Climate is long-term and weather is short-run, the professionals in those businesses keep reminding us. And this late, warm (for now) winter is largely due to the influence of El Niño, the warming phenomenon caused by unusually toasty ocean currents, many meteorologists say.

But Park Superintendent Jayne Miller sees a portent of climate change in the late ice-up of the Minneapolis park system's lakes this winter.

The last of them, Harriet and Calhoun (or Bde Maka Ska), finished icing over on Jan. 4, That's only the third time in the past 52 years of record-keeping that the freeze-up hasn't been complete until January.

What has Miller suggesting that a warming climate, rather than year to year weather variation, may be in play is that the last late icing came recently in 2011. That could be the coincidence of weather or it may support the view that the climate is warming. 

For the record, the icing over of the park system's lakes took more than a month, with small Birch Pond at Wirth Park reported frozen over on Nov. 30.

Miller's larger point was that the ice still isn't safe. She said ice depths are highly variable now, with a range from one to six inches. The Minnesota Department of Natural Resources recommends people wait until ice is four inches thick before walking onto it. A cold snap predicted to arrive this weekend may take care of that.

But even then, the city's prime skating venue at Lake of the Isles likely won't open until sometime into next week. Although it's on the faster-freezing shallow north arm of Isles, the rink depends on trucks to haul  pumps onto the lake ice to flood the surface with additional water.  The DNR recommends a thickness of eight to 12 inches for even small vehicles.

Skaters can get daily updates on the status of rinks on the Park Board's website. The park system typically tries to have rinks ready by the holiday break for schools, weather permitting

(Photo: Mike Walsh of St. Louis Park skated at Lake of the Isles last February. Credit: Jim Gehrz, Star Tribune)