Understanding the environmental influence of anthropogenic and natural climate forcing on Hamilton Inlet and Lake Melville, Labrador

Abstract

Recently, there has been growing interest in the climate variability in Newfoundland and Labrador and its impact on the environment. The warming temperature trend in the past two decades has driven changes in the ice thickness and characteristics of surface inland and coastal ocean waters. In the Hamilton Inlet, these changes are superimposed on the impact of hydroelectric development in Churchill River. Studies of the characteristics of regional climate change and anthropogenic factors are essential for understanding the environmental response. The main objective of this study is to assess the characteristics of climate variability and anthropogenic impact of recent hydroelectric development in Labrador. The method of the study is based on statistical analysis of observations of atmospheric and river flow characteristics. Decadal shifts in the distributions of the temperature in Newfoundland and Labrador are determined by using Kernel Density estimator. The non-parametric Mann-Kendall trend test and Sen’s methods are then applied then to determine the magnitude and significance of the trends. The first part of the study is focused on characteristics of seasonal, interannual and decadal variability of atmospheric temperature, precipitation, rain, snow and wind speed, and their spatial variations. We found in particular, that the multidecadal trend of atmospheric temperature was negative between 1970 and 1993 and changed to positive in the following period. The magnitude of this trend and its spatial variation across the province is assessed. The second part of the study presents results from an analysis of extremes of regional climate characteristics. Climate extremes are identified by calculating the 90th/10th percentiles of minimum and maximum daily temperature, which correspond to extreme warm/cold events; the 90th percentile was also calculated for total precipitation, snow and rain, to study extreme precipitation events. The final part of the study examines the relationship between climate indices and river discharge in Churchill River in Labrador. Here, river discharge volume is analyzed in the context of different climate conditions, before and after hydroelectric development in upper Churchill River.