It looks like low water levels on the Great Lakes will be added to the record-breaking climate-related events of 2012.
The water level on Lakes Michigan and Huron dropped another 2.5 inches (6 cm) in December, unofficially breaking a nearly 50-year-old record for the month. Last month’s average for both lakes – considered one lake for the purposes of hydrologic studies because of the connection at the Straits of Mackinac – was 576.15 feet, according to the U.S. Army Corps of Engineers (USACE) water level report. This is about a half-inch below the record for the same month set in 1964 since the USACE began keeping coordinated records in 1918.
Lake Superior continues to hover about six inches (16 cm) above record low water levels set in 1925. USACE forecasts for all of the Great Lakes predict that water levels will remain below the long-term average for the next few months.
As explained in a previous post about how climate change and variability affect low water levels on the Great Lakes, evaporation normally exceeds precipitation and runoff at this time of year. Human-induced climate change is likely making a bad situation worse by affecting factors that control water supply to the Great Lakes, including a severe drought in 2012, warming water temperatures, increased evaporation rates, loss of ice cover, and changing precipitation patterns.