Wednesday, November 24, 2010

Great Lakes are Warming Up, About 1 to 2 degrees per Decade

This summer, swimming in Lake Michigan was like swimming in warm bath water, with water temperatures rising into the 80s and staying consistently warm for months. Heavenly. As often as possible we tossed swimmy pants onto the kids, slung a towel or four over our shoulders and walked down to the lake to go for a refreshing dip.

It was pretty awesome, since usually it's kind of a crap shoot whether you'll get warm-ish water or freezing cold water rotated up from the chilly lake bottom in a storm. But this year, warm. Very warm.

Which tends to also mean rougher waters, more undertows and rip currents. 2010 saw a record number of Lake Michigan drownings, at 63, up from a typical 40 in 2009, due to the warm, more turbulent waters.

Another less dire consequence of the warm waters is that many fishermen needed to go further out since they weren't catching salmon in the warmer waters closer to shore.

Now, I realize that there's a difference between Climate and Weather, and what we experienced this year is "Weather" with the warm waters of 2010 more or less unrelated to a general warming trend...

...but there is, as it turns out, a general warming trend for the Great Lakes. According to a recent NASA report, water levels in the Great Lakes have been on the rise in the past 25 years:

NASA used satellite data to measure the surface temperatures of 167 lakes worldwide and found an average warming rate of .81 degrees Fahrenheit per decade and in some lakes, as much as 1.8 degrees Fahrenheit per decade, NASA said Tuesday.

This sort of thing disrupts underwater ecosystems, wetlands, and even has the potential to disturb land based eco-systems and weather patters, since the Great Lakes are already large enough that they influence the weather along the Lakeshore and create micro-climates ideal for fruit production to the East of the lake.

Interestingly, I also ran across an article talking about how lake cyclones work. In the cooling autumn months, the relatively warm waters cause a sudden rise in air exacerbating a cyclone and causing severe winds. As the waters warm over the decades, these we're looking at changing weather patterns on shore.

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