We’ve cut and pasted the following article by by Geoff Peach from the Lake Huron Centre for Coastal Conservation (lakehuron.ca):
Researchers have found that rising water temperatures are kicking up more powerful winds on Lake Superior, with a range of implications affecting currents, biological cycles, pollution and ecosystems on the world’s largest lake and its smaller Great Lakes siblings.
A wide temperature differential between water and air makes for a more stable atmosphere with calmer winds over the relatively cold water. However, as warming water closes the gap, as in the case of the Great Lakes, the atmosphere gets more turbulent.
“You get more powerful winds,” according to Professor Desai from the University of Wisconsin. “We’ve seen a 5 percent increase per decade in average wind speed on Lake Superior since 1985.”
One of the factors influencing higher water temperatures has been less winter ice cover. Reflective ice lessens the amount of solar radiation on the lake. Once the final ice-melt has occurred, however, the large lakes turn into dark surfaces that absorb solar radiation to the maximum of any natural surface. This absorbed solar radiation is the primary agent that warms the lake. The relative timing of final ice-melt to the summer solstice — the season when the sun provides most radiation — is therefore a key determinant of the degree of warming of lake waters (Rouse, 2009).
A result of longer periods of higher surface water temperatures is a weakening of the water–air temperature gradient. This has the effect of destabilizing the atmosphere above the lake, enabling faster wind speeds across the lake surface (Cruce, T., & Yurkovich, E., 2011).
There are some interesting implications for higher wind speeds off the lake, including movement of airborne pollutants to the shore, increased lake-effect streamers in winter, potentially stronger alongshore currents, and wind movement of sand on beaches and dunes.
Increased sand movement and dune erosion could present problems to communities who do not have well managed dune systems in place. This is particularly important for many of Lake Huron and Georgian Bay’s dune systems because they are made up of finite sand deposits where no new source of sand is present should the existing sands get eroded away. Erosion of beaches and dunes can be caused, or made worse, by high impact recreational activities, development pressure and poorly designed beach access.
The Coastal Centre has been working with several municipalities and community groups to establish measures that will help prevent beach and dune erosion, and this will become increasingly relevant under a higher wind regime. As researchers learn more about the changes affecting our region, coastal communities will need to consider the implications and adapt where necessary.