cyclones become weaker and substantially smaller in winter and deeper and larger in summer. RCMs as well as GCMs show an increase of cyclone frequency over the Baffin Bay, Barents Sea, north of Greenland, Canadian Archipelago, and a decrease over the Nordic Seas, Kara and Beaufort Seas and over the sub-arctic continental regions in winter. In summer, the models simulate an increase of cyclone frequency over the Central Arctic and Greenland Sea and a decrease over the Norwegian and Kara Seas by the end of the 21st century. The decrease is also found over the high-latitude continental areas, in particular, over east Siberia and Alaska. The sensitivity of the RCMs' projections to the boundary conditions and model physics is estimated. In general, different lateral boundary conditions from the GCMs have larger effects on the simulated RCM projections than the differences in RCMs' setup and/or physics.
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| 6. |
- Andrén, Elinor, et al.
(författare)
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Holocene climate and environmental change in north-eastern Kamchatka (Russian Far East), inferred from a multi-proxy study of lake sediments
- 2015
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Ingår i: Global and Planetary Change. - : Elsevier BV. - 0921-8181 .- 1872-6364. ; 134, s. 41-54
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Tidskriftsartikel (refereegranskat)abstract
- A sediment record from a small lake in the north-eastern part of the Kamchatka Peninsula has been investigated in a multi-proxy study to gain knowledge of Holocene climatic and environmental change. Pollen, diatoms, chironomids and selected geochemical parameters were analysed and the sediment record was dated with radiocarbon. The study shows Holocene changes in the terrestrial vegetation as well as responses of the lake ecosystem to catchment maturity and multiple stressors, such as climate change and volcanic eruptions. Climate change is the major driving force resulting in the recorded environmental changes in the lake, although recurrent tephra deposition events also contributed. The sediment record has an age at the base of about 10,000 cal yrs BP, and during the first 400 years the climate was cold and the lake exhibited extensive ice-cover during winter and relatively low primary production. Soils in the catchment were poor with shrub alder and birches dominatingthe vegetation surrounding the lake. At about 9600–8900 cal yrs BP the climate was cold and moist, and strong seasonal wind stress resulted in reduced ice-cover and increased primary production. After ca. 8900 cal yrs BP the forest density increased around the lake, runoff decreased in a generally drier climate resulting in decreasedprimary production in the lake until ca. 7000 cal yrs BP. This generally dry climate was interrupted by a brief climatic perturbation, possibly attributed to the 8.2 ka event, indicating increasingly windy conditions with thick snow cover, reduced ice-cover and slightly elevated primary production in the lake. The diatom record shows maximum thermal stratification at ca. 6300–5800 cal yrs BP and indicates together with the geochemical proxies a dry and slightly warmer climate resulting in a high productive lake. The most remarkably change in the catchment vegetation occurred at ca. 4200 cal yrs BP in the form of a conspicuous increase in Siberian dwarf pine (Pinus pumila), indicating a shift to a cooler climate with a thicker and more long-lasting snow cover. Thisvegetational change was accompanied by marked shifts in the diatom and chironomid stratigraphies, which are also indicative of colder climate and more extensive ice-cover.
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| 7. |
- Andrén, Elinor, et al.
(författare)
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The relative influences of climate and volcanic activity on Holocene lake development inferred from a mountain lake in central Kamchatka
- 2015
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Ingår i: Global and Planetary Change. - : Elsevier BV. - 1872-6364 .- 0921-8181. ; 134, s. 67-81
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Tidskriftsartikel (refereegranskat)abstract
- A sediment sequence was taken from a closed, high altitude lake (informal name Olive-backed Lake) in the central mountain range of Kamchatka, in the Russian Far East. The sequence was dated by radiocarbon and tephrochronology and used for multi-proxy analyses (chironomids, pollen, diatoms). Although the evolution of Beringian climate through the Holocene is primarily driven by global forcing mechanisms, regional controls, such as volcanic activity or vegetation dynamics, lead to a spatial heterogeneous response. This study aims to reconstruct past changes in the aquatic and terrestrial ecosystems and to separate the climate-driven response from a response to regional or localised environmental change. Radiocarbon dates from plant macrophytes gave a basal date of 7800 cal yr BP. Coring terminated in a tephra layer, so sedimentation at the lake started prior to this date, possibly in the early Holocene following local glacier retreat. Initially the catchment vegetation was dominated by Betula and Alnus woodland with a mosaic of open, wet, aquatic and semi-aquatic habitats. Between 7800 and 6000 cal yr BP the diatom-inferred lake water was pH 4.4-53 and chironomid and diatom assemblages in the lake were initially dominated by a small number of acidophilic/acid tolerant taxa. The frequency of Pinus pumila (Siberian dwarf pine) pollen increased from 5000 cal yr BP and threshold analysis indicates that P. pumila arrived in the catchment between 4200 and 3000 cal yr BP. Its range expansion was probably mediated by strengthening of the Aleutian Low pressure system and increased winter snowfall. The diatominferred pH reconstructions show that after an initial period of low pH, pH gradually increased from 5500 cal yr BP to pH 5.8 at 1500 cal yr BP. This trend of increasing pH through the Holocene is unusual in lake records, but the initially low pH may have resulted directly or indirectly from intense regional volcanic activity during the midHolocene. The chironomid-inferred July temperature reconstruction suggests cool periods between 32002800 cal yr BP and 1100-700 cal yr BP and a warmer period between 2800 and 1100 cal yr BP. Chironomid and diatom DCA scores decline from ca. 6000 cal yr BP, indicating compositional changes in these aquatic assemblages. In comparison declines in pollen PCA scores are delayed, starting ca. 5100 cal yr BP. The results suggest that while catchment vegetation was responding primarily to climate change, the biota within the lake and lake water chemistry were responding to localised environmental conditions. Crown Copyright (C) 2015 Published by Elsevier B.V. All rights reserved.
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| 8. |
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| 9. |
- Bigg, G. R., et al.
(författare)
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Sensitivity of the North Atlantic circulation to break-up of the marine sectors of the NW European ice sheets during the last Glacial : A synthesis of modelling and palaeoceanography
- 2012
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Ingår i: Global and Planetary Change. - : Elsevier BV. - 0921-8181 .- 1872-6364. ; 98-99, s. 153-165
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Tidskriftsartikel (refereegranskat)abstract
- The marine-based Atlantic periphery of the last NW European Ice Sheet experienced significant advances and retreats of its marine sector during its existence. It therefore had considerable potential to intermittently inject freshwater or ice pulses to the North Atlantic. These European inputs had poorly known consequences for ocean circulation and climate. Here we examine the history of the western margin of the European Ice Sheet, from 34 to 15 cal ka BP, and use a combination of modelling and proxy evidence to explore the impact on the North Atlantic of the fresh water and iceberg injections that accompanied phases of retreat of the marine sector of the NW European Ice Sheet. We find that the lack of geographical synchronicity in the responses of the different components of the 3000 km long sector meant that the scale of the climate consequences of ice discharge most likely remained regional, except during the final deglaciation phase, around 17-15 cal ka BP. At this time, as the later component of the recently introduced concept of an extended Heinrich event H1, both proxy and modelling evidence suggest rapid sector collapse led to partial shut-down of the Atlantic overturning and a basin-wide cooling.
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| 10. |
- Bohm, Katja, et al.
(författare)
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Neogene global climate change and East Asian dust sources : Combined rutile geochemistry and zircon U Pb analysis from the northern Chinese Loess Plateau
- 2023
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Ingår i: Global and Planetary Change. - : Elsevier. - 0921-8181 .- 1872-6364. ; 221
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Tidskriftsartikel (refereegranskat)abstract
- During the late Neogene, global climate underwent a long-term transition to cooler climates that culminated in the Quaternary icehouse conditions. In the East Asian terrestrial realm, atmospheric dustiness increased, and the volume of aeolian dust deposits expanded significantly. The Neogene Red Clay deposits, located on the Chinese Loess Plateau (CLP), provide an exceptional geologic archive to investigate pre-Quaternary climates and environments. Constraining the provenance of the Red Clay is crucial for unravelling the links between late Neogene Central-East Asian climate, tectonics and desertification. However, Red Clay provenance is highly debated and data are scarce. In this study, we have used a multi-proxy approach at a high sampling resolution to study the provenance of the c. 7–2.6 Ma Baode Red Clay. Our data consist of joint detrital zircon U-Pb ages and detrital rutile trace element geochemistry of the Baode Red Clay, and of a massive rutile geochemistry dataset from 14 potential dust source areas. The data indicate that the Mio-Pliocene and Plio-Pleistocene global climate transitions were coupled with gradual dust provenance shifts. We propose these shifts indicate the intensification of East Asian winter monsoon and/or enhanced Central-East Asian drying as a response to global cooling. We also identify temporary Pliocene provenance changes that interrupt the long-term winter monsoon -controlled dust transport at c. 4 Ma and c. 3.5 Ma. Several indicators point to dust transport by the westerly jet at c. 4 Ma, possibly caused by a shift in the jet position as a response to global cooling, and/or enhanced wet deposition caused by intensified summer monsoon. Alternatively, the role of the paleo-Yellow River should be investigated further. We infer the 3.5 Ma provenance signal was caused by increased Yellow River -transported material from eroding Northeastern Tibetan Plateau and/or western CLP. Implications of our results not only shed light on the links between late Cenozoic global climate change and Central-East Asian dust cycle, but also provide detailed information to further investigate the late Neogene regional geomorphology and its effects on dust emission, transport, and deposition. Our combined rutile-zircon analysis also verifies that a multi-proxy single-grain approach that targets different types of primary source rocks is needed for reliable provenance analysis of the CLP dust.
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