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Figure 28. The Nenana Ice Classic record of break-up on the Tanana River, Alaska: A, 1917–2004; B, 1967–2004; and C, mean annual air temperature anomalies in the Arctic, 1900–2003. Break-up is shown as number of days after the vernal equinox in order to avoid bias due to leap years (Sagarin, 2001). The area in the box in A is enlarged in B. The original break-up data were obtained from the Nenana Ice Classic Web site (http://www.nenanaakiceclassic.com/). The break-up data and the air temperature anomaly data have each been smoothed with an 11-year running average filter. (See also table 2.)