Sea-ice production over the Laptev Sea shelf inferred from historical summer-to-winter hydrographic observations of 1960s-1990s

The winter net sea-ice production (NSIP) over the Laptev Sea shelf is inferred from continuous summer-to-winter historical salinity records of 1960s–1990s. While the NSIP strongly depends on the assumed salinity of newly formed ice, the NSIP quasi-decadal variability can be linked to the wind-driven circulation anomalies in the Laptev Sea region. The increased wind-driven advection of ice away from the Laptev Sea coast when the Arctic Oscillation (AO) is positive implies enhanced coastal polynya sea-ice production and brine release in the shelf water. When the AO is negative, the NSIP and seasonal salinity amplitude tends to weaken. These results are in reasonable agreement with sea-ice observations and modeling

Last glacial benthic foraminiferal d18O anomalies in the polar North Atlantic: A modern analogue evaluation

Modern processes are evaluated to understand the possible mechanisms behind last glacial benthic foraminiferal δ18O anomalies that occurred concurrent with meltwater events in the polar North Atlantic; such anomalies in the Nordic seas were recently interpreted to be caused by brine formation. Despite intensive sea-ice production on circumarctic shelves, modern data show that brines ejected from sea-ice formation containing low δ18O water do not significantly contribute to deep waters in the Arctic Ocean today. Assuming that this process was, nevertheless, responsible for δ18O anomalies in Nordic seas deep water during the last glaciation, a broad, shallow shelf area adjacent to the Nordic seas, such as the Barents Sea, had to be seasonally free of sea-ice in order to serve as an area for brine formation. Another process which may explain δ18O-depleted water at depth is found in the Weddell Sea today, where a low δ18O signal in deep waters originates from ice shelf interactions. If temperature were considered the main mechanism for the low benthic δ18O values, an increase of 4°C must have occurred in the deep water. An analogous situation with a reversed water temperature pattern due to a subsurface inflow of warm Atlantic water is found today in the eastern Arctic Ocean, and deep water warming is observed in the Greenland Gyre in the absence of deep convection. Because paleoproxy data also indicate an Atlantic water inflow into the Nordic seas during such benthic δ18O anomalies, temperature as a principal mechanism of changing δ18O cannot be excluded

Linkages among runoff, dissolved organic carbon, and the stable oxygen isotope composition of seawater and other water mass indicators in the Arctic Ocean

Author Posting. © American Geophysical Union, 2005. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research 110 (2005): G02013, doi:10.1029/2005JG000031.Concentrations of dissolved organic carbon (DOC) and δ18O values have been determined following sampling of runoff from a number of major arctic rivers, including the Ob, Yenisey, Lena, Kolyma, Mackenzie and Yukon in 2003-2004. These data are considered in conjunction with marine data for DOC, δ18O values, nutrients, salinity, and fluorometric indicators of DOC that were obtained as part of the Shelf-Basin Interactions program at the continental shelf-basin boundary of the Chukchi and Beaufort Seas. These marine data indicate that the freshwater component is most likely derived from regional sources, such as the Mackenzie, the Bering Strait inflow and possibly eastern Siberian rivers, including the Kolyma, or the Lena but not rivers further west in the Eurasian arctic. Contributions of freshwater from melted sea ice to marine surface waters appeared to be insignificant over annual cycles compared to runoff, although on a seasonal basis, freshwater from melted sea ice was locally dominant following a major sea-ice retreat into the Canada Basin in 2002. DOC concentrations were correlated with the runoff fraction, with an apparent meteoric water DOC concentration of 174 ± 1 μM (standard error). This concentration is lower than the flow-weighted concentrations measured at river mouths of the five largest Arctic rivers (358 to 917 μM), indicating that removal of terrigenous DOC during transport through estuaries, shelves and in the deep basin. DOC data indicate that flow-weighted concentrations in the two largest North American arctic rivers, the Yukon (625μM) and the Mackenzie (382 μM), are lower than in the three largest Eurasian arctic rivers, the Ob (825 μM), the Yenesey (858 μM) and the Lena (917 μM). A fluorometric indicator of chromophoric dissolved organic matter (CDOM) that has provided estimates of terrigenous DOC concentrations in the Eurasian Arctic was not correlated with DOC concentrations in the Amerasian marine waters studied, except below the upper Arctic Ocean halocline. Nutrient distributions and concentrations as well as derived nutrient ratios suggest the CDOM fluorometer may be responding to the release of chromophoric materials from continental shelf sediments. Shipboard incubation experiments with undisturbed sediment cores indicate that continental shelf sediments on the Bering and Chukchi Sea shelves are likely to be a net source of DOC to the Arctic Ocean.The PARTNERS and SBI projects have been supported by the Office of Polar Programs of the U.S. National Science Foundation

Jack-of-all-trades, master of none: Postgraduate perspectives on interdisciplinary health research in Australia

BACKGROUND: Interdisciplinary health research is increasingly perceived as an expectation of research institutions and funding bodies within Australia. However, little consideration has been given to the extent to which this re-orientation has produced a new type of researcher – an interdisciplinary health researcher. DISCUSSION: As cross-enrolled postgraduate research students, we assert that we do not have an intellectual home. Rather, we must forge a virtual intellectual home through the process of bridging disciplines. In this paper we explain that this virtual home affords us the role of 'interlockers' in future health research. The interlocker role privileges a breadth of understandings across disciplines, rather than a depth in one. SUMMARY: We conclude by reiterating that there is an undeniable need for interdisciplinary health research, and that the roles and actions of interdisciplinary health researchers need to be better understood and catered for. We therefore call for increased consideration and discussion concerning the future roles and capacities of interdisciplinary health researchers such as ourselves

Tracking the provenance of Greenland-sourced, Holocene aged, individual sand-sized ice-rafted debris using the Pb-isotope compositions of feldspars and 40Ar/39Ar ages of hornblendes

The provenance of sand-sized ice-rafted debris (IRD) sourced from Greenland is currently difficult to determine. Such knowledge, if it could be ascertained with a high degree of certainty, could be applied to the Greenland-proximal marine records to improve both our understanding of modern-day spatial patterns of iceberg rafting and the past history of the Greenland Ice Sheet (GIS). Recent studies have highlighted the utility of the Pb-isotope composition of individual sand-sized feldspars and the 40Ar/39Ar ages of individual sand-sized hornblendes in this regard. However, before any such provenance toolkit can be applied to the palaeo-record, it is necessary first to determine whether this approach can be used to track the sources of known recent Greenland-proximal IRD deposition. To this end we present new records of the Pb-isotope composition and the 40Ar/39Ar ages of individual sand-sized grains of feldspars and hornblendes, respectively, from modern Greenland glacifluvial and fjord sands and Holocene to modern Greenland-proximal marine sediments. These new data demonstrate that sand-sized feldspars and hornblendes glacially eroded by the GIS exhibit distinct intra- and inter-tectonic terrane differences in their Pb-isotope compositions and ages and that these differences are clearly expressed in the geochemistry and geochronology of sand-sized IRD deposited in marine sediments around Greenland. Although overlap exists between some Greenland-proximal IRD ‘source fields’ defined by these data, our approach has the potential to both better understand spatial patterns of Greenland-derived IRD in the modern day as well as during past episodes of iceberg calving

“Stickier” learning through gameplay: an effective approach to climate change education

As the impacts of climate change grow, we need better ways to raise awareness and motivate action. Here we assess the effectiveness of an Arctic climate change card game in comparison with the more conventional approach of reading an illustrated article. In-person assessments with control/reading and treatment/game groups (N = 41), were followed four weeks later with a survey. The game was found to be as effective as the article in teaching content of the impacts of climate change over the short term, and was more effective than the article in long-term retention of new information. Game players also had higher levels of engagement and perceptions that they knew ways to help protect Arctic ecosystems. They were also more likely to recommend the game to friends or family than those in the control group were likely to recommend the article to friends or family. As we consider ways to broaden engagement with climate change, we should include games in our portfolio of approaches