Extremes - February 15, 2012

Another day, another light sprinkling of snow, another hover right around freezing. Another quick stroll in the park; Ingrid reports there was a spirited romp in the park.

And I spent a chunk of the day editing a map of the French Quarter in New Orleans. Not walking around it, mind you. Just writing about it from afar. Not fair.

I write about living in the weather here in Minnesota, and I know the really long cold winter is not what most of the rest of the country experiences. There's a lot of the country where enclosed malls don't make any sense for either summer or winter: coastal California, and Hawaii, for example. But the deserts as far south as New Mexico can get pretty cold at night, and there's frost in Florida sometimes. And whatever the weather extremes, that's when you really want good shelter.

We don't need to build shelter for the average days. It's the extremes that end up delineating survivability for any species (just ask the iguanas dropping from the trees in a recent Florida freeze). Perhaps this explains the ultimate failure of the Greenland Viking settlement: it was marginal, and then it fell under the margin.

Here's why I think this is an important point: When we talk about climate, we are talking about averages. But when we're talking about survivability, it's the extremes that end up determining the edge of any species' territory, including ours. It's not the average ground-shaking that determines whether a building is built strong enough for an earthquake zone, it's the 60 seconds of shaking in the maximum event that area will experience. It's not whether you can survive an average winter that determines if settlement is viable, it's whether you can survive the worst winter of your life there. Because if you can't, it will also be the last winter of your life.

They make headlines—they feel like hysteria-inducing, exclamation-point-ridden, excessively-hyped events—but weather extremes ultimately determine what and who will survive in any given place.