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Ice coverage on the Great Lakes is near record low levels for this time of year, and this is causing concern for wildlife species that depend on winter weather to survive.
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Scientific concern begins over lack of Great Lakes' ice

Scott Sutherland
Meteorologist/Science Writer

Thursday, February 4, 2016, 2:56 PM - Ice coverage on the Great Lakes is near record-low levels for this time of year, and scientists are concerned about the effect this will have on wildlife species in the months to come.

Southern Ontario set some record high temperatures on Wednesday, February 3, 2016. For example, the afternoon high of 16oC at Toronto's Pearson International Airport managed to beat out all other records for the day in the city going back to 1842. It was also the highest daily temperature ever recorded for Toronto in the month of February going back 174 years.

While typical February chills were interrupted by this unusually balmy day, the Great Lakes were still feeling the effects of an already unusually warm winter, with some of the lowest ice coverage numbers on record.

Back on January 11, coverage was logged at just 3.8 per cent - remarkably low, given what the previous two years were like by that time of the year, and largely a consequence of a warm December thanks a combination of climate change and the strong El Niño pattern in the Pacific Ocean.

Since then, although there were a few days in the latter half of January where coverage actually got up into the double-digits, as of February 3, only 5.7 per cent of the lakes were covered with ice.




By comparison, in 2015, ice coverage was at 50.5 per cent, while in 2014 - the year with the second highest coverage on record since 1973 - it was 71.6 per cent.

The unusually large expanse of open lake water so far this winter has been providing fuel for some pretty intense snow squalls. Looking at the current forecast for the rest of February, with a cold snap is expected going into Week 2, and then a return to mild weather later in the month, it's likely that will continue, even with a slight rebound in ice coverage that should come during that cold snap.

The overall outlook, however, doesn't give any indication that ice coverage on the Great Lakes will get anywhere near where it was during the past two years. Based on what we've seen so far, there was a brief surge up to about 15.8 per cent ice coverage on January 22, and we may see the same or slightly higher in the second week of February. If the weather does turn mild again afterward, though, there's a chance those two brief peaks will likely be it for ice coverage this year, which could land 2016 in the lowest five years on record, along with 1983 (18.1 per cent), 1998 (11.5 per cent), 2002 (9.5 per cent) and 2012 (12.9 per cent).

The Great Lakes from space

Credit: NASA Worldview

The above image presents a composite look at the Great Lakes, from January 30 to February 1. Since the open lake water promote cloud formation, the different sections of the image were chosen from a range of dates to show as little cloud coverage as possible, to reveal the largely ice-free water. By comparison, normally at this time of year, at least 30 per cent of Lake Superior, 25 per cent of Lake Michigan, around 50 per cent of Lakes Huron and Erie and roughly 15 per cent of Lake Ontario are covered with ice.

Wildlife impact

Intense squalls off the lakes qualify as potentially dangerous weather, and are known for causing traffic nightmares at the very least. For some scientists, however, the conditions on the lakes and in the rivers feeding them are a particular worry for what's to come in spring and summer this year.

As Elizabeth Hendricks, the director of the World Wildlife Fund's Freshwater Program, recently wrote:

"Winter is usually a time when less water is moving through rivers in Southern Ontario - also known as the low flow period - since precipitation accumulates as snow. In warm winters precipitation falls as rain or wet snow that melts quickly, increases river flow, which in turn can lead to river bank erosion and increased pollution. All of this impacts species such as minnows and hibernating turtles that are not accustomed to high flows in winter. Ice-free winters can also effect the reproductive success of important fish species such as Lake Trout and Lake Whitefish.
"Even more importantly, without an accumulation of snow and ice to melt in the spring, rivers may heat up faster than normal and throw the delicate food web out of balance. Some fish species time their spawning to water temperatures to allow their young to hatch and be ready for increases in plankton, a major food source for juvenile fish. In normal, colder Canadian winters, ice forms along shorelines and protects fish eggs spawned in the fall from the strong wind and waves of early winter.
"If these important events - low flow and then melting snow - don’t happen, an entire year’s worth of fish could be impacted."

With less ice coating the lakes now, and thus generally higher lake water temperatures, this also sets up the potential for more algae growth in the lake system.

Year to year, the expansive algal blooms that are seen in Lake Erie appear to have more to do with summer weather conditions (sunny days, with calm winds) than winter ice coverage on the lakes. For example, while the second largest bloom on record, in 2011, took place in a year with below average winter ice coverage, the 2015 bloom - the new largest on record - happened after ice coverage reached its fifth largest extent on record.

However, in general, whether it is a small, localized bloom that closes a beach, or one that grows to cover an entire lake, blue-green algae thrive in warm, still waters, with abundant sunshine and nutrients. Last year supplied these conditions for Lake Erie's record-setting algal bloom even with the extensive ice coverage on the lakes earlier in the year.

Due to climate change and El Niño, 2016 is already expected to be an even warmer year than 2015, overall. This doesn't necessarily mean we'll see the same weather patterns this summer as last year, but starting the lakes off warmer than they were in 2015 could result in more localized blooms, and an even larger Lake Erie bloom than the last one.

Sources: NOAA GLERL | WWF | The Weather Network

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