Can Regulation of Freshwater Runoff in Hudson Bay Affect the Climate of the North Atlantic?

Abstract

ABSTRACT. A sequence of phenomena links anthropogenic changes in the timing of freshwater runoff in Hudson Bay to a possible impact on the North Atlantic thermohaline circulation. The chain of events starts with the spreading of estuarine plumes under ice and continues with the effect of lowered salinity on the rate of ice formation, regional effects on the scale of Hudson Bay, the export of freshwater to the Labrador Sea, its impact on deep convection in that area, and the relative importance of such changes to the North Atlantic circulation. At each step we compare anthropogenic effects with other factors and place them within the perspective of natural variability.Our conclusion does not support the contention that freshwater runoff regulation, even of all rivers in the basins of Hudson and James Bays, could have a significant or even a detectable effect on the climate of the North Atlantic.Key words: freshwater regulation, Hudson Bay, climate RÉSUMÉ. Une séquence de phénomènes relie des changements anthropiques dans le moment où les eaux douces commencent à s'écouler dans la baie d'Hudson à leur répercussion possible sur les courants thermiques des eaux marines. La séquence débute par la formation d'un panache estuarien sous la glace et se poursuit avec l'effet de la baisse de salinité sur la vitesse de formation de la glace, des répercussions régionales affectant toute la baie d'Hudson, l'exportation d'eau douce vers la mer du Labrador et ses retombées sur la convection profonde dans cette zone, ainsi qu'avec l'importance relative de tels changements sur les courants nord-atlantiques. À chaque étape, on compare les influences anthropiques avec d'autres facteurs pour les situer dans un contexte de variabilité.Notre conclusion n'appuie pas la thèse que la régulation de l'écoulement des eaux douces, même si elle s'étendait à tous les cours d'eau des bassins de la baie d'Hudson et de la baie James, pourrait avoir des répercussions notables ou même détectables sur le climat nord-atlantique.Mots clés: régulation des eaux douces, baie d'Hudson, climat Traduit pour la revue Arctic par Nésida Loyer.

Interannual Variability of Hudson Bay Ice Thickness

“…Nevertheless, Saucier and Dionne (1998) observed that a 30% increase in runoff in the first half of the year produces an increase in ice thickness of 0.4 cm only over Hudson Bay. Likewise, LeBlond et al (1996) examined the impact of increased winter discharge due to Downloaded by [University of Toronto Libraries] at 15:49 04 June 2016 hydroelectric regulation in James Bay and concluded that the increase in sea ice would be marginal (0.23%).…”

Reconstructing the Natural Streamflow of a Regulated River: A Case Study of La Grande Rivière, Québec, Canada

“…Previous studies have investigated the physical and biological effects of flow regulation in the La Grande Rivière basin. Some of their findings show that the increase in winter runoff and accumulation of freshwater in the region have caused the under-ice plume around James Bay to extend over a larger area (Messier et al, 1989;LeBlond et al, 1996), resulting in the freshening of near-shore surface waters (Ingram and Larouche, 1987) and the disruption of surface currents (Messier et al, 1986). Thus, based on the ongoing research being conducted in this area, it is imperative that future oceanographic studies employ La Grande Rivière's reconstructed flows when assessing the magnitude of human impact and investigating the natural variations in the hydrological cycle of the basin.…”

Climate Variability and Climatic Change: Potential Implications for Hudson Bay Coastal Communities

“…While many investigations have focused on the potential response of HB to climate variability (e.g., Manak and Mysak, 1989;Cohen et al, 1994;Wang et al, 1994;Mysak et al, 1996) and climate change (e.g., Cohen et al, 1994;LeBlond et al, 1996;Saucier and Dionne, 1998;Gough and Wolfe, 2001;Gagnon and Gough, 2004), less has been written about the possible impacts of these changes on the human populations permanently inhabiting the region. In the HB and James Bay (JB) area, the Inuit tend to live north of the tree line, whereas the Cree peoples tend to live south of it (Berkes and Freeman, 1986), although the territories they travel may overlap in some regions.…”

“…Within these general cultural groupings, many unique communities employ different areas of HB/JB for a variety of resource uses, all of which tend to rely on seasonal cycles. Sea ice plays an important role in this climatic component through its delay of seasonal warming (Rouse, 1991;Gough and Wolfe, 2001;Gough and Leung, 2002;Gough et al, 2004), its influence on freshwater input (LeBlond et al, 1996), and its effect on salinity gradients and circulation (Jones and Anderson, 1994).…”