If we could avoid coating Lake Erie in a permanent layer of toxic algae, that would be great

So I wanted to discuss this issue in my post on lake levels in the Great Lakes, but length became a factor. Fortunately, two recent articles touched on the topic, so it gave me an opportunity to circle back to it.

First, two officials from the Cuyahoga Water and Soil Conservation District published an op-ed in The Plain Dealer on Sunday that discussed the disturbing rise in algal blooms on Lake Erie during recent years. As the author’s noted, Lake Erie and other inland lakes in Northern Ohio, including Grand Lake St. Mary’s, have become enveloped in large blue-green algal blooms. The issue became particularly acute in 2011 and 2012, largely due to extremely high temperatures during the latter and heavy precipitation in the former.

A satellite photo showing Lake Erie taken by NOAA on June 14. If you look at the bottom left portion of the image (Northwest Ohio), you can clearly see blue-green algal blooms growing already on the lake surface (courtesy of NOAA Great Lakes Environmental Research Laboratory).

A satellite photo showing Lake Erie taken by NOAA on June 14. If you look at the bottom left portion of the image (Northwest Ohio), you can clearly see blue-green algal blooms growing already on the lake surface (courtesy of NOAA Great Lakes Environmental Research Laboratory).

The most obvious cause for these algal blooms is the excessive application of chemical fertilizers on farms and, to a lesser extent, residential lawns in Northern Ohio. Farmers in Northwest Ohio, in particular, have switched to no-till practices in order to reduce soil erosion. Unfortunately, no-till farming typically requires even larger chemical inputs, as the soil is not turned over. No-till soil is also more susceptible to chemical runoff during precipitation events. It appears likely that commercial agriculture is the main culprit, as the Great Lakes are phosphorus-constrained environments, and agricultural fertilizers are rich in chemical phosphates. The algal blooms that have resulted threaten a $10 billion tourism industry in the region, pose a threat to public health, harm commercial fishing, and increase the costs of water treatment.

In related news, Scientific American published a piece today on a recent study examining the effects of climate change and rising water temperatures on nine large lakes in Austria. These lakes are vital for tourism, industry, and the ecology of the region. The region has warmed at a rate 3.5 times higher than the global average since 1980, and the study argues that surface water temperature (SWT) in these lakes will rise by at least 2°C through 2050. This rise in poses a major challenge to the ecology of the lakes. From the SciAm piece:

“The predicted changes in surface water temperatures will affect the thermal characteristics of the lakes,” said Dokulil. “Warmer water temperatures could lead to enhanced nutrient loads and affect water quality by promoting algal blooms and impairing the biological functions of aquatic organisms.

Interestingly (though, perhaps, not surprisingly), the CWSCD officials largely sidestepped the role of climate change in the algal blooms on Lake Erie. That said, the Austrian study makes it clear that, while it may not be the predominant issue to worry about at the moment (and it’s not one that local conservation officials can actively address), climate change does compound the anthropogenic impacts and will only get worse in the future.

Research suggests that SWT have increased at a significantly faster rate that air temperatures in the Great Lakes region. According to a 2007 study (PDF) from Jay A. Austin & Stephen M. Colman in Geophysical Research Letters, SWT on Lake Superior rose by 2.5°C from 1979-2006, a rate that was “significantly in excess of regional atmospheric warming.” The authors argue that this outcome largely stems from an increased albedo effect due to declining lake ice cover during this period. To make matters worse, they conclude by noting that, at the current rate of decline, Lake Superior will be completely ice free during the winter within the next three decades.

The number of days with extreme precipitation has increased through the country in recent years. The Midwest saw a substantial rise of 27% during this period (courtesy of the U.S. Global Change Research Program).

The number extreme precipitation days has increased through the country in recent years. The Midwest saw a 27% increase from 1958-2007 (courtesy of the U.S. Global Change Research Program).

This study accords with other research on these issues within the Great Lakes region. According to an excellent 2003 review (PDF) from the Union of Concerned Scientists, Confronting Climate Change in the Great Lakes Region, ice cover will continue to decrease dramatically on Lakes Erie and Superior in the coming decades. By 2030, up to 61% of winters could be ice free on Lake Erie; by 2090, this number could reach a staggering 96%.

Moreover, while there hasn’t been a large amount of research done in the past few years, a handful of studies from the 1990s and early 2000s suggest that SWTs in the Great Lakes may jump by another 1-7°C. Combine these higher SWTs with more extreme precipitation events, and we have a recipe for even more massive algal outbreaks.

We already know that extreme precipitation has increased by roughly 20% in the Central US over the last century. This trend is projected to continue into the future, particularly during the winter and spring months; runoff produced during these seasons largely controls the extent of algal growth during the summer months.

Considerable evidence exists to suggest that Cleveland will be well positioned to withstand the most severe effects of climate change, and the city may even see an influx of migrants from other, harder hit areas of the country. However, as I have argued ad nauseum, the city needs to be proactive to ensure that it will be prepared for the challenges that await it. The draft Climate Action Plan is a start, but it needs to put more focus on adapting to climate changes, lest we squander our best natural asset – Lake Erie.

Algae blooming on Lake Erie during the massive bloom that developed in 2011 (courtesy of The Plain Dealer).

Algae blooming on Lake Erie during the massive bloom that developed in 2011 (courtesy of The Plain Dealer).

Dropping cause it’s hot: On climate change & Great Lakes levels

Falling Great Lakes levels have garnered a considerable amount of media coverage in the past few days. First, the New York Times featured a full-length piece on the issue on Monday, and The Plain Dealer followed up yesterday with a piece focused primarily on Lake Erie.

As the Times piece notes, the average monthly mean for the five lakes during this past winter reached its lowest level since officials began taking measurements in 1918. For Lake Erie, 2012 was the first year on record that water levels fell during every month.  According to the 2009 National Climate Assessment, the maximum ice coverage in the Great Lakes decreased by roughly 30% from 1973-2008. The prolonged winter and extremely wet spring this year is beginning to counter the effects of last year’s record drought, but these changes are clearly part of a long-term trend, which one season or  one year worth of precipitation cannot change.

Current lake levels, compared to long-term averages, for (left to right) Lakes Michigan & Huron, Lake Erie, and Lake Superior (courtesy of NOAA GLERL).

Current lake levels, compared to long-term averages, for (left to right) Lakes Michigan & Huron, Lake Erie, and Lake Superior (courtesy of NOAA Great Lakes Environmental Research Laboratory).

Both pieces noted the causes and likely effects of these changes for the Great Lakes region. By and large, however, they focused on the role of dredging. From the Times piece:

A measure of the drop in water levels can also be attributed to the engineering that makes Great Lakes shipping possible. The 1962 dredging of the St. Clair River may have lowered the water in Lake Huron and Lake Michigan by five inches, said John Nevin…Other dredging projects may have emptied 16 inches in all from the lakes, Mr. Nevin said.

In the comments section on his piece, Robert Smith, the PD reporter who covered the story, explicitly noted that he was focusing on dredging. Clearly dredging matters, and it will continue to into the future. It is a complicated issue, however, as it costs a considerable amount of money and is controlled by action from the Army Corps of Engineers and the US Congress, who appear to be engaged in a fight over who bears the burden for the issue.

The effects of the drop in lake levels will continue to take a significant toll on the Great Lakes. According to the US Department of Transportation (PDF), every 1″ drop in lake levels reduces the cargo capacity of a 1,000-foot bulk carrier by 270 tons. Given that the Great Lakes maritime trade industry is worth $34 billion annually, any long-term reductions in lake level will significantly hamper the regional economy.

Unfortunately, that’s precisely what climate models project. While neither piece directly addressed the issue (though the Times article does mention it in passing), climate change is likely to add to any natural and direct anthropogenic impacts on lake levels. As the Union of Concerned Scientists has noted (PDF), higher air temperatures contribute to the reduction of lake levels in two main ways. First, they will continue to reduce the extent of lake ice cover during the winter months, which provides a crucial buffer against surface evaporation on the open water. Secondly, higher surface temperatures themselves lead to greater rates of surface evaporation.

Projected changes in lake levels on the Great Lakes according to the Canadian global climate model (courtesy of the Second National Climate Assessment).

Projected changes in lake levels on the Great Lakes according to the Canadian global climate model (courtesy of the Second National Climate Assessment).

According to the First National Climate Assessment, mean annual temperatures in the Midwest are expected to increase by 3-6°C (5-10°F) by the end of the century. These changes will lead to wholesale climatic shifts in the region. According to the World Bank (PDF), in a 4°C warmer world (which, as I’ve noted, is becoming increasingly likely), the coolest months in the Central US by 2070 will be significantly warmer than the warmest months today. Even as early as 2030, summers in Illinois are projected to resemble current summers in Oklahoma.

As such, the effects of rising temperatures will likely outweigh projected increases in regional precipitation, contributing to the long-term decline of lake levels. The First National Climate Assessment projected a 5-6 foot drop in lake levels for all five of the lakes, while the Second Assessment (2009) revised these down to 1-2 feet, depending on the climate model used. Regardless of the projection, these declining lake levels will significantly increase the cost of shipping (PDF) on the Great Lakes by as much as 30%.

While we should be careful to neither attribute all ecological changes to climate change nor to blame direct anthropogenic environmental changes on the effects of climate change, it’s not wise to treat them as completely distinct phenomena. Climate change is currently adjusting the baseline for all weather-related phenomena; we have already forced global atmospheric concentrations of CO2 to their highest levels in human history and increased global average temperatures by roughly 0.8-1°C. Anthropogenic environmental changes and climate change will interact with one another and almost certainly create multiplicative effects over the next several decades. We need to recognize as such.