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.
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.
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.