Saturday, August 18, 2007

Farm life...

It's hardly news to anyone in the North American continent that it is hot out there. We had a nice week away from home in Colorado, where we enjoyed balmy beach-weather at 8500 feet above sea level. In a dramatic break from tradition, even the nights were mild.

Back at home, the year of climate extremes continues. On the heels of our devastating spring freeze, we are in the midst of a wave of heat and drought that is bumping against the boundaries of historical precedent. The latest drought monitor shows us having finally crossed the threshold to "exceptional drought," the highest category. Temperature records are of course being broken left and right. At our place here, there have been about a dozen days this month that have been hotter than any day I recorded in the previous five years. Yesterday was a comparatively mild 103F, down from two consecutive days of 107F. I'm managing to keep the vegetable garden watered enough so things aren't dying, but heat like this puts an end to ripening of tomatoes. They just sit there and gradually get sort of bleached looking. I've harvested some of these and put them inside in paper bags with apples, which seems to be getting them to redden up.

Who can say what is going on with this? The worldwide scientific community hs reached concensus that global warming is happening. However, the line between climate variability and climate change is very hard to resolve at the local, year-by-year scale. The records we have been matching and breaking this year are mostly from 1952 and 1954, the height of the dust bowl. Most of what is happening lately is probably due primarily to ordinary drought cycles, with perhaps some additional nudge from long-term warming. We've not seen the truly, qualitatively unprecedented yet. Native vegetation is stressed but it is not showing wide-scale die-offs and shifts; at least not as of the present. Until we finish breaking all the records from the 19th and 20th Centuries, and start breaking records that were just set a few years previously, it is hard to say that our climate has actually shifted to an ecologically and sociologically meaningful degree.

We may not be far off, though. So far as I understand it, even if the weather in Nashville reverted to climatological averages starting today, August 2007 would still work out to be the hottest August in 137 years of records. Given that in fact the short- and long-range forcasts are for persistence of the extreme heat and drought into the indefinite future, well...


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