Variabilité et fréquence des cycles de gel‐dégel dans la région de Québec, 1977–2006

Freeze‐thaw cycles are most common at the beginning or near the end of the winter season. These cycles have various effects on the ecosystems of Eastern Canada, affecting both biotic and abiotic components of temperate cold environments. Using air temperature minima and maxima from four meteorological stations close to Québec City, we determined the frequency of daily freeze‐thaw cycles for the last 30 years. The results show no significant increase in the number of freeze‐thaw cycles despite a small increase in air temperature. Polynomial curves describing the relationship between mean air temperatures and the number of freeze‐thaw cycles were calculated. Based on these equations and anticipating a climate change scenario, we projected future freeze‐thaw cycles. Assuming a 5 °C increase in mean air temperatures by 2100, we estimated that the number of days with a freeze‐thaw cycle could increase by approximately 20 days per winter. The increase in the number of such cycles will be concentrated during the coldest months of the winter (January and February).     

Le Conte de deux cités1 : Analyse comparative des conflits urbains de Montréal et Valence, 1995–2010

A tale of two cities: 9 Comparative analysis of urban conflicts of Montreal and Valencia, 1995–2010 Metropolization processes at work in contemporary societies produce social and spatial change, which can raise strong opposition from a variety of urban actors, leading to acts of dissent. While such urban conflict has been examined in the past, geographical analysis of urban conflicts as sociospatial processes is more recent. Systematic quantitative research on urban conflict is virtually nonexistent in terms of comparative analysis conducted with an international perspective. Systematic comparative analysis sheds light on the existing relationship between urban conflicts and the socio‐territorial contexts in which conflicts emerge and evolve. This article presents a comparative analysis of urban conflict that occurred in a selection of boroughs in two cities characterized by different geographical realities, Valencia (Spain) and Montreal (Canada), between 1995 and 2010. Spatial autocorrelation techniques applied to a conflict database show a significant relationship between the emergence of urban conflict and the spatial distribution of some contextual variables. Indeed, for Montreal as for Valencia, the concentration of urban conflict is the greatest in the most deprived neighbourhoods. Also, regarding the management and regulation of urban conflict, results shed light on important differences between Montreal and Valencia. These differences include the outcome of urban conflicts, repertoire of action of actors involved in conflict activity, and the type of contestation faced by actors who promote the challenged urban projects.