Jeff Z. Gardener, biker, landscape architect and weather nut
By: eighthacrefarm , 5:24 AM GMT on March 04, 2013
this post with graphics and other weather and climate related rants available at www.eighthacrefarm.blogspot.com
This year's low temperature: -13F on February 1st. Image courtesy of wunderground.com
Now, thirteen degrees below zero may sound awfully cold, and it sure feels that way when you have to get up early in the morning, go out into the dark and catch a bus in the blowing wind. Thirteen below is no picnic. But it's not the historical norm for the Twin Cities.
-13F was where our temperature bottomed out on February 1st this year, and I'm going to be the first one to call it the low for the winter, as we're pretty unlikely to get that cold again at this point in March. The 10 day forecast is calling for highs above freezing, so I think that's about it for old man winter.
The reason that -13F is significant, is that it puts this winter, in the Twin Cities, in the zone 5b category. That is, a winter where the minimum temperature is between -10 and -15F. If we were still using the 1990 USDA zone map which was the standard until recently, we would expect a yearly minimum temperature between -25 and -30 to hit us some night in late January or early February. The fact that this hasn't happened in most of the last 15 years is significant.
I've always found maps fascinating, and when I was starting to become interested in gardening and horticulture and later landscape architecture, I pored over the 1990 USDA zone map, finding the growing zones of places I had been and thinking through what plants I had seen and what color the soil was and making a mental map of what grew where, and what could be expected in a similar place.
People talked about global warming, but it was just a theory, and nobody was really sure if it would really affect us, say nothing about whether it was really real.
And now- a decade or two later, in the Twin Cities, we are on a regular basis having the kind of winter that was formerly expected in St. Louis or Kansas City or Indianapolis.
detail of the 1990 USDA zone hardiness map
Take a look at the graphic above. It's from the 1990 zone map. Yes, the new and improved map has put the Twin Cities in 4B, with some tiny urban pockets in 5A. But I don't think that goes far enough. Zone 5b is the greenish-yellow band running through the middle of Missouri and Illinois and Indiana. That is now here. That used to be 500 miles south of here. It leapfrogged Iowa in two decades and is now is making itself at home in our yards in St. Paul and Minneapolis on a pretty regular basis.
I can't complain about the less-cold winter. I kind of like it really. It's the summers and the uncertainty about the future that's disconcerting. My zone 5 sweet cherry tree is thriving and I'm expecting a good harvest of apricots from my backyard tree this year. I'll probably plant a peach tree at our rental place. But will I be able to grow blueberries any more? While it's not an edible, I've noticed that the once reliable Astilbe now dies to the ground in our intense summer heat the last few years, and it usually doesn't come back. Is this a taste of what's coming?
The new pests that the warming trend is encouraging are pretty disturbing too. The new invader, Spotted-wing drosophila shouldn't be able to thrive here, but it is. An old-school Minnesota winter might have set the Emerald Ash borer population back a bit, but this one won't.
If you've followed this blog for any time, you know that I'm a skeptic when it comes to the future availability of cheap oil. So I'll forgive you if you are about to say that the coming of peak oil will offset climate change and everything will be fantastic.
Yes, growing peaches in Minnesota is fantastic, and we may someday be growing mangoes here if current trends continue and water supplies stay relatively intact. Because peak oil doesn't mean that there are no more hydrocarbons available. Alcoholics don't usually decide to go cold turkey when their favorite brand of sauce isn't available. They switch to Listerine or Lysol or Sterno or whatever else fills the bill. So too with hydrocarbons. There's still a lot of coal and peat and firewood in the world and it'll all get burned in short order by oil addicts needing a fix.
Add that to the inertia of the warming trend that would continue for decades even if we did somehow go cold turkey, and it's clear that we need to learn to adapt. The alternative isn't something to consider.
There clearly isn't going to be any sort of voluntary consensus to reduce the greenhouse gases by us or any other county or combination thereof. 'Our Way of Life is Non-Negotiable' as one charming former Vice President said it. So it is being negotiated for us, by the atmosphere, at terms that are less than advantageous to the human species. Can't say we didn't ask for it.
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