Great Lakes Ice Cover Down 71% Since 1973

Figure 1. A tale of two winters: Lake Superior was choked with ice at the end of the winter of 2008 – 2009 (top), but was virtually ice-free at the end of the winter of 2011 – 2012 (bottom.) Image credit: NASA.

by Jeff Masters, reposted from the WunderBlog

Ice cover on North America’s Great Lakes–Superior, Michigan, Huron, Ontario, and Erie–has declined 71% since 1973, says a new study published in the Journal of Climate by researchers at NOAA’s Great Lakes Environmental Research Laboratory.

The biggest loser of ice during the 1973 – 2010 time period was Lake Ontario, which saw an 88% decline in ice cover. During the same time period, Superior lost 79% of its ice, Michigan lost 77%, Huron lost 62%, and Erie lost 50%. The loss of ice is due to warming of the lake waters. Winter air temperatures over the lower Great Lake increased by about 2.7°F (1.5°C) from 1973 – 2010, and by 4 – 5°F (2.3 – 2.7°C) over the northern Lakes, including Lake Superior. Lake Superior’s summer surface water temperature warmed 4.5°F (2.5°C) over the period 1979 – 2006 (Austin and Colman 2007).

During the same period, Lake Michigan warmed by about 3.3°F (1.7°C), Lake Huron by 4.3°F (2.4°C), and Lake Erie showed almost no warming. The amount of warming of the waters in Lakes Superior, Huron, and Michigan is higher than one might expect, because of a process called the ice-albedo feedback: when ice melts, it exposes darker water, which absorbs more sunlight, warming the water, forcing even more ice to melt. This sort of vicious cycle is also responsible for the recent extreme loss of Arctic sea ice. The increase in temperature of the lakes could be due to a combination of global warming and natural cycles, the researchers said. They noted a pronounced 4-year and 8-year oscillation in ice coverage, which could be caused by the El Ninño/La Niña and Arctic Oscillation (AO), respectively.

The consequences of Great Lakes ice loss

Ice coverage on the Great Lakes was just 5% this past winter, the second lowest on record, behind 2002. The lack of Great Lakes ice this winter probably added a few degrees of warmth to the unprecedented “Summer in March” conditions observed in Michigan last week–an event the National Weather Service in Detroit called “perhaps the most anomalous weather event in Michigan since climate records began 130 years ago.” We can anticipate that areas surrounding the Great Lakes will see an increased incidence of warm spring weather due to decreased ice cover on the lakes.

The loss of Great Lakes ice has allowed much more water to evaporate in winter, resulting in heavier lake effect snow near the shore, and lower lake levels. Lower water levels have had a significant impact on the Great Lakes economy. Over 200 million tons of cargo are shipped every year through the Great Lakes.  Since 1998, when water levels took a severe drop, commercial ships were forced to light-load their vessels. For every inch of clearance that these oceangoing vessels lost because of low water levels, $11,000 – $22,000 in profits were lost per day. Hydropower plants have also been affected by low water levels; several New York and Michigan plants were run at reduced capacity, forcing them to buy higher priced energy from other sources, and passing on the higher costs to consumers.

The large loss of ice is also likely to accelerate shoreline erosion because of the increase in open water, and promote more algal blooms. It is uncertain if the Great Lake water levels will continue to fall as the climate warms, since the region is expected to see an increase in precipitation over the coming decades. In Michigan, annual precipitation increased by about 14% between 1895 – 2011, according to the National Climatic Data Center.

Figure 2. Great Lakes ice coverage for the period December 4 – March 5, from the winter of 1980 – 1981 through 2011 – 2012. The winter of 2011 – 2012 had the second lowest ice coverage on record, just 5%. Only 2001 – 2002 (4.5%) had lower ice cover. The median ice coverage between 1980 – 2011 was about 19%. Image credit: Environment Canada.

Figure 3. Water levels on Lake Superior between 1860 and February 2012. Since the late 1990s, water levels have seen a steep decline, due to the loss of ice cover allowing more evaporation. Image credit: NOAA/GLERL.

Jeff Masters is co-founder of the Weather Underground. This piece was originally published at the WunderBlog and was reprinted with permission.

Austin, J. A., and S. Colman, 2007, “Lake Superior summer water temperatures are increasing more rapidly than regional air temperatures: A positive ice-albedo feedback,” Geophys. Res. Lett., 34, L06604, doi:10.1029/2006GL029021.

Wang, J., X. Bai, H. Hu, A.H. Clites, M.C. Colton, and B.M. Lofgren, 2012, “Temporal and spatial variability of Great Lakes ice cover, 1973-2010,” Journal of Climate 25(4):1318-1329 (DOI:10.1175/2011JCLI4066.1)

14 Responses to Great Lakes Ice Cover Down 71% Since 1973

  1. Joe Uehlein says:

    When I was boy in the mid-60’s living near Cleveland my uncle would always drive his pickup truck out on Lake Erie in the winter and build a small shanty for ice-fishing — and he was not alone — I recall one time when I went with him and there were quite a few trucks out there. I don’t think they do that any more?

  2. fj says:

    Gotta believe that for all the satellites and remote sensors NASA has facing earth and out into the universe national security and the military have even more facing earth directly (& include NASA’s info also); and, at some time very soon they’ll something like “Jig’s up: We have to move right now on climate change at wartime speed before it obliterates our nation.”

  3. wili says:

    Glad to see Masters further observations on this. When I saw those 5-sigma anomalies in Michigan, I had to wonder if they were in part related to the 70+% reduction in ice cover of the Great Lakes–Michigan being essentially a peninsula (or a couple of them) nearly surrounded by these bodies.

    I would love to hear further informed speculation about influence further afield that Michigan. People sometime refer to the Arctic as the airconditioner for the Northern Hemisphere. To what extent do the Great Lakes serve the same function for the adjacent areas of North America?

  4. Tim says:

    This is one the top blogs on the web. I especially love the fact that, unlike the mainstream media, I get actual data that I can analyze for myself in order to put the headlines and text in context. With that in mind, you really should change the headline: “Great Lakes Ice Cover Down 71% Since 1973”. No honest trendline on Figure 2 would justify that headline. If we’re going to criticize a sleazeball like Pat Michaels for cherry-picking the 1998 El Niño year as a starting point for lying and saying ‘there hasn’t been any warming in 13 years’, then let’s not select the Great Lakes ice cover for 2011-2012 and compare it to the median in Figure 2 and make a 71% reduction claim.

    [JR: You misread the piece. The study goes to 2010.]

  5. Colorado Bob says:

    Many northern Minnesota lakes ice-free in March for first time on record
    Northern Minnesota lakes continue to lose their ice at all-time record early dates — even big Ontario border lakes like Gunflint, Crane and Sand Point — all ice-free in March for the first time on record.

  6. Tim says:

    I see – Thanks. Since I’m outside my university’s firewall at the moment I’ll have to see later why Figure 2 obscures the results of the study.

  7. squidboy6 says:

    yeah, I have a hard time seeing any trends on the graph except for a rebound in coverage the next Winter, but the time period is short and a longer one, if available may show more.

    I think it is definitely part of the mild Winter the upper mid-West experienced. The jet stream used to drop down at the Great Lakes and hit the mid-South and East Coast but instead it went way over across the Atlantic and hit Europe instead.

    It seems to show that each Winter, the table of coverage, that coverage returns but if it doesn’t then it might be a very real change in Climate, which it seems to me.

    I dove the West Coast from Palos Verdes Peninsula to Point Conception for three decades and the changes I saw in species made me a believer. I wasn’t there last year during record low temps (for which I was glad) but that could be short term phenomenon. I watch the buoy data all the time and the temperature is pretty much the way it would be this time of year and not colder than usual. Ten degrees Celsius was about as cold as I could stand and still get any work done. A look at the CDIP Current and Historical data for the Santa Barbara Channel shows little change between this year and last and the way I remember it being but the buoy near Santa Monica Bay was one degree C cooler last year than this year, so there seems to be something to the assertion that it was cooler besides the record number of Blue Whales showing up to feed. The water there is cooler due to the wind pattern, one trend that was evident because of change in the winds/offshore climate was the much larger surf that appeared near Santa Barbara than anything I’d ever seen in three decades there. Orders of magnitude larger than anything…..

  8. Joan Savage says:

    Declining water level due to greater evaporation is a factor not only for shipping but also shoreline wildlife habitat (notably fish spawning) and loss of the recreational use along the shore. The intake pipes for the city water supplies and the nuclear power plant cooling extend out into deeper water so are not as immediately vulnerable as shore inhabitants.

    Another feature of this that is identified on the GLERL page is that this year’s low ice occurred during La Niña, historically the colder part of the lakes’ cycles.

  9. Lou Grinzo says:

    Speaking as the resident Lake Ontarian, I have to say that these results don’t surprise me in the least. My wife and I live about 5 miles from LO and we drive to the lake shore numerous times every year, especially in the winter. Even in the short time we’ve lived here, since early 2004, we’ve seen a very noticeable drop in ice. It was not at all unusual to see massive ice buildup right along the shoreline, with huge blocks piled up from wave action. The long pier that extends from Rochester out into LO (very easy to find on Google maps) was routinely covered in several feet of ice and impossible to walk on until the Spring thaw. No longer. The ice coverage along the shore has declined dramatically, with the just-completed “winter” being the most extreme example so far. There was barely any ice along the shore.

  10. James Cole says:

    This article is not news to me. I am a resident on the North Shore of Lake Superior. My family settled here in 1880, so the family tradition has a lot of experience with lake ice conditions. It is clear that when I was a boy in the 1960’s as compared to today, the degree of ice cover has shrunk drastically.
    Needless to say average water temperatures have skyrocketed in the past five decades.
    We typically have no ice formation at all now in the winter, ice formation is now a rare event. In my youth, heavy ice formation lasting well into May was typical. Living on the shore line, in the 60 -70s the cold water made a micro climate like the arctic along the shore, now there is no difference between shore line living and inland living.
    I firmly believe most of this is due to climate change, simply based on the long hot summers and the increasingly short and warmer winters. This has become so pronounced, that I know of no person from this area in my age bracket that does not believe our climate has been warming and that the the rate of warming has increased in the last decade.

  11. Sasparilla says:

    That’s a good question. I know here at the IL and WI border people do this on the larger lakes in the area – and did it last year (the lakes always freeze over plenty deep enough).

    This year was unusual however in that we just did not have a winter (this is prior to the summer of the early spring we’ve had) and the lakes did not freeze over. I believe this happened all the way up into MI as well (based on comments from folks living up there).

    This is probably a preview of what the normal will be 15 or 20 years down the road.

  12. Sasparilla says:

    I hadn’t thought about the long term evaporation angle effect on the lake levels over a long period of time.

    Rather a bummer long term – another darn thing (however small) stacking against what we need.

  13. Joan Savage says:

    A feature of the Great Lakes Compact (made by states and provinces bordering the Great Lakes) is confining use of GL water to within the Great Lakes watershed. I live in Syracuse, part of the Lake Ontario watershed. We draw our water primarily from a Finger Lake that is a feeder to Lake Ontario, with Lake Ontario itself and a second Finger Lake as back up. We’ve been aware for some years that water-hungry areas outside the watershed have eyed the Great Lakes as yet another water resource that could be bought for a price. The foolishness of such an idea is all the more obvious given the several factors brought out in the post and the commments.

  14. Here in Michigan’s Upper Peninsula, ice cover (and shore ice) on the big lakes were non-existent. Only sheltered harbors and bays like Little Bay de Noc had anywhere near the usual ice thicknesses.

    Inland lakes had ice, but the lack of snow cover on them meant that they all melted off during the big heat wave in early March.

    Enough ice cover, anyway, for the annual truck falling through the ice contest to be held.