| 111. |
- Sharma, Sapna, et al.
(författare)
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Widespread loss of lake ice around the Northern Hemisphere in a warming world
- 2019
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Ingår i: Nature Climate Change. - : NATURE PUBLISHING GROUP. - 1758-678X .- 1758-6798. ; 9:3, s. 227-231
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Tidskriftsartikel (refereegranskat)abstract
- Ice provides a range of ecosystem services-including fish harvest(1), cultural traditions(2), transportation(3), recreation(4) and regulation of the hydrological cycle(5)-to more than half of the world's 117 million lakes. One of the earliest observed impacts of climatic warming has been the loss of freshwater ice(6), with corresponding climatic and ecological consequences(7). However, while trends in ice cover phenology have been widely documented(2,6,8,9), a comprehensive large-scale assessment of lake ice loss is absent. Here, using observations from 513 lakes around the Northern Hemisphere, we identify lakes vulnerable to ice-free winters. Our analyses reveal the importance of air temperature, lake depth, elevation and shoreline complexity in governing ice cover. We estimate that 14,800 lakes currently experience intermittent winter ice cover, increasing to 35,300 and 230,400 at 2 and 8 degrees C, respectively, and impacting up to 394 and 656 million people. Our study illustrates that an extensive loss of lake ice will occur within the next generation, stressing the importance of climate mitigation strategies to preserve ecosystem structure and function, as well as local winter cultural heritage.
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| 112. |
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| 113. |
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| 114. |
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| 115. |
- Van Dorst, Renee, et al.
(författare)
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Warmer and browner waters decrease fish biomass production
- 2019
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Ingår i: Global Change Biology. - : WILEY. - 1354-1013 .- 1365-2486. ; 25:4, s. 1395-1408
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Tidskriftsartikel (refereegranskat)abstract
- Climate change studies have long focused on effects of increasing temperatures, often without considering other simultaneously occurring environmental changes, such as browning of waters. Resolving how the combination of warming and browning of aquatic ecosystems affects fish biomass production is essential for future ecosystem functioning, fisheries, and food security. In this study, we analyzed individual- and population-level fish data from 52 temperate and boreal lakes in Northern Europe, covering large gradients in water temperature and color (absorbance, 420 nm). We show that fish (Eurasian perch, Perca fluviatilis) biomass production decreased with both high water temperatures and brown water color, being lowest in warm and brown lakes. However, while both high temperature and brown water decreased fish biomass production, the mechanisms behind the decrease differed: temperature affected the fish biomass production mainly through a decrease in population standing stock biomass, and through shifts in size- and age-distributions toward a higher proportion of young and small individuals in warm lakes; brown water color, on the other hand, mainly influenced fish biomass production through negative effects on individual body growth and length-at-age. In addition to these findings, we observed that the effects of temperature and brown water color on individual-level processes varied over ontogeny. Body growth only responded positively to higher temperatures among young perch, and brown water color had a stronger negative effect on body growth of old than on young individuals. Thus, to better understand and predict future fish biomass production, it is necessary to integrate both individual- and population-level responses and to acknowledge within-species variation. Our results suggest that global climate change, leading to browner and warmer waters, may negatively affect fish biomass production, and this effect may be stronger than caused by increased temperature or water color alone.
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| 116. |
- Vikström, Kevin, et al.
(författare)
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Rapid lake ice structure changes across Swedish lakes puts public ice safety at risk
- 2024
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Ingår i: Ambio. - 0044-7447.
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Tidskriftsartikel (refereegranskat)abstract
- Lakes are rapidly losing ice under global warming, but little is known about ice structure changes. Ice structure is a key regulator of ice stability and thus safety, affecting activities on ice. Here, we analysed spatial and temporal variations in ice structure across 21 Swedish lakes, spanning from 55 to 69 °N, and over five decades. We found regional differences in ice structure, with fastest changes occurring in southern Sweden. The stable clear ice layer was particularly sensitive to warming, showing a rapid decline. The number of days when temperatures exceeded the freezing point during the ice cover period was identified as a strong driver for how ice was structured. Since there is a high risk for increased occurrences of unsafe ice conditions under predicted air temperature changes, we recommend re-establishing ice structure monitoring programmes, informing society on the increased risks of being on ice and including ice structure to safety guidelines.
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| 117. |
- Wallin, Marcus, 1979-, et al.
(författare)
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Carbon dioxide and methane emissions of Swedish low-order streams : a national estimate and lessons learnt from more than a decade of observations
- 2018
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Ingår i: Limnology and Oceanography Letters. - : John Wiley & Sons. - 2378-2242. ; 3:3, s. 156-167
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Tidskriftsartikel (refereegranskat)abstract
- Low-order streams are suggested to dominate the atmospheric CO2 source of all inland waters. Yet, many large-scale stream estimates suffer from methods not designed for gas emission determination and rarely include other greenhouse gases such as CH4. Here, we present a compilation of directly measured CO2 and CH4 concentration data from Swedish low-order streams (> 1600 observations across > 500 streams) covering large climatological and land-use gradients. These data were combined with an empirically derived gas transfer model and the characteristics of a ca. 400,000 km stream network covering the entire country. The total stream CO2 and CH4 emission corresponded to 2.7 Tg C yr(-1) (95% confidence interval: 2.0-3.7) of which the CH4 accounted for 0.7% (0.02 Tg C yr(-1)). The study highlights the importance of low-order streams, as well as the critical need to better represent variability in emissions and stream areal extent to constrain future stream C emission estimates.
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| 118. |
- Wang, Jinling, et al.
(författare)
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Urbanization in developing countries overrides catchment productivity in fueling inland water CO2 emissions
- 2022
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Ingår i: Global Change Biology. - : John Wiley & Sons. - 1354-1013 .- 1365-2486. ; 29:1, s. 1-4
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Tidskriftsartikel (refereegranskat)abstract
- We compiled a nationwide dataset of carbon dioxide (CO2) efflux from 1405 measurements, and found that lakes, reservoirs, and rivers emit a total of 61.9 ± 55.3 TgC as CO2 each year, corresponding to 6.3% of the annual total national CO2 emission in 2020. Our analysis showed that the presence of anthropogenic disturbances in catchments strongly influences the emission of CO2 from these waters in the non-pristine areas, masking the catchment productivity effect on the emission of CO2. Our results highlight the need for adjusting climate change models for taking into account anthropogenic effects on CO2 emissions from inland waters.
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| 119. |
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| 120. |
- Weyhenmeyer, Gesa A., et al.
(författare)
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Browning of Boreal Freshwaters Coupled to Carbon-Iron Interactions along the Aquatic Continuum
- 2014
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 9:2, s. e88104-
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Tidskriftsartikel (refereegranskat)abstract
- The color of freshwaters, often measured as absorbance, influences a number of ecosystem services including biodiversity, fish production, and drinking water quality. Many countries have recently reported on increasing trends of water color in freshwaters, for which drivers are still not fully understood. We show here with more than 58000 water samples from the boreal and hemiboreal region of Sweden and Canada that absorbance of filtered water (a(420)) co-varied with dissolved organic carbon (DOC) concentrations (R-2 = 0.85, P<0.0001), but that a(420) relative to DOC is increased by the presence of iron (Fe). We found that concentrations of Fe significantly declined with increasing water retention in the landscape, resulting in significantly lower Fe concentrations in lakes compared to running waters. The Fe loss along the aquatic continuum corresponded to a proportional loss in a(420), suggesting a tight biogeochemical coupling between colored dissolved organic matter and Fe. Since water is being flushed at increasing rates due to enhanced runoff in the studied regions, diminished loss of Fe along the aquatic continuum may be one reason for observed trends in a(420), and in particular in a(420)/DOC increases. If trends of increased Fe concentrations in freshwaters continue, water color will further increase with various effects on ecosystem services and biogeochemical cycles.
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