Decreasing river discharge in northern Canada

Freshwater discharge to high‐latitude oceans in 64 Canadian rivers is investigated. The mean annual discharge rate attains 1252 km 3 yr −1 for an area of 5.6 × 10 6 km 2 , equating to a sink of 225 mm yr −1 in the surface water budget of northern Canada (excluding the Arctic Archipelago where insufficient data exist). Application of the Mann‐Kendall test to the data reveals a 10% decrease (−125 km 3 yr −1 or −22 mm yr −1 ) in the total annual river discharge to the Arctic and North Atlantic Oceans from 1964 to 2003. This trend in river runoff is consistent with a 21 mm yr −1 decline in observed precipitation over northern Canada between 1964 and 2000. We find evidence of statistically‐significant links between the Arctic Oscillation, El Niño/Southern Oscillation, and the Pacific Decadal Oscillation to the total annual freshwater discharge in northern Canada's rivers at interannual‐to‐decadal timescales.