Arctic rivers face big changes with a warming climate, permafrost thaw and an accelerating water cycle − the effects will have global consequences

By Michael A. Rawlins, UMass Amherst, Ambarish Karmalkar, University of Rhode Island

As the Arctic warms, its mighty rivers are changing in ways that could have vast consequences – not only for the Arctic region but for the world.

Rivers represent the land branch of the earth’s hydrological cycle. As rain and snow fall, rivers transport freshwater runoff along with dissolved organic and particulate materials, including carbon, to coastal areas. With the Arctic now warming nearly four times faster than the rest of the world, the region is seeing more precipitation and the permafrost is thawing, leading to stronger river flows.

We’re climate scientists who study how warming is influencing the water cycle and ecosystems. In a new study using historical data and sophisticated computer models of Earth’s climate and hydrology, we explored how climate change is altering Arctic rivers.

We found that thawing permafrost and intensifying storms will change how water moves into and through Arctic rivers. These changes will affect coastal regions, the Arctic Ocean and, potentially, the North Atlantic, as well as the climate.

Thawing permafrost: Big changes in Arctic soils

Permafrost thaw is one of the most consequential changes that the Arctic is experiencing as temperatures rise.

Permafrost is soil that has been frozen for at least two years and often for millennia. It covers approximately 8.8 million square miles (about 22.8 million square kilometers) in Earth’s Northern Hemisphere, but that area is shrinking as the permafrost thaws.

Historically, most water going into Arctic rivers flows atop frozen permafrost soils in spring. Scientists call this “overland runoff.”

However, our results suggest that as warming continues, an increasing fraction of annual river flow will come from under the surface, through thawed soils in the degrading permafrost. As the overall flow increases with more precipitation, as much as 30% more of it could be moving underground by the end of this century as subsurface pathways expand.

Read Full Story https://theconversation.com/arctic-rivers-face-big-changes-with-a-warming-climate-permafrost-thaw-and-an-accelerating-water-cycle-the-effects-will-have-global-consequences-224869