Kenton M. Stewart, professor of biological sciences, has been a UB faculty member since 1966. His research in limnology has involved lab and field investigation of lakes in the U.S.-including Lake Erie-as well as Europe and the Canadian High Arctic.

One of your research projects involves the study of freeze and thaw dates of lake ice as an indicator of global climate change. Can you elaborate?

Limnologists (lake scientists) and aquatic biologists generally have long been interested in the composition, abundance and seasonal activities of aquatic organisms. Of course, there is always an interplay of biotic (e.g., predator-prey) and abiotic (e.g., chemical and physical) influences on those organisms. However, because temperature alone can be a big influence on the biotic structure of lakes, knowledge of its variability within lakes is important. Periods of stratification and mixing in lakes are determined by the presence or absence of top-to-bottom differences in density and, for the vast majority of lakes, the water temperature is the main determinant of those differences. Lakes that develop an ice cover in winter can serve as proxy indicators of global climate change. The reasoning for this is that if the global temperature increases (as predicted), the thickness and duration of ice cover should decrease.

Based on your years of studying lake ice, is global climate change occurring? Is Buffalo really becoming the "Miami of the North" as we sometimes joke?

There is much year-to-year natural variability in the freeze and thaw dates. Thus, records for just a few years can be quite deceptive and might lead some to conclude that the world is going to burn up and others to think we are heading into an ice age (Read the delightful short poem by poet Robert Frost entitled "Fire and Ice"). Keep in mind that there are many spatial scales-from a few to millions of years-by which to judge climatic change. Anyway, based on the few longer records-100-150 years-I have seen for lakes here and abroad, the average break-up of lake ice in the spring is now occurring earlier. To conclude that Buffalo is becoming the "Miami of the North" is more than a little premature.

There's been a lot of talk the past several years about El Niņo and La Niņa years. Just what are they?

Both are major phenomena originating in the Pacific Ocean, but their influence is felt widely. Equatorial winds in the Pacific Ocean normally blow westerly. However, during El Niņo years (highly variable, but roughly every 3-7 years, for reasons not clearly understood) the winds oscillate backwards and blow easterly. Water much warmer than usual piles up in the eastern Pacific closer to Central and South America. This reversal is called the El Niņo Southern Oscillation (ENSO) and it may exert a global influence on interannual climatic variability. Some ENSO's are considerably stronger than others. For example, the winters of 1982-83 and 1997-98 were particularly mild-reflecting strong El Niņo years-and many frozen lakes in North America had a reduced ice cover during those winters. Lake LaSalle on the UB Campus also had less ice those winters. La Niņa years represent the more normal or "cold" phase, but there is considerably more variability in the jet stream and temperature/precipitation patterns during such years.

I hear we're entering another La Niņa year. How will that affect the Buffalo's weather? Are we likely to see a repeat of last year?

Although this past autumn and early part of the winter have been relatively mild, we are supposedly in a La Niņa phase now. It is important to remember that weather is highly variable. We don't have to have an equivalent of the Blizzard of 1977 to be in a La Niņa cooler winter. I can't predict whether this next year will be a repeat of last year. I can tell you from my measurements that during the last week of January in 1996, 1997, 1998, 1999 and 2000, the ice thickness on Lake LaSalle was approximately 18, 20, 11, 28 and 15 centimeters, respectively. Based on these local data, how far into the future would you care to predict?

How did you get interested in studying lake ice?

I started sampling lakes year-round as a graduate student and took hundreds of top-to-bottom thermal profiles of lakes in winter through holes in the ice. I became particularly intrigued with the rapid onset and loss of thermal and chemical stratification during periods of freeze-up and break-up. I wondered how those quick changes might affect the vertical distribution of fish and plankton. I also thought that long-term records of ice dates might provide excellent proxy information on climate change.

What's your favorite lake, with or without ice?

The late humorist/writer Will Rogers is supposed to have said, 'I never met a man I didn't like.' I would say, I never met a lake I didn't like. Each lake is unique, and so I have no favorite.

What question do you wish I had asked, and how would you have answered it?

Are there other influences on the interannual variability of weather in New York State weather besides that of El Niņo? Although little understood among biologists, the North Atlantic Oscillation (NAO) is a phenomenon in the Atlantic Ocean whose teleconnecting influence on the biota and lakes in our Northeast is probably underappreciated