• Energy Research

The aims of the present study were (i) to evaluate trends in runoff from small forested catchments of the GEOMON (GEOchemical MONitoring) network during the period 1994-2011, and (ii) to estimate the impact of anticipated climate change projected by ALADIN-Climate/CZ regional climate model coupled to ARPEGE-Climate global circulation model and forced with IPCC SRES A1B emission scenario on flow patterns in the periods 2021-2050 and 2071-2100. There were no general patterns found indicating either significant increases or decreases in runoff on either seasonal or annual levels across the investigated catchments within 1994-2011. Annual runoff is projected to decrease by 15% (2021-2050) and 35% (2071-2100) with a significant decrease in summer months and a slight increase in winter months as a result of expected climate change as simulated by the selected climate model.

The aims of the present study were (i) to evaluate trends in runoff from small forested catchments of the GEOMON (GEOchemical MONitoring) network during the period 1994-2011, and (ii) to estimate the impact of anticipated climate change projected by ALADIN-Climate/CZ regional climate model coupled to ARPEGE-Climate global circulation model and forced with IPCC SRES A1B emission scenario on flow patterns in the periods 2021-2050 and 2071-2100. There were no general patterns found indicating either significant increases or decreases in runoff on either seasonal or annual levels across the investigated catchments within 1994-2011. Annual runoff is projected to decrease by 15% (2021-2050) and 35% (2071-2100) with a significant decrease in summer months and a slight increase in winter months as a result of expected climate change as simulated by the selected climate model.

23 páginas, 7 figuras, 1 tabla. Over recent decades, palaeolimnological records from remote sites have provided convincing evidence for the onset and development of several facets of global environmental change. Remote lakes, defined here as those occurring in high latitude or high altitude regions, have the advantage of not being overprinted by local anthropogenic processes. As such, many of these sites record broad-scale environmental changes, frequently driven by regime shifts in the Earth system. Here, we review a selection of studies from North America and Europe and discuss their broader implications. The history of investigation has evolved synchronously with the scope and awareness of environmental problems. An initial focus on acid deposition switched to metal and other types of pollutants, then climate change and eventually to atmospheric deposition-fertilising effects. However, none of these topics is independent of the other, and all of them affect ecosystem function and biodiversity in profound ways. Currently, remote lake palaeolimnology is developing unique datasets for each region investigated that benchmark current trends with respect to past, purely natural variability in lake systems. Fostering conceptual and methodological bridges with other environmental disciplines will upturn contribution of remote lake palaeolimnology in solving existing and emerging questions in global change science and planetary stewardship. The authors acknowledge project support from GRACCIE (CSD2007-00067), NITROPIR (CGL2010- 19373), OCUPA (088/2009), the European Research Council (Starting Grant Project, 239858), the Natural Sciences and Engineering Research Council of Canada, the US Department of the Interior, the Commission for Scientific Research in Greenland, the Austrian Science Foundation (FWF R 29N10, FWF J 1963-Geo), the Alpine Research Programme of the Austrian Academy of Sciences (project DETECTIVE), and the Czech Science Foundation (project GACR 526/09/0567). Peer reviewed

23 páginas, 7 figuras, 1 tabla. Over recent decades, palaeolimnological records from remote sites have provided convincing evidence for the onset and development of several facets of global environmental change. Remote lakes, defined here as those occurring in high latitude or high altitude regions, have the advantage of not being overprinted by local anthropogenic processes. As such, many of these sites record broad-scale environmental changes, frequently driven by regime shifts in the Earth system. Here, we review a selection of studies from North America and Europe and discuss their broader implications. The history of investigation has evolved synchronously with the scope and awareness of environmental problems. An initial focus on acid deposition switched to metal and other types of pollutants, then climate change and eventually to atmospheric deposition-fertilising effects. However, none of these topics is independent of the other, and all of them affect ecosystem function and biodiversity in profound ways. Currently, remote lake palaeolimnology is developing unique datasets for each region investigated that benchmark current trends with respect to past, purely natural variability in lake systems. Fostering conceptual and methodological bridges with other environmental disciplines will upturn contribution of remote lake palaeolimnology in solving existing and emerging questions in global change science and planetary stewardship. The authors acknowledge project support from GRACCIE (CSD2007-00067), NITROPIR (CGL2010- 19373), OCUPA (088/2009), the European Research Council (Starting Grant Project, 239858), the Natural Sciences and Engineering Research Council of Canada, the US Department of the Interior, the Commission for Scientific Research in Greenland, the Austrian Science Foundation (FWF R 29N10, FWF J 1963-Geo), the Alpine Research Programme of the Austrian Academy of Sciences (project DETECTIVE), and the Czech Science Foundation (project GACR 526/09/0567). Peer reviewed

Climate change can reverse trends of decreasing calcium and magnesium [Ca + Mg] leaching to surface waters in granitic alpine regions recovering from acidification. Despite decreasing concentrations of strong acid anions (-1.4 μeq L-1 yr-1) during 2004-2016 in nonacidic alpine lakes in the Tatra Mountains (Central Europe), the average [Ca + Mg] concentrations increased (2.5 μeq L-1 yr-1), together with elevated terrestrial export of bicarbonate (HCO3-; 3.6 μeq L-1 yr-1). The percent increase in [Ca + Mg] concentrations in nonacidic lakes (0.3-3.2% yr-1) was significantly and positively correlated with scree proportion in the catchment area and negatively correlated with the extent of soil cover. Leaching experiments with freshly crushed granodiorite, the dominant bedrock, showed that accessory calcite and (to a lesser extent) apatite were important sources of Ca. We hypothesize that elevated terrestrial export of [Ca + Mg] and HCO3- resulted from increased weathering caused by accelerated physical erosion of rocks due to elevated climate-related mechanical forces (an increasing frequency of days with high precipitation amounts and air temperatures fluctuating around 0 °C) during the last 2-3 decades. These climatic effects on water chemistry are especially strong in catchments where fragmented rocks are more exposed to weathering, and their position is less stable than in soil.

Climate change can reverse trends of decreasing calcium and magnesium [Ca + Mg] leaching to surface waters in granitic alpine regions recovering from acidification. Despite decreasing concentrations of strong acid anions (-1.4 μeq L-1 yr-1) during 2004-2016 in nonacidic alpine lakes in the Tatra Mountains (Central Europe), the average [Ca + Mg] concentrations increased (2.5 μeq L-1 yr-1), together with elevated terrestrial export of bicarbonate (HCO3-; 3.6 μeq L-1 yr-1). The percent increase in [Ca + Mg] concentrations in nonacidic lakes (0.3-3.2% yr-1) was significantly and positively correlated with scree proportion in the catchment area and negatively correlated with the extent of soil cover. Leaching experiments with freshly crushed granodiorite, the dominant bedrock, showed that accessory calcite and (to a lesser extent) apatite were important sources of Ca. We hypothesize that elevated terrestrial export of [Ca + Mg] and HCO3- resulted from increased weathering caused by accelerated physical erosion of rocks due to elevated climate-related mechanical forces (an increasing frequency of days with high precipitation amounts and air temperatures fluctuating around 0 °C) during the last 2-3 decades. These climatic effects on water chemistry are especially strong in catchments where fragmented rocks are more exposed to weathering, and their position is less stable than in soil.

In headwaters, snowmelt affects the replenishment of water resources as well as the occurrence of natural hazards. The environmental impacts of snowpack were analysed in a small forest catchment (Jizera Mountains, Czech Republic) in the context of forest dynamics, atmospheric deposition, and climate, 1982–2021. Snowmelt dominates in March–May with 41% of the long-term annual water yield; however, there is also seasonal acidification of stream water. Forest clear-cutting together with air pollution control has contributed to a decrease in the acid atmospheric load, but, in the spring, streams’ pH is often below the environmental threshold of 5.3. Snowmelt volumes did not show significant transformation with forest canopy and do not affect summer low flows. Peak flows in the springtime do not exceed summer flash floods (frequencies up to 0.13 against 0.02). Mean annual air temperature is increasing by 0.26 ± 0.08 °C per decade with more intensive warming (0.64 ± 0.1 °C per decade) in the winter season. The seasonal reduction in snowpack duration and maximum snow water equivalent (5.5 ± 1.2 days and 34 ± 8.6 mm per decade) corresponds with the largest drop in snow cover duration reported in zones of seasonal temperatures ranging from −5° to +5 °C.

In headwaters, snowmelt affects the replenishment of water resources as well as the occurrence of natural hazards. The environmental impacts of snowpack were analysed in a small forest catchment (Jizera Mountains, Czech Republic) in the context of forest dynamics, atmospheric deposition, and climate, 1982–2021. Snowmelt dominates in March–May with 41% of the long-term annual water yield; however, there is also seasonal acidification of stream water. Forest clear-cutting together with air pollution control has contributed to a decrease in the acid atmospheric load, but, in the spring, streams’ pH is often below the environmental threshold of 5.3. Snowmelt volumes did not show significant transformation with forest canopy and do not affect summer low flows. Peak flows in the springtime do not exceed summer flash floods (frequencies up to 0.13 against 0.02). Mean annual air temperature is increasing by 0.26 ± 0.08 °C per decade with more intensive warming (0.64 ± 0.1 °C per decade) in the winter season. The seasonal reduction in snowpack duration and maximum snow water equivalent (5.5 ± 1.2 days and 34 ± 8.6 mm per decade) corresponds with the largest drop in snow cover duration reported in zones of seasonal temperatures ranging from −5° to +5 °C.