Lakes Have Not Developed Ice Covers This Winter

BUFFALO, N.Y. -- The freeze dates for many small- and intermediate-sized lakes in the Northeast and parts of the Midwest will come later than usual this year, in part as a reflection of continuing global warming, but also because of a stronger-than-expected El Nino phenomenon, says a University at Buffalo limnologist, a scientist who studies inland bodies of water.

Kenton Stewart, Ph.D., UB professor emeritus of biological sciences, maintains what may be the largest scientific inventory of lake-ice dates in North America from hundreds of lakes in several states.

"The initial predictions for this fall and early winter were for a relatively mild El Nino," says Stewart, "but it's looking like a very strong El Nino year, similar to the winter of 1997-98."

Stewart explains that the El Nino phenomenon is unusual warming in the equatorial waters of the Pacific Ocean, occurring roughly every three to seven years.

Some of that extra heat in the ocean waters may get transferred through the atmosphere to regions in the U.S.

"The influence of a mild El Nino is difficult to distinguish from the normal year-to-year variability in a given winter," says Stewart. "However, strong El Ninos -- such as the one that moderated the winter of 1997-98 -- may have a significant influence on many regions of the U.S."

Stewart notes that there was actually a colder-than-normal period in early December, causing many lakes in Minnesota and Wisconsin to develop ice covers.

Some of those lakes are still frozen but, he says, others have since lost all or part of their ice as a result of the unusually warm temperatures later in December and the relatively mild start to 2007.

"One of the consequences of this unexpectedly mild winter -- so far -- is that hundreds of other Midwestern and Northeastern lakes have yet to develop full ice covers," Stewart says.

In a recent interview with the Adirondack Daily Enterprise newspaper at Lake Placid, Stewart confirmed that Mirror Lake, one of the lakes he studies in the Adirondack region, froze on Dec. 28, the latest freeze date ever recorded for that lake.

As for whether Lake Erie will freeze this year, that's still questionable.

"The chances for Lake Erie freezing this winter are 'iiffy' at this stage," he says.

Stewart also gathers freeze-thaw information on the two small, shallow bodies of water known as Lake LaSalle on UB's North (Amherst) Campus.

"These lakes have frozen every year for the past two and half decades that I have been studying them," he says. "As of today, there is only a tiny bit of ice in the north basin of Lake LaSalle west, but I suspect they will freeze sometime this winter.

"General overall temperatures are rising and so there may come a time when these little lakes do not freeze at all," he said.

Stewart gathers freeze-thaw dates from contacting hundreds of lakeside observers in a loyal ad hoc network multiple times during each winter. He is able to evaluate the general trustworthiness of the lake-ice dates he gets by comparing them with what he knows about the depth and surface area of a lake, data from other observers in the area and the extent of detail provided by the observer.