I suspect that the complexity of global climate change is under-appreciated. If you live in a cold climate and I tell you that things will get warmer, you may see this as good news and look forward to a future where you no longer have to get your antifreeze checked and replace your old battery in September in preparation for the bitter cold of winter. But global warming is not the only kind of change happening because of the release of huge amounts of carbon in the atmosphere, and even with respect to the warming itself, things are much more complex than “it gets warm.” One example of this complexity is to be found in the Minnesota lakes, and in the closely related activity of fishing those lakes.
Minnesota normally gets quite cold, so ice forms on the lakes early, gets thick fast, survives any mid-winter warm spells, and stays solid late in the season. Minnesota normally gets relatively little snow and tends to be windy, so those ice-covered lakes, especially the larger ones, often have large areas where the ice is not covered by very much of the white fluffy stuff. Also, the waters at the time of freezing tend to be cooler than they strictly need to be to form ice; Deep water in the lakes stays cool all summer, so when winter comes the average temperature of the water in many lakes is lower than necessary to see ice formation at the surface.
Combined, these factors support two things:
1) Fish survival in the lakes and 2) Fishermen survival on top of the lakes.
Since the water is cold at the time of freezing, there is more oxygen in some of the lakes than there might otherwise be. Since some of the lake surface is covered with ice but not a thick layer of snow, sunlight gets into the lakes during the winter promoting photosynthesis in the algae living beneath the ice, which enhances oxygen supply. The occasional break-through of ice during the winter, if there is a warm up and sufficient wind, adds additional oxygen.
Meanwhile, if the ice gets thick fast and stays thick, fishermen and women can ice fish early, often, and well into the season. Many Minnesota lakes sport regular fish contests and festival’s during the winter that depend on this thick ice. Local businesses rely on these events to pay some of the bills during the winter when tourism is generally reduced.
In recent years, there have been some changes owing to global warming. In a warmer world, there will be some years (but certainly not all) where Minnesota experiences much more snow than it used to. This happened last year. Some lakes had so much snow on them last year that the algal activity was stifled and there was less oxygen in the water, and so those lakes experienced large die-offs of fish. Die-offs happen every year in some lakes, but it seems that the extra snow may have caused more fish to die than usual. (see “Winter’s Been Deadly For Minnesota Lakes, Fish“)
The lack of ice early in the year, thin ice during the winter, or early melt can have the opposite effect: More oxygen gets into the water, and thus, the chance of a die off is reduced. The thing is, the pattern of die-offs, when and why they happen, and their extent has changed for a reason that is not directly related to increasing temperature. This is an example of a complex system being altered and producing complex and generally negative results.
In warmer years, such as we are experiencing this winter (and in many previous winters) the lack of thick ice has caused numerous accidents and even fatalities as Minnesotans wandering around on insufficiently frozen lakes, falling in now and then. This, to me, is the ultimate form of Global Warming Denialism. One ignores through ignorance, or willful ignorance, the obvious change in our climate and as a result dies. The number of people falling through ice and drowning in Minnesota seems to be on the rise (though even with increased numbers, the quantities are small enough that a statistical test may be impossible). An excellent indicator of the increased dangers of ice with global warming can be found in what is happening with fishing contests. Contests on lakes in the central part of the state have been repeatedly canceled, and in the case of the Big Lake contests, permanently abandoned as an activity after being canceled several years in a row. In other words, global warming has caused Big Lake to no longer reliably freeze. It’s simply a new reality.
Leech Lake is quiet far north, and has always been a reliable place for ice fishing. However, last year, ice fishing was restricted only to more protected areas of the lake. I’m not sure of the status of the lake this year; Probably worse, as this winter has been much warmer. The annual eelpout festival (eelpout, also known as layer, is a snake-like land-locked cod) is held in mid February. These fish feed only when the water is very cold. And they hardly bit at all last year because the water was too warm. One wonders if the festival will even be held this year. The same thing happened last year at the fish tournament in Alexandria. Not a single fish was caught because conditions were too warm. There were 2,00 anglers, the lake was well stocked, and oxygen levels were sufficient. The Gull Lake Tournament scheduled for January 21st was canceled and moved to February because of thin ice. Although the tournament is officially on, no vehicles will be allowed on the lake because the ice won’t be thick enough.
And just to add insult to injury, the Ice Sculpture context, a center piece of the Saint Paul Winter Carnival, is being severely hampered by warm weather, something that pretty much seems to happen every year these days.
Yup, Global Warming is a) Real; b) complex and c) a serious matter.