Graph of the Day: Eurasian Arctic River Discharge to the Arctic Ocean, 1936-2008

Total annual river discharge to the Arctic Ocean from the six largest rivers in the Eurasian Arctic for the observational period 1936–2008 (updated from Peterson et al. 2002) (red line) and from the four large North American pan-Arctic rivers over 1970–2008 (blue line). The least squares linear trend lines are shown as dashed lines. Provisional estimates of annual discharge for the six major Eurasian Arctic rivers, based on near-real-time data from http://RIMS.unh.edu, are shown as red diamonds. Upper green line shows the September (minimum) sea ice extent in the Arctic Ocean over 1979–2009 from NSIDC (http://nsidc.org/data). Annual river discharge to the Arctic Ocean from the major Eurasian rivers in 2008 was 2078 km3. In general, river discharge shows an increasing trend over 1936–2008 with an average rate of annual change of 2.9 ± 0.4 km3 yr-1. An especially intensive increase in river discharge to the ocean was observed during the last 20 years when the sea ice extent in the Arctic Ocean began decreasing. Interestingly, the correlation between Eurasian river discharge and sea ice extent over 1979–2008 is r = -0.72, or greater than the correlation between precipitation (Willmott et al. 1996) and runoff in these Eurasian drainage basins (r = 0.54). This suggests that both rivers and sea ice were responding to changes in large-scale hemispheric climate patterns (Shiklomanov and Lammers 2009). There is also an increasing tendency in river discharge to the Arctic Ocean from North America (Shiklomanov and Shiklomanov 2003; Rawlins et al. 2010). The mean annual discharge to the ocean over 2000–08 from the four large North American Arctic rivers was 6% (31 km3) greater than the long-term mean from 1970–99.

State of the Climate in 2009, National Oceanic and Atmospheric Administration, National Climatic Data Center, as appearing in the June 2010 issue (Vol. 91) of the Bulletin of the American Meteorological Society (BAMS). [pdf]