Figure 4.6

Figure 4.6. Trends in river ice cover duration in Canada. Upward pointing triangles indicate lengthening of the ice cover period while downward triangles indicate shortening of the ice cover period. Trends significant at the 99 and 90% confidence levels are marked by larger filled and hollow triangles, respectively. Smaller triangles indicate trends that are not significant at the 90% level (Zhang et al., 2001).