Estimated high latitude water mass changes: three year trends over Siberian watersheds, Arctic and Antarctic glaciers and ice sheets

Author: M. Fang, B.H. Hager, C. Wunsch and Rui M. Ponte
Date: 
December 1, 2006
Type: 
Presentation
Venue: 
AGU Fall Meeting, San Francisco
Citation: 

Fang, M., B.H. Hager, C. Wunsch, and R.M. Ponte, 2006. Estimated high latitude water mass changes: three year trends over Siberian watersheds, Arctic and Antarctic glaciers and ice sheets, AGU Fall Meeting, San Francisco, December 2006.

Annual average temperatures in Western Siberia have increased by about 3C° over the last four decades. Accompanying this increase are noticeable physical and ecological changes. Meanwhile, ice-mass losses are found over Alaska and Greenland. The extent to which global warming is directly manifested as a high latitude loss of ice has many important consequences, including understanding of ice dynamics, the hydrological cycle, and global sea level rise. An important step towards understanding the complex climate pattern at high latitude is to consider the mass variability simultaneously over the entire region. In this work, temporally varying GRACE data given at monthly intervals from Jan. 2003 to Dec. 2005 are used to derive the apparent trends in water and ice mass distributions in selected Arctic and Antarctic regions. Water mass loss is found at the rate -93 ± 36 cubic km per year over the Ob basin and its northern extension, a region where melting of permafrost has been observed. Mass gain at the rate 82 ± 28 cubic km per year is found over the Lena basin. There is no significant trend found over the Yenisei basin, which is located between the Ob and Lena watersheds. The three-year trend of ice is -138 ± 44 cubic km per year over Alaska; and -144 ± 101 cubic km per year over Greenland. In other regions, including Antarctica, the variability at seasonal and interannual timescales, or uncertainties due to the postglacial rebound, are so great as to mask any secular changes. Although the results are encouraging for the ultimate detection of long-term climate change as manifested in changes in net water storage, the time span of the existing data is too short to draw reliable conclusions about secular change in total resident water in the polar regions.