Arctic Rivers Face a Warming Climate, Permafrost Thaw, and an Accelerating Water Cycle

The Science

The Arctic is defined by the presence of frozen soils called permafrost. The warming climate is thawing permafrost and accelerating the water cycle, which alters flows of water, carbon, and other nutrients and materials by Arctic rivers. A team of investigators used a hydrology model that simulates soil thawing and freezing to explore potential future changes in factors that influence river water exports. The results highlight the need to closely watch the Arctic’s transformation and take steps to mitigate the effects.

The Impact

Arctic rivers differ from those in temperate and tropical regions. They transport large quantities of freshwater and carbon following spring snowmelt. Study results show that thawing permafrost and an accelerating water cycle will shift these flows in several ways. More water will enter Arctic rivers in the far north, where massive amounts of carbon stored in soils are experiencing thaw. In turn, additional carbon and other nutrients will enter rivers. Climate change will alter the amount of land-to-ocean freshwater and materials transports, with impacts to coastal ecosystems, ice dynamics, and ocean biogeochemistry.

Summary

Arctic river field sampling has shown that climate warming, an enhanced water cycle, and permafrost thaw are transforming river flows to coastal areas. Researchers have found that warming is thawing ancient frozen carbon stored in permafrost. To understand how climate warming changes Arctic terrestrial hydrology, researchers used a numerical model to project how river flows will change as warming continues. By 2100, Arctic rivers will receive more runoff from northern areas where abundant soil carbon exists. More water will enter them via subsurface pathways, particularly in summer and autumn. Study simulations point to a general increase in land runoff to rivers. Importantly, the proportion of runoff from subsurface pathways is projected to increase by as much as 30%. More water coming into northern areas will mobilize carbon from soils, transfer it to growing channel networks, and transport dissolved and particulate carbon downstream. Each season sees an increase in subsurface runoff. Higher surface runoff is noted in spring only, and summer experiences a decline in total runoff despite increased subsurface flows. These shifts in the far north emphasize the need for more frequent and spatially extensive sampling of smaller rivers that ring the Arctic Ocean.

Principal Investigator

Michael Rawlins
University of Massachusetts
[email protected]

Program Manager

Daniel Stover
U.S. Department of Energy, Biological and Environmental Research (SC-33)
Environmental System Science
[email protected]

Funding

This research was supported by the U.S. Department of Energy’s Office of Science, NASA, and the U.S. National Science Foundation’s Division of Polar Programs.

Related Links

• Arctic Rivers Face Big Changes—The Effects Will Have Global Consequences
• We Know the Arctic is Warming—What Will Changing River Flows Do to Its Environment?

References