Global Warming

Minnesota Public Radio:

The air temperature part is no mystery. The climate has warmed measurably just like that in many places worldwide. Climatologists are calling it global warming.

"But what surprised us is that Lake Superior's water temperatures were warming around twice as fast as that," Austin says. "And it's, as far as I know, one of the largest changes in temperature of any natural system that's been observed over the last 25 years."...

"The date of what we call the spring overturn, has been getting earlier in the year," Austin says. "It's basically the start of the summer season in the lake. It's when you start to develop strong positive stratification: warm water sitting on top of cool water."