Analysis of the Arctic System for Freshwater Cycle Intensification: Observations and Expectations
Michael A. Rawlins1, Michael Steele2, Marika Holland3, Jennifer Adam4, Jessica Cherry5, Jennifer Francis6, Pavel Ya. Groisman7, Larry Hinzman8, Thomas Huntington9, Douglas Kane10, John Kimball11, Ron Kwok12, Richard Lammers13, Craig Lee14, Dennis Lettenmaier15, Kyle McDonald16, Erika Podest17, Jonathan Pundsack18, Bert Rudels19, Mark Serreze20, Alexander Shiklomanov21, Oystein Skagseth22, Tara Troy23, Charles Vorosmarty24, Mark Wensnahan25, Eric Wood26, Rebecca Woodgate27, Daqing Yang28, Ke Zhang29, Tingium Zhang30
1Department of Earth Sciences, Dartmouth College, Hanover, NH, USA
2Polar Science Center, University of Washington, Seattle, WA, USA
3National Center for Atmospheric Research, Boulder, CO, USA
4Department of Civil & Environmental Engineering, Washington State University, Pullman, WA
5International Arctic Research Center, University of Alaska, Fairbanks, AK, USA
6Institute of Marine and Coastal Sciences, Rutgers University, Highlands, NJ
7UCAR, UCAR at National Climatic Data Center, Asheville, NC
8University of Alaska, Fairbanks, AK, USA
9U.S. Geological Survey, Augusta, ME, USA
10Water and Environmental Research Center, University of Alaska, Fairbanks, AK, USA
11Numerical Terradynamic Simulation Group, University of Montana, Missoula, MT, USA
12Jet Propulsion Laboratory, Pasadena, CA, USA
13University of New Hampshire, Durham, NH, USA
14Ocean Physics Department, University of Washington, Seattle, WA, USA
15Civil and Environmental Engineering, University of Washington, Seattle, WA, USA
16Jet Propulsion Laboratory, Pasadena, CA, USA
17Jet Propulsion Laboratory, Pasadena, CA, USA
18Institute for the Study of Earth, Oceans, and Space, University of New Hampshire, Durham, NH, USA
19Department of Physical Sciences, University of Helsinki & Finnish Meteorological Instit., Helsinki, Finland
20National Snow and Ice Data Center, University of Colorado, Boulder, CO, USA
21University of New Hampshire, Durham, NH, USA
22Institute of Marine Research, Bjerknes Centre for Climate Research, Bergen, Norway
23Department of Civil and Environmental Engineering, Princeton University, Princeton, NJ, USA
24City College of New York, New York, NY, USA
25University of Washington, Seattle, WA, USA
26Department of Civil and Environmental Engineering, Princeton University, Princeton, NJ, USA
27University of Washington, Seattle, WA, USA
28Water and Environmental Research Center, University of Alaska, Fairbanks, AK, USA
29Numerical Terradynamic Simulation Group, University of Montana, Missoula, MT, USA
30National Snow and Ice Data Center, University of Colorado, Boulder, CO, USA
The effects of climatic warming are propagating through the arctic system, and arguably no components of the environment have been impacted more than the hydrosphere and cryosphere. Theory suggests that warming will lead to increases in precipitation, evaporation, and net precipitation along with related changes such as a lengthening of the growing season and attendant increases in evapotranspiration. Indeed, positive trends in discharge from major rivers suggest a recent intensification of the arctic hydrological cycle. But while there has been substantive evidence of a long-term increase in discharge from large Eurasian rivers and, more recently, positive trends in flow from rivers across North America, many questions regarding the major contributing factors for these and other changes in the hydrological cycle remain unanswered. For example, it has been suggested that positive trends in river discharge may be attributable to losses of ice-rich permafrost caused by warming. However, some studies point to an increase in groundwater storage throughout Eurasia in recent years which challenges the argument that degradation of permafrost may be a leading contributor for the discharge trends. Increases in cold-season precipitation over some regions raise the possibility that strong seasonality may be a leading causal factor. This presentation investigates intensification of the arctic hydrological cycle using observational data such as river discharge, precipitation, and evapotranspiration in the context of expectations from a suite of coupled general circulation models. Seasonal and spatial aspects of the precipitation trends along with related changes in atmospheric moisture flux are also examined along with potential linkages between climate warming, recent sea-ice declines, and moisture transport. Taken together, these data show a pattern of an increase in water flux through the system that supports the hypothesis of emerging intensification consistent with expectations.