On Ground Hog Day, 1996, a weather observer in Tower, Minn., tallied a new statewide record low temperature: minus 60 degrees Fahrenheit. At our house, about 35 miles west, it was minus 50.

Respectable, certainly, but I was unsatisfied.

Just before sunrise, an event seeming merely ceremonial under the circumstances, I hiked down to a neighboring bog clutching a thermometer. Inhaling the brittle air was uncomfortable, but I happily watched as the mercury dropped to minus 65, then separated into chunks as it crawled toward minus 70. Nothing official, of course, but good enough to establish that Jack London fibbed in one of his Yukon-based stories. He'd written that at minus 50, spittle would freeze before it hit the ground. Tried it. Not so.

Still, there was primitive delight in being outside in such an extreme. Little did I realize it was one of the last true cold snaps I'd experience in northern Minnesota.

Years ago, I worked on a wildland fire crew in Idaho with a tough old grunt nearing 60. He relished spinning yarns to rapt greenhorns about "the old days," gently mocking them with his signature narrative opening, "Once upon a time, when the trees were taller, the mountains were steeper and the winds were swifter ..."

What follows here is not the flawed nostalgia of an old-timer recalling the glories (or terrors) of legendary winters. I keep records; I have the numbers.

Beginning with the winter of 1997-98, a clear warming trend established itself, and continues until now. For example, during the winter I ventured down to the bog to spit, I recorded 74 days when the temperature dipped to zero or below. In 1997-98, there were a mere 23 such days, and the coldest morning was minus 25. Over the years we'd seen afternoons when such a relatively anemic nock was the high.

My data show that from the late 1970s into the late 1990s, a minus 30 reading at our house was routine. But beginning this century, we passed five winters without hitting minus 30, and six without savoring a minus 40, a reading that was always rarer, but not uncommon. That is startling.

Our firewood consumption is reduced by 25 percent. Our northern winters, fabled for their frigidity, once supplied grist for feature news stories. In 1996, I was interviewed by a BBC reporter from London intrigued by our crazy, gee-whiz cold -- the sun-split storm windows and Styrofoam outhouse seats, etc. That's a dated story line. Our winters have become relatively tepid, or as a neighbor put it, "luke-cold."

As a result, they're also shorter. I used to count on four and a half to five months of cross-country skiing that typically began before Thanksgiving and ran to April Fool's Day. For the past decade, three and a half months is the norm, and for snowmobiles, requiring more liberally cushioned trails, the season's even shorter. There is negative impact on tourism when snow that used to accumulate in November now arrives as rain, with the same reversal in mid-March.

Consider, however, a ramification of less snowy winters less obvious but perhaps more telling, and which certainly has impact on those directly involved -- frozen septic system drainfields. For the uninitiated to appreciate this misfortune requires a short primer on rural sewage disposal.

Down the drain

When we flush our toilet, drain a sink or take a shower, the effluent flows to a tank buried outside. The capacity of the tank is usually about 1,000 gallons, and to place that figure in perspective, an American family of four can easily generate 150 gallons of effluent per day. The purpose of the tank is to allow solids to settle out on the bottom as sludge, or float to the surface as scum. Effluent, ideally completely liquid (a baffle prevents scum from exiting), flows from the tank to a drainfield, usually consisting of perforated pipe bedded in gravel.

So far, so good, but here's the key concept relating to snow cover: The drainfield is not deeply buried -- because the effluent must be actively utilized, and therefore effectively treated, by soil bacteria, which mostly thrive near the surface. If the pipes are too deep, the system won't work. But since they are shallow, if there is insufficient snow cover -- less than six to eight inches in my experience -- the drainfield or the pipe that feeds it can freeze, even during our now more benign winters.

The first time this happened at our house was on January 4, 1990, after 12 winters of trouble-free septic bliss. The date is memorable because I used five-gallon buckets to portage about 70 gallons of backed-up raw sewage out of the basement. December 1989 -- still in the "old days" -- had been frigid, with 22 days of subzero temps, including several days when it did not rise above zero, and the month was also nearly snow-free. Such was an anomaly then.

Our drainfield didn't freeze again until 2002, but it's happened five times the past decade -- definitely a noteworthy trend. In February 2007, 80 percent of the septic systems in Itasca County -- including ours -- were locked up.

For most people, their first (and final) clue that this has occurred is when sewage re-enters the house. At that sad juncture, the septic tank must be pumped before it also freezes. In our neck of the woods, a septic hauler charges $185 for the service.

After that, the sewage is out of the house, but you no longer own a system, merely a 1,000-gallon holding tank that four Americans can refill in less than a week. Your options, reflecting general attitudes towards climate change, are:

A) Denial: Continue normal behavior and hope the pipes somehow thaw before your tank refills, or that the tank will magically expand;

B )Pay the piper: Plan on regular pumping for two to three months, until the frost leaves the ground; this could easily cost $1,000; or

C) Extreme conservation (my tactic). Take measures to ensure the modest tank capacity will last the rest of the winter by flushing the toilet only when absolutely necessary (determined by personal olfactory tolerance); by placing plastic tubs in the kitchen sink for dishwashing, then hand-carrying this gray-water out to the garden; by trimming bathing frequency to a minimum public health level, and by stockpiling dirty clothes for a monthly laundromat mission to town.

After the 1990 episode, I fashioned a septic-tank dipstick to monitor the progress of conservation, and more importantly to serve as early warning of freezing if I suspect we are headed for a problem (which I believe we are as I write). We're into that pattern again this season -- early winter rain and mild mornings, but cold enough for a few days (minus 16 for a seasonal low so far) to cause trouble. With only six inches of decomposing snow cover, I deploy the dipstick regularly. I pop the cap off a 3-inch access pipe, insert my stick to the bottom of the tank and measure the "freeboard." I can tell immediately when effluent has stopped flowing and it's time to call the pumper, before sewage backs into the basement.

Overflowing irony

This semiregular drainfield problem is new. You may speak to many old-timers who've been operating septic systems their entire lives who had never heard of such an affliction until the past dozen years. A desperate and dubious technological solution has, of course, appeared: electric septic-system heaters.

It's true. For around $1,400 you can purchase a unit -- "easy to install" -- that will force heated air through your entire septic system. I checked it out and determined that, given our rural electric rates, running the unit the entire winter (which is what you'd have to do) would demand about 3,000 kilowatt hours, the equivalent of seven months of our regular electricity consumption -- not to mention $200-plus out of pocket.

The math didn't work for me, but more crucial was the plain absurdity of heating our poop.

Think of it: In order to prevent a drainfield freeze-up caused by milder winters, we'd increase our carbon footprint and thus accelerate, however modestly, the climatic warming that's the root of the problem in the first place. I'm unsure whether the appropriate response to this is laughter or tears.

Via my own records and experience, I'm convinced our climate is heating up, and the evidence is compelling that human burning of fossil fuels is the chief cause. It's possible this situation may have catastrophic results -- the global analog of sewage in the basement.

If disaster does strike, there'll be more than one proximate cause. But I think our civilization's autopsy will indicate a lethal dose of irony.


Peter M. Leschak, of Side Lake, Minn., is the author of "Ghosts of the Fireground," "Letters from Side Lake" and other books.