Friday, January 29, 2016
How Great Are Those Lakes Anyway?
Concentrated bodies of water tend to see temperature rises that are significantly more rapid than experienced by the oceans and seas. Shallower surfaces, including lakes and streams, absorb and retain solar-generated heat faster than deeper bodies, a fairly intuitive observation. Some of the results we see happening in oceans are actually happening faster in these smaller bodies of water… even in larger water formations such as the Great Lakes.
Here are some of the symptoms where global climate change has impacted this fresh water sources of water: “Streams and lakes may become unsuitable for cold-water fish but support species that thrive in warmer waters. Some warm-water species are already moving to waters at higher latitudes and altitudes…In a warming climate, a warmer upper layer in deep lakes slows down air exchange—a process that normally adds oxygen to the water. This, in turn, often creates large ‘dead zones’—areas depleted of oxygen and unable to support life. Persistent dead zones can produce toxic algal blooms, foul-smelling drinking water, and massive fish kills…
“Earlier snowmelt, rising amounts of precipitation that falls as rain rather than snow, and more severe and frequent flooding—all linked to global warming—may affect the reproduction of aquatic species. Some salmon populations have declined, for example, as more intense spring floods have washed away salmon eggs laid in stream beds…
“When stream flow peaks earlier in the spring owing to warmer temperatures, low stream flow begins earlier in the summer and lasts longer in the fall. These changes stress aquatic plants and animals that have adapted to specific low-flow conditions. The survival rates of fish such as salmon and trout are known to diminish when water levels in rivers and streams are dangerously low, for example. That's partly because bears can snag spawning salmon more easily in very shallow water, as the salmon struggle upstream.
“The more intense precipitation that accompanies a warming world makes river flooding more likely. This flooding—combined with sewer system overflows and other problems stemming from inadequate sanitation infrastructure—can lead to disease outbreaks from water-borne bacteria.” ClimateHotMap.org. These changes are quite evident in our own Great Lakes.
But despite the inconvenience of flooding and the devastating impact on any number of critters and plant life that make (made?) the Great Lakes their home, there is an off-setting benefit according to others: “National Oceanic and Atmospheric Administration () show a beneficial increase in precipitation and soil moisture and a remarkable lack of drought during recent decades in the Great Lakes region and the Upper Midwest. During the first half of the twentieth century, when carbon dioxide emissions were minimal and global temperatures were cooler, precipitation was much less frequent and drought frequently afflicted the Upper Midwest. In contrast, NOAA records show, precipitation has been much more prevalent and drought conditions virtually nonexistent in the Upper Midwest during the past 50 years as the Earth continues its modest and beneficial recovery from the cold temperatures of the Little Ice Age.” Forbes.com, November 26, 2014.
Indeed, Russia, Canada, Greenland, Alaska and other northernmost regions may actually get richer over global warming. These lands have seen an opening in the Northwest Passage, deicing of vast plains making access to minerals, oil and gas easier and defrosting of tundra now (or soon) fit for farming. As ice that once contained frozen and trapped methane (over 23 times heavier than carbon dioxide) and reflected sunlight back off the earth’s surface, now melts and provides darker land and water that absorbs heat and that sunlight, releasing gobs of methane into the atmosphere, global warming accelerates. Good for these nations in part. Bad for just about everyone else.
We’ve learned a lot recently about our own Great Lakes, and since these are the most important bodies of fresh water in the United States, they merit special attention in these days of excessive flooding in parts of our nation and unending drought in others. “University of Minnesota Duluth Professor Jay Austin says the thick sheets of ice that blanketed Lake Superior for the past two winters did nothing to change the fact that Superior, like the other Great Lakes, is growing ever warmer.
“‘Lake Superior is one of the more rapidly warming lakes’ among the 235 lakes in the [recently released NASA-driven] study, Austin said. A two-degree temperature shift can mean the difference between an iced-over Superior or an ice-free lake, he said. ‘Relatively small changes can lead to large changes in systems that define our region. Duluth would be a fundamentally different place if Lake Superior never formed ice.’
“The study, which was funded by NASA and the National Science Foundation, found that lakes have been warming by more than half a degree per decade. That might not sound like much, but when lakes warm up, toxic clouds of algae can bloom, fish habitats can be disrupted and invasive species currently held at bay by Superior’s inhospitable cold might be able to make themselves at home…
“The world’s lakes are warming faster than the oceans or the atmosphere, Austin said. Unlike air temperatures, which can fluctuate wildly from day to day or even hourly, lake temperatures are stable, making them ideal systems for measuring climate change. It takes a significant shift to change the temperature of a lake — much as it takes as much energy to heat a pot of water on the stove as it does to heat an entire room.” Minneapolis Star Tribune, December 17th.
This NASA study of 235 lakes (more than half the world’s fresh water supply) produces some additional observations that impact us all: “Algal blooms, which can ultimately rob water of oxygen, are projected to increase 20 percent in lakes over the next century as warming rates increase. Algal blooms that are toxic to fish and animals would increase by 5 percent. If these rates continue, emissions of methane, a greenhouse gas 25 times more powerful than carbon dioxide on 100-year time scales, will increase 4 percent over the next decade.
“‘Society depends on surface water for the vast majority of human uses,’ said [NASA report] co-author Stephanie Hampton, director of Washington State University's Center for Environmental Research, Education and Outreach in Pullman. ‘Not just for drinking water, but manufacturing, for energy production, for irrigation of our crops. Protein from freshwater fish is especially important in the developing world.’
“The temperature of water influences a host of its other properties critical to the health and viability of ecosystems. When temperature swings quickly and widely from the norm, life forms in a lake can change dramatically and even disappear.” ScienceDaily.com, December 16th, which also presented the above graphic.
Bottom line: The world is going to face astounding changes at rates that we currently are unable to calculate with any certainty, all due to measurable climate change. The data we have generated speaks to some alterations we are unable to stop. We do not even know if we have passed the tipping-point-of-no-return on some of the biggest issues. Whole sections of the United States, coastal regions that face inevitable surges and flooding, have no real plans on what to do either to stem the tide or live with the geographical changes that threaten serious damage, including, for example, flooding the bottom 30% of the entire state of Florida. The only true thing is that we are not remotely doing enough, climate change deniers are a big part of the problem, and nature does not care if human beings become complete extinct. She’s been there before.
I’m Peter Dekom, and Nature is neither a voter nor a politician running for office, but she is quite prepared to deal with profligate humanity in the harshest terms imaginable.