It has been observed that water levels in the Great Lakes are declining. In 2007, The New York Times reported that the water level in Lake Ontario fell 7 inches from October 2006 to October 2007.The New York Times: Inch by Inch, Great Lakes Shrink, and Cargo Carriers Face Losses (October 22, 2007) The shrinking lakes have creating problems for commercial shipping. It is estimated for every inch of water that is lost in the lakes, ships must lighten their cargo load by 270 tons.The New York Times: Inch by Inch, Great Lakes Shrink, and Cargo Carriers Face Losses (October 22, 2007)

1. Increases in cost are felt in the transportation expense by companies
2. The five lakes are all below their long-term averagesThe New York Times: Inch by Inch, Great Lakes Shrink, and Cargo Carriers Face Losses (October 22, 2007)
3. In the past two years, evaporation rates have been higher than average
4. The International Joint Commission is conducting a $17 million study to determine conclusively whether the low water levels are the result of global warming or a seasonal fluctuation
5. Potential Causes: Low precipitation, mild winters and high evaporation