Great Lake Water Levels
Water levels in the Great Lakes have been the subject of scare stories about global warming for years.
Not too long ago, the National Geographic Magazine used Great Lake water levels to highlight global warming.
Fortunately, the National Oceanic and Atmospheric Administration (NOAA) maintain water level records for the Great Lakes. As they point out, “Great Lakes water levels constitute one of the longest high quality hydrometeorological data sets in North America with reference gauge records beginning about 1860 with sporadic records back to the early 1800s. These levels are collected and archived by NOAA’s National Ocean Service.”
NOAA has replaced the static charts on the NOAA web site with new interactive charts, allowing anyone to research water levels on each of the lakes back to 1860.
Go to http://www.glerl.noaa.gov/data/now/wlevels/dbd for these charts. The interactive charts are a resource that high school students and others should use.
The recent drought has affected the water levels in lakes Michigan, Huron and Superior. As noted in the Wall Street Journal, some of the effect on lakes Michigan and Huron may be due to dredging to deepen the channel between Lakes Huron and Erie. The dredging may have lowered the water levels in these lakes by as much as 16 inches.
Reviewing the NOAA charts show that water levels in all the Great Lakes have varied over the past century.
Lake Superior, for example, had its lowest water level in 1926, with current levels approaching the 1926 level.
Lakes Michigan-Huron had their lowest water levels in 1964.
Lake Erie had its lowest water levels between 1934 and 1936.
Lake Ontario had its lowest water level in 1965.
When all the lakes are viewed together, it’s clear that levels have risen and fallen for various reasons since 1860.
The current drought has had an effect, but there is no reason to believe that this isn’t anything other than part of a continuing process. Water levels in Lakes Erie and Ontario, for example, are at their long-term average.
Whether the water levels from dredging between Lakes Huron and Erie can be restored by narrowing the channel still needs to be determined.
It’s also true that lower water levels reduce the amount of material that ships can carry, which has an economic impact.
With water levels reaching their lowest point in differing years during the 1900s, e.g. 1926, 1934 and 1965, before the threat of global warming, it’s clear that global warming is not the cause of water level rise or fall in the Great Lakes.
Whenever a newspaper or magazine, such as the Wall Street Journal or National Geographic, publish an article about water levels in the Great Lakes, go to the NOAA website to see whether the article is factually correct. Open the interactive chart so that all the years between 1860 and 2011 can be seen.
For interactive NOAA charts go to http://www.glerl.noaa.gov/data/now/wlevels/dbd
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