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

Variability and frequency of the freeze thaw cycles in Québec region, 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). [ABSTRACT FROM AUTHOR]