Changing freshwater contributions to the Arctic : A 90-year trend analysis (1981-2070)

The pan-Arctic domain is undergoing some of Earth's most rapid and significant changes resulting from anthropogenic and climate-induced alteration of freshwater distribution. Changes in terrestrial freshwater discharge entering the Arctic Basin from pan-Arctic watersheds significantly impact oceanic circulation and sea ice dynamics. Historical streamflow records in high-latitude basins are often discontinuous (seasonal or with large temporal gaps) or sparse (poor spatial coverage), however, making trends from observed records difficult to quantify. Our objectives were to generate a more continuous 90-year record (1981-2070) of spatially distributed freshwater flux for the Arctic Basin (all Arctic draining rivers, including the Yukon), suitable for forcing ocean models, and to analyze the changing simulated trends in freshwater discharge across the domain. We established these data as valid during the historical period (1971-2015) and then used projected futures (preserving uncertainty by running a coupled climate-hydrologic ensemble) to analyze long-term (2021-2070) trends for major Arctic draining rivers. When compared to historic trends reported in the literature, we find that trends are projected to nearly double by 2070, with river discharge to the Arctic Basin increasing by 22% (on average) by 2070. We also find a significant trend toward earlier onset of spring freshet and a general flattening of the average annual hydrograph, with a trend toward decreasing seasonality of Arctic freshwater discharge with climate change and regulation combined. The coupled climate-hydrologic ensemble was then used to force an ocean circulation model to simulate freshwater content and thermohaline circulation. This research provides the marine research community with a daily time series of historic and projected freshwater discharge suitable for forcing sea ice and ocean models. Although important, this work is only a first step in mapping the impacts of climate change on the pan-Arctic region

Askeladden Delta Sequence (Palaeocene) on Spitsbergen?sedimentation and controls on delta formation

Because of its coal potential the basal Tertiary Firkanten Formation on Spitsbergen has received much attention. The formation is an offset stacked (overall transgressive) sequence comprising at least eight coastaydeltaic units each of which has a regressive character and is 10 to 30m thick. The lowermost coal-bearing unit (Todalen Member) represents deltas which were largely fluvial- and tide-dominated while the upper unit deltas (Endalen Member) were wave-dominated:One of the transitional deltaic units, the Askeladden Sequence, has been examined in some detail along depositional dip (-15 km) and strike (-55 km). This unit represents wave- (tide)dominated delta conditions, and two main facies associations are recognized: 1. Delta front/shoreline deposits (Facies Association I). 2. Delta plain/coastal plain deposits (Facies Association 11). Askeladden sequence accumulated in a shallow, low-gradient embayment (Nordenskiold Land subbasin) open to the south and southwest. Periodic, strong longshore currents caused a net northwards transport of sediment. Tidal range is considered close to the micro/meso-tidal boundary, and estimates of ancient wave regime indicate overall moderate wave conditions, suggesting that the extensive wavereworking of the delta front/shoreline sands is related to relatively slow rates of fluvial input. Climate and tectonics are considered important contributory controls on sedimentation