For today's blog posting, I decided to check on the progress of Lake Superiors water level and temperature.
Like ice sheets melting in the Arctic, Lake Superior has begun showing some of the world's most tangible evidence of global climate change. Until the last decade or so, harsher winters and cooler average temperatures caused Lake Superior to substantially freeze over in winter. In recent decades, the amount of ice cover has drastically diminished.
Ice reflects sunlight back out into space, which prevents the sun from warming the lakes. Scientists at the Large Lakes Observatory at the University of Minnesota Duluth has documented a strong connection between declining ice cover and warmer lake temperatures. A recent study in the Journal of Climate reports a nearly 80-percent loss of ice on the big lake in the last 40 years. This loss of ice cover leads to warmer water temperatures as well as in increase in evaporation. If you take away the ice, you allow the lake to warm up earlier.Less ice exposes the surface of Superior, the world's largest lake, to more evaporation. Surface water temperatures in Lake Superior have risen by 4.5 degrees Fahrenheit since 1979 – much more than average air temperatures in this region. During that time, wind speeds in the middle of the giant lake also have risen steadily -- around 30 percent.
In many ways, you in the Lake Superior basin are the canary in the mine,Lake Superior is really one of the early victims of climate change. These changes are now impacting the fauna and flora, shipping costs (freighters cannot carry full loads due to the low lake levels), water intake systems in towns and cities around the lake, and more.
Thankfully, there has been some recovery this year. The 2013 spring season was wet and cool across the Great Lakes region -- including Lake Superior. Despite average or above average snow fall last winter, above average spring precipitation, and subsequent water level rise, water levels in Lake Superior, Michigan, and Huron remain below average. Lake Michigan and Huron water levels rose by 24 cm (9.5 inches) in April and another 13 cm (5 inches) in May. Despite this water level rise, Lakes Michigan and Huron remain the lowest of the lakes relative to their long-term averages at 50 cm (20 inches) below normal. Lake Superior had the second largest May rise on record of 24 cm (8.5 inches), but at the end of May, Lake Superior still remained about 18 cm (7 inches) below its long-term average. Water levels in Lakes Erie and Ontario remain at or near their long-term average.
The Great Lakes U.S. basin received 267.5 mm (10.53inches) of precipitation, 124 percent of normal, making it the 9th wettest spring on record. Twenty of the 25 climate divisions were wetter than normal with 11 ranking spring 2013 among their top 10 wettest. In fact, with 169 percent of normal precipitation, central lower Michigan reported its wettest spring on record. The Canadian side of the Great Lakes received above normal precipitation as well. The north side averaged 250-300 mm (9.8 - 11.8 inches), which is 115-150 percent of normal.
Cooler spring temperatures caused ice-out on lakes to occur several weeks later than normal, coming just one year after ice-outs that were among the earliest on record in 2012.
Hopefully, the policy makers are looking at these numbers. Some scientists say that it is not too late. If we make changes now, we can slow down and maybe even reverse some of these climatic changes in the Great Lakes region.