04/16/2014 05:28 EDT | Updated 06/16/2014 05:59 EDT

More Ice Doesn't Mean Water Levels Have Stopped Declining

We are (hopefully) finally arriving at the end of a long, cold winter season. There has been a lot of commentary in the past few weeks about the ice coverage on the Great Lakes. It was very high this year compared to recent yearly averages.

However, one too many articles suggested that the heavy ice coverage presents a natural solution to the well-documented problem of declining Great Lake water levels.

This is not necessarily the case.

The Great Lakes are experiencing a prolonged year-over-year decline in water levels especially pronounced in the middle Great Lakes. This is a serious issue with likely major economic harms to tourism, shipping and property values, in addition to severe environmental degradation, habitat destruction and the loss of pristine coastline from the North Channel to Lake St Clair.

Now, suppose this summer we see an increase in the water levels as many are suggesting, and suppose it is predominately due to the melting ice and snow.

Were that to happen this summer, I caution against too much enthusiasm.

There's a simple reason why: Lake Michigan-Huron reached its all-time record low in December 2012 and January 2013. Moreover, Lake Michigan-Huron remains significantly below its long-term average - in fact we are 1.6 inches below the levels at the start of 2012. When you reach a record low, a one-time uptick is not a cause for celebration.

And an increase in ice coverage on the lakes does not necessarily indicate a corresponding increase in water levels in the summer. Although melting ice and snow will drain into the lake basins, part of this is just the natural annual ebb and flow of the lakes' levels. For instance, Lake Superior loses on average five feet of water every year due to this natural, seasonal ebb and flow.

Indeed, new research suggests cold winters are often preceded by periods of high evaporation in the autumn and early winter, as the warm water evaporates into the cold air. This evaporation can effectively offset the decrease in summertime evaporation that can result from colder water temperatures arising from the ice coverage in wintertime.

Ultimately, the issue of Great Lake water levels is too complex for one seasonal variant to have a major effect.

Future levels in the basin are hard to predict with accuracy because precipitation is no longer the driving force of the basin's water levels -- climate change is.

According to the best available modelling, low water levels will persist into the foreseeable future and this will mean significant environmental and economic costs for the region. Seasonal variations are natural and healthy. But when the starting point has moved to an all-time low, a one-time increase is not cause for celebration, especially when forecasts still leave the lakes well below average in Michigan-Huron.

We have to be careful about taking one aspect of the natural environment -- ice coverage -- and extrapolating it into a blanket solution for a complex, long-term problem like declining Great Lake water levels.


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