150 Years Of Ferry Traffic Schedules Provide Valuable Data On Lake Superior Ice

[hatrack]

What started as a high school science fair project is the latest piece of evidence that global warming is affecting Lake Superior. Forrest Howk, now a freshman at the University of Wisconsin in Madison, studied 150 years of data in his hometown of Bayfield, Wis., and found that the harbor's frozen season has shrunk from about 120 days to 80 days.

The findings, published in the latest issue of Journal of Great Lakes Research, are consistent with recent studies showing that maximum ice cover in the Great Lakes has decreased slowly but steadily over the years. "You hear about all these clues to global warming having to do with ice, and you think about just putting it in your back yard, which for me is Lake Superior," Howk said.

Howk studied Bayfield harbor, a popular summer destination for Minnesotans, to see how many days each winter it is locked in ice. For much of the year, ferries cross the 2 miles between Bayfield and Madeline Island, but they must stop each winter when harbor ice grows more than 6 inches thick.

His main sources of information were ferry boat records, the local newspaper and early settler accounts. By compiling the records from 1857 to 2007, Howk discovered that 150 years ago that the ferries usually stopped around Dec. 20 and began about April 20. Now the ferries typically stop the second week of January, and start again in late March.

EDIT

http://www.startribune.com/local/42563667.html?elr=KArks:DCiUHc3E7_V_nDaycUiD3aPc:_Yyc:aULPQL7PQLanchO7DiUr

[AlecBGreen]

1. its also possible

that increasing technology makes it more navigable for longer portions of the year.

[zipplewrath]

2. Yeah

One would have to exclude several other factors before making too much of an assumption here. Power and size of the boats would be my first start. Potential market size at various times of the year would be another. I'd probably try to find some other factors that were similarly affected like land shipments, annual temps, snowfall, etc.