Cooperative Institute for Research in Environmental Sciences

An Arctic hydrologic system in transition: Feedbacks and impacts on terrestrial, marine, and human life.

J. Francis, J.J. Cassano, W.J. Gutowski, L.D. Hinzman, M.M. Holland, M.A. Steele, D.M. White, and C.J. Vorosmaty

2009, Journal of Geophysical Research, 114, G04019, doi:10.1029/2008JG000902.

The pace of change in the Arctic physical/biological system during recent decades has captured the worlds attention. While observations and model simulations indicate that the Arctic experiences an amplified response to climate forcing relative to that at lower latitudes, the decline in permanent ice forms -- multiyear sea ice, permafrost, and ice sheets/glaciers that define this environment has exceeded even the most pessimistic projections. At the core of these changes is the Arctics hydrologic system, which includes not only ice, but also water in its other forms: gaseous vapor in the atmosphere, liquid water in soils and fluvial networks on land, and freshwater content of the ocean. The changes in stores and fluxes of freshwater have a direct impact on biological systems, not only of the Arctic region itself, but also well beyond its bounds. Unraveling the complex set of components, interactions, and feedbacks within the Arctic hydrologic system and the life that depends on it is a tremendous challenge. In this investigation, we adopt a heuristic, graphical approach to distill the system into its fundamental parts, document the key relationships between those parts as best we know them, and identify the feedbacks within the physical system as well as the effects of those feedbacks on ocean productivity, terrestrial vegetation, and the success of human communities in the region. The analysis illustrates relationships that are well understood, but also reveals others that are either unfamiliar, uncertain, or unexplored. These results highlight aspects of the Arctic system that require additional system-oriented research efforts that incorporate new observations and model simulations emerging from recent initiatives such as those participating in the International Polar Year. Finally, this graphical approach is used to provide a visual assessment of the Arctic hydrologic system in a possible future state with dramatically reduced permanent ice, and the consequent shifts in Arctic life.