The bar chart presents the ice cover percentage in five lakes located in northern America. The data is divided into two periods of 20 years, spanning from 1973-92 and 1992-2012.
Overall, it can be seen that across the first two decades, ice coverage in all the lakes was higher than that in the second one. Erie’s surface was the most frozen, and Ontario’s – the least over the period shown.
A closer look at the chart reveals that the glaciated part of Erie Lake, despite a reduction in the second 20-year period, had the highest percentage in both timeframes, starting at 30% in 1973-92 and reaching 27.5% in 1992-2012 after a slight decline. In contrast, Ontario Lake had the least amount, with approximately more than 5% from 1973 to 1992, and then reduced to less than 5% in the next period reported.
Two other lakes, including Superior and Huron, showed broad similarities in their solidified part, both were almost 26% at first, which decreased to around 14% and 20% respectively. Michigan, on the other hand, ranged from less than 15% to about 10%.