Side-by-side boxplots offer a different look at the data

Question

More on global warming

Problem: Side-by-side boxplots offer a different look at the data. Group the data into periods of roughly equal length: 1917 to 1939, 1940 to 1962, 1963 to 1985, and 1986 to 2010. Make boxplots to compare ice breakup dates in these four time periods.

Required:

1. Write a brief description of what the plots show.