Trends in Mackenzie River Discharge, Temperature, and Heat Flux into the Arctic Ocean

The Mackenzie River is the largest river flowing into the Arctic Ocean from North America and a major contributor of freshwater in the Beaufort Gyre. We examine its discharge, temperature, and heat flux into the Arctic Ocean based on in-situ observations from 1972 to 2023. Mean monthly discharge increases during the spring and fall and decreases during the summer. River temperatures are increasing in summer and fall, with little change in winter and early spring. There is a statistically significant increase in heat flux into the Arctic Ocean in September and October, coinciding with the beginning of the ice-formation season. We use a global climate model to project future discharge, temperature, and heat flux to the end of the century. We discuss implications of river discharge and freshwater storage in the Arctic Ocean as well as on the thermohaline circulation in the North Atlantic.